Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies [1 ed.] 9781622570164, 9781612098272

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Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

PUBLIC HEALTH IN THE 21ST CENTURY

RADIATION EXPOSURE IN MEDICINE AND THE ENVIRONMENT

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

RISKS AND PROTECTIVE STRATEGIES

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Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

PUBLIC HEALTH IN THE 21ST CENTURY

RADIATION EXPOSURE IN MEDICINE AND THE ENVIRONMENT RISKS AND PROTECTIVE STRATEGIES

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

NICOLE E. PARNELL EDITOR

Nova Biomedical Books New York

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Copyright © 2012 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works.

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Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Additional color graphics may be available in the e-book version of this book. Library of Congress Cataloging-in-Publication Data Radiation exposure in medicine and the environment : risks and protective strategies / editor, Nicole E. Parnell. p. ; cm. Includes bibliographical references and index. ISBN 978-1-62257-016-4 (E-Book) 1. Radiation--Toxicology. 2. Radiation--Dosage. 3. Radiation--Safety measures. I. Parnell, Nicole E. [DNLM: 1. Radiation Dosage. 2. Environmental Exposure. 3. Radiation Protection. 4. Risk. WN 665] RA1231.R2R275 2011 363.17'99--dc22 2011003562 Published by Nova Science Publishers, Inc.© New York Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Contents vii 

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Preface Chapter I

Radiation Exposure of Aircrews of Commercial Aircraft Kyle Copeland, Wallace Friedberg, Frances E. Duke and Joyce S. Nicholas  

Chapter II

Theoretical Predictions of Radionuclide Deposition in the Human Respiratory Tract Robert Sturm 

Chapter III

Cosmic Radiation in Commercial Aviation Michael Bagshaw 

Chapter IV

Radiation Interaction with Blast Furnace Slag: A Comparative Study from the Point of Radiation Shielding Murat Kurudirek, Yüksel Özdemir   and Ahmed Mahmoud El-Khayatt 

Chapter V

Radiation Exposure of Tunisian Aircrews: Doses Simulations Neïla Zarrouk and Raouf Bennaceur 

Chapter VI

Radiation Induced Polymerization of Nanostructured Conductive Polymer Composites Mohammad Rezaul Karim 

1 

31  57 

75 

97 

107 

Chapter VII

Thermal Radiation and Fire Safety Yaping He 

119 

Chapter VIII

Radiation Hazards in Intervention Cardiology Rajesh Vijayvergiya and Anand Subramaniyan 

157 

Chapter IX

Environmental Radiation Monitoring: Public Dose Limits, Measurements and Interpretation Gladys A. Klemic and Deborah Elcock 

Chapter X

Mobile Telephony Radiation Effects on Living Organisms Dimitris J. Panagopoulos and Lukas H. Margaritis 

Index

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Preface This new book examines the risks and protective strategies of radiation exposure in the fields of medicine and the environment. Topics discussed in this compilation include: radiation exposure of aircrews of commercial aircraft; radionuclide deposition in the human respiratory tract; mobile telephony radiation effect on living organisms and environmental radiation monitoring of public dose limits and measurements. Chapter I - Aircrews of commercial aircraft are exposed to higher doses of ionizing radiation than members of the general population in most parts of the world. The principal ionizing radiation to which aircrews are exposed is galactic cosmic radiation, which is thought to come primarily from supernovae. On infrequent occasions, radiation from the Sun (solar cosmic radiation) leads to an increase in the ionizing radiation at flight altitudes. Air shipments of radioactive material and thunderstorms are other possible sources of ionizing radiation. Aircrews are exposed to nonionizing radiation in the form of electric and magnetic fields generated by the aircraft’s electronic and electrical systems. Also, crewmembers may accidentally be exposed to nonionizing radiation in the form of laser light, from a nearby laser show or careless laser-pointer user, or in the form of microwave radiation from an aircraft's weather radar left turned on while the aircraft is on the ground. An increased risk of fatal cancer is the principal health concern associated with exposure to ionizing radiation at the doses received by crewmembers. There is evidence of radiation induced cataractogenesis at unusually low doses. For the child of a crewmember irradiated during prenatal development, the greatest risks are death in utero and fatal cancer. A child is also at risk of inheriting genetic defects because of the radiation received by one or both parents before the child's conception. Exposure to nonionizing radiation may also increase a crewmember’s risk of health effects, which include spontaneous abortion and leukemia. Chapter II - The human respiratory tract represents an essential pathway for radionuclides and other hazardous airborne materials to enter the body. Although particularly workers are endangered by the uptake of radioactive gases or particles, this risk may be also given for the general population, especially in the case of environmental radon and the intended or accidental release of radionuclides from industrial and medical operations. Radioactive material inhaled and deposited in the respiratory tract causes the irradiation of bronchial/alveolar tissues and cells, at the worst resulting in a malignant cellular transformation and the development of lung cancer. Naturally occurring radionuclides (e.g., 222Rn, 40K, 14C) are usually attached to so-called carrier aerosols. Dust or smoke particles, which are characterized by irregular shapes and, as a

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Nicole E. Parnell

consequence of that, by highly increased surface areas, have a preferential ability for significant temporary radionuclide adsorption. The aerodynamic diameters of such radioactively labelled carrier particles generally vary between several nanometers (ultrafine particles) and few micrometers, with highest particle fractions adopting sizes around 100 nm. Theoretical calculations of radioactive particle deposition in the respiratory tract was conducted by (1) using a stochastic lung geometry and a particle transport/deposition model being founded upon a random-walk algorithm, (2) assuming a polydisperse carrier aerosol (diameter: 1 nm–10 µm, ρ ≈ 1 g cm-3) with irregularly shaped particles, and (3) considering the effect of breathing characteristics and certain respiratory parameters on the radiation doses to bronchial/alveolar tissues and cells. Results of deposition modeling clearly show that distribution patterns of radiation doses chiefly depend upon the size of the carrier aerosol. Whilst ultrafine (< 10 nm) and large (> 2 µm) aerosols are preferentially deposited in the extrathoracic and upper bronchial region, aerosols with intermediate size (10 nm–2 µm) may penetrate to deeper lung regions, causing an enhanced damage of the alveolar tissue by the attached radionuclides. Chapter III - Cosmic rays were discovered in 1911 by the Austrian physicist, Victor Hess. The planet earth is continuously bathed in high-energy galactic cosmic ionising radiation (GCR), emanating from outside the solar system, and sporadically exposed to bursts of energetic particles from the sun referred to as solar particle events (SPEs). The main source of GCR is believed to be supernovae (exploding stars), while occasionally a disturbance in the sun's atmosphere (solar flare or coronal mass ejection) leads to a surge of radiation particles with sufficient energy to penetrate the earth's magnetic field and enter the atmosphere. The inhabitants of planet earth gain protection from the effects of cosmic radiation from the earth’s magnetic field and the atmosphere, as well as from the sun's magnetic field and solar wind. These protective effects extend to the occupants of aircraft flying within the earth’s atmosphere, although the effects can be complex for aircraft flying at high altitudes and high latitudes. There are differences between the Northern and Southern hemispheres; data in this chapter are derived in Northern latitudes. Chapter IV - Cement is the most produced and used binding material in the world with its 1.6 billion tons of annual production. The high consumption of energy for its production causes high CO2 emission due to the nature and processes of raw materials. The world cement industry is responsible for 7% of the total CO2 emission. Thus, the cement industry has a crucial role in global warming. From this point of view, it is of interest to focus on different alternative building materials such as blast furnaces to be used as substitutes for cement. The blast furnace slag (BFS) is used by replacing with cement in different weight proportions for improving the mechanical properties, decreasing the rate of hydration, decreasing the alkali aggregate reactivity and decreasing the permeability of concrete. Moreover, use of supplementary cementitious materials such as BFS with portland cement has become increasing significantly in all world. Besides, keeping in mind the extensive use of cement containing concretes in radiation shielding applications, it would be interesting to study the gamma ray and neutron attenuation properties of BFS for its potential use as an alternative shielding material. For shield design, neutrons and γ-rays (or X-rays) are the main types of nuclear radiation, which have to be considered, since any shield which attenuates neutrons and γ-rays will be more effective for attenuating other radiations. At this point, the present study aimed at the investigation of X and/or gamma radiation interaction with this type of

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Preface

ix

composite material in extended energy regions (1keV-100GeV for photon interaction, 1keV20MeV for photon energy absorption) including the parameters effective atomic number, effective electron density, kerma relative to air, photon energy absorption attenuation length, total photon interaction attenuation length, energy absorption and exposure buildup factors from 0.015 to 15 MeV up to 40 mfp penetration depths and macroscopic fast neutron removal cross-sections. Attenuation of fast neutrons through the studied materials has been investigated by employing the removal cross-section values of their elemental composition. Upon investigation of these parameters, the BFS has been compared with other building materials such as fly ash (FA), silica fume (SF) and natural zeolite (NZ) with respect to the radiation attenuation properties wherever possible. Finally, possible conclusions were drawn with respect to the changes in photon energy, chemical composition, penetration depth and density. Chapter V - Owing to their professional activity, aircraft crew and even frequent flyers may receive a dose of some millisieverts within a year from cosmic radiations of galactic and solar origin and from secondary radiation produced in the atmosphere. The effective dose is estimated using various experimental and calculation tools. The need to assess the dose received by aircrew and frequent flyers has arisen following the Recommendations of the International Commission on Radiological Protection in publication 60 ICRP 60. In 1996 the European Union introduced a revised Basic Safety Standards Directive that included exposure to natural sources of ionising radiations, including cosmic radiation as occupational exposure. Several equipments were used for both neutron and non-neutron components of the onboard radiation field produced by cosmic rays. A good agreement was observed for both passive and active detectors determining the different components of the radiation field. Such a field is very complex, therefore dose measurement is complex and the use of appropriate computer programs for dose calculation is essential. The author’s results concerning effective doses received by Tunisian flights, computed with CARI-6, EPCARD 3.2, PCAIRE, and SIEVERT codes, show a mean effective dose rate ranging between 3 and 4 mSv/h. The advantages of the small passive detectors as an-easy to handle monitoring system for in-flight surveillance are demonstrated by several measurements. Indeed the evaluation of thermoluminescent dosimeters (TLDs) according to the high-temperature ratio (HTR) method enables the determination of the dose average linear energy transfer ; the mean quality factor and the dose equivalent in mixed radiation field. The authors give their investigations of the HTR method associated to neural network system for assessment of total dose and dose caused by neutrons. These NNT-HTR equivalent doses for Tunisian flights are then in general clearly higher than effective doses obtained by codes calculations. Chapter VI - Radiation induced polymerization of nanostructured conductive polymer composites (NCPC) is on the boost recently. Different important chemical processes like polymerization, grafting and curing of NCPC can proceed successfully by radiation techniques. The radiation technology is preferred over the other conventional energy resources due to some reasons, e.g. large reactions as well as product quality can be controlled, saving energy as well as resources, clean processes, automation and saving of human resources etc. Apart from this, radiation is also a good sterilizing technique over other conventional sterilizing techniques. The irradiation of polymers can be applied in various sectors. In this regard, the attention has been focused primarily to four sectors in worldwide, i.e. biomedical, textile, electrical and membrane technology. The properties of these

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polymeric materials are considered. The benefits of radiation-chemical procedures for manufacturing smart polymers are discussed. The areas of their practical use are outlined. Chapter VII - Thermal radiation is one of the hazards produced by fires. Protection against thermal radiation is an important issue in fire fighting and in fire safety engineering design to prevent fire spread, protect building structure and provide safe egress conditions for building occupants in case of fire emergencies. This chapter describes the methods for evaluating fire thermal radiation hazards in natural and built environments. Fundamental concept of radiation heat transfer is discussed in relation to fire dynamics and fire safety. A portion of this chapter covers thermal, mechanical and optical properties of materials pertinent to fire protection. Discussions are also given on detection, measurement technologies and techniques for thermal radiation protection. Chapter VIII - Increasing number of interventions is being performed in last two decades following advancement in interventional cardiology. This includes both the number of procedures and also complicated procedures requiring prolonged fluoroscopy time. Though there is an obvious clinical benefit to patients following these interventions, the radiation hazards to both patient and operator is often ignored at the time of intervention. This hazard following the use of X-rays is of two type- Stochastic / Random effects and Deterministic / Threshold based effects. There is a concern about overexposure of radiation dose in certain complex intervention causing deterministic effects to the patient. For health care workers, the prolonged cumulative exposure in catheterization laboratory results into side effects like cataract and cancer. The various factors linked with radiation dose during interventions are related with patient, operator, type of intervention and equipment. It is important to have adequate radiation protection at work place to prevent radiation induced hazards. The details about basics of radiation, its side effects, factors affecting radiation doses during procedure, and workplace radiation protection, monitoring & safety have been discussed in the chapter. Chapter IX - Determination of the man-made component of the external radiation dose in the vicinity of a nuclear or radiological facility is performed by the facility operator to demonstrate compliance with regulations that limit the allowable dose to the public from man-made sources. Such measurements must include removal of the natural background radiation component that is typically in the same range as the public dose limits. Current technology is adequate to measure the total direct radiation levels, but distinguishing a potential man-made component from the naturally varying radiation background is a more complex problem. This chapter reviews the regulations on public dose limits in the United States and the technologies that are used for environmental monitoring. It also discusses issues associated with the interpretation of routine monitoring data. Chapter X - A number of serious non thermal biological effects, ranging from changes in cellular function like proliferation rate changes or gene expression changes to cell death induction, decrease in the rate of melatonin production and changes in electroencephalogram patterns in humans, population declinations of birds and insects, and small but statistically significant increases of certain types of cancer, are attributed in the author’s days to the radiations emitted by mobile telephony antennas of both handsets and base stations. This chapter reviews briefly the most important experimental, clinical and statistical findings and presents more extensively a series of experiments, concerning cell death induction on a model biological system. Mobile telephony radiation is found to decrease significantly and non thermally insect reproduction by up to 60%, after a few minutes daily exposure for only few days. Both sexes were found to be affected. The effect is due to DNA fragmentation in the

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gonads caused by both types of digital mobile telephony radiation used in Europe, GSM 900MHz, (Global System for Mobile telecommunications), and DCS 1800MHz, (Digital Cellular System). GSM was found to be even more bioactive than DCS, due to its higher intensity under equal conditions. The decrease in reproductive capacity seems to be nonlinearly depended on radiation intensity, exhibiting a peak for intensities higher than 200 μW/cm2 and an intensity “window” around 10μW/cm2 were it becomes maximum. In terms of the distance from a mobile phone antenna, the intensity of this “window”corresponds under usual conditions to a distance of 20-30 cm. The importance of different parameters of the radiation like intensity, carrier frequency and pulse repetition frequency, in relation to the recorded effects are discussed. Finally, this chapter describes a plausible biophysical and biochemical mechanism which can explain the recorded effects of mobile telephony radiations on living organisms.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter I

Radiation Exposure of Aircrews on Commercial Aircraft

a

Kyle Copeland a, Wallace Friedberg a, Frances E. Duke a and Joyce S. Nicholas b

Federal Aviation Administration, Civil Aerospace Medical Institute, Oklahoma City, OK b Department of Medicine, Division of Biostatistics and Epidemiology, Medical University of South Carolina, Charleston, SC

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Abstract Aircrews of commercial aircraft are exposed to higher doses of ionizing radiation than members of the general population in most parts of the world. The principal ionizing radiation to which aircrews are exposed is galactic cosmic radiation, which is thought to come primarily from supernovae. On infrequent occasions, radiation from the Sun (solar cosmic radiation) leads to an increase in the ionizing radiation at flight altitudes. Air shipments of radioactive material and thunderstorms are other possible sources of ionizing radiation. Aircrews are exposed to nonionizing radiation in the form of electric and magnetic fields generated by the aircraft’s electronic and electrical systems. Also, crewmembers may accidentally be exposed to nonionizing radiation in the form of laser light, from a nearby laser show or careless laser-pointer user, or in the form of microwave radiation from an aircraft's weather radar left turned on while the aircraft is on the ground. An increased risk of fatal cancer is the principal health concern associated with exposure to ionizing radiation at the doses received by crewmembers. There is evidence of radiation induced cataractogenesis at unusually low doses. For the child of a crewmember irradiated during prenatal development, the greatest risks are death in utero and fatal cancer. A child is also at risk of inheriting genetic defects because of the radiation received by one or both parents before the child's conception. Exposure to nonionizing radiation may also increase a crewmember’s risk of health effects, which include spontaneous abortion and leukemia.

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Introduction Aircrews of commercial aircraft are occupationally exposed to ionizing and nonioinizing radiation. Doses can exceed those received by members of the general population in most parts of the world. In this chapter, we examine sources and doses of radiation received by crewmembers aboard commercial aircraft and the possible health effects associated with such exposures.

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Ionizing Radiation Radiation is energy in transit. The energy travels as: (a) subatomic particles of matter (e.g., electrons, neutrons, protons, alpha particles), and (b) electromagnetic radiation, which consists of packets of energy called photons (e.g., visible light, ultraviolet light, radio waves, microwaves, gamma radiation, X-radiation). A subatomic particle or photon that is sufficiently energetic to directly or indirectly eject an orbital electron from an atom is called ionizing radiation. A photon or charged particle such as an electron, proton, or alpha particle ionizes directly by means of electromagnetic interaction with an orbital electron. Neutrons cannot ionize directly. However, a neutron can ionize indirectly if on impacting the nucleus of an atom: (a) it induces emission of a gamma radiation photon sufficiently energetic to eject an orbital electron, (b) it breaks apart the nucleus and imparts sufficient energy to an ejected nuclear proton to eject an orbital electron, or (c) it breaks apart the nucleus and a charged particle created from energy that held the nucleus together is sufficiently energetic to eject an orbital electron. Recommended ionizing radiation exposure limits for aircrews are based on long-term effects such as cancer, severe genetic defects, and years of life lost.

Ionizing Radiation Exposure Terms When considering radiation exposure, the most basic quantity is the absorbed dose (D), which is the amount of energy absorbed by a medium divided by the mass of the medium. The medium could be the human body or a particular tissue or organ in the body. Terms used in this chapter to quantify the absorbed dose and the biological impact of the absorbed dose are discussed below. Gray The gray (Gy) is the International System (SI) unit of absorbed dose of ionizing radiation. One Gy is 1 joule (J) of radiation energy absorbed per kilogram (kg) of matter. The rad (radiation absorbed dose) is an older unit of absorbed dose of ionizing radiation (1 Gy = 100 rads). The roentgen (R) is another older unit of ionizing radiation. One R is the amount of Xradiation or gamma radiation that creates 1 electrostatic unit (esu) of ions in 1 cm3 of dry air at 0o C and 1 atm (760 mm Hg, 101.325 kPa). The effect of 1 R and 1 rad on dry air is about the same.

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Linear energy transfer 1 Linear energy transfer (LET) is the average amount of energy per unit track length imparted to a medium by ionizing radiation of a specified energy, when penetrating a short 2 distance. The energy imparted to the medium includes energy from any secondary radiation, such as nuclear particles released from a nucleus impacted by a high-energy neutron. LET is usually expressed in units of keV/μm (thousand electron volts per micrometer). A radiation with an LET 50 keV/μm is generally considered high-LET. Neutrons, pions, and alpha particles are examples of radiations that are most often high-LET. Except near the end of its track, a proton is low-LET. However, protons are more damaging than other low-LET radiations (Hada and Sutherland, 2006). Thus, when risk estimates are calculated later in this chapter, protons are grouped with high-LET radiations.

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Relative Biological Effectiveness Relative biological effectiveness (RBE) is the ratio of absorbed dose of a reference radiation (usually 250 kVp X-radiation or cobalt-60 gamma radiation) to absorbed dose of the radiation in question, in producing the same magnitude of the same effect in a particular experimental organism or tissue. The RBE is influenced by the biological endpoint and the LET of the radiation. With killing human cells as the endpoint, the RBE increases with an increase in LET to about 100 keV/µm and then decreases with further increase in LET. At LET 100 keV/µm, the average separation between ionizing events is close to the diameter of the DNA double helix. Therefore, a radiation with LET 100 keV/µm can most efficiently produce a double-strand break in a DNA molecule by a single LET track (Hall and Giaccia, 2006). Double-strand breaks in DNA molecules are thought to be the main cause of biological effects. Organ Equivalent Dose The organ equivalent dose, H, to a tissue or organ T from radiation R, is defined as:

HT , R = wR DT , R

(1)

where, wR = radiation weighting factor for radiation R (Table 1) (ICRP, 1991; NCRP, 1993; ICRP, 2007); DT,R = absorbed dose to tissue or organ T from radiation R. Values of wR are based on RBEs for stochastic effects (health effects for which the probability of occurrence, but not severity, is dose dependent). For each type of primary

1 The path a subatomic particle travels is called a track. 2 Radiation that arrives directly from its source without interacting with matter is called primary radiation. Secondary radiation is particles or photons produced by the interaction of primary radiation with matter.

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radiation from outside the body or from an internal emitter, the radiation weighting factor takes into account the effectiveness of the primary radiation and all its secondary radiations. Organ equivalent dose is also called equivalent dose. For multiple radiations, HT, the total organ equivalent dose to tissue or organ T, is the sum of the organ equivalent doses from each type of radiation:

HT = ∑ HT , R

(2)

R

Table 1. Recommended values for radiation weighting factors (wR).a Type and energy of the radiation

wR ICRP (2007)

photons, electrons, muons protons, charged pions alpha particles, fission fragments, heavy ions neutrons (energy, En) En50 MeV

1 2 20 2.5 + 18.2 x exp(-(ln(En))2 /6) 5.0 + 17.0 x exp(-(ln(2En))2 /6) 2.5 + 3.25 x exp(-(ln(0.04En))2 /6)

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NCRP (1993) photons, electrons, muons protons b alpha particles, fission fragments, heavy ions neutrons (energy, En) En100 keV to 2 MeV En>2 MeV to 20 MeV En>20 MeV ICRP (1991)

1 2c 20 5 10 20 10 5

photons, electrons, muons protons b alpha particles, fission fragments, heavy ions

1 5 20

neutrons (energy, En) En100 keV to 2 MeV En>2 MeV to 20 MeV En>20 MeV

5 10 20 10 5

a

For radiations not in the table, both ICRP and NCRP recommend using the mean quality factor, rounded to the nearest whole number. b Except recoil protons, Ep >2 MeV. c If Ep >100 MeV, NCRP suggests wR=1 is more appropriate.

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Effective Dose Effective dose, E, was introduced as a radiation protection quantity by the International Commission on Radiological Protection (ICRP) in their 1990 recommendations (ICRP, 1991). The ICRP currently defines effective dose as a weighted average of the sex-averaged organ equivalent doses to several different radiation-sensitive organs and tissues (ICRP, 2007):

⎛ ⎞ E = ∑ wT H T , sex − averaged = ∑ wT ⎜ ∑ wR DT , R ⎟ T T ⎝ R ⎠ sex − averaged

(3)

The tissue weighting factors, wT, take into account the sensitivity of the various organs and tissues to radiation induced stochastic effects. Sievert 3 Sievert (Sv) is the SI unit of organ equivalent dose and of effective dose. It quantifies harm from stochastic effects and replaces an older unit called the roentgen equivalent man (rem; 1 Sv = 100 rem).

Ionizing Radiation Exposure Limits

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Each country has its own aviation radiation protection laws and recommendations. ICRP For a non-pregnant, occupationally exposed person, the ICRP 2007 recommendations limit exposure to ionizing radiation to a 5-year average of 20 mSv per year (100 mSv in 5 years), with no more than 50 mSv in a single year. Annual equivalent dose limits are recommended for the lens of the eye, 150 mSv; for skin, 500 mSv (averaged over a 1 cm2 area); either hand, 500 mSv; and either foot, 500 mSv. For a pregnant worker, starting when she reports her pregnancy to management, the working conditions should be such that any additional dose to the conceptus (any stage of development from the fertilized egg to birth) would not exceed about 1 mSv during the remainder of the pregnancy. Radiation exposure as part of a medical procedure is not subject to recommended limits. U.S. Federal Aviation Administration The U.S. Federal Aviation Administration (FAA) accepts the most recent recommendations of the American Conference of Government Industrial Hygienists (ACGIH) (FAA, 2008; ACGIH, 2010). For a non-pregnant air carrier crewmember, the FAArecommended limits for exposure to ionizing radiation are the same as those recommended by the ICRP. For a pregnant air carrier crewmember, starting when she reports her pregnancy to 3 There are other dosimetric quantities expressed in sieverts, e.g., dose equivalent, ambient dose equivalent, and effective dose equivalent.

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management, the FAA-recommended ionizing radiation exposure limits for the conceptus are 0.5 mSv in any month and 1 mSv during the remainder of the pregnancy. Radiation exposure as part of a medical or dental procedure is not subject to recommended limits. However, any radiation exposure of a pregnant woman should consider the conceptus. European Union The ICRP recommended limits have been adopted with additional requirements. According to a Directive issued by the Commission of the European Communities (1996) and an associated document regarding its implementation (CEC, 1997), assessments of occupational radiation exposure should be made for crewmembers likely to be occupationally exposed to more than 1 mSv in a year. These assessments should include radiation received on the job from natural sources. Work schedules for crewmembers should be arranged to keep annual exposures below 6 mSv. For those workers whose annual exposure exceeds 6 mSv, medical surveillance and record keeping are recommended. For a pregnant crewmember, the Directive states in Article 10 that starting when she reports her pregnancy to management her work schedule should be such that the equivalent dose to the conceptus will be as low as reasonably achievable and unlikely to exceed 1 mSv, either for the remainder of the pregnancy or for the whole pregnancy, according to how Article 10 is implemented in national legislation.

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Galactic Cosmic Radiation Ionizing radiation from outside our solar system is called galactic cosmic radiation (GCR). The principle source of GCR in our galaxy is stellar material and surrounding interstellar gas, accelerated by exploding stars (supernovae). When primary GCR particles (mostly protons and alpha particles) enter the Earth’s atmosphere they collide with and break apart nuclei of nitrogen, oxygen, and other air atoms. The collisions release a host of secondary subatomic particles. The particles released include protons, neutrons, and electrons. In addition, photons, charged pions, muons, electrons, positrons, and other more exotic subatomic particles are generated by energy-mass transformations and decay processes. The impacting particle and those released or generated may have enough energy to produce still more particles. The cycle of particle production continues until the particles do not have sufficient energy to ionize impacted atoms. Thus, when GCR enters the atmosphere, the number of ionizing particles initially increases with decreasing altitude and then decreases with further decrease in altitude. A single primary GCR particle may be sufficiently energetic to generate a shower of millions of secondary GCR particles. Measurements of showers indicate that individual primary particles sometimes have the energy required to lift a 20pound weight more than 7 inches (Bird et al., 1995). The effective dose rate, a measure of the biological harmfulness of the radiation in the atmosphere, follows the same general pattern as the number of ionizing subatomic particles: Initially the dose rate increases with decreasing altitude, then decreases with further decrease in altitude. At any geographic location, the altitude of the maximum dose rate varies with solar activity and with changes in the geomagnetic field (Earth’s magnetic field).

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Solar Wind The number of GCR particles that enter the atmosphere varies inversely with the rise and decline in solar activity, resulting in variations in radiation dose rates in the atmosphere. The variations are brought about by magnetic fields carried by the solar wind (low-energy subatomic particles continuously being emitted from the Sun). Irregularities in these magnetic fields scatter low-energy GCR particles that might otherwise enter the Earth’s atmosphere (Wilson, 1976). When solar activity is high, the solar wind carries more irregularities, resulting in more scattering of low-energy GCR particles and a corresponding decrease in dose rates. The particles that comprise the solar wind are themselves too low in energy to cause an increase in ionizing radiation levels at aircraft flight altitudes. 4 Sunspot numbers for the past 290 years indicate solar activity has varied in approximately 11.1-year cycles, corresponding to solar magnetic pole reversals (Smart and Shea, 1997). More recently, other parameters based on measurements of the GCR secondary neutron flux reaching the Earth’s surface, such as heliocentric potential (O’Brien, 1979) and solar deceleration parameter (Badhwar and O’Neil 1996), have been developed as indicators of solar activity. Geomagnetic Field The geomagnetic field has a shape similar to that which would be produced by a bar magnet with its north pole near the geographic south pole and its south pole near the geographic north pole. The geomagnetic field deflects many GCR particles that would otherwise enter the atmosphere (Wilson, 1976). This shielding is particularly effective for the lower-energy GCR particles which are subject to scattering by the magnetic fields carried by the solar wind. In general, the shielding is greatest over the geomagnetic equator (near the geographic equator) and gradually decreases to zero as one goes north or south. With the exception of temporary changes during geomagnetic storms, the geomagnetic field changes very slowly over time. For the past several decades it has been slowly weakening, but it is unknown whether this weakening is temporary or part of a long term trend. Combined Effects of Solar Wind, Geomagnetic Field, and Earth’s Atmosphere At high latitudes during solar minimum conditions, the number of low-energy particles that enter the atmosphere reaches a maximum and the radiation level peaks at the highest altitudes. With decreasing latitude and increasing solar activity, fewer low-energy particles enter the atmosphere and the altitude of maximum dose rate decreases. o Figure 1 shows the GCR effective dose rate at 20 E longitude, as related to geographic latitude. Dose rates in the figure are calculated for mean solar activity in the period January 1958 through December 2008. The calculations were made with CARI-6P (Friedberg et al, 2005), using NCRP (1993) recommendations. If one were to fly an aircraft at a constant altitude from the geomagnetic equator towards the north or south magnetic pole, the dose rate would increase with distance from the equator until it reached a plateau at high latitude, 4 A sunspot is an area on the photosphere that is seen as a dark spot in contrast with its surroundings. Sunspots appear dark because the area is cooler than the surrounding photosphere. Sunspots occur where areas of the Sun's magnetic field loop up from the surface of the Sun and disrupt convection of hot gases from below.

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where shielding by the geomagnetic field is minimal. The region where the dose rate flattens with increasing latitude is called the cosmic ray knee. Above the cosmic ray knee, the primary radiation shielding of an aircraft from GCR is the atmosphere. There is also some shielding by magnetic fields carried by the solar wind (the interplanetary magnetic field), even when the Sun is quiet. The North Atlantic Air Route, which is among the busiest in the world, is mostly above the cosmic ray knee.

o

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Figure 1. Effective dose rate as related to geographic latitude at selected altitudes, at 20 E longitude, calculated using CARI-6P at the average solar activity level in the period January 1958 through December 2008.

Figure 2 depicts monthly average GCR effective dose rates at monthly intervals from o o January 1958 through December 2008 at selected altitudes, at 80 N latitude, 20 E longitude o o and at 0 latitude, 20 E longitude. At the high-latitude location, radiation shielding by the geomagnetic field was practically nonexistent and large modulations occurred due to cyclic changes in solar activity. The dose rates were highest in December 2008 and lowest in June 1991. The cyclic variation in dose rates was least evident at low altitudes where the atmosphere had already absorbed most of the incoming radiation. At the equatorial location, shielding by the geomagnetic field was close to its maximum and was quite effective in screening out low-energy GCR particles. As a result of this screening effect, there was considerably less variation in dose rate than at the high-latitude location. Components of Galactic Cosmic Radiation Dose Rates at Selected Altitudes GCR varies considerably in composition with changes in altitude, latitude, and to some extent with solar activity (Friedberg et al., 2000a; 2003). Figures 3 and 4 show average contributions of the most important particles to the mean effective dose rate of each of the principle types of cosmic radiation particles, as related to altitude at the equator (Figure 3) and at a high geographic latitude (Figure 4), from January 1958 through December 2008. The equatorial and high-latitude data both show that at 20-40 kft, where subsonic air-carrier aircraft commonly cruise, 88-97% of the mean effective dose rate was from neutrons, protons, and electromagnetic showers (electrons, positrons, and photons). At sea level, at the equator and at the high latitude, more than 67% of the mean effective dose rate was from muons.

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Other subatomic particles generated in the atmosphere either decay so rapidly that only their decay products contribute significantly to the dose, or they do not interact with matter often enough to make a significant contribution to the dose.

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Figure 2. Effective dose rates from galactic cosmic radiation from January 1958 through December 2008 at selected altitudes, calculated with CARI-6P. Solar cycle numbers are circled. Shaded areas indicate solar cycles 20 (October 1964-June 1976) and 22 (September 1986-May 1996). White areas indicate solar cycles 19 (April 1954-October 1964), 21 (June 1976-September 1986), and 23 (May 1996-December 2008).

Figure 3. Contribution of the principal galactic cosmic radiation particles to the mean effective dose rate for the 50-year period January 1958-December 2007 as related to altitude at the geographic equator (00, 200 E).

Estimating Galactic Cosmic Radiation Dose Rates And Doses Unless otherwise noted, effective doses of GCR reported in this chapter were calculated with CARI-6P (Friedberg et al., 2005) or CARI-6PM (Friedberg et al., 2006). These programs are research oriented versions of CARI-6 (Friedberg et al., 2000b) and CARI-6M

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(Friedberg et al., 2000c), respectively. In addition to calculating GCR effective dose as described in ICRP Pub. 60 (1991), the “P” and “PM” versions calculate effective dose as described in NCRP Report No. 116 (1993) and calculate whole-body absorbed dose. The programs report these three doses both as totals and as doses from the most important contributors (electromagnetic showers,5 muons, pions, protons and neutrons). CARI-6 and CARI-6P are analogous in that they both calculate the GCR effective dose received by a crewmember flying a geodesic route6 (or a close approximation) between 2 airports. Programs CARI-6M and CARI-6PM are for flights that do not follow at least an approximate geodesic route. These programs allow the user to specify the flight path by entering, for each waypoint, the geographic coordinates, time, and altitude. Programs CARI-6 and CARI-6M can be downloaded from the FAA’s Radiobiology Research Team Web site: www.faa.gov/data_research/research/med_ humanfacs / aeromedical/radiobiology/.

Figure 4. Contribution of the principal galactic cosmic radiation particles to the mean effective dose rate for the 50-year period January 1958-December 2007 as related to altitude at a high geographic o o latitude (80 N, 20 E).

There is a link from the Web site to an interactive version of CARI-6 which can be run directly on the Internet. All versions of CARI-6 are available from the authors on request and are based on the LUIN99 radiation transport code (O’Brien, 1999; O’Brien et al., 2003). Other computer programs that are available for estimating GCR doses on aircraft flights and at single locations in the atmosphere include: EPCARD (GRCEH, 2010), JISCARDEX (Yasuda, 2008), PCAire (PCAIRE Inc., 2010), SIEVERT (Logatique, 2010).

Solar Cosmic Radiation Disturbances in the Sun’s atmosphere often result in explosive emissions of huge amounts of matter consisting mostly of ionized, low-energy particles. Through shock

5 The term “electromagnetic showers” refers to electrons, positrons, and photons. 6 A geodesic route is the shortest route over the surface of the Earth taking into account that Earth is not a perfect sphere.

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acceleration, this occasionally leads to a significant increase in the flux of very energetic particles. Such an increase is referred to by various terms: solar-particle event, solar-proton event, solar energetic-particle event, and solar cosmic-ray event. If the particles enter the Earth's atmosphere, they interact with air atoms in the same way as GCR particles and are called solar cosmic radiation (SCR). With regard to radiation exposure of aircrews, the most important of these SCR particles are protons. The term solar-proton event is used when the proton flux as measured aboard GOES satellites meets criteria specified by the Space Weather Prediction Center of the National Oceanic and Atmospheric Administration: the mean flux of protons with energies greater than 10 MeV is equal to or greater than 10 protons/cm2 . steradian . sec for at least 3 consecutive 5minute periods (NOAA, 2010). Solar-proton events occur most frequently during the active period of the solar cycle (NOAA, 2010; Smart and Shea, 1997). During such an event there may be an increase in ionizing radiation levels at commercial aircraft flight altitudes, but usually any increase is small. Only on rare occasions does a solar-proton event lead to a substantial increase in the ionizing radiation at these altitudes (Copeland et al., 2008). The term solar flare is sometimes used to indicate a solar-proton event. However, to solar scientists “solar flare” refers to the electromagnetic energy and particles released suddenly from a relatively small volume of the Sun (Smart and Shea, 1997). The most energetic SCR particles can reach the Earth's atmosphere within 10 minutes after ejection from the Sun (Mathews and Lanzerotti, 1973). These earliest-arriving particles come from the direction of the Sun, but soon solar particles are coming from all directions because of the spreading effect on the particles caused by the interplanetary and Earth’s magnetic fields. One-half to a few hours after the start of an event, radiation levels in the atmosphere on the dark and light sides of the Earth come close to being the same (Foelsche et al, 1974). Thus, radiation from these events cannot be avoided by flying only at night. Solarproton events cannot be reliably predicted, nor is it known how high the radiation levels will reach even after the event has begun. From 1 January 1986 through 1 January 2008, there were 170 solar proton events. During 169 of these events, Copeland et al. (2008) estimated doses of SCR and doses of GCR received on simulated high-latitude aircraft flights. To estimate SCR, the authors used GOES measurements, near sea-level neutron-monitor data, and Monte Carlo calculations. For GCR they used CARI-6P. For each event, they calculated the GCR dose rate and the mean SCR dose rate, for an adult and for a 1 µm) are preferentially deposited by inertial impaction and gravitational settling. Aerosol particles with intermediate sizes (0.1-1 µm) do not represent targets of a specific deposition force, or, in other words, they are to large to be deposited in significant amounts by Brownian motion and to small to be remarkably deposited by inertial impaction and gravitational settling. By increasing the tidal volume but maintaining the flow rate (breathing scenario 2) total deposition is subject to a general enhancement, and, additionally, the related deposition curve tends to pass from U-shape with wide minimum into V-shape with narrow minimum (Figure 7b). At the minimum (dae = 0.5 µm), total deposition adopts values of 14 % (mouth) and 19 % (nose), respectively, whilst nanoparticles are deposited with amounts of 93 % (mouth) and 100 % (nose), and largest inhalable particles exhibit deposition values of 87% (mouth) and 100 % (nose). Any enhancement of the tidal volume under constant flow rates results in 1) a deeper penetration of the particle-loaded air into the respiratory system and 2) a longer residence time of single particles in the air volumes of the bronchial tubes and alveolar

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spaces. Since Brownian motion and gravitational settling are characterized by an indirect, positively correlated time dependence, they cause a significant increase in deposition at the given breathing conditions.

Figure 7. Total deposition of variably sized particles in the human respiratory tract. Whilst deposition curves represent theoretical predictions, plotted circles mark respective results from experiments (solid line/open circle: mouth breathing; dashed line/full circle: nose breathing); a) Tidal volume: 500 cm3, breathing cycle length: 4 s, flow rate: 250 cm3 s-1; b) Tidal volume: 1000 cm3, breathing cycle length: 8 s, flow rate: 250 cm3 s-1; c) Tidal volume: 1500 cm3, breathing cycle length: 4 s, flow rate: 750 cm3 s-1; d) Tidal volume: 1000 cm3, breathing cycle length: 16 s, flow rate: 125 cm3 s-1.

A further enhancement of the tidal volume as well as an additional increase of the flow rate (breathing scenario 3) have a noticeable effect on the velocity of the air flowing through the bronchial and alveolar system. The logical result is an intensification of particle deposition due to inertial impaction (i.e., increasing deposition from minimum towards larger particles) but a lessening of particle deposition due to Brownian motion (i.e., decreasing deposition from minimum towards smaller particles; Figure 7c). The contrary effect may be observed by decreasing the flow rate to a remarkable extent (breathing scenario 4; Figure 7d).

Regional Deposition of Radioactive Particles As already suggested by the ICRP [5], the human respiratory tract is subdivided into three main regions, namely the extrathoracic region (ET), the bronchial/bronchiolar region (BB+ bb), representing the airway system, and the alveolar region (AI); particle deposition fractions for these regions have been computed and, wherever possible, compared with experimental data [57].

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Regarding the deposition of variably sized radioactive particles in the extrathoracic passages, some very interesting details may be recognized from the graphs of Figure 8. In general, deposition curves are again characterized by more or less perfect U-shapes. By application of breathing scenario 1, particles with dae ranging from 0.07 µm to 1 µm do not excel by a measureable deposition in the oropharynx, whilst their deposition in the nasal airways varies between 7 and 15 %. This significant discrepancy in deposition between mouth and nose is also given for ultrafine and large particles: for particles with dae = 0.001 µm nasal deposition efficiency exceeds that of the mouth by a factor of 2.4 (34 % vs. 82 %), whereas particles with dae = 10 µm exhibit a nasal deposition that exceeds oral deposition by a factor of 2.7 (32 % vs. 86 %; Figure 8a). An increase of the tidal volume and maintenance of the flow rate (breathing scenario 2) has only negligible effects on the deposition curves; nasal deposition is generally decreased by a few percent (Figure 8b). By enhancing the flow rate (breathing scenario 3), those phenomena, which have been already described for total deposition, are also noticeable for extrathoracic deposition. Whilst particles with intermediate size do not remarkably change their deposition behavior with respect to breathing scenario 1, large particles are characterized by a partly dramatic increase in deposition (10 µm: 45 % in mouth, 96 % in nose), and, on the other hand, ultrafine particles deposit in the extrathoracic passages with reduced efficiencies (1 nm: 23 % in mouth, 48 % in nose; Figure 8c). By reducing the flow rate (breathing scenario 4), large particle deposition is again subject to a decrease, and ultrafine particle deposition is maximized.

Figure 8. Extrathoracic deposition of particles with different aerodynamic diameters. Whilst deposition curves represent theoretical predictions, plotted circles mark respective results from experiments (solid line/open circle: mouth breathing; dashed line/full circle: nose breathing); a) Tidal volume: 500 cm3, breathing cycle length: 4 s, flow rate: 250 cm3 s-1; b) Tidal volume: 1000 cm3, breathing cycle length: 8 s, flow rate: 250 cm3 s-1; c) Tidal volume: 1500 cm3, breathing cycle length: 4 s, flow rate: 750 cm3 s-1; d) Tidal volume: 1000 cm3, breathing cycle length: 16 s, flow rate: 125 cm3 s-1.

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Deposition of radioactive particles in the bronchial airways commonly exhibits similar characteristics as particle accumulation in the extrathoracic region, i.e., particles with intermediate sizes (0.1-1 µm) are marked by deposition efficiencies reaching only several percent, whereas ultrafine and large particles deposit in the air-conducting system in valuable amounts. A main difference between extrathoracic and bronchial particle deposition consists in the circumstance that the deposition curves obtained from oral and nasal breathing change their positions (Figure 9): particles inspired through the mouth are more effevtively accumulated in the bronchial tubes than particles inhaled through the nose. The reason for that is simply explained: As extrathoracic filtering efficiency of the nasal pathway is remarkably higher than that of the oral passage, only a very reduced amount of particulate matter can reach the airway system. A detailed analysis of the graphs of Figure 9 reveals phenomena, which differ in some parts from those already introduced above: generally, deposition based upon the oral breathing mode varies between 3 % and 60 %, deposition founded upon the nasal breathing mode between 2 % and 20 %. Any increase of the tidal volume, which is realized by changing from breathing scenario 1 to scenario 2, again causes an enhancement of ultrafine and large particle deposition (Figure 9b), whereas accumulation of particles with intermediate sizes remains unaffected. An increase of the flow rate (breathing scenario 3) produces a rather surprising effect, since not large particles but ultrafines are subject to an increased collision on the bronchial walls (Figure 9c).

Figure 9. Bronchial deposition of particles with aerodynamic diameters ranging from 0.001 µm to 10 µm. Whilst deposition curves represent theoretical predictions, plotted circles mark respective results from experiments (solid line/open circle: mouth breathing; dashed line/full circle: nose breathing); a) Tidal volume: 500 cm3, breathing cycle length: 4 s, flow rate: 250 cm3 s-1; b) Tidal volume: 1000 cm3, breathing cycle length: 8 s, flow rate: 250 cm3 s-1; c) Tidal volume: 1500 cm3, breathing cycle length: 4 s, flow rate: 750 cm3 s-1; d) Tidal volume: 1000 cm3, breathing cycle length: 16 s, flow rate: 125 cm3 s-1.

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The reason for that phenomenon may be again found in the high extrathoracic deposition of large particles and, as a consequence, their dramatically declined ability to reach the bronchial system. Under low flow rates (breathing scenario 4), deposition of large particles is enhanced again, thereby partly exceeding the respective accumulation efficiency of ultrafine particles (Figure 9d). Here, gravitational settling of large particulate bodies in the peripheral airways may be regarded as the main cause.

Figure 10. Alveolar deposition of variably sized particles. Whilst deposition curves represent theoretical predictions, plotted circles mark respective results from experiments (solid line/open circle: mouth breathing; dashed line/full circle: nose breathing); a) Tidal volume: 500 cm3, breathing cycle length: 4 s, flow rate: 250 cm3 s-1; b) Tidal volume: 1000 cm3, breathing cycle length: 8 s, flow rate: 250 cm3 s-1; c) Tidal volume: 1500 cm3, breathing cycle length: 4 s, flow rate: 750 cm3 s-1; d) Tidal volume: 1000 cm3, breathing cycle length: 16 s, flow rate: 125 cm3 s-1.

The dependence of alveolar deposition upon particle size is expressed by bimodal functions which significantly differ in shape from the deposition curves introduced above (Figure 10). Independent of the applied breathing scenario the deposition graphs are characterized by the following properties: 1) The maxima of deposition are commonly positioned at aerodynamic particle diameters of 0.04 µm and 2-3 µm, respectively, whilst minimal deposition may be recognized for particles with intermediate sizes (≈ 0.5 µm) and, appearing as a novum, for ultrafine and large particles; 2) Alveolar particle deposition emanating from oral breathing is again higher than respective deposition produced by breathing through the nose, whereby most significant discrepancies between the two breathing modes are noticeable at the deposition maxima. Generally, alveolar deposition for ultrafine and large particles varies between 1 % and 18 %, that for intermediately sized particles between 3 % and 19 %. Depending upon the selected breathing scenario the left

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maximum takes values between 16 % and 55 %, whilst deposition measured at the right maximum ranges from 14 % to 52 %. By enhancing the tidal volume (breathing scenario 2; Figure 10b), alveolar deposition is proportionally increased for all particle sizes due to the ability of particulate substances to enter deeper regions of the respiratory system. A similar effect is attained by an increase of the flow rate (deposition scenario 3; Figure 10c), whereby the half-width of the peaks is subject to a slight reduction. Additionally, the left peak significantly exceeds the right one in height, because, under conditions of high flow velocity, particles mainly deposited by Brownian motion are transported to more peripheral airways, where they finally collide with the epithelial surface. A reduction of the flow rate (breathing scenario 4; Figure 10d) results in an increase of the right peak height and a respective decrease of the left one. This phenomenon may be explained by the fact that efficiency of gravitational settling, which mainly affects particles with dae = 2-3 µm, reaches its optimum under the given flow velocities.

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Theoretical Predictions of Radioactive Particle Deposition in Single Airway Generations For demonstrative purposes, deposition of radioactive particles in single airway generations was computed under the assumption of mouth breathing. As displayed in Figure 11, percental deposition values were plotted from generation 0, corresponding with the trachea, to generation 20, representing the distal bronchioles. Deposition curves of 5 different particle sizes, namely 0.001 µm, 0.01 µm, 0.1 µm, 1 µm, and 10 µm, were drawn together in one graph to provide the possibility of intercomparison. Independent of the selected breathing scenario, the obtained deposition functions may be described as follows: molecule-sized particles (0.001 µm) exhibit high deposition in the proximal generations (4 %-10 %), which is subject to a dramatic decrease towards more peripheral airways. Particles with dae = 0.01 µm commonly deposit in the trachea with ≈ 1 % but increase their deposition continuously towards generation 15/16, where respective values range from 4.5 % to 7 %. Right from the maximum, deposition declines more or less rapidly. Aerosol particles with sizes of 0.1 µm are characterized by deposition values that do not exceed 1 % in the upper bronchial airways but, on the other hand, increase successively towards the terminal and respiratory bronchioles, where they may finally range from 2 % to about 4.5 %. Concerning intermediately sized particles with an aerodynamic diameter of 1 µm, similar tendencies as described for the 0.1 µm particles may be observed. Main differences between the two particle classes are noticeable insofar as deposition values of 1 µm particles are lower than those of 0.1 µm particles, thereby reaching maximal values of 3.7 %. An extraordinary deposition behavior may be attested for large particles (dae = 10 µm) which show a small deposition maximum at airway generation 2/3, with respective deposition values ranging from 0.8 % to 2.3 %, and a more remarkable one at airway generation 10/11 (deposition values: 0.8 % to 5 %). Towards more peripheral airways deposition continuously approaches the zero line. By increasing the tidal volume (breathing scenario 2; Figure 11b), a general increase in deposition may be recognized, which is not remarkable for small to intermediately sized particles and corresponds well with the above introduced findings for total and regional deposition.

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Figure 11. Generation-specific particle deposition for the exemplary case of mouth breathing; a) Tidal volume: 500 cm3, breathing cycle length: 4 s, flow rate: 250 cm3 s-1; b) Tidal volume: 1000 cm3, breathing cycle length: 8 s, flow rate: 250 cm3 s-1; c) Tidal volume: 1500 cm3, breathing cycle length: 4 s, flow rate: 750 cm3 s-1; d) Tidal volume: 1000 cm3, breathing cycle length: 16 s, flow rate: 125 cm3 s-1.

An enhancement of the flow rate (breathing scenario 3; Figure 11c) has several effects on generation-specific particle deposition: whilst deposition curves of 0.001 µm and 0.01 µm particles are significantly changed in shape, indicating a displacement of maximal deposition values towards more distal airways, deposition of 10 µm particles is subject to a general reduction that may be traced back to the increased extrathoracic deposition. Slow inhalation (breathing scenario 4; Figure 11d) again causes a partly dramatic increase of the generationspecific deposition values, now also affecting the 10 µm particles due to the enhanced efficacy of gravitational settling.

Conclusion From the theoretical results presented in this chapter several conclusions can be drawn, which are essential to understand the behavior of particles that are attached by radioactive elements and inhaled into the human respiratory system. As generally determined from modeling calculations and related experiments, deposition sites and intensities of radioactively contaminated particulate substances depend upon geometric (shape) as well as physical (e.g., density) characteristics of single components being suspended in the ambient atmosphere. In order to consider both geometric and physical particle properties for transport and deposition computations, the aerodynamic diameter concept was established here and consequently applied to solve any questions which are of physical and medical interest. As revealed by the total deposition graphs, highest deposition efficiencies in the human

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respiratory system may be attested for those particles which either are very small, thereby commonly adopting diameters < 10 nm, or very large (dae ≈ 3-10 µm), whilst particles with intermediate sizes are to a significant extent expired from the respiratory tract again. Hence, highest danger for both the irradiation of epithelial cells and the malignant transformation of lung tissues emanates from aerosols containing either ultrafine or large particles. Predictions of regional particle depositions clearly demonstrate that particles belonging to the two risk classes are preferably accumulated in the extrathoracic compartment and the upper bronchi, so that resulting carcinomas may be also localized at the respective sites. Intermediately sized particles, as far as being deposited in the human respiratory system, are chiefly accumulated in the distal bronchioles and the alveoli. As demonstrated by respective computations maximal alveolar deposition is restricted to rather small particle diameter intervals: particles with dae ≈ 0.04 µm and dae ≈ 2 µm have the alveolar region as their primary target and, thus, may cause enhanced cellular damage within this part of the lung. The predictions of regional particle deposition are confirmed by the generation-specific deposition plots, where 0.001 µm and 10 µm particles clearly tend to deposit in the proximal airway generations, whereas the remaining particle sizes studied here (0.01 µm, 0.1 µm, 1 µm) preferentially accumulate in intermediate to distal airway generations. An essential question concerns the possible effect of breathing mode on deposition. Therefore, the number of hazardous particles reaching the bronchial and alveolar region is more or less remarkably declined by inhaling through the nose, whilst any change of breathing frequency and tidal volume may handicap depostion of one particle class but favor deposition of the other.

References

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[1] [2]

[3]

[4] [5]

[6]

[7]

Dagle, G. E. and Sanders, C. L. (1984). Radionuclide Injury to the Lung. Environmental Health Perspectives, 55, 129-137. De Villiers, A. J. and Windish, J. P. (1964). Lung cancer in a fluorspar mining community. I. Radiation, dust and mortality experience. British Journal of Industrial Medicine, 21, 94-109. Wagoner, J. K., Archer, V. E., Lundin, F. E., Holaday, D. A. and Lloyd, J. W. (1965). Radiation as the cause of lung cancer among uranium miners. New English Journal of Medicine, 273, 181-188. Lorenz, E. (1944). Radioactivity and lung cancer; a critical review of cancer in the miners of Schneeberg and Joachimstal. Journal of the National Cancer Institute, 5, 1-5. International Commission on Radiological Protection (ICRP). (1994). Human respiratory tract model for radiological protection, Publication 66. Oxford, GB: Pergamon Press. Stahlhofen, W., Gebhart, J. and Heyder, J. (1981). Biological variability of regional deposition of aerosol particles in the human respiratory tract. American Industrial Hygiene Association Journal, 42, 348-352. Heyder, J., Gebhart, J., Stahlhofen, W. and Stuck, B. (1982). Biological variability of particle deposition in the human respiratory tract during controlled and spontaneous mouth-breathing. Annals of Occupational Hygiene, 26, 137-147.

Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Theoretical Predictions of Radionuclide Deposition … [8] [9]

[10] [11]

[12]

[13]

[14]

[15]

[16]

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

[17] [18] [19] [20] [21] [22] [23] [24] [25]

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Heyder, J., Gebhart, J., and Scheuch, G. (1988). Influence of human lung morphology on particle deposition. Journal of Aerosol Medicine, 1, 81-88. Charlton, D. E., Nikjoo, H. and Humm, J. L. (1989). Calculation of initial yields of single- and double-strand breaks in cell nuclei from electrons, protons and alpha particles. International Journal of Radiation Biology, 56, 1-19. Chatterjee, A. and Holley, W. R. (1992). Biochemical mechanisms and clusters of damage for high LET radiation. Advanced Space Research, 12, 33-43. Goodhead, D. T., Munson, R. J., Thacker, J. and Cox, R. (1980). Mutation and inactivation of cultured mammalian cells exposed to beams of accelerated heavy ions IV. Biophysical interpretation. International Journal of Radiation Biology, 37, 135-167. Chapman, J. D., Doern, S. D., Reuvers, A. P., Gillespie, C. J., Chatterjee, A., Blakely, E. A., Smith, K. C. and Tobias, C. A. (1979). Radioprotection by DMSO of mammalian cells exposed to X-rays and the heavy-charged particle beams. Radiation and Environmental Biophysics, 16, 29-41. DeLara, C. M., Jenner, T. J., Townsend, K. M. S., Marsden, S. J. and O’Neill, P. (1995). The effect of dimethyl sulfoxide on the induction of DANN double-strand breaks in V79-4 mammalian cells by alpha particles. Radiation Research, 144, 43-49. Goodhead, D. T. and Nikjoo, H. (1989). Track structure analysis of ultrasoft X-rays compared to high- and low-LET radiations. International Journal of Radiation Biology, 55, 513-529. Nikjoo, H., Goodhead, D. T., Charlton, D. E. and Paretzke, H. G. (1991). Energy deposition in small cylindrical targets by monoenergetic electrons. International Journal of Radiation Biology, 60, 739-756. McDowell, E. H., McLaughlin, D. K., Merenyl, J. S., Kiefer, R. F., Harris, C. C. and Trump, B. F. (1978). The respiratory epithelium. V. Histogenesis of lung carcinomas in the human. Journal of the National Cancer Institute, 61, 587-606. Yesner, R. (1981). The dynamic histopathologic spectrum of lung cancer. Yale Journal of Biology and Medicine, 54, 447-456. Spencer, H. (1985). Carcinoma of the lung: Pathology of the lung. New York, NY: Pergamon Press. Gazdar, A. F. and Linnoila, R. I. (1988). The pathology of lung cancer – changing concepts and newer diagnostic techniques. Seminars in Oncology, 15, 215-225. McDowell, E. M. (1987). Bronchogenic carcinomas. In: E. M. McDowell (Ed.), Lung Carcinomas (pp. 255-285). New York, NY: Churchill Livingston. McDowell, E. M. and Beals, T. F. (1987). Epithelial neoplasms. In: W. B. Saunders (Ed.), Biopsy Pathology of the Bronchi (pp. 308-367). Philadelphia, PA. Johnson, N. and Hubbs, A. (1990). Epithelial progenitor cells in the rat trachea. American Journal of Respiratory Cell and Molecular Biology, 3, 579-585. Ford, J. R. and Terzaghi-Howe, M. (1992). Basal cells are the progenitors of primary tracheal epithelial cell cultures. Experimental Cell Research, 198, 69-77. Ford, J. R. and Terzaghi-Howe, M. (1992). Characteristics of magnetically separated rat tracheal epithelial cell populations. American Journal of Physiology, 263, L568-L574. Ayers, M. and Jeffery, P. K. (1982). Cell division and differentiation in bronchial epithelium. In: G. Cumming and B. Bonsignore (Eds.), Cellular Biology of the Lung (pp. 33-59). New York, NY: Plenum Press.

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[26] Smith, M. N., Greenberg, S. D. and Spjut, H. J. (1979). The Clara cell: a comparative ultrastructural study in mammals. American Journal of Anatomy, 155, 15-30. [27] ICRP (1980). Statement and recommendations of the 1980 Brighton meeting of the ICRP, Annals of the ICRP 4. [28] Batsakis, J. G. (1976). Tumors of the Head and Neck. Baltimore, MD, Williams and Wilkins. [29] Reznik-Schüller, H. M. (1983). The respiratory tract in rodents. In: H. M. ReznikSchüller (Ed.), Comparative Respiratory Tract Carcinogenesis, Volume I (pp. 79-93). Boca Raton, FL: CRC Press. [30] Yamamoto, M., Shimokata, K. and Nagura, H. (1987). Immunoelectron microscopic study of the histogenesis of epidermoid metaplasia in respiratory epithelium. American Review of Respiratory Diseases, 135, 713-718. [31] Del Regato, J. A., Spjut, H. J. and Cox, J. D. (Eds.). (1985). Cancer. Diagnosis, Treatment, and Prognosis. St. Louis, Toronto, Princeton: The CV Mosby Company. [32] Yamamoto, T., Kopecky, K. J., Fujikura, T. et al. (1987). Lung cancer incidence among Japanese A-bomb survivors, 1950-80. Journal of Radiation Research, 28, 156-171. [33] Weibel, E. R. (1963). Morphometry of the Human Lung. Berlin, GER: Springer-Verlag. [34] Horsfield, K. and Cumming, G. (1968). Morphology of the bronchial tree in man. Journal of Applied Physiology, 24, 373-383. [35] James, A. C. (1988). Lung dosimetry. In: W. W. Nazaroff and A. V. Nero (Eds.), Radon and its decay products in indoor air (pp. 259-309). New York, NY: Wiley Interscience. [36] Hansen, J. E. and Ampaya, E. P. (1975). Human airspace shapes, sizes, areas, and volumes. Journal of Applied Physiology, 38, 990-995. [37] Phalen, R. F., Oldham, M. J., Beaucage, C. B., Crocker, T. T. and Mortensen, J. D. (1985). Postnatal Enlargement of Human Tracheobronchial Airways and Implications for Particle Deposition. Anatomical Records, 212, 368-380. [38] Zeltner, T. B., Caduff, J. H., Gehr, P., Pfenninger, J. and Burri, P. H. (1987). The postnatal development and growth of the human lung. I. Morphometry. Respiratory Physiology, 67, 247-267. [39] Horsfield, K., Dart, G., Olson, D. E., Filley, G. F. and Cumming, G. (1971). Models of the human bronchial tree. Journal of Applied Physiology, 31, 207-217. [40] Yeh, H. C. and Schum, G. M. (1980). Models of the human lung airways and their application to inhaled particle deposition. Bulletin of Mathematical Biology, 42, 461480. [41] Koblinger, L. and Hofmann, W. (1990). Monte Carlo modeling of aerosol deposition in human lungs. Part I: simulation of particle transport in a stochastic lung structure. Journal of Aerosol Science, 21, 661-674. [42] Soong, T. T., Nicolaides, P., Yu, C. P. and Soong, S. C. (1979). A statistical description of the human tracheobronchial tree geometry. Respiratory Physiology, 37, 161-172. [43] Yu, C. P., Nicolaides, P. and Soong, T. T. (1979). Effect of random airway sizes on aerosol deposition. American Industrial Hygiene Association Journal, 40, 999-1005. [44] Koblinger, L. and Hofmann, W. (1985). Analysis of human lung morphometric data for stochastic aerosol deposition calculations. Physics in Medicine and Biology, 30, 541556.

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[45] Raabe, O. G., Yeh, H. C., Schum, G. M. and Phalen, R. F. (1976). Tracheobronchial Geometry: Human, Dog, Rat, Hamster, LF-53. Albuquerque, NM: Lovelace Foundation. [46] Haefeli-Bleuer, B. and Weibel, E. R. (1988). Morphometry of the human pulmonary acinus. Anatomical Records, 220, 401-414. [47] Yu, C. P. and Diu, C. K. (1982). A probabilistic model for intersubject deposition variability of inhaled particles. Aerosol Science and Technology, 1, 335-362. [48] Phillips, C. G. and Kaye, S. R. (1997). On the asymmetry of bifurcations in the bronchial tree. Respiratory Physiology, 107, 85-98. [49] Carslow, H. S. and Jaeger, H. C. (1959). Conduction of Heat in Solids. Oxford, GB: Clarendon Press. [50] Cohen, B. S. and Asgharian, B. (1990). Deposition of ultrafine particles in the upper airways. Journal of Aerosol Science, 21, 789-797. [51] Ingham, D. B. (1975). Diffusion of aerosol from a stream flowing through a cylindrical tube. Journal of Aerosol Science, 6, 125-132. [52] Cheng, K. H., Cheng, Y. S., Yeh, H. C., Guilmette, R. A., Simpson, S. Q., Yang, Y. and Swift, D. L. (1996). In vivo measurements of nasal airway dimensions and ultrafine aerosol deposition in the human nasal and oral airways. Journal of Aerosol Science, 27, 785-801. [53] Stahlhofen, W., Rudolf, G. and James, A. C. (1989). Intercomparison of experimental regional aerosol deposition data. Journal of Aerosol Medicine, 2, 285-308. [54] Davies, C. N. (1979). Particle-fluid interaction. Journal of Aerosol Science, 10, 477513. [55] Kasper, G. (1982). Dynamics and measurement of smokes. I Size characterization of nonspherical particles. Aerosol Science and Technology, 1, 187-199. [56] Sturm, R. and Hofmann, W. (2009). A theoretical approach to the deposition and clearance of fibers with variable size in the human respiratory tract. Journal of hazardous materials, 170, 210-221. [57] Heyder, J., Gebhart, J., Rudolf, G., Schiller, C. F. and Stahlhofen, W. (1986). Deposition of particles in the human respiratory tract in the size range 0.005–15 µm. Journal of Aerosol Science, 17, 811-825.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter III

Cosmic Radiation in Commercial Aviation Michael Bagshaw King’s College London, School of Biomedical and Health Sciences

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Introduction Cosmic rays were discovered in 1911 by the Austrian physicist, Victor Hess. The planet earth is continuously bathed in high-energy galactic cosmic ionising radiation (GCR), emanating from outside the solar system, and sporadically exposed to bursts of energetic particles from the sun referred to as solar particle events (SPEs). The main source of GCR is believed to be supernovae (exploding stars), while occasionally a disturbance in the sun's atmosphere (solar flare or coronal mass ejection) leads to a surge of radiation particles with sufficient energy to penetrate the earth's magnetic field and enter the atmosphere. The inhabitants of planet earth gain protection from the effects of cosmic radiation from the earth’s magnetic field and the atmosphere, as well as from the sun's magnetic field and solar wind. These protective effects extend to the occupants of aircraft flying within the earth’s atmosphere, although the effects can be complex for aircraft flying at high altitudes and high latitudes. There are differences between the Northern and Southern hemispheres; data in this chapter are derived in Northern latitudes.

Ionising Radiation Ionising radiation refers to subatomic particles that, on interacting with an atom, can directly or indirectly cause the atom to lose an electron or break apart its nucleus. It is when these events occur in body tissue that potentially health effects may result if the human body's self-repair mechanism fails.

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Michael Bagshaw Ionising radiation types and their properties are shown in Table 1. Table 1. Radiation Type alpha particles beta particles gamma rays X rays neutrons

Consists of

Range in air

2 protons + 2 neutrons (Helium) an electron electromagnetic ray electromagnetic ray free neutrons

few cm several metres many metres many metres many metres

Range in human tissue cannot penetrate skin few mm many cm many cm many cm

Hazard site internal internal + external internal + external external external

Outside the earth's atmosphere, GCR consists mostly of fast-moving protons (hydrogen nuclei) and alpha particles (helium particles). GCR is 98% atomic nuclei and 2% electrons [44]. Of the energetic nuclei, 87% are protons, 12% are helium ions and 1% are heavier ions. On entering the earth's atmosphere, the particles collide with the nuclei of nitrogen, oxygen and other atmospheric atoms, generating additional ionising radiation particles. At normal commercial aircraft flight altitudes this GCR consists mainly of neutrons, protons, electrons, positrons and photons.

Terrestrial Protection from GCR

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Protection from cosmic radiation for the earth's inhabitants is provided by three variables: 1. the sun's magnetic field and solar wind (solar cycle) 2. the earth's magnetic field (latitude) 3. the earth's atmosphere (altitude). 1. The sun has a varying magnetic field with a basic dipole component which reverses direction approximately every 11 years. Recently solar maximum period peaked around 200002 and the next one is expected around 2011. Near the reversal, at 'solar minimum' (around 2006 in the current cycle), there are few sunspots and the magnetic field extending throughout the solar system is relatively weak and smooth. At solar maximum there are many sunspots and other manifestations of magnetic turbulence, and the plasma of protons and electrons ejected from the sun (the solar wind) carries a relatively strong and convoluted magnetic field with it outward through the solar system [19]. When the solar magnetic field is stronger, the paths of the electrically charged ions are deflected further and less GCR reaches the earth. Thus solar maximum causes a radiation minimum and, conversely, solar minimum is the time of radiation maximum. The effect of this depends on the other two variables, altitude and geomagnetic latitude. At the altitudes flown by commercial jet aircraft and at polar latitudes, the ratio for GCR at solar minimum to that at solar maximum is in the region of 1.2 to 2 and increases with altitude [4, 5]. 2. The earth's magnetic field has a larger effect than the sun's magnetic field on cosmic radiation approaching the atmosphere.

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Near the equator the geomagnetic field is almost parallel to the earth's surface. Near the magnetic poles the geomagnetic field is nearly vertical and the maximum number of primary cosmic rays can reach the atmosphere. At extremes of latitude, there is no further increase in GCR flux with increasing latitude and this is known as the polar plateau. As a result, cosmic radiation levels are higher in polar regions and decline towards the equator, the size of this effect depending upon altitude and the point in the solar cycle. At the altitudes flown by commercial jet aircraft, at solar minimum, GCR is 2.5 to 5 times more intense in polar regions than near the equator, with larger latitude dependence as altitude increases [55]. 3. Life on earth is shielded from cosmic radiation by the atmosphere. The charged cosmic radiation particles lose energy as they penetrate the atmosphere by ionising the atoms and molecules of the air (releasing electrons). The particles also collide with the atomic nuclei of nitrogen, oxygen and other atmospheric constituents. The ambient radiation increases with altitude by approximately 15% for each increase of around 2,000 ft (~600 m) (dependent on latitude), with certain secondary particles reaching a maximum at around 65,000 feet (20 km) (the Pfotzer maximum). Primary heavy ions and secondary fragments become important above this point. As well as providing shielding from GCR, the atmosphere contributes different components to the radiation flux as a function of atmospheric depth. Accordingly the potential biological effects of cosmic radiation on aircraft occupants are directly altitude dependent.

Figure 1. Total variation of particle type with altitude.

The total effective dose rate at 30,000 ft is about 90 times the rate at sea level. It increases by a factor of 2 between 30,000 ft and 40,000 ft, and by another factor of 2 between 40,000 ft and 65,000 ft. It should be noted that at all altitudes from 10,000 ft to over 80,000 ft (3 to 25 km) neutrons are the dominant component. They are less dominant at lower latitudes, but still contribute 40 to 65% of the total dose equivalent rate.

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Solar Flares Occasionally a disturbance in the sun's atmosphere, known as a solar particle event (SPE), leads to a surge of radiation particles. These are produced by sudden sporadic releases of energy in the solar atmosphere (solar flares) and by coronal mass ejections (CMEs), and are usually of insufficient energy to contribute to the radiation field at aviation altitudes. However, on occasions proton particles are produced with sufficient energy to penetrate the earth's magnetic field and enter the atmosphere. These particles interact with air atoms in the same way as GCR particles. Such events are comparatively short lived and vary with the 11year solar cycle, being more frequent at solar maximum. Long distance radio communications are sometimes disrupted because of increased ionisation of the earth’s upper atmosphere by X-rays, protons or ultra-violet radiation from the sun. This can occur in the absence of excessive ionising radiation levels at commercial flight altitudes. Similarly the Aurorae Borealis and Australis (northern and southern lights), while resulting from the interaction of charged particles with air in the upper atmosphere, are not an indication of increased ionising radiation levels at flight altitudes. When primary solar particle energies are sufficient to produce secondary particles detected at ground level by neutron monitors, this is known as ground level enhancement (GLE). GLEs are rare, averaging about one per year grouped around solar maximum, and the spectrum varies between events [34]. Any rise in dose rates associated with an event is rapid, usually taking place in minutes. The duration may be hours to several days. The strong magnetic disturbance associated with SPEs can lead to significant decreases in GCR dose rate over many hours as a result of the enhanced solar wind (Forbush decrease). The disturbance to the geomagnetic field can allow easier access to cosmic rays and solar particles. This can give significant increases at lower latitudes particularly for SPEs. Thus the combined effect of an SPE may be a net decrease or increase in radiation dose, and further work is needed to understand the contribution of SPEs to dose. Prediction of which SPEs will give rise to significant increases in radiation dose rates at commercial aircraft operating altitudes is not currently possible, and work continues with this aspect of space weather. GLEs have been recorded and analysed since 1942, and are numbered sequentially [12]. With the exception of GLE5 (February 1956), of the 64 GLEs observed up to 2003, none has presented any risk of attaining an annual dose of 1 mSv (the ICRP recommended public exposure limit) [29]. For GLE60, which occurred in April 2001, the total contribution to radiation dose from the SPE was measured as 20 μSv [51] GLE42, which occurred in September 1989, was the most intense observed since that of 1956 (GLE5) with a recorded magnitude of 252%. However this represented about one month of GCR exposure only, which would not have given an annual dose in excess of 1mSv [30]. Concorde supersonic transport aircraft of British Airways were flying during this solar event and the on-board monitoring equipment did not activate a radiation warning alert, which is triggered at 0.5mSv per hour. However it should be cautioned that the latitude effect exceeds the altitude effect for SPEs and Concorde did not reach very high magnetic latitudes. It has been reported [29] that a number of airlines have changed flight plans to avoid high geomagnetic latitudes during periods of predicted solar flare ground level events, with significant cost and delays to service. Data indicate that these actions were unnecessary in terms of radiation dose protection.

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Biological Effects of Ionising Radiation Very high levels of ionising radiation, such as that from a nuclear explosion, will cause severe cell damage or cell death. This may lead to the immediate death of the individual as a result of acute exposure, or to longer-term consequences such as the development of cancer, or to genetic mal-development as a result of damage to the reproductive cells. It is more difficult to predict the effects of low-level doses of ionising radiation such as cosmic radiation or medical X-rays because of the individual variability in the body’s self-repair process. Indeed, it has even been suggested that the effect of radiation on human health is not linear, but is a J-shaped curve with exposure being beneficial at low doses [27, 53]. The ionisation process in living tissues consists of ejecting bound electrons from the cellular molecules, leaving behind chemically active radicals which are the source of adverse changes. Many of the radicals resulting from radiation injury are similar to those produced in normal metabolic processes, for which the cell has developed recovery mechanisms needed for long term survival [7]. The substantive target of radiation injury is considered to be the DNA structure which may be changed or injured directly by a passing ionising particle [56]. The ability of the cell to repair the effects of ionisation depends in part on the number of such events occurring within the cell from the passage of a single particle, and the rate at which such passages occur. The number of ionisation events per particle passage is related to the physical processes by which particle kinetic energy is transferred to the cellular bound electrons [56]. As charged particles slow down when passing through human tissue, they lose energy. This is caused by electromagnetic interactions transferring energy to electrons leading to ionisation and excitation. The rate of energy loss increases rapidly with increasing charge of the particle and decreasing speed [56]. The distance travelled depends on the energy, and massive particles are more penetrating than lighter particles of the same charge and speed. Uncharged particles have longer free paths and, for neutrons, larger energy transfers per event resulting in energy losses which appear as isolated occurrences along the particle's path. The rate at which ions produce electrons in isolated cells is important, since repair of a single event is relatively efficient unless many events occur within the repair period [53]. Biological effectiveness depends on the spatial distribution of the energy imparted and the density of the ionisations per unit path length of the ionising particles. The energy loss per unit path length of a charged particle is referred to as the ‘stopping power’, while the energy deposited is referred to as 'linear energy transfer' (LET). The biological effect of ionising radiation depends upon whether it is high- or low-LET. Early studies of the effect of identical doses of different types of radiation on biological systems showed that they produced different amounts of damage. This led to the concept of ‘relative biological effectiveness’ (RBE), which is defined as the ratio of a dose of a particular type of radiation to the dose of gamma-rays or X-rays that yield the same biological end point. The dose equivalent to the tissue (DE) is the product of the absorbed dose (D) and the quality factor (Q or QF), Q being dependent upon LET. The numerical value of Q depends not only upon appropriate biological data, but also on the judgement of the ICRP. It establishes the value of the absorbed dose of any radiation that engenders the same risk as a given absorbed dose of a reference radiation [24]. The radiation weighting factor (WR) takes

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account of quality factor, and recommendations are published from time to time by the ICRP [24]. Low-LET radiation, all with a weighting factor of 1, includes photons, X and gamma rays, as well as electrons and muons. Electrons are the low-LET radiation of prime concern at aircraft operating altitudes. Neutrons, alpha particles, fission fragments and heavy nuclei are classified as high-LET, neutrons providing about half the effective dose at high altitudes. The current weighting factors are shown in Table 2. Table 2.

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Type and energy range of incident radiation Photons (all energies) Electrons and muons (all energies) Protons (incident) Neutrons 100 keV - 2 MeV Neutrons >2 MeV - 20 MeV Neutrons >20 MeV Alpha particles, fission fragments, heavy ions

Weighting factor 1 1 5 (but see text) 5 10 20 10 5 20

The ICRP has proposed [24] that the weighting factor for protons should be reduced from a value of 5 (as recommended in ICRP Publication 60, 1991) to a value of 2. The weighting factor for neutrons depends upon the energy of the incident neutrons. ICRP Publication 92 proposes that the means of computation of the factor should be a continuous function of energy rather than the step function given in Publication 60 [24]. These proposals are based on current knowledge of biophysics and radiobiology, and acknowledge that judgements on these factors may change from time to time. [ICRP recommends that no attempt be made to retrospectively correct individual historical estimates of effective dose or equivalent dose in a single tissue or organ. Rather the revised weighting factor should be applied from the date of adoption.] At all altitudes from 10,000 ft to over 80,000 ft (3 to 25 km) neutrons are the dominant component of the cosmic radiation field. They are less dominant at lower latitudes, but still contribute 40 to 65% of the total dose equivalent rate. Because neutron interactions produce low-energy ions, neutron radiation is more effective in inducing biological damage than gamma radiation. However, there are no adequate epidemiological data to evaluate to what extent neutrons are carcinogenic to humans [23].

Chromosome Aberrations Tissue cells may be damaged by physical agents such as heat, cold, vibration and radiation. Throughout life there is a continuous ongoing cycle of cell damage and repair utilising the body’s self-repair mechanism. During the repair process, gene translocation and other chromosome aberrations may occur.

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A number of studies have identified an increased rate of unstable chromosome aberrations such as dicentrics and rings in flight crew members, and related these to cosmic radiation exposure [21, 46, 47]. Nicholas et al note that unstable aberrations decrease with time and thus do not serve as good indicators of cumulative exposure to GCR. They postulate that structural chromosome aberrations such as translocations may be a better marker since they are relatively stable with time since exposure [35]. The Nicholas et al study showed that the mean number of translocations per cell was significantly higher amongst the airline pilots studied than among the controls. However, within the radiation exposure range encountered in the study, observed values among the pilots did not follow the dose-response pattern expected based on available models for chronic low dose radiation exposure. This study fails to determine the role of radiation in the induction of translocations. There is so far no epidemiological evidence to link these aberrations with the development of cancers.

Radiation Units of Measurement

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The standard unit of radioactivity is the Becquerel (Bq), which is defined as the decay of one nucleus per second. When considering cosmic radiation the practical interest is in the biological effect of a radiation dose, the dose equivalent being measured in Sievert (Sv). The ICRP has recommended a number of quantities based on weighting absorbed dose, to take account of the RBE of different types of radiation. Dose equivalent (Sv) is one of these. Dose equivalent (H) is defined as H(LET) = Q(LET) x D(LET) where Q is the quality factor and is a function of LET, and D is the absorbed dose. The effective dose is obtained by the use of absorbed dose, D, along with different weighting factors for organs and tissues. Doses of cosmic radiation are of such a level that values are usually quoted in microSievert (µSv) per hour or milli-Sievert (mSv) per year (1mSv = 1000µSv). The Sievert has superseded the rem as the unit of measurement of effective dose [1Sv = 100rem, 1mSv = 100mrem, 1µSv = 0.1mrem].

Other Terrestrial Sources of Ionising Radiation There is a constant background flux of ionising radiation at ground level. Terrestrial background radiation from the earth’s materials contributes 2.6 mSv per annum in the United Kingdom and 3 mSv per annum in the USA [58]. This flux is dominated by the low-LET component (93%). Inhaled radon gas contributes around 2 mSv per annum to the total overall background ionising radiation level [58].

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Medical X-rays are delivered in a concentrated localised manner, and usual doses are of the order [58]: ⎯ ⎯ ⎯ ⎯ ⎯

Chest X-ray Body CT scan Chest CT scan IVP Mammogram

0.1 mSv (100 μSv) 10 mSv 8 mSv 1.6 mSv 0.7 mSv (700 μSv)

Doses received from radiotherapy for cancer treatment range from 20 to 80 Sv [31]. These are all average figures with wide individual variations.

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Radiological Protection Workers in the nuclear industry and those who work with medical X-rays may be designated as ‘classified workers’ and have their occupational radiation exposure monitored and recorded. For classified workers, the International Commission on Radiological Protection (ICRP) recommends maximum mean body effective dose limits of 20mSv per year (averaged over 5 years, with a maximum in any one year of 50mSv), with an additional recommendation that the equivalent dose to the foetus should not exceed 1mSv during the declared term of the pregnancy. This limit for the foetus is in line with the ICRP recommendation that the limit for the general public should be 1mSv per year [25]. Workers in the nuclear industry and in medical physics are at potential risk of accidental high exposure, and radiological protection regulations require that they be educated to take every effort to avoid such accidents. The situation differs in the aerospace environment where exposure to radiation is not the result of an accident and is unavoidable. In the UK, the National Radiological Protection Board (NRPB) recommends that a record should be kept of exposure rates and there should be a systematic assessment of the individual dose of any worker considered likely to receive an effective dose of more than 6mSv per year, this being referred to as the control level. This value is a cautious arbitrary figure, representing 3/10 of the annual maximum for classified workers and has no radiobiological significance [10]. In 1991 the ICRP recommended that exposure of flight crew members to cosmic radiation in jet aircraft should be considered part of occupational exposure to ionising radiation [25]. In 1994 the Federal Aviation Administration (FAA) of the USA formally recognised that air carrier aircrews are occupationally exposed to ionising radiation, and recommended that they be informed about their radiation exposure and associated health risks and that they be assisted in making informed decisions with regard to their work environment [15]. The FAA subsequently issued a technical report in October 2003 advising aircrew about their occupational exposure to ionising radiation [16]. The FAA recommends the limit for an aircrew member of a 5-year average effective dose of 20mSv per year, with no more than 50mSv in a single year [17]. For a pregnant aircrew

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member starting when she reports her pregnancy to management, the recommended limit for the conceptus is an equivalent dose of 1mSv, with no more than 0.5mSv in any month [17]. Following the ICRP recommendation, the Council of the European Union adopted a directive laying down safety standards for the protection of the health of workers and the general public against the effects of ionising radiation [14]. Article 42, which deals with protection of aircrew, states that for aircrew who are liable to be subject to exposure of more than 1 mSv per annum appropriate measures must be taken. In particular the employer must: • • • •

assess the exposure of the crew concerned; take into account the assessed exposure when organising working schedules with a view to reducing the doses of highly exposed aircrew; inform the workers concerned of the health risks their work involves; and apply special protection for female aircrew during declared pregnancy.

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The European Directive applies the ICRP limits for occupational exposure (20mSv per year) and the 1mSv exposure limit to the foetus for the duration of declared pregnancy. In addition, the European Directive indicates that radiation exposure to a pregnant crew member should be ‘as low as reasonably achievable’ (ALARA) [14]. This was transformed into national law of the EU member states in May 2000. Both the European Directive and the FAA Technical Report follow the ICRP recommended limits for occupational exposure, but there are differences for pregnancy. The European Directive uses the ‘ALARA’ principle in recommending that radiation exposure to the pregnant worker should be as low as reasonably achievable, with an absolute maximum of 1mSv. However, the FAA recommends a maximum dose to the foetus of 1mSV but allows 0.5mSv in any month, making no reference to ALARA. Maximum mean effective dose limits are summarised in Table 3. Table 3

General Public Occupationally exposed Foetus equivalent dose Control level

ICRP 1 mSv y-1 20 mSv y-1, 5 yr average, but not more than 50 mSv in 1y 1 mSv y-1

N/a

EU 1 mSv y-1 20 mSv y-1, 5 yr average, but not more than 50 mSv in 1y 1 mSv for declared term of pregnancy and ALARA 6 mSv

FAA 1 mSv y-1 20 mSv y-1, 5 yr average, but not more than 50 mSv in 1y 1 mSV maximum, but 0.5 mSv in any month N/a

Health Risks of Cosmic Radiation 1. Development of Cancer A cell may become cancerous as a result of being irradiated, the likelihood being dependent upon the energy and the dose received. For an accumulated cosmic radiation dose

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of 5 mSv per year over a career span of 20 years (a typical prediction for a long haul crew member), the likelihood of developing cancer will be 0.4% [16, 18]. The overall risk of cancer death in the western population is 23%, so the cosmic radiation exposure increases the risk of cancer death from 23% to 23.4% [16, 18]. For a career span of 30 years, the cancer risk increases from 23% to 23.6%.

2. Genetic Risk A child conceived after exposure of a parent to ionising radiation is at risk of inheriting radiation-induced genetic defects. These may take the form of anatomical or functional abnormalities apparent at birth or later in life. The risk following an accumulated dose of 5 mSv per year over a career span of 20 years will be 1 in 2,510 [16]. For a 30-year career, the risk increases to 1 in 1,700. Again this needs to be considered against a background incidence in the general western population of approximately 1 in 51 for genetic abnormalities, with 2 – 3% of liveborn children having one or more severe abnormalities at birth [16].

3. Risk to the Health of the Foetus

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The risks to the foetus from ionising radiation are cancer and mental retardation. There is a background rate for both these conditions within the general population. It is estimated that exposure of the foetus to cosmic radiation for 80 block hours per month will increase the risk by between 1 in 6,000 and 1 in 30,000 depending on the routes flown. The increased lifetime risk of fatal cancer from 1 mSv received during prenatal development is 1 in 10,000 (0.01%) [16].

Measurement of Cosmic Radiation Doses in Aviation The ICRP 1991 recommendations require that cosmic radiation exposure for flight crew members should be assessed and recorded [25]. It has been seen that the galactic cosmic radiation field at aircraft operating altitudes is complex, with a large energy range and the presence of all particle types. The Concorde supersonic transport aircraft first flew in 1969 and entered service with Air France and British Airways in 1976, retiring in 2003. From the outset it was appreciated that cosmic radiation (both galactic and solar) could present a hazard at the operating altitude of around 60,000 ft (18km). Accordingly, ionising radiation monitoring equipment was permanently installed in all Concordes and much data were derived [1, 2, 9, 11, 38]. The introduction of aircraft such as the Boeing 747-400 and the Airbus A330 and A340, has led to the development of ultra-longhaul flights of up to 18 hours duration with the potential for even longer flight times. Many of the routes flown are trans-Polar or transSiberian, where geomagnetic and, to a lesser extent, atmospheric shielding from GCR are less than for routes at lower latitudes.

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Galactic cosmic radiation can be measured actively or passively. Many detectors measure only one type of radiation accurately and usually for only a limited energy range, but they may show some sensitivity to other types of radiation. An active direct reading instrument displays the appropriate values immediately or after a short delay, whereas passive integrating instruments need to be evaluated in a laboratory after the flight. A number of studies have been published giving effective dose rates for sub-sonic flights, measured both actively and passively [1, 2, 4, 18, 28, 32, 33, 43, 48, 50, 51]. Effective dose is not directly measurable, but measured operational quantity ambient dose equivalent can be a good estimator of the effective dose received from cosmic radiation. (See ‘Radiation Units of Measurement’, above) Calculations of ambient dose equivalent rate or route doses can be validated by direct measurement. Concorde was the only commercial aircraft to be equipped with radiation dosimeters measuring data for the duration of every flight. Based on data derived from these measurements, cost-benefit analysis makes it difficult to justify the cost of installation, calibration and maintenance for such equipment in the worldwide fleet of subsonic aircraft. It is frequently suggested that individual dosimeters in the form of film badges should be worn by crew members. However, the sensitivity of such passive dosimeters is very low and the badges would have to be worn for several sectors for meaningful data to become available. Lantos et al report that during an experiment involving voluntary crew members wearing personal dosimeters, 8% of the badges were lost or not used and 2% had received additional X-rays during baggage security screening [30]. The logistical costs of issuing, tracking and processing many thousands of film badges within a commercial airline operation are prohibitive. Computer programs have been developed for the calculation of effective dose from galactic cosmic radiation, taking account of • • • • • •

geographic coordinates of origin and destination airports longitude and latitude of all points of the aircraft’s track altitude at all times of the flight helicocentric potential, to account for solar activity date and time of flight quality of the radiation field through which the aircraft flies.

The most widely used program is CARI-6, developed by the US FAA based on the LUIN transport code [36]. It is limited to the galactic cosmic ray component, which is isotropic and of constant spectrum outside of the heliosphere. The CARI program has been validated by inflight measurement and found to be accurate to within about 7% [30]. However, other workers question this accuracy because of uncertainty of the contribution of solar particles. There is a freely available interactive version of CARI-6, which runs on the Internet and is accessed via . There is also a more sophisticated downloadable version, which allows the user to store and process multiple flight profiles and to calculate dose rates at user-specified locations in the atmosphere. Another package, EPCARD (European Programme Package for the Calculation of Aviation Route Doses), has been developed on behalf of the European Commission [49]. This

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is based on the FLUKA transport code [45] and again is limited to the galactic cosmic ray component, which is isotropic and of constant spectrum outside of the heliosphere. A further program is the SIEVERT system (Systeme d’Information et d’Evaluation par Vol de l’Exposition au Rayonnement cosmique dans les Transport aeriens) which has been developed on behalf of the French Aviation Administration (DGAC) [30]. This program is freely available via . A similar validated Canadian program is known as PCAIRE and is freely available from www.pcaire.com [32] These computer programs allow airline companies and their employees to comply with the ICRP recommendations to monitor radiation exposure.

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Cosmic Radiation Doses Received by Aircraft Occupants There have been many studies of cosmic radiation dose rates both in Concorde and subsonic aircraft [1, 2, 4, 18, 22, 28, 32, 33, 43, 48-51], all giving similar results. European airlines have been required to monitor and record occupational exposure since May 2000 to comply with the European Directive. This is achieved using a computer program such as CARI, EPCARD, SIEVERT or PCAIRE, periodically validated by on-board measurement of the radiation field. Exposure depends on the route, altitude and aircraft type (which influences rate of climb and descent) and is usually quoted as microSievert (μSv) per block hour (block hours are based on the time from when the aircraft first moves under its own power to the time of engine shut-down at the end of the flight). Short haul operations tend to fly at lower altitudes than long haul, gaining the benefit of atmospheric shielding as well as a shorter duration of exposure. Conversely, many long-haul routes are flown at higher latitudes as well as at higher altitudes. For operations in the northern hemisphere, mean ambient equivalent dose rates have been measured in the region of: • • •

Concorde: 12 -15 µSv per hour Long-haul: 4 – 5 µSv per hour Short-haul: 1 – 3 µSv per hour.

In general, for UK-based crew members operating to the maximum flight time limitations, it is calculated that: • •

Long-haul crew have an annual mean effective exposure of 2 – 3 mSv per year, ie less than one fifth of the ICRP recommended dose limit; Short-haul crew have an annual mean effective exposure of 1 – 2 mSv per year, ie less than one tenth of the recommended dose limit.

On the worst-case UK high latitude polar routes, such as London Heathrow to Tokyo Narita, the mean ambient equivalent dose rate has been measured at 6 µSv per hour (4). For a Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

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crew member flying 900 hours per year only on this route, the annual exposure would be in the region of 5.4 mSv, ie less than three tenths of the ICRP recommended dose limit. For ultra-long range airline operations (arbitrarily defined as sector lengths in excess of 18 hours), recent studies [22] have shown a mean effective sector exposure of 80 μSv on the Dubai to Los Angeles route. A crew member flying 3 return trips per month would accrue an annual exposure of 5.76 mSv. The FAA has calculated the worst case USA high altitude, high latitude long-haul flight to be New York to Athens, with an equivalent dose of 6.3 µSv per hour [16] For a pregnant crew member working on this worst-case route, she could work 79 block hours each month without the dose to the conceptus exceeding the FAA monthlyrecommended limit of 0.5 mSv (0.5/0.0063 = 79). She could work 2 months without the dose to the conceptus exceeding the recommended pregnancy limit of 1 mSv (1/0.5 = 2). A number of airlines require crew members to cease flying on declaration of pregnancy, in conformity with the European Directive requirement for the radiation exposure to the foetus to be as low as reasonably achievable [3]. For passengers, the ICRP limit for the general public of 1 mSv per year would have equated to about 100 hours flying per year on Concorde, and equates to about 200 hours per year on trans-Equatorial subsonic routes [11]. There are essentially two types of airline passenger – the occasional social traveller and the frequent business traveller. The public limit of 1 mSv per year will be of no consequence to the former, but could be of significance to the frequent business traveller who would exceed the 1 mSv limit if flying more than 8 transatlantic or 5 UK-Antipodean return subsonic journeys per year [11]. However, business travellers are exposed to radiation as an essential part of their occupation and it is logical to apply the occupational limit of 20 mSv to this group. This view has the support of the ICRP [6]. Although business travellers may exceed the doses for aircrew, there is no mechanism in place to monitor or control their exposure.

Epidemiology of Commercial Aircraft Crew Members The annual aircrew dose of cosmic radiation is a relatively low level of overall exposure, with the maximum being no more than 2 or 3 times the annual level of exposure to background radiation at ground level. There have been a number of epidemiological surveys of cancer mortality and incidence in commercial flight crew members over the years, which have reported small excesses of a variety of cancers. However the results have lacked consistency. This lack of consistency mainly derives from the small size of cohorts examined and the lack of data on exposure and confounding factors that might explain the findings. In Europe two large mortality cohort studies, one amongst flight deck crew [8] and one amongst cabin crew [57], together with a large cancer incidence study amongst Nordic pilots [39] have been published. They are based on data from many of the individual studies in the literature but contain additional data, providing increased statistical power in looking at small

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excesses, allow measures of consistency between studies to be determined, and provide the basis for dose-response assessments. Both the Blettner et al paper [8], which looked at 28,000 flight deck crew with 591,584 person years at risk, and the Pukkala et al paper [39], comprising 177,000 person years at risk from 10,211 pilots, concluded that occupational risk factors were of limited influence on the findings. There was consistency though in the mortality study showing an excess of malignant melanoma. In the incidence study, this excess referred to both malignant melanoma and other forms of skin cancer as well. Blettner concluded that the excess melanoma incidence may be attributable to ultraviolet radiation, perhaps due to leisure-time sun exposure, but more work is required. Pukkala et al [39] concluded that although the risk of melanoma increased with estimated dose of ionizing radiation, the excess may well be attributable to solar ultra-violet radiation. In the study by Zeeb et al [57], the excess mortality from malignant melanoma was restricted to male cabin crew members. Several studies in the last decade have suggested a small excess of breast cancer amongst female flight attendants (cabin crew). However, the interpretation has been hampered by sample size and lack of detailed information on confounding factors. In an attempt to unify the findings, the study by Zeeb et al [57] examined data from eight European countries. Mortality patterns among more than 51,000 airline cabin crew members were investigated, yielding approximately 659,000 person-years of follow-up. Among female cabin crew, overall mortality and all-cancer mortality were slightly reduced, while breast cancer mortality was slightly but non-significantly increased. The authors concluded that ionising radiation could contribute in a small way to an excess risk of breast cancer among cabin crew, but the association may be confounded by differences in reproductive factors or other lifestyle factors, such as circadian rhythm disruption. A study by Raffnson et al in 2003 based on 35 cases of breast cancer [42], for which more detailed information on reproductive history is available, attempted to further identify the relative contribution of occupation to the excess seen in their earlier cohort study [40]. When the results are examined the risk is seen to be significantly increased only during the period prior to 1971, when cosmic radiation doses would have been lower due to altitude considerations. No excess is seen in the period after 1971 showing the difficulty of disentangling the contribution of cosmic radiation to the aetiology of breast cancer Overall the conclusion from Zeeb et al [57] was that among airline cabin crew in Europe, there was no increase in mortality that could be attributed to cosmic radiation or other occupational exposures to any substantial extent. A population-based case-controlled study from Iceland published by Raffnson et al in 2005 [41] concluded that the association between the cosmic radiation exposure of pilots and the risk of developing eye nuclear cataracts, adjusted for age, smoking status, and sunbathing habits, indicates that cosmic radiation may be a causative factor in nuclear cataracts among commercial airline pilots. However the study fails to address the variability in objective assessment of cataracts and the possibility of observer bias; it is not possible to exclude the confounder of sunbathing habits. A report by Stern from the German Center of Aerospace in 2006 [52] concluded that the occurrence of cataract surgery amongst their pilot population is smaller than in the normal population, with no cases of pilots having to undergo cataract surgery during their career

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(other than one case of traumatic cataract). Similar findings are reported by the UK CAA (personal communication, 2007). Any association between exposure of airline pilots to cosmic radiation and the development of cataracts would appear to be weak.

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Conclusion for Commercial Aircraft Travellers Whilst it is known that there is no level of ionising radiation exposure below which effects do not occur, the evidence so far indicates that the probability of airline crew members or passengers suffering any abnormality or disease as a result of exposure to cosmic radiation is very low. Epidemiological studies of flight deck crew and cabin crew have so far not shown any increase in cancer mortality or cancer incidence that could be directly attributable to ionising radiation exposure. However, individual mortality studies and combined analyses have shown an excess of malignant melanoma. Separate and combined analyses of cancer incidence have shown an excess for malignant melanoma and for other skin cancers. Many authors believe the findings can be explained by exposure to ultraviolet light. Some others believe that the influence of cosmic radiation cannot be entirely excluded, although no plausible pathological mechanism has been identified With respect to the suggestion that cabin crew may be at a higher risk of contracting breast cancer than those females in a non-flying occupation, it is very difficult to effectively disentangle the relative contributions of occupational, reproductive and other factors associated with breast cancer using the data currently available. Similarly when considering the reported association between cosmic radiation and eye cataracts, it is difficult to exclude observer bias and the influence of sunlight, smoking, dehydration and diet associated with the protein structure changes in the lens associated with age. The European Union has in place a legislative framework for assessing the cosmic radiation exposure for airline crew members, which appears to be effective. Other jurisdictions, such as the USA, rely on advisory material and educational programmes. There is a need to improve worldwide consistency, accuracy of calculations, measurements and allowance for, and avoidance of, solar particle events.

Acknowledgment The assistance in epidemiological interpretation given by Mr David Irvine, formerly of British Airways, is gratefully acknowledged.

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References [1] [2] [3] [4] [5]

[6] [7] [8] [9] [10] [11] [12]

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[13]

[14]

[15] [16]

[17]

[18]

Bagshaw M. Cosmic radiation measurements in airline service. Radiat. Prot. Dosim.; 86(4): 33-33. 1999. Bagshaw M. British Airways measurement of cosmic radiation exposure on Concorde supersonic transport. Health Physics; 79(5): 591-591. 2000. Bagshaw M. Perspectives of those impacted. Health Physics; 79(5): 608-9. 2000 Bagshaw M, Irvine D, Davies DM. Exposure to cosmic radiation of British Airways flying crew on ultralonghaul routes. Occ. Environ. Med.; 53: 515-518. 1996. Bartlett DT. Cosmic radiation fields at aircraft altitudes and their measurement. Proceedings of the Royal Aeronautical Society symposium on in-flight cosmic radiation. London. 6 February 1997. Beninson D, Dunster HI. ICRP public statement, London, 9 May 1991. Billen D. Spontaneous DNA damage and its significance for the 'negligible dose' controversy in radiation protection. Radiat. Res. 124:242-251; 1990. Blettner M, Zeeb H, Auvinen A, et al. Mortality from cancer and other causes among male cockpit crew in Europe. Int. J. Cancer: 106: 951-958. 2003. Campbell RD, Bagshaw M. Human Performance and Limitations in Aviation 3ed. BSP, Oxford. 2003. Document of the National Radiological Protection Board. Chilton, Oxford: NRPB 1993, 4. Davies DM. Cosmic radiation in Concorde operations and the impact of the new ICRP recommendations on commercial aviation. Radiat. Prot. Dosim; 51: 121-124.1993 Duggal SP. Relativistic solar cosmic rays. Rev. Geophys. Space Sci. 17(5); 1021-1058. 1979. EURADOS Working Group 11, Eurados Report 1996-01.The radiation exposure and monitoring of aircrew. European Commission Publication: Radiation Protection 85. Luxembourg, EC. 1996. European Communities. The basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiation. Luxembourg: Office for Official Publications of the European Communities; Council Directive 96/29/EURATOM of 13 May 1996; Official Journal of the European Communities 39:L159; 1996. Federal Aviation Administration. Crewmember training on in-flight radiation exposure. Advisory circular 120-61, May 19, 1994. Friedburg W, Copeland K. What aircrews should know about their occupational exposure to ionizing radiation. DOT/FAA/AM-03/16. Office of Aerospace Medicine, Washington, DC 20591; October 2003. Friedberg W, Copeland K, Duke FE, Nicholas JS, Darden Jr EB, O’Brien III K. Radiation exposure of aircrews, Occupational Medicine: state of the art reviews 17(2): 292-309, 2002. Friedberg W, Faulkener DN, Snyder L, Darden Jr EB, O’Brien K. Galactic cosmic radiation exposure and associated health risks for air carrier crew members. Aviat. Space Environ. Med.; 60: 1104-8. 1989

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73

[19] Goldhagen P. Overview of aircraft radiation exposure and recent ER-2 measurements. Health Physics 79(5):586-591; 2000 [20] Gundestrup M, Storm HH. Radiation-induced acute myeloid leukaemia and other cancers in commercial jet flight deck crew: a population-based cohort study. Lancet; 358: 2029-2031. 1999 [21] Heimers A, Schroder H, Lengfelder E, Schmitz-Feuerhake I. Chromosome aberration analysis in aircrew members. Radiat. Prot. Dosimetry 1995; 60:171-5. [22] Hosegood I. Occupational health issues in ultra-long range (ULR) airline operations. Proceedings of IATA Cabin Health Conference. Geneva, 2004. [23] IARC monographs on the Evaluation of Carcinogenic Risks to Humans. Vol 75. Ionizing Radiation, Part 1: X- and gamma radiation, and neutrons. Lyon: International Agency for Research on Cancer; 2000. [24] ICRP Publication 92: 33(4); 2003. ISSN 0151-6513. [25] International Commission on Radiological Protection. 1990 recommendations of the International Commission for Radiological Protection. New York: Elsevier Science; ICRP Publication 60; Annals of the ICRP21; 1991 [26] Irvine D, Davies DM. British Airways flightdeck mortality study, 1951-1992. Aviat. Space Environ. Med.; 70: 591-59. 1999 [27] Jaworoski Z. Low level radiation no danger. http://news.bbc.co.uk/1/hi/health accessed 12 August 2004. [28] Kaji M, Fujitaka K, Sekiya T, Asukata I, Ohkoshi H, Miyazaki H, et al. In-situ measurements of cosmic radiation dose equivalent on board aircraft to/from Japan: 2nd report. Aviat. Space Environ. Med.; 66: 517. 1995. [29] Lantos P, Fuller N. Solar radiation doses on board aeroplanes. Radiat. Prot. Dosim. 104(3); 199-210. 2003. [30] Lantos P, Fuller N, Bottollier-Depois JF. Methods for estimating radiation doses received by commercial aircrew. Aviat. Space Environ. Med.; 74(7): 751-758. 2003. [31] Leibel SA, Phillips TL. Textbook of radiation oncology. Philadelphia: WB Saunders Co; 1998. [32] Lewis BJ, Bennett LG, Green AR, McCall MJ, et al. Galactic and solar radiation exposure to aircrew during a solar cycle. Radiat. Prot. Dosim.; 102(3): 207-27 2002. [33] Lindborg L, Karlberg J, Elfhag T. Legislation and dose equivalents aboard domestic flights in Sweden. Stockholm: Swedish Radiation Protection Institute, 1991 (SSI Report 91-12). [34] Lovell JL, Duldig ML, Humble J. An extended analysis of the September 1989 cosmic ray ground level enhancement. J. Geophys. Res. 103; 23733-23742. 1998. [35] Nicholas JS, Butler GC, Davis S, Bryant E, Hoel DG, Mohr LC Jr. Stable chromosome aberrations and ionizing radiation in airline pilots. Aviat. Space Environ. Med.; 74(9): 953-958. 2003. [36] O’Brien K. LUIN, a code for the calculation of cosmic ray propagation in the atmosphere. EML-338. New York: Environmental Measures Laboratory, 1978 [37] Oksanen PJ. Estimated individual annual cosmic radiation doses for flight crews. Aviat. Space Environ. Med.; 69: 621-625. 1998. [38] Preston FS. Eight years of Concorde operations: medical aspects. J. R. Soc. Med.; 78: 193. 1985.

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[39] Pukkala E, Aspholm R, Auvinen A, et al. Cancer incidence among 10,211 airline pilots: a Nordic study. Aviat. Space Environ. Med.; 74(7): 699-706. 2003. [40] Rafnsson V, Tulinius H, Jonasson JG, et al. Risk of breast cancer in female flight attendants: a population-based study (Iceland). Cancer Causes Control;12: 95-101. 2001. [41] Rafnsson V, Olafsdottir E, Hrafnkelsson J, Sasaki H, Arnarsson A, Jonasson F. Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based casecontrol study. Arch. Ophthalmol.;123:1102-1105. 2005. [42] Rafnsson V, Sulem P, Tulinius H, Hrafnkelsson J. Breast cancer risk in airline cabin attendants: a nested case-control study in Iceland. Occup. Environ. Med.; 60: 807-809. 2003. [43] Regulla D, David J. Radiation measurements in civil aviation. Final report GSF/BG/DLH research project. Germany: Institut fur Strahlenschutz, 1993. [44] Reitz G. Radiation environment in the stratosphere. Radiat. Prot. Dosim. 51:3; 1993 [45] Roesler S, Heinrich W, Schraube H. Calculation of radiation fields in the atmosphere and comparison to experimental data. Radiat. Res.; 151: 87-97. 1998. [46] Roman E, Ferrucci L, Nicolai F, et al. Increase of chromosomal aberrations induced by ionizing radiations in peripheral blood lymphocytes of civil aviation pilots and crew members. Mutat. Res. 1997; 377:89-93. [47] Scheid W, Weber J, Traut H. Chromosome aberrations induced in the lymphocytes of pilots and stewardesses. Naturwissenschaften 1993; 80:588-30. [48] Schumacher H, Schrewe UJ. Dose equivalent measurements on board civil aircraft. Braunschweig, Germany: 1993. (Report PTB-Bericht N-13). [49] Scraube H, Mares V, Roesler S, Heinrich W. Experimental verification and calculation of route doses. Radiat. Prot. Dosim.; 86: 309-15. 1999. [50] Spurny F, Dachev T. Measurement onboard an aircraft during an intense solar flare, ground level event 60, on April 15 2001. Radiat. Prot. Dosim.; 95: 273-5. 2001. [51] Spurny F, Obraz O, Pernicka F, Votockova I, Turek K. Dosimetry on board subsonic aircraft, CSA flight routes, data and their new interpretation. In: Proceedings of the 24th symposium on radiation protection physics. Gaussig, Germany: 1992. [52] Stern CH. Cataract surgery in pilots. Aviat. Space Environ. Med.; 77 (3): 305-306. 2006. [53] Taverne D. Nuclear Power is fine – radiation is good for you. Sunday Telegraph, August 8, 2004: 20. [54] Wilson JW, Cucinotta FA, Shinn JL. Cell kinetics and track structure. In: Swenberg CE, Horneck G, Stassinopoulos G, eds. Biological effects and physics of solar and galactic cosmic radiation. New York: Plenum Press; 1993: 295-338. [55] Wilson JW, Nealy JE, Cucinotta FA, Shinn JL, Hajnal F, Reginatto M, Goldhagen P. Radiation safety aspects of commercial high-speed flight transportation. Springfield, VA: National Technical Information Service; NASA Technical Paper 3584; 1995. [56] Wilson JW. Radiation environments and human exposures. Health Physics. 79(5):510514; 2000. [57] Zeeb H, Blettner M, Langner I, et al. Mortality from cancer and other causes among airline cabin attendants in Europe: A collaborative study in eight countries. Am. J. Epidemiol.; 158: 35-51. 2003. [58] www.radiologyinfo.org, accessed 22 Aug 2006.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter IV

Radiation Interaction with Blast Furnace Slag: A Comparative Study from the Point of Radiation Shielding Murat Kurudireka,8∗, Yüksel Özdemira and Ahmed Mahmoud El-Khayattb a

b

Faculty o f Science, Department of Physics, Ataturk University,25240, Erzurum-Turkey

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Reactor Physics Department, Nuclear Research Centre, Atomic Energy Authority, Cairo, Egypt

Abstract Cement is the most produced and used binding material in the world with its 1.6 billion tons of annual production. The high consumption of energy for its production causes high CO2 emission due to the nature and processes of raw materials. The world cement industry is responsible for 7% of the total CO2 emission. Thus, the cement industry has a crucial role in global warming. From this point of view, it is of interest to focus on different alternative building materials such as blast furnaces to be used as substitutes for cement. The blast furnace slag (BFS) is used by replacing with cement in different weight proportions for improving the mechanical properties, decreasing the rate of hydration, decreasing the alkali aggregate reactivity and decreasing the permeability of concrete. Moreover, use of supplementary cementitious materials such as BFS with portland cement has become increasing significantly in all world. Besides, keeping in mind the extensive use of cement containing concretes in radiation shielding applications, it would be interesting to study the gamma ray and neutron attenuation properties of BFS for its potential use as an alternative shielding material. For shield design, neutrons and γrays (or X-rays) are the main types of nuclear radiation, which have to be considered, since any shield which attenuates neutrons and γ-rays will be more effective for attenuating other radiations. At this point, the present study aimed at the investigation of ∗ Tel.: +90 442 2314167; f ax: +90 442 23609 48. e-ma il address: [email protected].

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt X and/or gamma radiation interaction with this type of composite material in extended energy regions (1keV-100GeV for photon interaction, 1keV-20MeV for photon energy absorption) including the parameters effective atomic number, effective electron density, kerma relative to air, photon energy absorption attenuation length, total photon interaction attenuation length, energy absorption and exposure buildup factors from 0.015 to 15 MeV up to 40 mfp penetration depths and macroscopic fast neutron removal crosssections. Attenuation of fast neutrons through the studied materials has been investigated by employing the removal cross-section values of their elemental composition. Upon investigation of these parameters, the BFS has been compared with other building materials such as fly ash (FA), silica fume (SF) and natural zeolite (NZ) with respect to the radiation attenuation properties wherever possible. Finally, possible conclusions were drawn with respect to the changes in photon energy, chemical composition, penetration depth and density.

Keywords: Blast furnace slag, cement, radiation shielding, X and gamma rays, fast neutrons

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Introduction By the extensive use of nuclear energy and radioactive isotopes, X- and/or gamma rays in various fields’ viz. reactors, nuclear power plants, nuclear engineering and space technology as well as in medical fields such as nuclear diagnostics (computerized tomography), nuclear medicine, radiation dosimetry and radiation biophysics, the radiation shielding became an important subject due to required proper precautions to avoid the radiation hazards. Since the radiation is not only hazardous for living organisms but also hazardous for other materials i.e. laboratory equipments, the needed precautions must be taken by shielding the radiation sources which can emit X-and gamma photons as well as penetrative neutrons. The intensity of photons can be reduced by the parameters viz. time, distance and shielding. However, the most appropriate way to attenuate radiation is shielding. Among the radiation shielding materials, concrete is one of the widely used shielding material because of its low price and good shielding performance. Concrete is an inorganic material consisting of cement, water and aggregates [1]. On the other hand, the huge economical and environmental concerns on cement production gave rise to the investigation of alternative building materials which have properties of low cost and high pozzolanic activity. The blast furnace slag, silica fume, flyash and natural zeolite are considered to be these types of cementitious materials. The blast furnace slag (BFS) is used by replacing with cement in different weight proportions for improving the mechanical properties, decreasing the rate of hydration, decreasing the alkali aggregate reactivity and decreasing the permeability of concrete [2]. Moreover, use of supplementary cementitious materials such as BFS with Portland cement has become increasing significantly in all over world [3]. Apart from the use as alternative building material, one should especially note BFS due to its potential use in radiation shielding. Before using this type of building material as shielding material, the characteristics of this material based on radiation interaction with matter must be known. When passing through an absorbing medium, the intensity of radiation is reduced by either absorption or scattering processes. The total photon attenuation length, photon energy absorption attenuation length, effective atomic number, effective electron density, kerma relative to air, buildup factor and

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Radiation Interaction with Blast Furnace Slag

77

fast neutron removal cross sections are basic and important parameters representing the attenuation of radiation through the different media. The total photon attenuation length and photon energy absorption attenuation length represent the average distance between two successive interactions of photons. The effective atomic number and effective electron density are the quantities determining the constitutive structure of an unknown object or material. Using the constants like effective atomic number (Zeff) and effective electron density (Ne) of multi-element materials, one can calculate the energy absorption in a given medium via well established formulas. Effective atomic number (Zeff) which is representing the radiation interaction with matter also takes place in some applications viz. designing radiation shielding, computing absorbed dose and build-up factor [4]. In some cases, in order to have some initial information about the chemical composition of a material the Zeff can be utilized [5]. For example the materials having Zeff large generally corresponds to the inorganic compounds and metals, while a small Zeff (≤10) is an indicator of organic substances [6]. It was pointed out by Hine that the effective atomic number cannot be expressed by a single number and the various atomic numbers present in the compound have to be weighted differently [7]. In some cases, the intensity of incident radiation is not only attenuated but also increased by the secondary photons inside the absorbing medium. That is called the “buildup” of radiation and classified into two categories: a) the energy absorption buildup factor that is the buildup factor in which the quantity of interest is the absorbed or deposited energy in the interacting material and the detector response function is that of absorption in the interacting material, b) the exposure buildup factor is the buildup factor in which the quantity of interest is the exposure and the detector response function is that of absorption in air [8]. The probability per unit length of a neutron losing all its energy above thermal is called the fast neutrons removal cross-section ΣR. Also it can be defined as the probability that a fast or fission energy neutron undergoes a first collision, which removes it from the group of penetrating, uncollided neutrons [9]. ΣR is usually determined empirically and in certain instances it may be necessary to estimate a value of ΣR for a material for which there is no satisfactory experimental value available. To meet this requirement ΣR must be calculated. ElKhayatt and El-Sayed [10] developed the MERCSF-N program for calculating ΣR for fast neutrons transmitted through homogeneous mixtures, composites, concretes and compounds. The required physical data representing most periodic table elements have been compiled on the basis of the recommended published data and stored in a data base file. Many calculated values had been published for different compounds and materials [11,12]. The present investigation mainly possesses on determining the radiation attenuation characteristics of BFS for not only X- and gamma radiations but also penetrative neutrons along with making a comparison between BFS and other alternative building materials.

Theory Total Mass Attenuation and Mass Energy Absorption Coefficient According to the Lambert-Beer law, a parallel beam of monoenergetic X-ray and γ- ray photons is attenuated in matter by the following exponential attenuation equation

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

I = I 0e

where

I0

(−

μ )t ρ

(1)

,

I

and

are the incident intensity of photons without attenuation and the attenuated

intensity of photons in the sample, respectively, t ( g / cm 2 ) is the areal density of the sample,

μ ρ (cm2 g ) is the mass attenuation coefficient which is a density independent quantity. In case of a multi-element material (i.e. chemical compound or homogeneous mixture) constituting the sample, the mass attenuation coefficient can be obtained from the coefficients for the constituent elements according to the weighted average

μ ρ = ∑Wi (μ ρ )i

(2)

i

where Wi is the proportion by weight of the i th constituent element. The mass energy absorption coefficients of the given materials can be obtained from Eq. (2) by substituting the mass energy absorption coefficient for the mass attenuation coefficient. However, it should be mentioned that the Eq. (2) is valid for mass energy absorption under the assumption that the errors in calculating mass energy absorption coefficients are small for photon energies below 20 MeV [13].

Total Photon Interaction and Energy Absorption Attenuation Length

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The average distance between two successive interactions representing the total photon interaction attenuation length (TPIAL) is given as follows [14]: ∞

TPIAL =

∫ xe 0 ∞

∫e

− μx

− μx

dx =

dx

(3)

1

μ

0

where

μ

is the linear attenuation coefficient and

x is the linear thickness of absorber.

As in the same manner, the photon energy absorption attenuation length (PEAAL) can be obtained by substituting

μ energy

for

μ

in the Eq. (3).

Effective Atomic Number, Electron Density and Kerma Relative to Air The effective atomic numbers of BFS, SF, FA and NZ have been obtained by means of the practical formula [15]:

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Radiation Interaction with Blast Furnace Slag

Z PI

∑ f i Ai ( i

=

eff

μ )i ρ Aj μ ( ) Z j ρ

79

∑ f j

j

(4) j

where f i is the fraction by mole of the each constituent element providing that ∑ f = 1 , A i is i i

the atomic weight, Z j is the atomic number, ( μ )i is the mass attenuation coefficient. The ρ effective atomic number for photon energy absorption ( Z PEA ) can be obtained from Eq. (4) eff

by substituting the mass energy absorption coefficient for the mass attenuation coefficient. Also, the effective electron density is expressed by the following relation [15]:

N

E

= N

nZ A

eff

∑ ni Ai

= N

Z A

eff

〈 A〉

( electrons

/ g)

(5)

i

where

〈 A〉

is the average atomic mass of the material. Thus, using the obtained values of Z eff

one can calculate the values of

N E by using the Eq. (5).

The kinetic energy released per unit mass (kerma) is defined as the initial kinetic energy of all secondary charged particles liberated per unit mass at a point of interested by uncharged radiation [16,17]. To obtain the relationship between kerma and mass energy absorption coefficient, let ψ (Jm-2) be the energy fluence of mono-energetic photons passing normally through an area A in an absorber. Keeping in mind the energy transferred to charged particles Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

and the mass in the volume with density

ρ

being ψAμ en dx and ρ Adx , respectively, the

kerma is then [18] K =

ψ A μ en dx μ = ψ ( en ) ρ ρ Adx

(6)

Since the kerma is the product of the energy fluence and the mass energy absorption coefficient, kerma of a material relative to air can be expressed as the ratio between the mass energy absorption coefficient of the used material and the mass energy absorption coefficient of air [16]: KERMA

=

(μ en ρ )Material (μ en ρ ) Air

(7)

Energy Absorption and Exposure Buildup Factors To calculate the buildup factors, the G-P fitting parameters were obtained by the method of interpolation from the equivalent atomic number ( Z eq ). Computations are illustrated step by step as follows:

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80

Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt a) Calculation of the equivalent atomic number, Z eq b) Calculation of geometric progression (G-P) fitting parameters c) Calculation of energy absorption and exposure buildup factors At the first step, the equivalent atomic number, Z eq for a particular material has been

calculated by matching the ratio, (μ

ρ )Compton /(μ ρ )Total ,

of that material at a specific

energy with the corresponding ratio of an element at the same energy. Thus, firstly the Compton partial mass attenuation coefficient, (μ coefficients, (μ

ρ )Compton, and the total mass attenuation

ρ )Total , were obtained for the elements of Z = 4 − 40

and for the chosen

building materials in the energy region 0.015-15 MeV, using the WinXCom computer program [19,20] (initially developed as XCOM [21] ). For the interpolation of Z eq for which the ratio

(μ ρ ) Compton /(μ ρ )Total lies between two successive ratios of elements, the

following formula has been employed:

Z eq =

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where

Z1

Z 1 (log R2 − log R ) + Z 2 (log R − log R1 ) log R2 − log R1

(8)

Z2 are the atomic numbers of elements corresponding to the ratios R1 and R2 R is the ratio for the chosen building materials at a specific energy.

and

respectively, At the second step, to calculate the G-P fitting parameters a similar interpolation procedure was adopted as in the case of the equivalent atomic number. The G-P fitting parameters for elements were taken from the ANSI/ANS-6.4.3 [22] standard reference database which provides the G-P fitting parameters for elements from beryllium to iron in the energy region 0.015-15 MeV up to 40 mfp. At the final step, these parameters were used to calculate the energy absorption and exposure buildup factors from the G-P fitting formula [23]:

B( E , X ) =1 +

b −1 ( K x − 1) for K ≠ 1 K −1

B ( E , X ) = 1 + (b − 1) x for K = 1

(9)

(10)

where,

K ( E, x) = cx a + d

tanh(x X k − 2) − tanh(−2) for x ≤ 40 mfp 1 − tanh(−2)

(11)

E is the incident photon energy, x is the penetration depth in mfp, a , b , c , d and X k are the G-P fitting parameters and b is the value of buildup factor at 1 mfp. The

where

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Radiation Interaction with Blast Furnace Slag

81

parameter K represents the photon dose multiplication and the change in the shape of the spectrum. Fast Neutron Removal Cross Section

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The removal cross-sections are the cross-sections ΣR to be used in calculating the attenuation of fast neutrons. In shielding analysis; these called removal coefficients, with units cm-1. It can be viewed as giving the probability of large angle scattering (both elastic and inelastic), which would tend to remove n. The concept of removal cross-section is based upon the presence of hydrogen in the absorber. It can also be applied to other substances backed up by hydrogen absorbers. A number of precise empirical expressions have been proposed for relating ΣR/ρ to the atomic number Z, or to the atomic mass A of the element in question in use are given as follows [24]:

∑ R ρ = 0.21A−0.56 cm2 g −1

(12)

∑R

(13)

ρ = 0.00662 A −1 3 + 0.33 A − 2 3 − 0.211 A −1cm 2 g −1 (for A> 12)

∑ R ρ = 0.19Z −0.743cm2 g −1 (for A≤ 8)

(14)

∑ R ρ = 0.125Z −0.565cm 2 g −1 (for A> 8)

(15)

where ΣR/ρ (cm2.g-1) is called mass removal cross-section of the material. These equations (from 12 to 15) are conditioned by the well known total cross- section, neutron energy range and are restricted for A and Z at certain values. The macroscopic cross-section ΣR is the neutron removal coefficient for materials or elements used without a layer of hydrogenous material, it is calculated as: −1 ΣR = Nσ cm

(16)

where N: is the number of atoms (or molecules)/cm3, and σ removal microscopic cross section of element. The effective removal cross-section for compounds and homogeneous mixtures (concrete, composites) may be calculated from the value ΣR or ΣR/ρ for various elements in the compounds or mixtures by the general formula [24,25]: (17) ΣR / ρ = ( Fw ) i (Σ R / ρ ) i

∑ i

or

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

Σ R = ∑ ρ i (Σ R / ρ ) i

(18)

i

where

ρi

and (Σ R / ρ ) i are the partial density (the density as it appears in the mixture) and the

mass removal cross-section of the ith constituent, respectively and Fw is the weight fraction. In the compound the weight fraction of ith element is given by ( Fw ) i =

ai M i , ∑ a jM j

(19)

j

where ai and M i are, respectively, the number of formula units and atomic weight of the ith element. The values obtained by Eqs. (18) and (19) are usually accurate to within about 10% of that values which determined experimentally [26].

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Calculations Mass attenuation coefficients of BFS, SF, FA and NZ and of elements constituting these composite materials have been calculated by the WinXCom program. This program provides total cross-sections and attenuation coefficients of elements, compounds or mixtures as well as partial cross-sections for incoherent and coherent scattering, photoelectric absorption and pair production both in the field of nucleus and electrons at energies from 1 keV to 100 GeV [20]. The linear attenuation coefficients for the given materials were calculated from the mass attenuation coefficients by multiplying the mass attenuation coefficients with the densities of materials wherever possible. The density values and chemical composition data were taken from elsewhere [3,27]. The obtained linear attenuation coefficients were then used to calculate the TPIAL and PEAAL of the used materials. Several experimental and theoretical values for mass removal cross-sections for most elements and some compounds have been tabulated [12, 25, 28, 29]. Using such tables one can get the value for any compound or material not listed in these tables by employing the above additivity rule Eq. 18. One can save a lot of manual work involved in such an approach, by using, instead, computer programs, such as MERCSF-N program [10] for calculating removal and mass removal cross-section for any compound or shielding material. The calculated values of removal cross-sections are valid for fast neutrons in the range 2-12 MeV. Since the removal cross-section is considered to be approximately constant for those neutron energies [25].

Results

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Radiation Interaction with Blast Furnace Slag

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Effective Atomic Number and Electron Density The variations of Z PIeff with photon energies are shown in Figure 1. From the results, it can be clearly seen that the effective atomic number varies with energy (Figure 1). In the continuous energy range (1 keV-100 GeV), the variation of Z PIeff with energy is mainly dominated by different partial photon interaction processes namely photoelectric absorption, Compton scattering and pair production. The variation in Z PI is large below 100 keV where eff

photoelectric process dominates and the variation is negligible between about 0.2-3 MeV where the Compton scattering is pre-dominating and further there is also a significant change in Z PI which is due to the pair production process. Therefore, the Z PI varies from a higher eff

eff

value at lower energies to a lower value at higher energies with a peak due to photoelectric effect near the K edge of the high Z element present in the material, then it becomes constant with a minimum value at intermediate energies, further there is an increasing trend in Z PI eff

values due to the relative domination of photon interaction processes in different energy regions [30]. The all variations can be clearly explained by the Z dependence of total atomic cross sections thus effective atomic numbers as Z 4− 5 for photoelectric absorption,

Z for

2

Compton scattering and Z for pair production. Likewise, the variation of Z PEA with energy is attributed to the different partial photon

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eff

interaction processes (e.g. photoelectric absorption, Compton scattering and pair production) which are relatively dominant in different energy regions (Figure 4). From the Figs. 1,4, it was observed that BFS has highest values of effective atomic number when compared with other building materials in the continuous energy range. The variation of the effective electron densities, ( N e ) , calculated by the use of Eq. (5) with energy are given in Figs. 2,5. The decreasing trends observed are almost similar to the trends observed for effective atomic numbers. It can be clearly seen that there is no straightline relationship between composition of the given materials and effective electron densities.

KERMA Relative to Air The variation of kerma relative to air with energy is shown in Figure 7. On the basis of the relative domination of the partial photon interaction processes, viz., photoelectric absorption, Compton scattering and pair production, it is worth mentioning that the variation of kerma with energy is clear. It is seen that there is a sharp increase in kerma up to about 40 keV and then there is a sharp decrease up to about 200 keV for the given building materials. The values of kerma keep constant from 0.2 to 4 MeV. After this energy region, there is again a slight increase in kerma beyond 4 MeV. Between 5-100 keV, BFS has higher kerma values than the other materials. After 100 keV, the kerma values seem to be independent of the chemical composition of the given materials.

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

TPIAL and PEAAL

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The Figures 3,6 show the variations of TPIAL and PEAAL values against the photon energies. From these figures, it is observed that the attenuation lengths were found to increase with increase in photon energies. Among the given materials, it was observed that the BFS has lowest values of attenuation lengths thus indicating that it is more effective for radiation shielding than the other materials (Figs. 3,6).

Figure 1. Effective atomic numbers of the given materials for total photon interaction from 1 keV to 100 GeV.

Figure 2. Effective electron densities of the given materials for total photon interaction from 1 keV to 100 GeV. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Radiation Interaction with Blast Furnace Slag

85

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Figure 3. Total photon interaction attenuation lengths of the given materials from 1 keV to 100 GeV.

Figure 4. Effective atomic numbers of the given materials for photon energy absorption from 1 keV to 20 MeV.

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

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Figure 5. Effective electron densities of the given materials for photon energy absorption from 1 keV to 20 MeV.

Figure 6. Photon energy absorption attenuation lengths from 1 keV to 20 MeV.

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87

Figure 7. KERMA relative to air for given materials from 1 keV to 20 MeV.

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EABF and EBF Figures 8,10 (a,b,c,d,e) show the variation of EABF and EBF with incident photon energy in the energy region 0.015-15 MeV at different penetration depths up to 40 mfp. The variation of EABF and EBF with penetration depth is also shown in Figures 9,11 (a,b,c,d) at some incident photon energies. It is worth noting that all the building materials show similar variations in the continuous energy region based on dominations of different photon interaction processes in different energy regions (Figs. 8,10). At lower energies the dominant photon interaction process is photoelectric absorption for which the atomic cross section is

Z 4 −5 proportional with τ ∝ 7 2 , at intermediate energies the Compton scattering process starts E dominating with linear atomic number dependence, at further energies pair production process gives domination with an atomic number dependence which is in the order of Z 2 . The maxiumum values of EABF and EBF were observed at intermediate energies where Compton scattering dominates. For this process, the photons are not completely removed but their energies are only degraded. Hence, this process results with more multiple scattered photons which lead to increase in buildup of photons in the medium. From the Figs. 8,9,10,11, generally, it can be easily seen that buildup of photons are less in BFS when compared with other building materials. This state clearly confirms the availability of BFS with respect to the attenuating of incident photons.

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

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Figure 8. (a,b,c,d,e) The energy absorption buildup factor in the energy region 0.015-15 MeV at 1,5,10,20,40 mfp.

Figure 9. (a,b,c,d) The energy absorption buildup factor up to 40 mfp at 0.015, 0.15, 1.5, 15 MeV. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Radiation Interaction with Blast Furnace Slag

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Figure 10. (a,b,c,d,e) The exposure buildup factor in the energy region 0.015-15 MeV at 1,5,10,20,40 mfp.

Figure 11. (a,b,c,d) The exposure buildup factor up to 40 mfp at 0.015, 0.15, 1.5, 15 MeV. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

Effective Removal Cross Section The effective removal cross –section or the removal coefficient (ΣR) of fast neutron have been calculated for cement, BFS, SF and NZ using the MERCSF-N program. The calculated ΣR for these samples and their partial densities are given in Table 1. The elemental contributions of the materials are arranged in ascending order based on atomic numbers.

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Table 1. Calculations of the fast neutron effective removal cross section for some building materials Elem.

Silica fume ρ = 1.520 (g.cm-3) Natural Zeolite ρ = 1.420 (g.cm-) Partial ΣR cm-1 Partial ΣR cm-1 density g.cm-3 density g.cm-3

O F Na Mg Al Si P S Cl K Ca Ti V Cr Mn Fe Ni Cu Zn Ga As Se Br Rb Sr Y Zr Ba Pb ΣR

7.94E-01 2.30E-03 6.54E-03 9.26E-03 2.41E-03 6.78E-01 9.71E-04 2.27E-03 1.46E-03 1.16E-02 2.56E-03

3.21E-02 8.32E-05 2.23E-04 3.08E-04 7.06E-05 2.00E-02 2.75E-05 6.29E-05 3.67E-05 2.87E-04 6.23E-05

3.51E-04 4.07E-04 2.33E-03 3.94E-05 4.25E-05 5.35E-03 3.96E-05

7.29E-06 8.27E-06 4.98E-05 7.49E-07 7.91E-07 9.79E-05 5.15E-07

1.73E-05 4.41E-05 6.81E-05 3.47E-05

2.94E-07 7.41E-07 1.11E-06 5.55E-07

3.58E-04

3.73E-06 0.0535

6.98E-01

2.83E-02

9.07E-03 1.46E-02 1.06E-01 4.89E-01 4.27E-04 1.13E-03 1.79E-04 4.60E-02 2.97E-02 9.09E-04

Blast furnace slag ρ = 1.940 g.cm-3) Partial ΣR cm-1 density g.cm-3

3.09E-04 4.85E-04 3.10E-03 1.44E-02 1.21E-05 3.13E-05 4.51E-06 1.14E-03 7.22E-04 1.86E-05

7.95E-01 5.61E-03 1.39E-02 1.12E-01 1.16E-01 3.24E-01 8.12E-04 1.86E-02 5.45E-04 2.46E-02 4.66E-01 9.57E-03

3.22E-02 2.02E-04 4.73E-04 3.72E-03 3.38E-03 9.56E-03 2.30E-05 5.14E-04 1.37E-05 6.06E-04 1.13E-02 1.96E-04

1.07E-04 1.01E-03 2.10E-02 3.12E-05

2.22E-06 2.05E-05 4.50E-04 5.94E-07

3.85E-04 2.29E-02 2.36E-02 8.99E-05

8.01E-06 4.65E-04 5.05E-04 1.71E-06

7.53E-05 2.75E-05 2.09E-04

1.38E-06 3.57E-07 3.61E-06

4.80E-04 1.50E-03 8.16E-05

7.83E-06 2.40E-05 9.22E-07

6.75E-04 1.02E-04

8.71E-06 1.06E-06 0.049

1.15E-04 1.73E-03 9.78E-05 3.92E-04 4.98E-03

1.88E-06 2.77E-05 1.11E-06 6.12E-06 6.42E-05 0.0633

From the results, BFS has higher removal coefficient than both SF and NZ. Therefore a higher ability for neutron shielding can be expected. Also it has a comparable value with respect to cement, 0.0633 cm-1 (not listed in Table 1). However, the mass removal coefficient ΣR/ρ (cm2g) for BFS (0.0330 cm2/g) is slightly higher than that assigned value for cement (0.0313 cm2/g). With regarding to gamma-ray shielding, because of the relatively higher density of BFS with respect to SF and NZ, it can be preferred as a replacement for cement.

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Radiation Interaction with Blast Furnace Slag

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Calculation Uncertainty The accuracy of the calculated values of parameters related with photon interaction and energy absorption is based on mass attenuation coefficients. The mass attenuation coefficients of the elements have been taken from the WinXCom [19,20] database which is the successor of the XCom [21] database. WinXCom is a very useful computer program that one can calculate the mass attenuation coefficients of elements, compounds and mixtures for total and partial photon interaction processes with its facilitating to export the cross sectional data to a predefined MS Excel template which is further used for graphical or numerical progresses.

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a)

b)

Figure 12. (a,b) Difference (%) between ANSI database and present work with respect to the calculated values of EABF and EBF for air at some energies up to 40 mfp.

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

Recently, it was reported by Hubbell [31] that the envelope of the uncertainty of mass attenuation coefficient is of the order of 1-2% in the energy range from 5 keV to a few MeV. In case of the energies of 1 to 4 keV, the discrepancies are known to reach to a value of 25 to 50%. Recently, Chantler has successfully addressed the huge discrepancies below 4 keV and derived new theoretical results of substantially higher accuracy in near-edge soft X-ray regions in detail [32]. The most interested energies widely used in biological, medical and shielding applications cover the energies larger than 5 keV, hence the presented results for building materials have an uncertainty of a few percentages. With respect to the accuracy of the calculated values of EABF and EBF , it should be noted that calculations have been checked by comparing EABF and EBF for air present in ANSI [22] database with our calculated EABF and EBF for air in the energy region 0.015-15 MeV and penetration depth up to 40 mfp. From the Figure 12 it can be clearly seen that our calculated values for air agree well with that of ANSI [22] database within a few percent uncertainty. The general expression of the relative combined uncertainty as obtained by applying the theory of the uncertainty propagation to Eq. 17 is given as following

uc − rel (Σ R / ρ ) =

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where

n

∑ (u i =1

2 Fi

+ u(2Σ R / ρ ) )

(19)

uF2i and u(2Σ R / ρ )i are the relative uncertainties of mass fraction and mass removal cross-

section of the element i in the compound C, respectively. For compounds the relative uncertainties in atomic masses of the elements were in the range 8.7x10-8 (Na)…4.83x10-4 (Pb) [33]. The weight of such component in Eq. (19) is negligible. Unfortunately, the last parameter includes the significant component not reported in many cases [34,35] and as a result the uncertainties in the calculated values were not reported. On the other hand, for any homogeneous mixture or composite the main source of uncertainty produced by uncertainties of mass fraction values for its constituents. In all cases, the values obtained by Eqs. (17 and/or 18) are considered to be accurate within about 10% of that values which were experimentally determined [26].

Conclusion To meet the energy demands for technological developments, the nuclear energy has widely been considered as an energy source along with its main advantages of more energy production capability, no release of green house gases, small amount of fuel needed but large amount of energy production and inexpensiveness. Different types of radiation i.e. X-rays, gamma rays, neutrons are produced during the process and use of nuclear power plants and radioactive isotopes which are commercially, industrially and militarily available. Since the radiation is not only hazardous for living organisms but also hazardous for other materials i.e. laboratory equipments, the needed precautions must be taken by shielding the radiation sources which can emit X-and gamma photons as well as penetrative neutrons. By the increasing use of nuclear energy and radioactive isotopes, the researchers and engineers have

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intensely focused on effective radiation shielding technologies. Among the radiation shielding materials, concrete is one of the widely used shielding materials because of its low price and good shielding performance. Cement, as one of the constituents of concrete, is the most produced and used binding material in the world with its 1.6 billion tons of annual production [36]. However, the high consumption of energy for its production causes high CO2 emission due to the nature and processes of raw materials [37]. The world cement industry is responsible for 7% of the total CO2 emission [38]. Thus, the cement industry has a crucial role in global warming. What are needed today are alternative building materials of high radiation attenuation capability, low cost and environmentally friendly. As a conclusion, the comparison of BFS with other building materials such as SF, FA and NZ showed that BFS has superior properties than the other materials with respect to the radiation attenuation properties in the continuous energy region, thus confirming the availability of using BFS instead of SF, FA and NZ for radiation shielding purposes.

References

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[1]

Lee, C. M.; Lee, Y. H.; Lee, K. Cracking effect on gamma-ray shielding performance in concrete structure Proc. Nucl. Energy 2007, 49, 303-312. [2] Demirboga, R.; Türkmen, İ.; Karakoç, M. B. Relationship between ultrasonic velocity and compressive strength for high-volume mineral-admixtured concrete. Cem. Concr. Res. 2004, 34, 2329–2336. [3] Kurudirek, M.; Türkmen, İ.; Özdemir, Y. A study of photon interaction in some building materials: High-volume admixture of blast furnace slag into Portland cement Rad. Phys. and Chem. 2009, 78, 751-759. [4] Özdemir, Y.; Kurudirek, M. A study of total mass attenuation coefficients, effective atomic numbers and electron densities for various organic and inorganic compounds at 59.54 keV Ann. Nucl. Energy 2009, 36, 1769-1773. [5] Kurudirek, M.; Aygun, M.; Erzeneoğlu, S.Z. Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions Appl. Radiat. Isot. 68, 2010, 1006-1011. [6] Manohara, S. R.; Hanagodimath, S. M.; Gerward, L. Studies on effective atomic number, electron density and kerma for some fatty acids and carbohydrates. Phys. Med. Biol. 2008, 53, 377-386. [7] Hine, G. J. The effective atomic numbers of materials for various gamma interactions. Phys. Rev. 1952, 85, 725. [8] Singh, S. P.; Singh, T.; Kaur, P. Variation of energy absorption buildup factors with incident photon energy and penetration depth for some commonly used solvents Ann. Nucl. Energy 2008, 35, 1093-1097. [9] Blizard, E. P.; Abbott, L.S. Reactor Handbook, vol. III, Part B, Shielding. John Wiley and Sons, Inc. 1962. [10] El-Khayatt, A.M.; El-Sayed Abdo, A. MERCSF-N calculation program for fast neutron removal cross-sections in composite shields. Ann. Nucl. Energy 2009, 36, 832-836.

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Murat Kurudirek, Yüksel Özdemir and Ahmed Mahmoud El-Khayatt

[11] El-Khayatt, A.M. Radiation shielding of concretes containing different lime/silica ratios. Ann. Nucl. Energy 2010, 37 (7), 991-995. [12] El-Khayatt, A.M. Calculation of fast neutron removal cross-sections for some compounds and materials. Ann. Nucl. Energy 2010, 37(2), 218-222. [13] Hubbell, J.H.; Seltzer, S.M.; 1995. Tables of X- ray mass attenuation coefficients and mass energy absorption coefficients from 1 keV to 20 MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest National Institute of Standards and Technology Gaithersburg, MD20899, Report NISTIR 5632. [14] Tsoulfaniidis, N. Measurement and detection of radiation. Hemisphere Publishing Corporation: Mcgraw-Hill Book Company; 1983, p. 151. [15] Manohara, S. R.; Hanagodimath, S. M.; Thind, K. S.; Gerward, L. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV. Nucl. Instr. And Meth. B 2008, 266, 3906-3912. [16] Manohara, S. R.; Hanagodimath, S. M. Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV. Nucl. Instr. And Meth. B 2007, 264, 9-14. [17] Attix, F. H. Introduction to Radiological Physics and Radiation Dosimetry (New York: Wiley) 1986. [18] ICRU. Radiation Quantities and Units Report 33 of the International Commission on Radiation Units and Measurements (Bethesda, MD: ICRU) 1980. [19] Gerward, L.; Guilbert, N.; Jensen, K. B.; Levring, H. X-ray absorption in matter. Reengineering XCOM Rad. Phys. and Chem. 2001, 60, 23-24. [20] Gerward, L.; Guilbert, N.; Jensen, K. B.; Levring, H. WinXCom- a program for calculating X-ray attenuation coefficients Rad. Phys. and Chem. 2004, 71, 653-654. [21] Berger, M. J.; Hubbell, J. H. 1999 XCOM: Photon Cross Sections Database. Web Version 1.2, available at http:// physics.nist.gov/xcom, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA, August 1999. Originally published as NBSIR 87-3597, XCOM: Photon Cross Sections on a Personal Computer (July 1987) 1987-1999. [22] ANSI/ANS-6.4.3. Gamma ray attenuation coefficient and buildup factors for engineering materials American Nuclear Society, La Grange Park, Illinois 1991. [23] Harima, Y.; Sakamoto, Y.; Tanaka, S.; Kawai, M. Validity of the geometricprogression formula in approximating gamma ray build up factors Nucl. Sci. Eng. 1986, 94, 24-35. [24] Wood, J., 1982. Computational Methods in Reactor Shielding. Pergamon Press, Inc., New York, USA. [25] Kaplan, M.F., 1989. Concrete Radiation Shielding. John Wiley and Sons, Inc., New York. [26] Glasstone, S. and Sesonske, A., 1986. Nuclear Reactor Engineering. Third Edition,CBS Publishers and Distributors, Shahdara, Delhi, India. [27] Türkmen, İ.; Özdemir, Y.; Kurudirek, M.; Demir, F.; Simsek, Ö.; Demirboğa, R. Calculation of radiation attenuation coefficients in Portland cements mixed with silica fume, blast furnace slag and natural zeolite. Ann. Nucl. Energy 2008, 35, 1937-1943. [28] Profio, A.E., 1979. Radiation Shielding and Dosimetry. John Wiley and Sons, Inc., New York.

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[29] Chilton, A.B.; Shultis, J.K.; Faw, R.E. Principles of Radiation Shielding. Prentice-Hall, Englewood Cliffs, NJ 1984. [30] Kurudirek, M.; Büyükyıldız, M.; Özdemir, Y. Effective atomic number study of various alloys for total photon interaction in the energy region of 1 keV–100 GeV Nucl. Instrum. Methods Phys. Res., Sect. A 2010, 613, 251-256. [31] Hubbell, J. H. Review of photon interaction cross section data in the medical and biological context Physics in Medicine and Biology 1999, 44, R1-R22. [32] Chantler, C.T. Detailed Tabulation of Atomic Form Factors, Photoelectric Absorption and Scattering Cross Section, and Mass Attenuation Coefficients in the Vicinity of Absorption Edges in the Soft X-Ray (Z=30–36, Z=60–89, E=0.1 keV–10 keV), Addressing Convergence Issues of Earlier Work Detailed Tabulation of Atomic Form Factors, Photoelectric Absorption and Scattering Cross Section, and Mass Attenuation Coefficients in the Vicinity of Absorption Edges in the Soft X-Ray (Z=30–36, Z=60– 89, E=0.1 keV–10 keV), Addressing Convergence Issues of Earlier Work. J. Phys. Chem. Ref. Data 2000, 29, 597. [33] Wieser, M.E. Pure Appl. Chem. 78 (11), 2051–2066 ((IUPAC Technical Report). (‘‘Atomic weights of the elements 2005”) 2006. [34] Turner, J.E., 2007. Atoms, Radiation, and Radiation. Third, Completely Revised and Enlarged Edition, Wiley-VCH. Verlag, GmbhandCo. KGaA, Weinheim. [35] Bloz, R. E., and Tuve, G. L., 1973. CRC Hand Book of tables for applied engineering science, 2nd edition, CRC Press LLC, USA. [36] Worrell, E.; Martin, N.; Price, L. Potentials for energy efficiency improvement in the US cement industry. Energy 2000, 25, 1189. [37] Kurudirek, M.; Özdemir, Y.; Türkmen, İ.; Levet, A. A study of chemical composition and radiation attenuation properties in clinoptilolite-rich natural zeolite. Rad. Phys. and Chem. 2010, 79, 1120-1126. [38] Mehta, P.K. Greening of the concrete industry for sustainable development. Concrete International 2002, 24, 23.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter V

Radiation Exposure of Tunisian Aircrews: Doses Simulations Neïla Zarrouk9 and Raouf Bennaceur Laboratoire de Physique de la Matière Condensée, Faculté des Sciences de Tunis, Tunisia

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Abstract Owing to their professional activity, aircraft crew and even frequent flyers may receive a dose of some millisieverts within a year from cosmic radiations of galactic and solar origin and from secondary radiation produced in the atmosphere. The effective dose is estimated using various experimental and calculation tools. The need to assess the dose received by aircrew and frequent flyers has arisen following the Recommendations of the International Commission on Radiological Protection in publication 60 ICRP 60. In 1996 the European Union introduced a revised Basic Safety Standards Directive that included exposure to natural sources of ionising radiations, including cosmic radiation as occupational exposure. Several equipments were used for both neutron and non-neutron components of the onboard radiation field produced by cosmic rays. A good agreement was observed for both passive and active detectors determining the different components of the radiation field. Such a field is very complex, therefore dose measurement is complex and the use of appropriate computer programs for dose calculation is essential. Our results concerning effective doses received by Tunisian flights, computed with CARI-6, EPCARD 3.2, PCAIRE, and SIEVERT codes, show a mean effective dose rate ranging between 3 and 4 mSv/h. The advantages of the small passive detectors as an-easy to handle monitoring system for in-flight surveillance are demonstrated by several measurements. Indeed the evaluation of thermoluminescent dosimeters (TLDs) according to the high-temperature ratio (HTR) method enables the determination of the dose average linear energy transfer ;

9 Email adress: [email protected].

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Neïla Zarrouk and Raouf Bennaceur the mean quality factor and the dose equivalent in mixed radiation field. We give in this work our investigations of the HTR method associated to neural network system for assessment of total dose and dose caused by neutrons. These NNT-HTR equivalent doses for Tunisian flights are then in general clearly higher than effective doses obtained by codes calculations.

Introduction

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The radiation risk due to highly ionizing cosmic ray nuclei is of particular importance for astronauts, aircrews and even for frequent flyers. Indeed with the steadily increasing human mobility and the development of improved high altitude jet aircraft, a number of studies on cosmic radiation exposure of local airlines crews have been undertaken in many countries in recent years [1-4]. We present and compare as first step in this chapter the different results of other works concerning dose measurements and calculations due to cosmic rays on board aircrafts. In another part we have investigated the results of our previous work [21] and those of M.Noll et al and M.Hajek et al [85,86]. We present then our results concerning cosmic rays equivalent doses for Tunisian flights obtained with neural network system. The training was performed on equivalent dose rates obtained with high temperature ratio (HTR) method for a series of flights studied in other works [85, 86]. These results are then confronted to those for effective doses of cosmic rays received by Tunisian flights, computed with CARI-6, EPCARD 3.2, PCAIRE, and SIEVERT codes.

1. Cosmic Rays Doses on Board Aircrafts: Measurements and Calculations 1.1. A Summarised Comparison between Different Measurements from other Works 1.1.1. Choice of Materials and Methods for the Complex Radiation Field Primary cosmic rays (85% protons, 12% alpha particles, 1% heavy nuclei ranging from carbon to iron, and 2% electrons and positrons) arrive at the hemisphere isotropically. Their sources are thought to include supernovae, pulsar acceleration, and explosion of galactic nuclei. [9-11].These particles can have energies in excess of 1020 eV. In the atmosphere and at ground level, the flux of cosmic ray particles is mostly due to galactic protons incident on the atmosphere. At typical cruising altitudes (33000-43000 ft), aircrews are exposed to higher levels of radiation from galactic cosmic rays than persons on the ground receive from natural background radiation. At such altitudes, most of the radiation dose originates from the secondary particles coming from interaction of primary particles with upper atmosphere. Measurements on board aircraft have been performed with many different types of instruments. Some are electronic instruments measuring the dose continuously during a flight

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either as dose rate (dose per hour, µSv /h) or as the dose for the complete route (route dose, µSv). The result is basically available immediately after the flight. Among these active detectors: the Tissue Equivalent Proportional Counter (TEPCs), considered as a reference instrument for air-crew dosimetry, being sensitive to environmental conditions (such as vibrations, noise, change of pressure, etc.), and requiring specialized service and maintenance, is not applicable as a routine monitoring instrument; ionisation chambers; neutron monitors; Geiger-Muller-(GM)-counters and detectors based on semiconductor techniques. Such detectors are detecting the electric charge that ionising radiation creates, when passing a material. The electric current or electric charge generated in many of those detectors is extremely small and the detectors themselves are often fragile. The equipment has then to be handled with great care. Another feature is that they need a power supply (either a battery or a connection to the power line onboard the aircraft). As such installations have to follow certain regulations or routines special permissions are usually requested. Passive detectors store the dose of a particle deposit when passing the detector. Here the radiation produces a reversible or non-reversible effect in the detector. The result is evaluated after the flight with special equipment. Such detectors are without electronic components and are rugged and usually quite small. For that reason they are very easy to use on board. However the sensitivity is usually low and to improve it with counting statistics, several detectors are often stacked together and /or could be flown several times before being evaluated. Examples of such detectors are thermoluminescence detectors (TLDs), bubble detectors and track etched detectors (a common material is PADC). Detectors based on neutron-induced fissions in Bismuth and Gold have been developed ad hoc for cosmic ray dosimetry , which make it possible to measure the component of high energy neutrons selectively. Some detectors are sensitive to only a part of the radiation qualities present onboard aircrafts and several different detectors are then needed. All instruments need to be calibrated carefully and traceability to international dose standard needs to be established. According to the detectable component of radiation, the instruments have been divided into those designed to measure the non-neutron (some authors use “ionising”) and the neutron components of the cosmic radiation. The non-neutron component approximately corresponds to the low-LET component ( 1.4 kWm2

(21)

where tp is time to experience pain (s) and qr is the irradiance. A more general expression is found in Purser (2008) for different end effects of radiation exposure

t rad =

r q

4/3 r

(22)

where trad is the tolerance time (min) for different end effects, r (kW4/3m−8/3min) is the radiation exposure does required for given end effects. The values of r for three different effects are listed in Table 4. Table 4. Critical radiation exposure doses for different end effects.

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End effect Skin pain, or first degree burn Second degree burn Third degree burn

r (kW4/3m−8/3min) 1.33 ~1.67 4.0 ~12.2 16.7

Equation (22) may be normalized into a form similar to Eq.(21)

t rad

⎛q ⎞ = c⎜⎜ c ⎟⎟ ⎝ qr ⎠

4/3

(23)

where c is a conversion factor and is equal to 1 min, qc is the critical radiant heat flux (kWm−2) to inflict a given damage effect within one minute. The values of qc for different damage effects can be obtained from those of r and are listed in Table 5. Table 5. Critical radiant heat flux for different end effects. End effect qc (kWm−2) Skin pain, or first degree burn 1.24 ~1.47 Second degree burn 2.83 ~6.53 Third degree burn 8.26

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Yaping He

t (min)

The variation in the critical heat flux for a damage effect reflects the variations or uncertainties in the physical and mental threshold tolerance of individual human beings, as well as the variations in the conditions under which the tests were conducted to obtain the data. It may be asserted that any given value of qc represents the critical heat flux for certain percentile of the human population. Figure 8 is a plot of Eq.(23) for three types of skin damage with the corresponding critical radiant heat fluxes. Figure 8 may be used to determine tenability limit in fire safety engineering design. When designing fire safety systems, engineers will consider maintaining the conditions in any given locations tenable for sufficient period of time such that building occupants can evacuate to place of safety. From conservative point of view, skin burns are to be avoided. Therefore, the lower critical value of r =1.33 kW4/3m−8/3min, or qc=1.24 kWm−2 may be selected (Purser, 2008), though some value as high as qc=2.5 kWm−2 has been suggested in the literature (Babrauskas, 1979).

q c =1.24 kWm-2

1.6

Skin pain Series1

1.4

2nd degree Series2

burn q c =2.83 kWm-2

1.2

3rd degree Series3

burn q c =8.26 kWm-2

1 0.8 0.6 0.4

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0.2 0 0

5

10 15 -2 q (kWm )

20

25

Figure 8. Thermal radiation exposure time to skin damage.

4. Fire Generated Thermal Radiation The evaluation methods of thermal radiation hazard produced by fires are discussed in this section.

4.1. Radiation from Flames Fire is a combustion process involving exothermic chemical reactions in which energy is released in the form of heat. The exothermic reaction usually takes place in gaseous phase and temperature of the product gases is elevated. The physical space where the reaction takes

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place is loosely referred to as flame region. The heat is released from the flame region to the surrounding environment by both radiation and convection. For clean combustions where only gaseous products are produced, the radiation energy is released at distinct wavelengths that are particularly associated with the molecular structures of the product species (Drysdale, 1998). Most of these wavelengths are associated with fire product gases, such as CO, CO2, H2O and HCl, and are in infrared region which are invisible by human eyes. Therefore, flames of clean combustion are non-luminous. Complete or clean combustions are rarely observed in nature. Incomplete burning of organic fuel produces carbonaceous particles (Lahaye, 1990) with the size in the order of tens of nanometres. These carbonaceous particles usually aggregate together to form agglomerates known as soot with sizes ranging from hundreds of nanometres to a few micrometres (Mulholland, 2008). Presented in Figure 9 is a micrograph of soot particles.

Figure 9. Micrograph of soot particles [taken from Lahaye (1990)].

The presence of soot in the product gas and air mixture changes the radiation and optical properties of the mixture dramatically. Soot or aerosol particles are major emitters in flames and smoke. The black body like behaviour of soot generates thermal radiation in a much broader wavelength band, making flames visible or luminous. Soot particles also obscure light and reduce visibility through smoke (Jin, 2008, Weinert, 2003). The soot and gas mixture can be treated as a grey body (de Ris, 1979). The emissivity of soot laden gas, or smoke, is related to its optical property and characteristic dimension by Bouguer’s law (Mulholland, 2008) [it is also referred to as Lambert-Beer law (Drysdale, 1998) or BeerLambert-Bouguer law]

ε = 1 − exp( − KL )

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(24)

134

Yaping He

where K is the light extinction coefficient and L is the characteristic length of the flame or smoke region. The above expression holds when the media of soot-gas mixture is uniform, or homogeneous. For non-homogeneous media where extinction coefficient is dependent on the location along the path, s, the following more generally defined expression can be used

⎞ ⎛ L ε = 1 − exp⎜⎜ − ∫ K (s )ds ⎟⎟ ⎠ ⎝ 0

(25)

where the integral is referred to as the optical pathlength. If the average extinction coefficient is known, as produced by the type of fire model known as zone fire models (Peacock, 2008), then the average value, Ka, can be used in Eq.(24) in place of K (He, 2009). The average extinction coefficient is defined as

Ka =

1 L K ( s)ds L ∫0

(26)

Based on this definition, Eq.(25) can be written as

ε = 1 − exp(− K a L)

(27)

The extinction coefficient is a function of the density, or mass concentration of soot particles in the gas mixture, ms

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K = Kmms

(28)

where Km is the extinction coefficient per unit mass (m2/g). The value of Km is found by Mulholland and Croarkin (2000) to be 8.7±1.14 m2/g for smoke produced by flaming combustion of wood and plastics. This value has been used by some popular fire simulation models to estimate thermal radiation by flame and hot smoke (Peacock, 2008, McGrattan, 2009). The mass concentration of soot particles in the gas mixture produced by a fire depends on soot production rate by the fire and the air entrainment rate into the fire plume. The former is related to the burning rate and soot yield of the fuel (Tewarson, 2008). The latter is also related to the burning rate, or heat release rate of the fire (Heskestad, 2008). It should be noted that from Eqs.(17) and (29)

⎞ ⎛ L τ = 1 − ε = exp⎜⎜ − ∫ K (s )ds ⎟⎟ ⎠ ⎝ 0

(29)

4.2. Evaluation of Thermal Rational Hazards As discussed in Section 0, radiant heat flux generated by fires is one of the key parameters in calculation of fire hazard and tenability of physical conditions (Beyler, 2008,

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Thermal Radiation and Fire Safety

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Cooper, 1995). It is also a key parameter in flaming ignition of a solid combustible material and the subsequent spread of flames over its surface and steady burning which have been identified as the critical processes in the development of a fire (Fernandez-Pello, 1995). The fire spread to noncontiguous surfaces out of the plume region is predominantly controlled by thermal radiation heat transfer. Pre-heating of the solid material is the first step of the ignition process (Drysdale, 1998). The preheating of the non-burning fuel bed surrounding an established fire source is primarily achieved via thermal radiation heat transfer. Thermal radiation from a fire source can also trigger other events such as the activation of thermal detectors and sprinklers (Luo, 1999). In determining thermal radiation hazard, one is interested in the maximum heat flux, or irradiance, at a distance from a given emitting source and Eq.(19) can be used for evaluation. For conservative estimate, or if the distance between the emitting source and the point of interest is small, the transmissivity of the media can be assumed to be unity. The main task in the evaluation is to determine the configuration factor, the emissivity of the source and its temperature. 4.2.1. Thermal Radiation Hazard from Open Fires A particular problem, which is encountered in fire protection and in the analysis of fire initiation and spread, is the maximum irradiance at a distance from the base of a fire flame. The simplest method to estimate this parameter is to approximate the fire source as a point source and the point is at the centre of the flame region as shown in Figure 10. If the distance L from the target T to the fire source P is significantly greater than the fire diameter D, i.e., L>>D, then the irradiance at the target can be estimated from

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(30) where Q is the heat release rate of the fire (kWm-2), χ is the radiant fraction usually taken as 0.3 (Drysdale, 1998). The point source location P can be set at the half way of the flame height, H. In this case /

(31)

The evaluation of flame height H is given at the later part of this subsection. See Eq.(43).

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Yaping He

P T

H

θ L D

Figure 10. Geometry for irradiance evaluation.

Fire flames from a horizontal fuel bed can be treated as finite cylindrical emitting bodies (Dayan, 1974). The geometry of an idealised cylinder representing a fire flame and an arbitrary differential element area are shown in Figure 11.

R

z

H

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dA1

γ α

A2

n

β y L

x

Figure 11. Configuration of a cylinder and a differential element area.

As mentioned in Section 0, the configuration factor also depends on the orientation of the receiver. The orientation of an element area is denoted by a unit vector normal to the element area, n. Its components along x, y, and z coordinates are denoted by nx, ny and nz. It follows that

n = nx i + n y j + nz k and

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(32)

Thermal Radiation and Fire Safety

n x2 + n y2 + n z2 = 1

137

(33)

By definition

n x = cosα ,

n y = cos β

and

n z = cosγ

(34)

where α, β and γ are angles between n and x-axis, y-axis and z-axis respectively (see Figure 11). An expression for calculating the heat flux from the cylindrical flame to the target element area is given by Karlsson and Quintiere (2000)

q = σT f4ε ( F1 + F2 + F3 )

(35) where Tf is flame temperature and ε is flame emissivity. The parameters F1, F2 and F3 are component configuration factors and are defined as

F1 = n xφ x ,

F2 = n yφ y

and F3 = n zφ z

(36)

where φx, φy and φz are the configuration factors between the finite area and the differential areas perpendicular to x-axis, y-axis and z-axis respectively. In general, the configuration factor between a finite area and a differential area of arbitrary orientation can be expressed as (Siegel, 1992)

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φ = F1 + F2 + F3 = n x φ x + n yφ y + n zφ z

(37)

It can be shown (see Appendix A) that maximum value of the configuration factor is the vector sum of the three component configuration factors

φ max = φ x2 + φ y2 + φ z2

(38)

Intuitively, for a symmetrical cylinder the maximum configuration factor is attained when the differential element is directly facing the cylinder. In this case, as depicted in Figure 11, α=π/2 and nx=0. The term Fx is then dropped from Eq.(38) (Beyler, 2008).

φmax = φ y2 + φ z2 The expressions for the component configuration factors are

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(39)

138

Yaping He

(

)

1 ⎧⎪ a a 2 + b2 +1 a 2 + (b + 1) ⎛ b − 1 ⎞ −1 tan φy = ⎨ ⎟ 2 ⎜ πb ⎪ [a 2 + (b + 1)2 ][a 2 + (b − 1)2 ] a 2 + (b − 1) ⎝ b + 1 ⎠ ⎩ + tan −1

a b2 −1

− a tan −1

2

b −1 ⎫ ⎬ b +1 ⎭

(40)

and 2 1 ⎧⎪ −1 b + 1 a2 + b2 −1 a 2 + (b + 1) ⎛ b − 1 ⎞ ⎫⎪ −1 φ z = ⎨tan tan − ⎟⎬ 2 ⎜ 2 2 π⎪ b −1 a 2 + (b − 1) ⎝ b + 1 ⎠ ⎪ [a 2 + (b + 1) ][a 2 + (b − 1) ] ⎭ (41) ⎩

where

a=

H R

and

b=

L R

(42) For a given fire with known diameter, D, and heat release rate, Q, the flame height, H, can be estimate from (Heskestad, 2008)

H = 3.7Q*2 / 5 − 1.02 D

(43)

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The Froude number, Q*, in the above equation is defined as

Q* =

Q

ρ∞ c pT∞ gDD2

(44)

where ρ∞ is the ambient air density (kg/m3), cp is the specific heat of air at constant pressure (kJ.kg-1.C-1), T∞ is the ambient air temperature (K), g is the acceleration due to gravity (m.s-2). 4.2.2. Radiation from Openings of Fire Enclosures When an opening (usually rectangular) exists in a fire enclosure, which may be created by window glass breakage (see Section 0), thermal radiation will escape from the opening. In addition, flame and fire plume may form outside of the opening as a result of flashover (Drysdale, 1998). The radiation from the opening and the flame outside of the opening could cause fire spread to adjacent buildings and is of a concern for fire safety engineering design. To evaluate the irradiance at the location of the adjacent building, the opening can be treated as a black body radiation panel. For the rectangular radiation panel, the two component configuration factors in the coordinate system as shown in Figure 12 are given as

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(45) and

(46) where

(47) H is the panel height, B is the panel width and L is the distance of the receiver to the panel. The expression for φx is similar to Eq.(46) except that the positions of parameters X and Y are swopped.

B

z

y

H Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

L o x

Figure 12. Configuration of a rectangular panel and a differential element area.

For a rectangular panel of uniform temperature, the maximum irradiance or configuration factor is known to be along the centre line perpendicular to the panel when the receiver is facing the panel as shown in Figure 13. The configuration factor of this configuration is the sum of the configuration factors of the four quadrants which are equal in value. ∑

4

(48)

where φ2 can be calculated using Eq.(45), however, the parameters X and Y in this case are evaluated as in the following

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B 1 3 L

2 4

H

Figure 13. The maximum configuration factor between a rectangular panel and a differential element area.

To include the radiation from the external flame issued from the opening and the flame together, the flame dimension needs to be evaluated. The following correlation were developed by Thomas and Law (1974) from data on flame projection from buildings in the absence of wind: 12.8

/

(50)

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and .

0.454

(51)

wherez = height of flame tip above window soffit (m) m = burning rate (kgs-1) x = horizontal reach from building facade (m) The definitions of dimensions are illustrated in Figure 14. The flame tip is identified as the point where the temperature of the flame is 540 °C. The burning rate is given by one of two equations, which ever gives the lower value. The first expression for burning rate is based upon the fuel load in the compartment and the assumption that most fires burn out in 20 minutes (1200 s). kg/s where M is fuel load (kg) inside the enclosure. The second expression for burning rate is

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(52)

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.

1

0.18

exp

0.036

√

(53)

where AT = total internal surface area of walls & ceiling excluding ventilation openings (m2) Av = area of window or vent openings (m2) D = depth of compartment (m) W =width of compartment (m) The window flame can be treated approximately as a radiation panel with its height evaluated from Eq.(50). The width of the panel, or the flame front, can be taken as the width of the vent opening (B).

x

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z

Flame

H

Figure 14. Projection of flame from a window.

4.3. Evaluation of Thermal Radiation Hazard Using Fire Modelling Tools Computerised fire models are available for evaluation of thermal radiation hazards for more complicated scenarios as well as the simplified scenarios covered in the previous subsections. The fundamental principles used in computer models are the same. The differences are in the assumptions and the computation algorithm or technique employed. Some of the models are introduced in the following subsections.

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4.3.1. Firewind FIREWIND is the window version of FIRECALC (CSIRO, 1993), a fire engineering software package developed by Commonwealth Science and Industry Research Organisation (CSIRO) in Australia. The software is capable of calculating sprinkler activation time and smoke filling process in a room as a consequence of a fire. The software is capable of calculating thermal radiation from multiple window openings. It requires the user to provide descriptions of window orientations and dimensions. The program generates tabulated irradiance readings in a grid around the specified location and a corresponding irradiance contour map.

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4.3.2. Cfast CFAST is a computer software package developed at National Institute of Standards and Technology, USA (Peacock, 2008). Its core engine is a zone model as described in Peacock (1993). Zone models divide the enclosure into two zones (or control volumes), namely, the upper hot smoke zone and the relatively cooler lower air zone. The approach of two zone fire models evolved from the experimental observation of stratifying, or layering effect in enclosure fires. It is assumed in zone modelling approach that the variations in temperature, smoke density and gas concentrations in a layer are small as compared to the variations between the layers. Zone models use predictive equations and source terms to model the fire growth and transport of smoke and gases. The predictive equations are derived from the fundamental conservation of mass and energy as well as equations for the ideal gas law and internal energy. CFAST is capable of simulating smoke movement in multiple enclosures. The model generates output of radiant heat flux imposed on floor or a target in fire affected rooms, as well as smoke layer temperature, extinction coefficient and toxic species concentrations. 4.3.3. Fire Dynamic Simulator Fire Dynamic Simulator (FDS) is a computational fluid dynamics model (McGrattan, 2010a, McGrattan, 2010b). It is developed at the National Institute of Standards and Technology, U.S.A. The software solves numerically a form of the Navier-Stokes equations appropriate for low-speed, thermally-driven flow with an emphasis on smoke and heat transport from fires. In calculating radiant heat transfer the model treats the mixture of air and fire product gases as a grey gas. The model generates output of radiant heat flux at the solid surface of any specified object as well as radiant heat flux at any given point in gas phase.

4.4. Thermal Radiation and Fire Detection The radiant energy released by fires gives clues of their presence. Various radiant energy sensing devices are available for fire or flame detection (Heitmann, 1983, Qiao, 1992, Dungan, 2008). They are primarily used in industrial applications. Depending on their response wavelength, the radiant energy sensing fire detectors are classified into ultraviolet (UV) flame detectors and infrared (IR) flame detectors. The former are sensitive to radiant

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energy within the wavelength band of 0.1 μm to 0.35 μm and can be used to detect most fires. The latter are sensitive to radiant energy within the wavelength band of 0.76 μm to 220 μm and are used to detect fires involving carbon-containing fuels. As many natural fires emit both infrared and ultraviolet radiation waves, combined UV/IR flame detectors have been developed (see Figure 15). Flame detectors are often used in premises where flammable liquids processing is undertaken in the detection zone. Aircraft hangers are one example of places where flame detectors find their use. Flame detectors are line of sight detectors. Their mounting locations are critical for effective detection. Another problem associated with the radiant energy sensing detectors is the nuisance detections, or false detections, which are triggered by background radiation noise or radiation emitted from legitimate sources such as wielding sparks, torches and sunlight. To address this problem, an integrator device is included in flame detectors, which senses the flickering of flames. The characteristic flickering frequency of flames is in the range of 5 to 15 Hz (Hamins, 1992). Flame detectors are therefore set up to detect thermal radiation signal with characteristic frequency within this range.

Figure 15. A combined UV/IR flame detector (courtesy of General Monitors)

There has been significant development in video-based fire detection systems in recent decades (Verstockt, 2009). The sensors in these systems are video cameras which are responsive to visible light or much wider spectrum including UV and IR (Chen, 2004, Qi, 2009). The sensors are integrated into systems which use various algorithms to filter out noises and extract true fire signals (Chen, 2010).

5. Glazing Materials and Fire Protection Glass is a favoured material in modern building construction (Wigginton, 1996). It replaces, in many places, the traditional concrete panels, brick walls, stud walls and many other opaque elements to create the spatial effect and/or energy savings. The commonly used ordinary glass is also a very fragile material at elevated temperatures. The effective use and

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protection of glazing is a frequently encountered problem in fire safety engineering design and assessment (Colvin, 2003). When a fire occurs in a building, the room which encloses the fire origin initially acts as fire barrier. This barrier often incorporates glass in windows and doors. It prevents fire and toxic smoke spreading to adjacent rooms and the rest of the building, hence provides crucial time for building occupants to evacuate to safety. However, as the fire grows in the enclosure, the heat generated from the combustion will cause cracking damage, and even complete dislodgment, of the glass. The consequences can be disastrous. The broken windows and doors will create openings for fire and smoke and escalate danger in the rest of the building. Fire induced flow will help supply fresh air into the burn room through the openings. This will assist the fire to develop into what is called a flashover condition. It is this type of fire that causes significant life and property losses. Understanding of glass behaviour under elevated temperature is an important step in predicting the dynamic behaviour of fire growth and smoke movement in buildings. Sometimes glazing material may be part of the construction of egress way or compartmentation wall which are required to have fire ratings by building codes. Protection of the glazed elements is then crucial for the prevention of fire and smoke spread and safeguarding the evacuation of building occupants. In order to develop effective use and protection of glazing in building design, one needs to understand the mechanical and optical properties of glazing materials and the heat transfer process associated with the breaking of glazing materials.

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5.1. Attenuation of Radiation by Glazing Materials Although ordinary glazing materials are transparent to visible light, they are almost opaque to radiation waves with wavelengths greater than 2.5 μm (Bach, 1995). A plot of transmissivity of soda lime float glass is given in Figure 16 together with the energy spectrum of black body thermal radiation. It is seen that the transmissivity of soda lime float glass is approximately 0.9 within the wavelength range of 0.3 μm to 2.5 μm. Outside of this range its transmissivity is almost zero.

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80

Transmissivity of soda lime float glass

T =1400 K

70

1 Transmissivityτλ

50

2

Eb λ (kW/m μm)

60

40

1200 K

30 20

1000 K

10

800 K

0

0 0

2

Visible light

4 Infrared

6

8

10

λ (μm)

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Figure 16. Transmissivity of soda lime float glass and energy spectrum of thermal radiation.

It was mentioned earlier that almost all thermal radiation energy produced by fires is emitted in the infrared region. However, only a relatively small proportion of that energy is transmittable through ordinary glass. For example, at T=1,000 K more than 85% of the total energy is radiated at wavelengths greater than 2.5 μm. That amount of radiant heat is either reflected or absorbed, but not transmitted through soda lime float glass. Table 6 lists the radiant energy through piecewise grey glass when exposed to the thermal radiation from a black body. Note that it is the absorbed proportion that contributes to the heating of the glass. Data from Table 6 also reveals that a glass pane can act as a radiation shield, provided that the glass pane itself is not too hot and it is able to maintain its integrity. Table 6. Radiant energy split through piecewise grey glass (Pagni, 2003). Temperature (K) 800 1000 1200 1400

Transmitted (%) 5 13 22 31

Absorbed (%) 85 77 68 59

Reflected (%) 10 10 10 10

The thermal radiation attenuation capabilities of some fire-resistant glasses have been tested in a standard fire-resistance furnace in Building Research Association of New Zealand (Cowles, 1997) and the results are presented in Table 7. Table 7. Attenuation rates of various glasses (Cowles, 1997). Type of glass

Attenuation value

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Wire-reinforced float glass Ceramic glass Borosilicate glass Calcium silica glass

The attenuation, a, is defined as

a=

qi − qt qi

(54)

where qi is the incident radiant heat flux and qt is the transmitted radiant heat flux. The results in Table 7 were obtained using the ISO834 (2000) standard fire test for up to 90 minutes exposure. The ISO fire is a simulated post-flashover compartment fire used to evaluate fire resistance ratings for building components. There are special types of glasses that have quite different optical properties than the nonce mentioned above. Quartz has high transmitivity for a very wide band of wavelength. It is used in many specialised areas of industry and science. For example, it is used to make radiometers (see Section 0). The use of other special glasses can be found in medicine (see Chapter ? of this book).

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5.2. The Mechanism of Glass Breaking in Fires The stress that causes window glass to break in fires is attributed to mechanical forces (pressure difference between an enclosure and the outside) and thermal expansion. Among these two factors, the latter is dominant, since thermal stress is usually orders of magnitudes greater than mechanical stress caused by pressure variations in fires. It is, therefore, sufficient to analysis thermal stress in the study of window glass breakage in fires. Glass is usually mounted in frames where the edges are shaded from radiant and convective heat transfer, as shown in Figure 17. When such a configuration is exposed to flames and hot gases, the centre of the glass pane is heated whereas the edges are not. This uneven heating of glass pane will create uneven temperature distribution.

Exposed to fire

Rubber gasket

Frame

Glass

The edge is shaded from radiant and convective heat transfer Figure 17. A typical mounting of window glass.

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Significant research effort has been given to the investigation of window glass breakage. It has been suggested that thermally induced tensile stress is the mechanism for window glass breakage in fires (Emmons, 1986). Theoretical and numerical analyses have attributed the initial cracking of window glass to the temperature difference between shaded and unshaded regions of the glass (Hassani, 1995, Joshi, 1994a). A generalised expression for thermally induced stress at the edge of the glass pane reads

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σ y = βEΔT

(55)

where σy is the normal failure stress, E is Young’s Modulus, β is the coefficient of linear expansion ΔT is the temperature difference between the heated glass and the insulated edge. For soda-ash glass, we have σy=50 MPa, β=8×10−6 °C−1 and E=80 GPa. Hence, the estimated breakpoint temperature difference is ΔT≈80 °C. The mechanical and thermal properties of a range of glasses can be found in Holloway (1993). The commonly used silica based glasses are isotropic, elastic solids, which are essentially homogeneous with all the constituent atoms very strongly bonded together. Moreover, most of their physical properties are not particularly sensitive to the precise composition or to the presence of small numbers of impurity atoms. These characteristics imply that glass should be mechanically strong. However, the real strength of most glasses is usually much lower than the theoretical strength due to the flaws in the glass, such as surface and volume flaws, pitches and bubbles. The flaws amplify the stress in their neighbourhood by many orders such that the local stress may exceed the molecular strength even though the average stress is still well below the critical value (Tada, 1985). Poor finish or poorly cut edges may also cause concentration of stress. In reality, one may find that a moderate temperature rise could cause glass to fracture. For example, a frequent request to glass fitters is to fix shower screens broken by hot shower. There is also a ‘size effect’ on strength. Holloway (1986) argued that large specimens tend to be weaker than smaller ones, since a greater probability of a larger flaw exists, if the surface area is greater. However, experiments by Khanina et al. (2000) did not support this argument. It was speculated that the cracking of glass may be correlated with the flaw density (number of flaws per unit area or volume) rather than the size of the flaws. Due to the fact that a glass has the homogeneous structure of a liquid, a crack, once begun, encounters no internal boundaries or discontinuity to interrupt its progress. It bifurcates and very quickly propagates across the window. A major cause for rapid occurrence of cracking in glass panes is thermal stresses along the edges. The central area of a differentially heated sheet expands but is partly restrained by the cooler perimeter. Tensile strains are induced in the perimeter and if the tensile strain capacity of the glass at the edge of the sheet is exceeded, fracture ensues. The greatest tensile strain may exist at some distance from the edge. Experiments, in which glass surface temperature was measured, have been conducted by Skelly and Roby (1991) to test the results of theoretical and numerical analyses. Their experiments revealed a large variation in breakpoint temperature (61 °C − 132 °C). The deterministic approach to calculate glass fracture demands the knowledge of the data on the distribution (location), dimension and orientation of flows, as well as the variation of physical properties due to impurity and thermal treatment process during manufacturing.

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However, in real life such demand can hardly be met. The breakpoint temperature variation range in the experiment by Skelly and Roby (1991) also recently by Chow et al (2007) simply reflected the high degree of uncertainties in these parameters.

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5.3. Modeling of Glass Fracture in Fires The window glass temperature in a fire environment is determined by the heat transfer process. Traditional modeling approach by-passes the analysis of convective, conductive and radiant heat transfer and correlates, as the first order approximation, the glass fracture with the hot layer gas temperature in the room (Skelly, 1991, Milter, 1987). It may be of a concern that such an approach sacrifices the accuracy in the predicted time of fracture as a trade-off for efficiency. The gas temperature corresponding to the window glass fracture varied from 257 °C to 377 °C in the FIRST model (Milter, 1987). In a fire growth model developed at National research council of Canada (Hadjisophocleous, 1992), it was set at 300°C. Glass is a semi-transparent solid material. Radiant energy is absorbed, emitted and transmitted along the optical path of such material. Modeling heat transfer in a semitransparent material is more complicated than in an opaque material. Heat absorption, heat transfer through convection, conduction and radiation has to be considered (Figure 18). The wavelength and temperature dependence of the properties of glass complicate the matter further (Siegel, 1992, Bach, 1995). Sincaglia and Barnett (1997) provided a detailed analysis of radiation heat transfer in window glass and developed a relatively sophisticated onedimensional heat transfer model to predict temperature distribution inside the glass exposed to a radiant heat source. Their model produced excellent agreement with experimental results of glass surface temperature and time of fracture with a relative error of 3.2%. Their experiments were conducted in a compartment with burning liquid hexane as heat release source. However, some uncertainties existed in the measurement of glass surface temperature and it is not known whether the model has been validated against realistic transient fires.

Radiation Convection

Reflection

Absorption

Radiation

Conduction

Transmission

Convection

Figure 18. Heat transfer through glass.

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An engineering model, called BREAK1, for predicting window glass breakage was developed by Joshi and Pagni (1991). The model is available free of charge at the NIST Building and Fire Research Laboratory website. BREAK1 is based on simple heat transfer analysis to estimate the temperature difference between the exposed centre pane and the shaded edges. Good agreement with experimental data has been reported (Joshi, 1994b). The model requires the input of the temperature of hot gas to which the window is exposed, the glass thickness and the depth of shaded region. To obtain hot gas temperature, one may use other compartment fire models, such as CFAST (Peacock, 2008).

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5.4. Protection of Glazing 5.4.1. Drencher Protection A glazing structure may be part of a required fire rated element, such as part of the wall of an egress route. Drenchers, or sprinklers are sometimes used to protect glazing structures and to achieve the required fire rating (Brown, 2001). The water curtains formed by drencher spray on glass serves two purposes. Firstly, it cools the glass so that integrity of the glass pane is maintained (Richardson, 1987). Secondly, it provides additional attenuation to thermal radiation. A 90% attenuation was reported by Moulen and Grubits (1975) for water sprayed window glass pane in an experimental investigation. An important issue concerning the drencher protection of glazing structures is the reliability of the drencher system. The integrity and reliability of the protected glazing are as good as the adequacy and reliability of the drenchers that provided the protection. In a fire safety engineering assessment, the risk of drencher system failure may need to be analysed. Generally, the reliability of the drencher system should be comparable to that of the passive protection system that is required by the building regulations. If a fire source is close to a glazed wall, the localised heating may cause damage to the glazing before the fire grows big enough to active the protecting drencher. See Figure 19. Such a situation is to be avoided. In building design, consideration should be given to removal of potential fire sources near glazing structures.

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Ceiling

This fire may activate the drencher first before it can damage the glazing.

Drencher

Glazing

This fire may damage the glazing before it activates the drencher. Floor

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Figure 19. Danger of localised heating by a small fire.

5.4.2. Double Glazing Double glazing windows used to be the design feature of buildings in cold climate to minimise heat lose to ambient. It is now widely adopted in building even in warm climate to conserve energy for air conditioning. Double glazing also offers another advantage in fire protection. Not only double glazing attenuate more thermal radiation, it also resists fire attack better than single glazing. The first pane of a double glazing design acts as a band pass filter only transmitting a small fraction of the incident radiation. Therefore, flames and hot gases of the original heat sources do not radiatively heat the panes beyond the first exposed pane. The cracking of window glass subjected to a fire will release the stress within the glass. Provided that the glass pane is mounted properly, the broken pieces may not dislodge immediately after cracking (He, 1998) and can still provide shielding against radiation for a limited time. This phenomenon sets the basis for double glazing design for fire protection (Cuzzillo, 1998) In a double glazing configuration, the glass pane on the side which is not exposed to a fire will receive less radiant heat than the exposed pane. The shielding provided by the exposed pane will delay or may even prevent the fracture of the non-exposed pane, thus preventing fire spread or providing crucial time for building occupants to escape to safety. 5.4.3. Other Means of Glass Protection And Enhancement Other means of glass protection and enhancement include wired glass, toughened (tempered or heat treated) glass, laminated glass and intumescent glass (Belles, 2002, Colvin, 2003). These treatments either improve the properties of the glass elements or help prevent or delay fire damages to glass elements so that adequate time is provided for occupant evacuation.

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6. Personal Protection Against Thermal Radiation 6.1. Fire Fighter Protections 6.1.1. Tunic And Flash Hood A firefighter's tunic is made from fire resistant, synthetic fabric which retains its structural strength after fire exposure, and resists cuts and tears. It is designed to enable good flexibility. Its collar has a long zip to ensure complete closure of the jacket to the neck. It provides a high level of thermal resistance protection without being overly heavy to wear. The flash hood is a one-piece garment that provides extra protection to the head and neck for fire fighters. 6.1.2. Bushfire Jacket The bushfire jacket is designed primarily for bushfire fighting applications. The jacket is lightweight, comfortable and affords the wearer moderate levels of both radiant and convective thermal protection to minimise the possibility of heat stress.

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6.1.3. Boots Firefighting boots are designed to provide superior safety and comfort to the wearer. They have a dual density cushioned rubber sole which reduces the boot weight and provides orthotic superiority, greater ankle support and reduces skeletal impact related injuries. Additionally, the boot is fire retardant and resistant to water penetration. A full interior synthetic fire retardant liner provides increased wearer comfort, by allowing better foot breathability and increased thermal and radiant heat protection. 6.1.4. Fire Hose There are specially designed fire hose nozzles that create water spray pattern to form a heat shield. Fire fighters use this shield to protect themselves when conducting emergency operation near fire sources, such as rescue or shutting down equipments that are in proximity of a fire source.

References Babrauskas, V. 1979. Full Scale Burning of Upholstered Chairs, Technical Note1103. Washington, DC: National Bureau of Standars. Babrauskas, V. 2003. Ignition Handbook, Issaquah, Fire Science Publishers. Bach, H., Neuroth, N. (ed.) 1995. The Properties of Optical Glass, Berlin: Springer-Verlag. Belles, D. W. 2002. History and Use of Wired Glass in Fire Rated Applications. In: DECICCO, P. R. (ed.) Behavior of Glass and Other Materials Exposed to Fire. Amityville, NY: Baywood Publishing Co. Inc. Beyler, C. L. 2008. Fire Hazard Calculations for Large, Open Hydrocarbon Fires. In: DINENNO, P. J. (ed.) SFPE Handbook of Fire Protection Engineering. 4th ed. Quincy, Massachusetts: National Fire Protection Association. Brown, P. 2001. Rated Interior Glass Walls With Sprinklers. Sprinkler Age, 20, 19-20.

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Chen, J., He, Y., Wang, J. 2010. Multi-Feature Fusion Based Fast Video Flame Detection. Building and Environment, 45, 1113-1122. Chen, T., Yuan, H.Y., Su, G.F., Fan, W. C. 2004. Automatic fire searching and suppression system for large spaces. Fire Safety Journal, 39, 297–307. Chow, C. L., Chow, W. K., Gao, Y., Zou, G. W. 2007. Experimental Studies on Cracking of Glass Panes in a Fire. Journal of Applied Fire Science, 16, 83-96. Colvin, J. 2003. Glass for Fire Protection. Fire Safety Engineering, 10, 22-24. Cooper, L. Y. 1995. Compartment Fire-Generated Environment and Smoke Filling. In: DINENNO, P. J. (ed.) The SFPE Handbook of Fire Protection Engineering. 2nd ed. Boston: Society of Fire Protection Engineers. Cowles, G. S. Year. The Attenuation of Radiation from Building Fires through Fire-resistant Glazing. In: Proceedings of the 5th International Symposium on Fire Safety Science, 1997 Melbourne, Australia. International Association of Fire Safety Science, 1357. Csiro 1993. FIRECALC: Computer Software for the Fire Engineering Professional, ver. 2.3. Sydney, Australia: Commonwealth Science and Industry Research Organisation. Cuzzillo, B. R., PAGNI, P. J. 1998. Thermal Breakage of Double-Pane Glazing by Fire. Journal of Fire Protection Engineering, 9, 1-11. Dayan, A., Tien, C. L. 1974. Radiant Heating from a Cylindrical Fire Column. Combustion Science and Technology, 9, 41-47. De Ris, J. 1979. Fire Radiation - A Review. Seventeenth Symp. (Int.) on Combustion. Pittsburg: The Combustion Institute. Drysdale, D. D. 1998. An Introduction to Fire Dynamics, Chichester, UK., John Wiley and Sons. Dungan, K. W. 2008. Automatic Fire Detectors. In: COTE, A. E. (ed.) Fire Protection Handbook. Quincy, Massachusetts: National Fire Protection Association Emmons, H. W. Year. The Needed Fire Science. In: GRANT, C. E., PAGNI, P. J., ed. Fire Safety Science - Proceedings of the First International Symposium, 1986 Washington, D.C.: Hemisphere, 33-53. Fernandez-Pello, A. C. 1995. The Solid Phase In: COX, G. (ed.) Combustion Fundamentals of Fire. San Diego: Academic Press. Fincham, W. H. A., Freeman, M.H. 1974. Optics, London, Butterworth pty. ltd. Hadjisophocleous, G. V., Yung, D. 1992. A Model for Calculating the Probabilities of Smoke Hazard from Fires in Multi-Storey Buildings. Journal of Fire Protection Engineering, 4, 67-80. Hamins, A., Yang, J. C., Kashiwagi, T. Year. An experimental investigation of the pulsation frequency of flames. In: Proceedings of the 24th (International) Symposium on Combustion 1992. Combustion Institute, 1695-1702. Hassani, S. K. S., Shields, T. J., Silcock, G. W. 1995. Thermal Fracture of Window Glazing: Performance of Glazing in Fire. Journal of Applied Fire Science, 4, 249-263. He, Y. 2009. Evaluating Visibility Using FDS Modelling Result. International Fire Safety Engineering Conference FSE 2009. Melbourne, Australia: Society of Fire Safety, Engineer Australia. He, Y., Poon, L. 1998. Experimental Observations and Modelling of Window Glass Breakage in Building Fires. Fire Science and Technology - Proceedings of the Third Asia-Oceania Symposium, Asia-Oceania Association of Fire Science and Technology. Singapore.

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Heitmann, H. 1983. Design and Testing of the Ultraviolet Flame Radiation Detectors for Automatic Fire Detection. Fire Safety Journal, 6, 183-191. Heskestad, G. 2008. Fire Plumes, Flame Height and Air Entrainment. In: DINENNO, P. J. (ed.) SFPE Handbook of Fire Protection Engineering. 4th ed. Boston, Massachusetts, USA: Society of Fire Protection Engineers. Holloway, D. G. 1986. The Fracture Behaviour of Glass. Glass Technology, 27. Holloway, D. G. 1993. The Physical Properties of Glass, London, Wykeham Publications. Holman, J. P. 2002. Heat Transfer, New York, McGraw-Hill Companies. Iso-834 2000. Fire-resistance tests - Elements of building construction. Jin, T. 2008. Visibility and Human Behaviour in Fire Smoke. In: DINENNO, P. J. (ed.) SFPE Handbook of Fire Protection Engineering. 4th ed. Quincy, Massachusetts: National Fire Protection Association. Joshi, A. A., Pagni, P. J. 1991. User’s Gauide to BREAK1, the Berkeley Algorithm for Breaking Window Galss in a Compartment Fire. Gaithersburg, MD USA: National Institute of Standards and Technology Joshi, A. A., Pagni, P. J. 1994a. Fire-Induced Thermal Fields in Window Glass. I - Theory. Fire Safety Journal, 22, 25-43. Joshi, A. A., Pagni, P. J. 1994b. Fire-Induced Thermal Fields in Window Glass. II Experiments. Fire Safety Jounal, 22, 45-65. Karlsson, B., Quintiere, J.G. 2000. Enclosure Fire Dynamics, Florida, CRC Press LLC. Khanina, I., Vergara, M. C., He, Y. 2000. Window Glass Breakage in Fires. Proceedings of the Seventh Australian Heat and Mass Transfer Conference. Townsville, Australia. Lahaye, J. 1990. Mechanisms of Soot Formation. Polymer Degradation and Stability, 30, 111-121. Luo, M., Bressington, P. Year. Activation of Sprinkler Heads under Perforated Ceiling. In: Proceedings of the 8th international Fire Science and Engineering Conference, Interflam’99, 29 June - 1 July 1999 Edinburgh. Interscience Communications, 59-68. Mcgrattan, K., Baum, H., Rehm, R., Mell, W., Mcdermott, R. 2010a. Fire Dynamic Simulator (Version 5) Technical Reference Guide. NIST Special Publication 1018-5, National Institute of Standards and Technology. Mcgrattan, K., Hostikka, S., Floyd, J., Baum, H., Rehm, R., Mell, W., Mcdermott, M. 2009. Fire Dynamic Simulator (Version 5) Technical Reference Guide. NIST Special Publication 1018-5, National Institute of Standards and Technology. Mcgrattan, K., Mcdermott, R., Hostikka, S., Floyd, J. 2010b. Fire Dynamics Simulator (Version 5) User’s Guide. NIST Special Publication 1019-5, National Institute of Standards and Technology. Milter, H. E., Rockett, J. A. 1987. User’s Guide to FIRST, A Comprehensive Single-Room Fire Model. Gaithersburg, MD, USA.: National Institute of Standards and Technology. Moulen, A. W., Grubits, S. J. 1975. Water-curtains to shield glass from radiant heat from Building Fires. Sydney, Australia: Experimental Building Station, CSIRO. MULHOLLAND, G. W. 2008. Smoke Production and Properties. In: DINENNO, P. J. (ed.) The SFPE Handbook of Fire Protection Engineering. 4th ed. Boston: Society of Fire Protection Engineers. Mulholland, G. W., Croarkin, C. 2000. Specific Extinction Coefficient of Flame Generated Smoke. Fire and Materials, 24, 209-252.

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Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

154

Yaping He

Pagni, P. J. 2003. Thermal Glass Breakage. Proceedings of the 7th International Symposium on Fire Safety Science. Worcester Politechnic Institute: International Association of Fire Safety Science. Peacock, R. D., G. P. Forney, P. Reneke, R. Portier And W. W. Jones 1993. CFAST, the Consolidated Model of Fire Growth and Smoke Transport. Gaithersburg, MD 208990001, USA.: Building and Fire Research Laboratory, National Institute of Standards and Technology. Peacock, R. D., Jones, W. W., Reneke, P. R. And Forney, G. P. 2008. CFAST – Consolidated Model of Fire Growth and Smoke Transport (Version 6) User’s Guide. National Institute of Standard and Technology. Purser, D. A. 2008. Assessment of Hazards to Occupants from Smoke, Toxic Gase, and Heat. In: DINENNO, P. J. (ed.) The SFPE Handbook of Fire Protection Engineering. 4th ed. Boston: Society of Fire Protection Engineers. Qi, X., Ebert, J. 2009. A computer vision based method for fire detection in color videos. International Journal of Imaging, 2, 22-34. Qiao, X., Cheng, X. Year. Micro-Portable Heat Radiation Detector and Its Application. In: FAN, W., ed. Fire Science and Technology. Asian Conference, 1st (ACFST) October 913 1992 Hefei, China. International Academic Publishers, 386-391 Richardson, J. K., Oleszkiewicz, I. 1987. Fire tests on window assemblies protected by automatic sprinklers. Fire Technology, 23, 115-132. Siegel, R., Howell, J. R. 1992. Thermal Radiation Heat Transfer, Washington, Hemisphere Publishing Corporation. Sincaglia, P. E., Barnett, J. R. 1997. Development of a Glass Window Fracture Model for Zone Type Computer Fire Codes. Journal of Fire Protection Engineering, 8, 1-18. Skelly, M. J., Roby, R. J. 1991. An Experimental Investigation of Glass Breakage in Compartment Fires. Journal of Fire Protection Engineering, 3, 25-34. Tada, H., Paris, P. C., Irwin, G. R, 1985. The Stress Analysis of Cracks Handbook, Paris Productions, Inc. Tewarson, A. 2008. Generation of Heat and Gaseous, Liquid, and Solid Products in Fires. In: DINENNO, P. J. (ed.) SFPE Handbook of Fire Protection Engineering. 4th ed. Boston: Society of Fire Protection Engineers. THOMAS, P. H., LAW, M. 1974. The projection of flames from buildings on fire. Fire Research Note, No. 921. Tien, C. L., Lee, K. Y., Stretton 2008. Radiation Heat Transfer. In: DINENNO, P. J. (ed.) The SFPE Handbook of Fire Protection Engineering. Quincy, Massachusetts: National Fire Protectin Association. Verstockt, S., Merci, B., Sette, B., Lambert, P. Van De Walle, R. Year. State of the art in vision-based fire and smoke detection. In: Proceedings of the 14th International Conference on Automatic Fire Detection, 2009. 285-292. Walker, J. S. 2007. Physics, Upper Saddle River, NJ, Pearson Prentice Hall. Weinert, D. W., Cleary, T. G., Mulholland, G. W., Beever, P. F. 2003. Light Scattering Characteristics and Size Distribution of Smoke and Nuisance Aerosols. In: EVANS, D. D. (ed.) Seventh (7th) International Symposium. International Association for Fire Safety Science (IAFSS). Worcester, MA, USA: International Association for Fire Safety Science. Wigginton, M. 1996. Glass in Architecture, London, Phaidon.

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Young, H. D., Freedman, R. A., Ford, A. L. 2008. Sears and Zemansky's university physics : with modern physics San Francisco, Sydney Pearson/Addison Wesley.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter VIII

Radiation Hazards in Intervention Cardiology Rajesh Vijayvergiya* and Anand Subramaniyan Department of Cardiology, Advance Cardiac Centre, Post Graduate Institute of Medical Education & Research, Chandigarh, INDIA

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1. Abstract Increasing number of interventions is being performed in last two decades following advancement in interventional cardiology. This includes both the number of procedures and also complicated procedures requiring prolonged fluoroscopy time. Though there is an obvious clinical benefit to patients following these interventions, the radiation hazards to both patient and operator is often ignored at the time of intervention. This hazard following the use of X-rays is of two type- Stochastic / Random effects and Deterministic / Threshold based effects. There is a concern about overexposure of radiation dose in certain complex intervention causing deterministic effects to the patient. For health care workers, the prolonged cumulative exposure in catheterization laboratory results into side effects like cataract and cancer. The various factors linked with radiation dose during interventions are related with patient, operator, type of intervention and equipment. It is important to have adequate radiation protection at work place to prevent radiation induced hazards. The details about basics of radiation, its side effects, factors affecting radiation doses during procedure, and workplace radiation protection, monitoring & safety have been discussed in the chapter.

* Address for Correspondence:- Dr Rajesh Vijayvergiya, MD, DM, Assistant Professor, Department of Cardiology, Advance Cardiac Centre (ACC), Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh–160 012, INDIA., Tel No +91-172-2756512, Fax No +91-172-2744401, Email rajeshvijay999 @hotmail.com

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2. Introduction X-ray has become the essential tool for various diagnostic tests and therapeutic interventions in today’s clinical practice. Following the advancement in interventional cardiology in last two decades, increasing number of procedures are being been preformed worldwide. Though the benefits of cardiac interventions outweigh the risks associated with it, the potential radiation related risks are often ignored. Along with the patients, health care workers like interventional cardiologist, peripheral interventionist and radiologists are also at greater risk for radiation exposure and its potential hazards. Ninety percent of radiation dose in general population is received from various X-rays related investigations. A recent US based survey has estimated that the collective radiation dose received from medical uses has significantly increased by >700% from 1980 to 2006. Among the total computerized tomography (CT) scan performed cardiac CT accounts for 1.5% of collective X-ray doses. Among nuclear medicine studies, cardiac imaging represents 57% of total number of cases and constitute about 85% of the radiation dose [1]. Cineangiography and fluoroscopy make cardiac catheterization the largest producer of X-ray doses in diagnostic & interventional field. In the present chapter, the X-rays related radiation risk, various factors affecting its doses, and safety measures to decrease the occupation dose has been described.

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3. Type of Radiation Radiations is mainly of two types – ionizing and non-ionizing. It is ionizing radiation which is harmful to human tissues. The ionizing radiation is of two types – electromagnetic and particulate. Electromagnetic radiations include X-rays and gamma rays, whereas particulate radiations include alpha, beta particles, protons and neutrons. In this chapter, radiation related aspects of ionizing electromagnetic radiation i.e. X-ray has been described.

4. Radiation Units Various radiations units, which are in common use in medical fields are as follows: - The amount of energy per unit of radiation in dry air is expressed in Roentgen ( R). The amount of energy imparted by radiation per unit mass in any medium is expressed in Rad ( r ) or in standard international (SI) unit as Gray (Gy). The amount of energy imparted by radiation per unit mass in human is expressed in Rem or Sievert (Sv) unit. For both gamma and X-rays, the Rad and Rem unit is equal for human tissues (table 1). Dose area product (DAP) is the product of the dose in air in a given plane by the area of irradiating beam. It is independent of the distance from the X-ray source and is best applied for interventions with varying angulations. The effective dose (ED) is the sum of all weighted dose equivalents subjected to the organs in the body. The DAP to ED conversion factors for cardiac interventions under conditions of undercouch tube position have been calculated to be approximately 0.20 mSv / Gy X cm2 [2].

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Table 1. Radiation quantities and units [16]. Term Quantity Absorbed dose Absorbed Dose in humans

Definition Quantity of energy in dry air Amount of energy imparted by radiation per mass in any medium Amount of energy imparted by radiation per mass in human

Unit SI unit Equivalents Roentgen ( R) Coulomb/kg -----Radiation absorbed dose(Rad) Rem

Gray(Gy)

1Gy=100 Rads 1Gy=1000 milliGy

Sievert (Sv) 1 Sv=100 rem 1 Sv =1000milli Sv

For gamma and X- rays, the Rad and Rem is equivalent. For soft tissue exposure Roentgen( R) is equal to Rad.

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5. Risk of Radiation X-rays causes two type of side effects – Stochastic / Random effects and Deterministic / Threshold based effects. Stochastic effects: - It occurs at low level of radiation exposure, hence does not require the minimal threshold dose. Genetic effects like mutations in germ cells, birth defects and somatic effects like carcinogenesis are stochastic type of effects [3]. Deterministic effects: - These are threshold based effects. Skin changes like erythema, late skin necrosis, scarring, epilation, desquamation; cataract, leucopenia, anorexia, organ atrophy, fibrosis, sterility and fetal effects during pregnancy are few examples. The threshold for bone marrow suppression and cataract formation is 500 and 5000 mSv, respectively. The intensity and severity of these effects increases above these doses. Genetic effects of radiation: - The germ cells are very sensitive to radiation related injury. It is estimated that single dose of 6 – 10 Gy results in permanent sterility in male. After a fractionated dose of 8 - 10 cGy to testis, 9 – 18 months are required for the recovery of decreased sperm counts. A single dose of 3 – 4 Gy can induce amenorrhoea in almost all women of more than 40 years age, while embryonic death can occur at a dose of 0.1 - 0.5 Gy. It is also observed that oogenesis is less radiosensitive than spermatogenesis. In radiation lab, maximum acceptable limit of gonadal dose for medical workers is 20 mSv / year (table 2), which is associated with 0.1% increase risk of birth defects over 20 years and which off course is less in comparison to spontaneous mutation risk of 6% [3, 4]. Risk of cancer: - It is estimated that approximately 1% of cancers are caused by exposure of diagnostic X-rays [5]. With the recommended occupational dose limit of 50 mSv / year (Table 2), there is an additional 0.2% per year increase risk of cancer, in association with lifetime risk of 20% for spontaneous cancer [3]. There is a “Linear no-threshold hypothesis” for radiation induced malignancy. It means there is no threshold below which it is absolutely safe and the risk increases linearly with increasing radiation dose. It is observed that a radiation dose of 1000 mSv is leukemogenic [4]. The risk of fatal cancer is 0.04% per Rem (4% per Sv) following life time cumulative whole body radiation dose. The brain is the least protected organ during catheterization, and there are anecdotal reports of hematologic malignancy and brain tumor among the interventionist. The estimated risk of

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fatal malignancy or lifetime odds of premature death per 1000 individuals exposed to the radiation has been described in table 3 [6]. The risk of malignancy per 60 minutes of fluoroscopy is 2600: 1 million males and about 1400: 1 million females. The risk of hereditary defects is 50 cm, and the distance between patient body and image intensifier should be minimum to prevent scatter radiation. An image acquisition during expiration generally has twice the radiation dose in comparison to one taken during full inspiration. The image quality is also better during full inspiration.

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b. Operator Factors The X-ray beam is two types- a). Primary beam- It is directed to the patient body from Xray tube. This is the main source of radiation dose to the patient. b) Scatter beam- It is the dissipated beam from the main or primary beam. This is the main source of radiation to operators and assistants. It is highly asymmetric and is more in oblique view compared to antero-posterior view. The 90° scatter exposure at a distance of 1 meter from the centre of the primary beam is 1 / 1000 of patient skin exposure. It is also important to note that cineangiography increases radiation exposure by 10 times compared to flouroscopy (93 Roentgen/min v/s 10 Roentgen / min, respectively)[15]. The total exposure depends upon combined use of both fluoroscopy and cineangiography. The fluoroscopy contribution to total dose is about 30% for diagnostic catheterization and 60% for PCI [17]. It is fluoroscopy during percutaneous coronary intervention (PCI) & radio-frequency ablation (RFA) and cineangiography during diagnostic catheterization, which mainly contributes to total radiation dose. Though the dose of scatter radiation to operator is very minimal compared to primary beam to the patient, it is the cumulative dose to operator, which is important in long term. As the distance matters for scatter beam exposure, the subclavian approach during RFA or pacemaker / defibrillator implantation results into more radiation exposure compared to conventional trans-femoral approach. Other factors like exposure to primary beam, inability to use movable ceiling mounted and table side shields also contribute to more radiation exposure with subclavian approach [18]. The angiographic views with X-ray tube near the

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operator like lateral, left anterior oblique (LAO) cranial and antero-posterior (AP) cranial views have higher radiation exposure compared to views like right anterior oblique (RAO) and AP views. Any cranial or caudal angulations compared to non-angulated views causes more radiation to the patient and also more scatter radiation to the operator[19]. Any procedure with increasing fluoroscopic time and more cine views leads to more radiation exposure like coronary angiography in post coronary artery bypass graft (CABG) patients, combined coronary angiography and angioplasty, multi-vessel PCI, PCI of chronic totally occluded (CTO) coronary lesions, etc[20]. The smaller or magnified field size (i.e. 5 inch) have higher dose per frame. Hence, it results in more intense scatter radiation. Similarly, the higher frame rate as required for left ventriculogram, pediatric catheterization (30 fps each), and peripheral angiogram (45 fps) compared to coronary angiography (15 fps) results in more radiation exposure. The equipment setting for peripheral angiogram is also different than cardiac catheterization as maximum duration of cine length is more for peripheral angiogram (15 v/s 10 secs). During catheterization, the principle of the study should be to have minimal fluoroscopic time and cine numbers maintaining the quality of the study, as the scatter radiation dose is proportional to patient’s dose. One should record the total fluoroscopy and cine times on a case-to-case basis. During coronary intervention, an initial clarification of coronary flow and exclusion of collateral pathways, the cine angiographic runs of one or two cardiac cycle lengths is sufficient to provide adequate visual impressions without any diagnostic or procedural impact. Minimizing the radiographic frames towards essential numbers, restriction to adequate instead of best image quality and the consistent use of collimation enable DAP reductions of approximately 50% each[19]. An operator performance in term of fluoroscopic time and cine frame count / numbers can be used to control the radiation in two distinct situations – 1) Participation of the attending physician in the interventional case when fellow exceeds predetermined cine and fluoroscopic times. 2) In a complex case, when even the experienced operator find themselves using substantially more imaging time, which is acceptable considering the potential benefit [21]. Last fluoroscopic image loop with playback option helps in minimizing the total fluoroscopic time and cine numbers. Primary operator’s fatigue also influences the radiation exposure during PCI. It is found in a study that radiation dose significantly increase by 28%, mainly due to more and longer radiographic runs, after the cardiologists is working for more than 6 hours[22].

c. Equipment Factors Pulsed-current fluoroscopy in comparison to conventional continuous-current fluoroscopy decreases the radiation exposure and also improves the image quality. The newer systems have more sensitive radiation detectors, more filtration (e.g., copper filter), optimal beam collimation without fluoroscopy, pulsed fluoroscopy mode and low dose mode, which reduces radiation output for equal exposure time. The storage and replay of last fluoroscopic image, thus avoiding repetitive cine-angiography, also significantly reduces the radiation dose. A real time alert system for cumulative radiation dose makes the operator vigilant about the total exposure. Flat detector fluoroscopy system has largely replaced image intensifiers in most of the modern catheterization laboratory. It has enhanced contrast resolution and better

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image quality with automatic exposure control. In steep projection and obese patients, it automatically increases the radiation dose for better image quality, which can be harmful in prolonged interventional procedures [23]. The present day’s digital acquisition requires shorter cine-angiographic runs and yields better quality images, compared to old time radiographic films acquisition. An additional advantage of digital image is that it can be transmitted online to other tertiary care centers for expert opinion and further management. Rotational angiography in which there is manual movement of the gantry through a series of four 25° arcs, two in cranial and caudal position each during cine-angiogram is also found to reduce radiation dose, procedural time and also dye load [24]. The equipment should be monitored periodically for meticulous quality performance balancing image quality and radiation dose by the appropriate institutional team comprising experts on radiation protection, medical physicist and radiographer. A comprehensive maintenance and capital replacement program should be implemented to ensure consistent and safe performance, as the deteriorating performance results in automatic increase in radiation dose per image. The “High Level Control (HLC)” fluoroscopy technique which enhances the fluoroscopic digital imaging is being incorporated in most of the presently available catheterization labs. HLC fluoroscopy results in more radiation exposure and sometimes even equivalent to cine-angiography, hence its use should be restricted whenever necessary with manual instead of automatic mode and with a frame rate of ≤15 / seconds [25]. The computerized records of fluoroscopy time, frame rate, cine length, variation of image frequency in series and patient dose parameters are very helpful in evaluation and control of radiation dose.

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d. Type of Intervention According to recent review by Kim KP, et al [26], the effective radiation dose per procedure to the primary operator ranges from 0.02 to 38 µSv for diagnostic catheterization, 0.17 to 31 µSv for PCI, 0.24 to 9.6 µSv for radiofrequency ablation, and 0.29 to about 17 µSv for pacemaker / defibrillator implantation. The reported mean fluoroscopy time is 8 min for diagnostic catheterization, 18 min for PCI, 47 min for radiofrequency ablation, and 6 min for pacemaker / defibrillator implantation. i. Coronary Intervention The radiation dose independently increases with more cine runs & fluoroscopy time and increase body weight. The 2 Gy threshold for early transient erythema can be exceeded in those who had multi-vessel stenting [27]. Otherwise also, those undergoing multi-vessel stenting and who had previous CABG had 42% higher radiation exposures [15]. The total fluoroscopic time required for PCI of CTO (42.6 min) is 3 times more than the time required for PCI of single stenosis (14.6 min) [28]. The mean entrance skin dose for CTO patient is 3.2 ± 2.1 Gy (range 0.5-10.2Gy, median 2.7Gy), which is sufficient to cause various type of skin injuries [29]. It is important to plan the procedure in advance to limit the fluoroscopy and cine runs especially for complex intervention. A change in fluoroscopic view during intervention also results in wide distributed area of exposed skin and helps in decreasing the radiation side effect to the patient. A staged procedure is not the substitution to decrease the radiation dose

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related side effects as total cumulative dose results in late skin manifestation and other deterministic effects. There is increasing trend of trans-radial approach for cardiac catheterization considering its advantage of less local vascular complication, patient comfort and lower cost, compared to conventional trans-femoral approach. However, the trans-radial approach is associated with more radiation exposure, procedural duration and fluoroscopy time for both diagnostic catheterization and PCI, despite optimal radiation protection measures and adequate operator’s experience [30]. The technical difficulties in crossing the radial-brachial arterial system because of tortuosity or spasm, advancing catheters across the aortic arch and selectively cannulation of coronaries are few of the reasons for increasing fluoroscopy time during radial approach. A slightly closer position of the operator near the X-ray tube and inconvenience in using ceiling suspended lead shield during trans-radial approach are other reasons for increase radiation exposure to the operator[30,31]. Magnetic navigation system: - This is a new development in field of interventional cardiology, which has drastically decreased the use of fluoroscopy during PCI. This system incorporate magnetic field instead of fluoroscopy to precisely navigate the magnet tip coronary guide wire across the complex coronary lesion. With the robotic assistance and external magnetic field application, the wire tip can be navigated across tortuous angulated lesions; therefore one can complete the complex PCI with minimal radiation exposure [32]. This technology is expensive thus has the limited use worldwide. ii. Pediatric Catheterization There is high radiation exposure to both pediatric patients and the operator during catheterization because of factors like greater magnification for optimal visualization of structures in children, use of higher frame rates during cine angiography, interference from patient movement, difficulty in optimal use of shielding in variably angulated or biplane views, large area of body being irradiated for the given body surface area and high radiosensitivity of children. In recent years, increasing use of therapeutic interventions has also resulted into higher patient exposure. Even the effective radiation dose is higher in them in comparison to adults because of increase radio-sensitivity and larger area of exposure [33]. Younger the age more is the effective dose for equivalent radiation exposure in pediatric patients. As there is a latent period of at least 10 - 20 years for development of radiation induced cancer, children are more likely to have them during their life time in comparison to elderly population. The risk of cancer following cardiac catheterization is 4 - 8 times higher in infants in comparison to adults [33]. A lifetime risk per Sievert radiation dose is 4% in adult population, which increase to 11 - 15% in infants [34]. The Physician exposure per pediatric case is about 0.014 - 0.34 mSv at eye lens and 0.015 - 0.66 mSv at the level of thyroid [35]. The median effective dose during diagnostic and therapeutic catheterization to pediatric patients is 4.6 mSv and 6.0 mSv respectively [36]. Balloon dilations carry higher exposure rate (8.1 mSv) than PDA and ASD device closures (2.8 and 7.6 mSv respectively) [37]. Use of large-plate abdominal and gonodal shielding in pediatric patients is a must as primary beam is closer to the gonads. A selective thyroid shield must also be used. Use of extra-thin copper filters and a small field size should be used whenever possible. With the recent advances in non-invasive cardiac imaging by multi-detector array CT (64-slice MDCT), increasing number of pediatric patients are evaluated by CT with or without cardiac catheterization for complex congenital heart disease. This is the evolving practice for the

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precise diagnosis of congenital heart disease without considering the radiation risk. A gated cardiac CT though provide excellent anatomic information, it does have high tube current and increasing radiation dose. The doses during gated cardiac CT range from 7 to 25 mSv in children [38], which is higher than the conventional diagnostic cardiac catheterization [36]. Hence, it is important for the treating physician to have the accurate diagnosis without subjecting them for increasing radiation dose. Another evolving trend in congenital heart disease management is the “hybrid procedure”, in which both cardiac surgeon and interventional cardiologist perform the hybrid intervention in same sitting like intra-operative stent placement, balloon valvuloplasty, VSD device closure, palliative procedure in hypoplastic left heart syndrome, etc. The fluoroscopy and cine-angiography is required as an imaging modality to facilitate these “hybrid” procedures, for which the operating team should be adequately educated / trained regarding radiation risk and “ALARA” principle [39].

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iii. Balloon mitral valvuloplasty (BMV) Because of high prevalence of rheumatic heart disease in certain geographical areas worldwide, it is common to come across pregnant patients having symptomatic, critical mitral stenosis requiring balloon mitral valvuloplasty (BMV). As there is a concern about radiation safety of the fetus, BMV is avoided during first trimester (95% in most of the series [50]. However, the radiation exposure in CT angiography is approximately twice to that of conventional contrast angiography in post CABG patients (12.95 v/s 6.27 mSv) [51]. The factors related to higher exposure during CT angio includes obese patients, higher voltage, longer scan length and higher heart rate. An increase in scan length of 1 cm increases the exposure rate by 5%. However the coronary calcium scoring needs lower exposure (1.5 - 2.7 mSv, Table 5). Recently, some dose saving algorithms are incorporated which utilizes automated exposure controls depending upon the body size and resolution. Electrocardiogram (ECG) gated Tube Current Modulation automatically acquire images during diastole and exposure is minimal in systole. This requires a lower (2 Gy as in intervention related with CTO, complex PCI, abdominal aortic aneurysm & RFA should be counseled for the future possibility of erythema or more serious skin damage and followed up for several weeks after the exposure [58]. A detailed account about total cumulative dose, reasoning about excess dose and instruction regarding personal inspection for skin erythema / burns should be advised accordingly.

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9. Radiation Protection and Safety The first and paramount aspect of every radiation exposure is to ensure that adequate radiation protection and safety measures are taken into consideration prior to its use. The daily exposure of radiation, orthopedically burdensome lead apron which is partially protective, and poor ergonomic design of fluoroscopic equipment / procedure rooms constitutes the “inconvenient truth” of interventional cardiology. Most of operators do not wear the radiation badges accepting the radiation risk at the cost of doing the intervention business. They are afraid to know the truth of excess radiation exposure, or even worse to be expelled out of the laboratory as a result of excess monthly exposure. Though the radiation exposure to medical staff has declined over the years because of awareness and technical improvement of equipment, the increasing number of interventions has lead to overexposure to most of the busy interventional cardiologists, commonly exceeding their recommended annual radiation dose [59]. As more number of complex procedures with increasing fluoroscopy / cine time are performed, the favorable effect of improved technology and procedural protocol on radiation exposure got negated. As reported, complex PCI have more than 2 fold increase in DAP compared to simple PCI [60]. The casual approach of interventionist for adequate lead shielding and monitoring should be curtailed for the benefit of both patients and the medical fraternity. Though the average operator dose is quantitatively related to the average patient dose, a greater variation is observed in operator’s compared to patient’s doses [61]. This could be due to the variable practice of using shielding devices, the distance of the operator from primary beam, and different mechanical radiation protection parameters. A brief course about radiation safety measures prior to issuing the radiation badge and a periodic supervision / monitoring of radiation safety measures is a must. Individual should wear the dosimeter in consistent manner whenever working in catheterization lab. Radiation protection includes three “principles” namely (a) Justification, (b) Optimization and (c) Dose limitation; & three “actions” as (a) Reducing exposure time, (b) Providing adequate shielding and (c) Distance from the radiation source. The “As Low As Reasonably Achievable (ALARA)” principle is applied for radiation exposure [62]. Minimal fluoroscopy time and lower number of cine angiography run considerably reduce the exposure time to both patient and the operator. It is important to note that the operator dose is directly proportional to the patient dose. On an average, the fluoroscopy dose is 2-4 Rem / minute and cine dose is 40 Rem / minute. A cine-angiographic exposure depends upon radiation dose per frame and duration of exposure. For a cine-angiographic run at the rate of 60 frame per second (fps) and radiation dose of about 25 microRem / frame, the adult skin exposure rate ranges from 45-90 Rem / min (0.45 - 0.9 Sv / min). The Inter-society Commission for Heart Disease Resources has recommended 30 - 40 microRem / frame for a 15 - 17 cm field size image intensifier as a balance between picture quality and minimal radiation exposure [63]. Radiation intensity in relation to the distance from primary beam follows the “inverse square rule” which means that the intensity of exposure is inversely proportional to the square of distance from the primary source. A distance of 2 feet from the source decreases the exposure by 4 times. Assistants and other para-medical staffs should maintain a maximum practical distance from the X-ray tube to minimize the exposure. It is observed that assistant operator receive about 10-30% of the dose, what a primary operator do receive. Unnecessary personnel should not be there in the operating room to minimize radiation exposure and also scatter

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radiation from them. In critically ill patients, there is more number of medical personals in the lab and also image acquisition has to be done in odd views with distant image intensifier, which results in more radiation exposure. Personal Shielding:- A lead apron of about 0.5mm thick should be worn by all medical staff exposed to radiation. The protective value of a lead apron is specified in mm of lead equivalent. A 0.5 mm and 0.25 mm lead apron stop about 98% and 95% of the scatter radiation respectively. It protects the gonads and the highly radio-sensitive bone marrow. Wrap-around two piece lead apron is better than the front piece single apron, for the protection of the back as well. These aprons should be inspected annually under fluoroscopy to look for any damage and timely replacement. As discussed earlier, the dosimeter X-ray badges should be worn one at the level of the collar and other at the level of waist for periodic radiation dose calculation. The thyroid lead collar with 0.5 mm lead equivalent should also be worn. The annual thyroid dose is 1.7 and 3.5 mSv with and without use of thyroid collar, respectively. Hands and eyes are generally less shielded because of infrequent use of leaded gloves and spectacles. The eye glasses with 0.6 mm lead equivalent decreases eye exposure by 6 - 8 times. Ordinary spectacles with photo-chromatic glasses containing lead also offer some protection [64]. A 0.5mm lead equivalent radiation cap is highly effective in protection of operator’s head [65], however it is not being used by most of the interventionists. A ceiling suspended lead glass barriers should be routinely used to reduce scatter radiation by 85%. It should be placed as close to primary beam as possible. This also provides shielding to unprotected area like arms, legs and head. With an under table X-ray tube, the operator's legs receive a higher scatter dose than thyroid or eyes [66]. Tableside and dropdown shields should also be used to decrease the scattered radiation dose. Operator also receive the higher exposure dose on his left side compared to right as left side is near to the radiation source, when intervention via trans-femoral approach is performed. Kicken et al.[67] reported a 1.5 to 2.5 times greater dose on the operator’s left side compared to the operator’s front, while Chong et al.[68] reported a six-fold higher exposure to the lens of the left eye than the to the right eye lens. Pregnant health workers and radiation protection: - The exposure limits should not exceed the prescribed dose limits (table 2). It is advisable to avoid exposure during 8 - 15th weeks of gestation in particular to reduce the chances of fetal mental retardation. Use of wrap- around two piece lead apron and periodic dose monitoring with two lead badges are recommended in routine to pregnant health workers. Lastly, if a pregnant worker wants a change of work schedule and work place, it must be acknowledged and appropriate counseling should be given to them. Training and expertise: - Interventional procedures are complex, demanding and operator’s skill dependant. The fluoroscopy time and cine angiographic runs (both number and duration) for any catheterization are highly operator dependant. The interventionists should be adequately trained in intervention techniques, quality control and radiation protection. An appropriate institutional independent body should supervise the radiation dose given to the patients for various study protocols by the interventionists. A periodical outcome audit should be done with the aim of modifying the selection of patients, choice of techniques and operational procedure to improve the clinical outcome, image quality and also reducing the radiation related complications. The radiation protection and dose control techniques should be the integral part of interventional training programme. There should be live cumulative patient’s skin dose display during the procedure, so that operator is aware of

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radiation exposure. An educational course regarding minimizing the radiation dose can significantly reduce the dose like Kuon E et al who demonstrated a 38% reduction in radiation dose following 90min educational course entitled “Encourage to Less Irradiating Cardiologic Interventional Techniques (ELICIT)” [69]. The reduction was mainly because of shorter angiographic runs, radiation reducing angiographic angulation and better collimation to the area of interest.

Conclusion Though the modern sophisticated catheterization laboratories are equipped with various radiation protection parameters, the increasing number of complex interventional procedures performed has resulted into occupational radiation hazards, which must be acknowledged, better understood, and mitigated to the greatest extent to reduce workplace radiation hazard. To minimize the radiation dose, there is a need for strict compliance to ALARA principle. Every effort should be made at individual and institutional level to reduce the radiation dose, while maintaining the appropriate quality control of the imaging. The interventionist should understand the gravity of situation when dealing with X-rays, and should have optimal lead shielding to protect himself and others. There is also a need of collaboration with industry for further innovations in radiation protection field.

Acknowledgment

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We are thankful to Drs. Anil Grover & Mukesh K. Yadav for correction of the manuscript. There is no conflict of interest of any of the authors of the manuscript.

References [1]

[2]

[3]

[4]

[5]

Mettler FA Jr, Thomadsen BR, Bhargavan M, Gilley DB, Gray,JE, Lipoti JA, et al. Medical radiation exposure in the U.S. in 2006:preliminary results. Health Physics.2008; 95:502-7. Hart D, Jones DG, Wall BF. Estimation of effective dose in diagnostic radiology from entrance surface dose and dose area product measurements. National Radiological Protection Board (NRPB-R 262), London: HMSO Publication Centre, 1–57. Hahn SM, Glastein E. In: Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL,editors. Harrison’s Principles of Internal Medicine, 16th Edition, Mc Graw-Hill Medical Publishing Division, 2001. p. 2585-2590. Balter S, Baim D S. Cineangiographic Imaging, Radiation Safety and Contrast Agents. In:Donald.S.Baim, editor. Grossman’s Cardiac Catheterization, Angiography, and Intervention.7th edition. Lippincott Williams and Wilkins Publications. 2006. p.25-30. Berrington de González A, Darby S. Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries. Lancet. 2004 Jan 31;363(9406):345-51.

Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

172 [6]

[7] [8]

[9] [10]

[11]

[12] [13]

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

[14] [15]

[16]

[17]

[18]

[19] [20]

[21]

Rajesh Vijayvergiya and Anand Subramaniyan Gerber TC, Carr JJ, Arai AE, Dixon RL, Ferrari VA, Gomes AS, et al. Ionizing radiation in cardiac imaging: a science advisory from the American Heart Association Committee on Cardiac Imaging of the Council on Clinical Cardiology and Committee on Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention. Circulation. 2009 Feb 24;119(7):1056-65. Roguin A, Nair P. Radiation during Cardiovascular imaging. Br J Cardiol 2007; 14: 289-92. Valentin J. International commission on radiation protection ICRP Publication 85. Avoidance of radiation injuries from medical interventional procedures. Annals of ICRP. 2000;30(2):1-67 Merriam GR, Focht EF. A cinical study of radiation cataracts and the relationship to dose. Am J Roentgenol 1957; 77:759-785. Kleiman NJ. Radiation cataract. In: Working Party on Research Implications on Health and Safety Standards of the Article 31 Group of Experts, editor. Radiation Protection 145. EU Scientific Seminar 2006. New insights in radiation risk and basic safety standards. Brussels: European Commission, 2007; 81–95. Council Directive laying down basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionizing radiation., 96/29/Euratom 1996(May 13th), Official journal No. L159, June 1996, 1-114. National Council on Radiation Protection and Measurements. Limitation of exposure to ionizing radiation. Bethesda (MD):NCRP 1993;NCRP Report no.116. Schull WJ, Otake M, Yoshimaru H. Effect on Intelligence Test Score of Prenatal Exposure to Ionizing Radiation in Hiroshima and Nagasaki: A Comparison of the T65DRk and DS86 Dosimetry Systems. Hiroshima: Radiation Effects Research Foundation, 1988:3– 88. Schull WJ. Effects of Atomic Radiation—A Half Century of Studies FromHiroshima and Nagasaki. Am J Epid 1996; 143(10):1080-1. Johnson LJ, Moore RJ, Balter S. Review of radiation safety in the cardiac catheterization laboratory. Catheterization and Cardiovascular Diagnosis 1992;25:18694. Limacher MC, Douglas PS, Germano G, Laskey WK, Lindsay BD, McKetty MH, et al. American College of Cardiology Expert Consensus document. Radiation safety in the practice of cardiology. J Am Coll Cardiol 1998; 31:892-913. Efstathopoulos EP, Makrygiannis SS, Kottou S, Karvouni E, Giazitzoglou E, Korovesis S, et al. Medical personnel and patient dosimetry during coronary angiography and intervention. Phys Med Biol 48:3059 –3068; 2003. Trianni A, Padovani R, Foti C, Cragnolini E, Chizzola G, Toh H, et al. Dose to cardiologists in haemodynamic and electrophysiology cardiac interventional procedures. Radiat Prot Dosim 117:111–115; 2005. Kuon E. Radiation Heart. 2008 May; 94(5):667-74. Bakalyar DM, Castellani MD, Safian RD. Radiation exposure to patients undergoing diagnostic and interventional cardiac catheterization procedures. Cathet Cardiovasc Diagn. 1997 Oct;42(2):121-5 Balter S. Why measure radiation during cardiac catheterization? Cath Cardiovasc Diagnosis 1998; 43:371.

Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

Radiation Hazards in Intervention Cardiology

173

[22] Kuon E, Dahm JB, Schmitt M, Glaser C, Gefeller O, Pfahlberg A.. Short communication: time of day influences patient radiation exposure from percutaneous cardiac interventions. Br J Radiol 2003; 76:189–91. [23] Gurley JC. Flat detectors and new aspects of radiation Cardiol Clin. 2009 Aug; 27(3):385-94. [24] Klein AJ, Garcia JA. Rotational coronary angiography Cardiol Clin. 2009 Aug; 27(3):395-405. [25] Cagnon CH, Benedict SH, Mankovich NJ, Bushberg JT, Siebert JA, Whiting JS. Exposure rates in high-level-control fluoroscopy for image enhancement. Radiology. 1991 Mar; 178(3):643-6. [26] Kim KP, Miller DL, Balter S, Kleinerman RA, Linet MS, Kwon D, et al. Occupational radiation Health Phys. 2008 Mar; 94(3):211-27. [27] Hwang E, Gaxiola E, Vlietstra RE, Brenner A, Ebersole D, Browne K. Real-time measurement Cathet Cardiovasc Diagn. 1998 Apr; 43(4):367-70. [28] Suzuki S, Furui S, Kohtake H, Yokoyama N, Kozuma K, Yamamoto Y, et al. Radiation exposure to patient’s skin during percutaneous coronary intervention for various lesions, including chronic total occlusion. Circ J 2006; 70:44–48. [29] Suzuki S, Furui S, Isshiki T, Kozuma K, Koyama Y, Yamamoto H, et al. Patients' skin Catheter Cardiovasc Interv. 2008 Feb 1; 71(2):160-4. [30] Brasselet C, Blanpain T, Tassan-Mangina S, Deschildre A, Duval S, Vitry F, et al. Comparison of operator radiation exposure with optimized radiation protection devices during coronary angiograms and ad hoc percutaneous coronary interventions by radial and femoral routes. Eur Heart J. 2008 Jan; 29(1):63-70. [31] Lange HW, von Boetticher H. Randomized comparison of operator radiation exposure during coronary angiography and intervention by radial or femoral approach. Catheter Cardiovasc Interv 2006; 67: 12–16. [32] Atmakuri SR, Lev EI, Alviar C, Ibarra E, Raizner AE, Solomon SL, et al. Initial experience with a magnetic navigation system for percutaneous coronary intervention in complex coronary artery lesions. J Am Coll Cardiol. 2006 Feb 7; 47(3):515-21. [33] Rassow J, Schmaltz AA, Hentrich F, Streffer C. Effective doses to patients from paediatric cardiac catheterization Br J Radiol. 2000 Feb; 73(866):172-83. [34] Partridge J. Radiation Heart. 2005 Dec; 91(12):1615-20. [35] Li LB, Kai M, Takano K, Ikeda S, Matsuura M, Kusama T. Occupational exposure in pediatric cardiac catheterization . Health Physics 1995; 69:261-4. [36] Bacher K, Bogaert E, Lapere R, De Wolf D, Thierens H. Patient-specific dose and radiation Circulation 2005;111:83-89. [37] Campbell RM, Strieper MJ, Frias PA, Jeager G, Balfour G, Costello L, et al. Quantifying and minimizing radiation exposure during pediatric cardiac catheterization.Pediatric Cardiology 2005; 26(1):29-33. [38] Frush DP, Yoshizumi T. Conventional and CT angiography Pediatr Radiol. 2006 Sep;36 Suppl 2:154-8. [39] Sawdy JM, Gocha MD, Olshove V, Chisolm JL, Hill SL, Phillips A, et al. Radiation protection during hybrid procedures: innovation creates new challenges. J Invasive Cardiol. 2009 Sep; 21(9):437-40.

Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

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Rajesh Vijayvergiya and Anand Subramaniyan

[40] Ben Farhat M, Gamra H, Betbout F, Maatouk F, Jarrar M, Addad F, et al. Percutaneous balloon mitral commissurotomy during pregnancy. Heart. 1997 Jun;77(6):564-7 [41] Mishra S, Narang R, Sharma M, Chopra A, Seth S, Ramamurthy S, et al. Percutaneous transseptal mitral commissurotomy in pregnant women with critical mitral stenosis. Indian Heart J. 2001 Mar-Apr;53(2):192-6 [42] Routray SN, Mishra TK, Swain S, Patnaik UK, Behera M. Balloon mitral valvuloplasty during pregnancy. Int J Gynaecol Obstet. 2004 Apr;85(1):18-23. [43] Weerakkody RA, Walsh SR, Cousins C, Goldstone KE, Tang TY, Gaunt ME. Radiation exposure during endovascular aneurysm repair. Br J Surg. 2008 Jun; 95(6):699-702. [44] Calkins H, Niklason L, Sousa J, El-Atassi R, Langberg J, Morady F. Radiation exposure during radiofrequency catheter ablation of accessory atrioventricular connections. Circulation 1991; 84:2376 –2382. [45] Park TH, Eichling JO, Schechtman KB, Bromberg BI, Smith JM, Lindsay BD. Risk of Radiation induced skin injuries from arrhythmia ablation procedures. PACE 1996; 19:1363–1369. [46] Lindsay B, Eichling J, Ambos H, Cain M. Radiation exposure to patients and medical personnel during radiofrequency catheter ablation for supraventricular tachycardia. Am J Cardiol 1992; 70:218 –223. [47] Rosenthal LS, Mahesh M, Beck TJ, Saul JP, Miller JM, Kay N, et al. Predictors of fluoroscopy time and estimated radiation Am J Cardiol. 1998 Aug 15; 82(4):451-8. [48] Bertaglia E, Bella PD, Tondo C, Proclemer A, Bottoni N, De Ponti R, et al. Image integration increases efficacy of paroxysmal atrial fibrillation catheter ablation: results from the CartoMerge Italian Registry. Europace. 2009 Aug; 11(8):1004-10. [49] Hindricks G, Willems S, Kautzner J, De Chillou C, Wiedemann M, Schepel S, et al. Effect of electroanatomically guided versus conventional catheter ablation of typical atrial flutter on the fluoroscopy time and resource use: a prospective randomized multicenter study. J Cardiovasc Electrophysiol. 2009 Jul; 20(7):734-40. [50] Hamon M, Biondi-Zoccai GG, Malagutti P, Agostoni P, Morello R, Valgimigli M, et al. Diagnostic performance of multislice spiral computed tomography of coronary arteries as compared with conventional invasive coronary angiography: a meta-analysis. J Am Coll Cardiol. 2006 Nov 7; 48(9):1896-910. [51] Dill T, Deetjen A, Ekinci O, Möllmann S, Conradi G, Kluge A, et al. Radiation dose exposure in multislice computed tomography of the coronaries in comparison with conventional coronary angiography. Int J Cardiol. 2008 Mar 14; 124(3):307-11. [52] Wink O, Hecht HS, Ruijters D. Coronary computed tomographic angiography Cardiol Clin. 2009 Aug; 27(3):513-29. [53] Baumüller S, Leschka S, Desbiolles L, Stolzmann P, Scheffel H, Seifert B, et al. Dualsource versus 64-section CT coronary angiography at lower heart rates: comparison of accuracy and radiation dose. Radiology. 2009 Oct; 253(1):56-64. [54] Bastarrika G, Lee YS, Ruzsics B, Schoepf UJ. Coronary CT angiography Radiol Clin North Am. 2009 Jan;47(1):91-107. [55] Ruzsics B, Lee H, Powers ER, Flohr TG, Costello P, Schoepf UJ. Images in cardiovascular medicine. Myocardial ischemia diagnosed by dual-energy computed

Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

Radiation Hazards in Intervention Cardiology

[56]

[57]

[58]

[59]

[60]

[61] [62]

[63]

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

[64]

[65] [66] [67]

[68]

[69]

175

tomography: correlation with single-photon emission computed tomography. Circulation. 2008 Mar 4; 117(9):1244-5. Motoyama S, Anno H, Sarai M, Sato T, Sanda Y, Ozaki Y, et al. Noninvasive coronary angiography with a prototype 256-row area detector computed tomography system: comparison with conventional invasive coronary angiography. J Am Coll Cardiol. 2008 Feb 19; 51(7):773-5. Hoe J, Toh KH. First experience with 320-row multidetector CT coronary angiography scanning with prospective electrocardiogram gating to reduce radiation dose. J Cardiovasc Comput Tomogr. 2009 Jul-Aug; 3(4):257-61. International Commission on Radiological Protection. ICRP Publication 85. Avoidance of radiation injuries from medical interventional procedures. Annals of ICRP 2000; 30(2):1–67. Hendee WR. Estimation of radiation risks. BEIR V and its significance for medicine. JAMA 1992; 268:620–624. Padovani R, Bernardi G, Malisan MR, Vañó E, Morocutti G, Fioretti PM. Patient dose related to the complexity of interventional cardiology procedures. Radiat Prot Dosimetry. 2001; 94(1-2):189-92. Kim KP, Miller DL, Balter S, Kleinerman RA, Linet MS, Kwon D, et al. Occupational radiation Health Phys. 2008 Mar; 94(3):211-27. NCRP (1971). National Council on Radiation Protection and Measurements. Basic Radiation Protection Criteria, NCRP Report No. 39 (National Council on Radiation Protection and Measurements, Washington, D.C.). Friesinger GC, Adams DF, Bourassa MG. Optimal resources for examination of heart and lungs: Cardiac catheterization and radiographic facilities. Examination of the chest and cardiovascular system study group. Circulation 1983; 68:893A-930A. Marshall NW, Faulkner K, Clarke P. An investigation into the effect of protective devices on the dose to radiosensitive organs in the head and neck. Br J Radiol 1992; 65:799—802. Kuon E, Birkel J, Schmitt M, Dahm JB. Radiation exposure benefit of a lead cap in invasive cardiology. Heart. 2003 Oct;89(10):1205-10. Waldman JD, Rummerfield PS, Gilpin EA, Kirkpatrick SE. Radiation exposure to the child during cardiac catheterization. Circulation 1981;64:158-163. Kicken PJH, Kemerink GJ, Schultz FW, Zoetelief J, Broerse JJ, van Engelshoven JMA. Dosimetry of occupationally exposed persons in diagnostic and interventional arteriography.Part II: Assessment of effective dose. Radiat Prot Dosim 82:105–114; 1999. Chong NS, Yin WH, Chan P, Cheng MC, Ko HL, Jeng SC, et al. Evaluation of absorbed radiation dose to working staff during cardiac catheterization procedures. Chinese Med J 63:816–821; 2000. Kuon E, Empen K, Robinson DM, Pfahlberg A, Gefeller O, Dahm JB. Efficiency of a minicourse in radiation reducing techniques: a pilot initiative to encourage less irradiating cardiological interventional techniques (ELICIT). Heart. 2005 Sep;91(9):1221-2.

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13. Important Internet Sites [1] [2] [3] [4] [5]

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[6]

National Council on Radiation at http://www.ncrponline.org/ ICRP - International Commission on Radiological Protection at http://www.icrp.org/ Annals of the ICRP at http://www.sciencedirect.com/science The Ionising Radiation (Medical Exposure) Regulations 2000 at http://www.opsi.gov.uk/si/si2000/20001059.htm European Commission. Radiation protection at http://ec.europa.eu/geninfo/query/resultaction.jsp?userinput=radiation protection National Cancer Institute (2006) Interventional fluoroscopy: reducing radiation risks for patients and staff, available at http://www.cancer

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Chapter IX

Environmental Radiation Monitoring: Public Dose Limits, Measurements and Interpretation Gladys A. Klemic111 and Deborah Elcock122 1

Environmental Measurements Laboratory Science and Technology Directorate, U.S. Department of Homeland Security New York, USA 2 Argonne National Laboratory, Environmental Science Division, SWWashington, DC 20024, USA

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Abstract Determination of the man-made component of the external radiation dose in the vicinity of a nuclear or radiological facility is performed by the facility operator to demonstrate compliance with regulations that limit the allowable dose to the public from man-made sources. Such measurements must include removal of the natural background radiation component that is typically in the same range as the public dose limits. Current technology is adequate to measure the total direct radiation levels, but distinguishing a potential man-made component from the naturally varying radiation background is a more complex problem. This chapter reviews the regulations on public dose limits in the United States and the technologies that are used for environmental monitoring. It also discusses issues associated with the interpretation of routine monitoring data.

11 Science and Technology Directorate, U.S. Department of Homeland Security. 201 Varick Street, 5th Floor, New York, NY 10014, USA. E-mail: [email protected]. 12 2Argonne National Laboratory, Environmental Science Division, 955 L’Enfant Plaza, W, Suite 6000 Washington, DC 20024, USA. E-mail:[email protected].

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Introduction Exploration of the issues related to environmental monitoring of the external (direct) radiation dose at this time is warranted because of increased emphasis on utilization of nuclear power to reduce greenhouse gas emissions. The U.S. Department of Energy (DOE) has programs to support near-term nuclear plant deployment, develop new generation capacity, extend existing plant life, and develop advanced nuclear power plant technologies. It also helps assure supplies of fuel for power plants, and it recently funded nearly $50 million to advance new nuclear technologies in support of the nation’s energy goals. The development of new reactors can be expected to rekindle public concern about exposures to radiation. In addition, funding cuts to the Yucca Mountain Waste Repository may lead to the use of alternative spent fuel storage options and attendant radiation monitoring needs. Measurement of the external radiation dose at the boundary (or beyond) of a nuclear or radiological facility is one component of environmental monitoring programs intended to assess the dose to the general public. Measurements may be performed by the facility operator or, in some cases, by state government authorities to demonstrate compliance with regulations that limit the allowable dose to the public from man-made sources. Such measurements must include consideration of the natural background radiation field, which is typically in the same range as the public dose limits.

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Regulations In the United States, DOE and two other federal government agencies have oversight over nuclear and radiological facilities. The U.S. Environmental Protection Agency (EPA) is responsible for establishing generally applicable standards for the protection of the public from radioactive material. The U.S. Nuclear Regulatory Commission (NRC) is responsible for licensing commercial nuclear power reactors; fuel cycle facilities; and the disposal of nuclear materials and waste; as well as medical, academic, and industrial uses of nuclear materials. The NRC and DOE have established specific public dose restrictions on facilities under their jurisdiction to ensure that they meet the EPA’s general requirements for protection of the public. In 1977, the EPA promulgated environmental radiation protection standards for nuclear power operations [1] that limited the annual public dose equivalent resulting from uranium fuel cycle operations (milling, chemical conversion, isotopic enrichment, fuel fabrication, light-water-cooled reactors, and fuel reprocessing, but not mining, transportation, or waste management operations). The EPA annual dose equivalent limits are not to exceed 25 millirem to the whole body, 75 millirem to the thyroid, and 25 millirem to any other organ. The NRC incorporated these EPA standards into its regulations in 1991.[2] In 1985, the EPA promulgated a 0.25-mSv/yr dose limit for management and storage of spent nuclear fuel or high-level or transuranic radioactive wastes, [3] and a 0.15-mSv/yr effective dose limit for disposal of spent nuclear fuel or high-level or transuranic radioactive wastes for 10,000 years after disposal, assuming undisturbed performance of the disposal system.[4] In 2008, the EPA promulgated a two-part public dose limit for the Yucca Mountain Waste Repository. A 0.15-mSv/yr committed effective dose equivalent applies to the reasonably exposed

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individual for 10,000 years following disposal, and a 1-mSv/yr limit applies after 10,000 years but within the period of geologic stability.[5] In 1994, the EPA proposed guidance for federal agencies that sets the effective dose equivalent received by or committed in a single year to a typical member of any critical group of most highly exposed members of the general public from all sources combined (other than from background, radon, or received for medical purposes) at 1 mSv. The limit may be exceeded temporarily in situations that are not anticipated to recur chronically, provided that the radiation dose incurred in any year does not exceed a 5-mSv effective dose equivalent. Although this proposed guidance was never finalized, both the NRC and DOE have adopted the same 1-mSv/yr limit, but they did so prior to the EPA’s guidance. The NRC adopted the limit for licensed operations in 1991, [6] on the basis of the 1990 recommendations of the International Commission on Radiological Protection (ICRP). In adopting this limit, the NRC also required that nuclear power plants comply with the 0.25-mSv/yr dose limit. DOE adopted the 1-mSv/yr limit in 1990, [7] also based on recommendations of the ICRP. DOE Order 5400.5, Radiation Protection of the Public and the Environment, also requires that DOE operators “make a reasonable effort to be aware of the existence of other than DOE man-made sources of radiation which, combined with the DOE sources, might present a potential for exceeding contributions of 10 mrem (0.1 mSv) effective dose equivalent in a year.” The public dose limits apply to doses from exposures to radiation sources from routine activities, including remedial actions and naturally occurring radionuclides released by DOE processes and operations. In addition to the above limits, which include exposure from all pathways, the EPA has issued regulations, which DOE and the NRC have adopted, that set specific dose limits for gaseous and liquid effluents. Such limits will not be considered in detail here except as they have bearing on the limits and measurements of external dose. The NRC can delegate to individual states the authority to regulate the use of by-product, source, and small quantities of special nuclear material if certain conditions are met. When the conditions are met, the NRC enters into an agreement with the governor of a state to turn over the regulatory authority. Generally these “Agreement States” regulate all sources of radiation in the state except nuclear power plants, large quantities of certain nuclear material, and any high-level radioactive waste stored in the state. There are 35 agreement states. In general, these states have adopted the NRC’s public dose limit, that is, the total effective dose equivalent (TEDE) to individual members of the public from the licensed operation cannot exceed 1 mSv in a year, exclusive of the dose contributions from background radiation or from medical procedures. Under certain conditions, the licensee or license applicant may apply for prior authorization to operate up to an annual dose limit for an individual member of the public of 5 mSv. At least two nonagreement states (Connecticut and Vermont) retain the public dose limit of 5 mSv/yr, which was used by the NRC prior to its adoption of the 1mSv/yr limit in 1991. Both of these states are proposing to revise these limits to be consistent with the 1-mSv/yr limit. Vermont has separate, more restrictive, specific limits that apply to its nuclear power plant, Vermont Yankee. These limits are as follows: 0.25 mSv/yr from all sources, with a maximum of 0.05 mSv/yr from each of the following: gaseous discharges, liquid discharges, radioiodine discharges, radioactive particulate discharges, and emanations of direct gamma radiation.[8] For direct radiation to the public, 0.20 mSv/yr at any point on the site boundary bordered by land is considered equal to a 0.05-mSv/yr dose at the nearest residences in Vermont. Table 1 summarizes public dose limits for direct radiation monitoring.

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Gladys A. Klemic and Deborah Elcock Table 1. Public dose limits relevant for direct radiation monitoring Agency NRC – restricted areas

Annual dose limit 1 mSv (100 mrem)

NRC -– unrestricted areas EPA – unrestricted areas

0.25 mSv (25 mrem)

EPA – long-term disposal State of Vermont – at site boundary DOE – restricted or unrestricted areas

0.15 mSv (15 mrem) 0.20 mSv (20 mrem)

Notes; reference Member of the public in restricted area; 10 CFR 20.1301(a)(1) Member of the public in unrestricted area; 10 CFR 20.1301(e) 40 CFR 190.10; 40 CFR 191.03 and 191.04 40 CFR Part 197 18 V.S.A., Chapter 32, Section 5-305

1 mSv (100 mrem)

DOE Order 5400.5

0.25 mSv (25 mrem)

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Radiation Montoring Requirements The NRC requires licensed nuclear power plants to perform surveys of radiation levels in controlled areas and unrestricted areas and of radioactive materials released in effluents to demonstrate compliance with public dose limits (10 CFR 20.1302). NRC Regulatory Guide 1.21 [9] provides guidance for meeting the requirements of 10 CFR 20.1302. In its introduction, this guidance clarifies that nuclear power plant technical specifications essentially require compliance to be demonstrated by measurement or calculation that the TEDE to the individual likely to receive the highest dose from the licensed operation does not exceed the annual dose limit. NRC Regulatory Guide 1.21 also discusses the differences in EPA and NRC requirements, and in Section 5.2 it states that “in effect, annual dose limits to members of the public while in the unrestricted area are the EPA limits of 25 mrem whole body…” and that the NRC’s 100-mrem TEDE limit applies to the annual dose limit for a member of the public in the licensee’s controlled area. The guidance also notes that demonstrating compliance with the 0.25-mSv limit (to the whole body and to any organ) includes the concept of total dose from all sources related to the uranium fuel cycle and that included in the total dose are contributions from radioactive effluents, as well as from direct radiation. Most of the details provided in NRC Regulatory Guide 1.21 are for monitoring effluents that could result in an internal dose. Regarding external dose, NRC regulatory guidance states that the dose contributions for direct radiation may be estimated on the basis of direct radiation measurements by using such instruments as thermoluminescent dosimeters (TLDs), optically stimulated devices, or ion chambers; calculations; or a combination of measurements and calculations. The guidance suggests that when the direct radiation dose is determined by measurement, estimates of background levels of radiation may be subtracted based on selected control locations, that the doses measured from control and indicator locations should be taken from the same time period, and that the choice of control locations should take into account the historical variability in doses measured at control and indicator locations. Also noted is that extrapolation methods may be used to determine the dose to the maximally exposed individual member of the public.

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Variability in Background Radiation The background radiation field is defined as radiation from cosmic sources; naturally occurring radioactive material; and global fallout, including nuclear explosive devises and past nuclear accidents such as Chernobyl. Background radiation levels vary both spatially and temporally. The terrestrial component depends on the local relative concentrations of radionuclides, and the annual dose can range from 0.1 mSv per year to 1.4 mSv or more per year. The cosmic dose at any given location depends on the altitude; for example, it is about 0.3 mSv per year at sea level and about twice that at elevations of 1.6 km. There are also smaller variations on the order of a few percent with latitude, because of the effects of the earth's magnetic field. Perhaps more significant for direct radiation monitoring are the temporal variations due to well-known diurnal and precipitation effects. Temperature changes and the accompanying atmospheric turbulence are the cause of diurnal effects: gamma-emitting progeny from radon gas exhaled from soil overnight causes an increase in the radiation background. During the day, vertical diffusion of the warming air reduces the radon concentration and the ground level background radiation decreases. Such diurnal effects can be as much as 10% in places where the radon exhalation rate is very high. Precipitation also plays a major role in natural variations in background radiation since rain or snow scavenging of airborne radon progeny causes an increase in radiation levels by up to a factor of 2 for several hours. Subsequently, wet ground or snow cover attenuates the terrestrial component causing radiation levels to drop below the previous baseline. Other possible natural variations are related to seasonal influences, such as frozen soil allowing less radon gas to escape. The cosmic-ray component does not vary as much as the terrestrial component on a day-to-day basis. The 11-year solar cycle, however, can result in variations on the order of 10% from the average value, and occasional solar flares have been observed to produce measurable increases up to a factor of 3 at sea level.

Direct Radiation Monitoring Pressurized ionization chambers (PICs) can provide a detailed time record of the dose rate. PICs are sensitive to small changes, typically allowing measurements every minute or less, and can store long-term data. TLDs and optically stimulated luminescence (OSL) dosimeters are passive devices that measure the integrated dose. The TLD or OSL results may be converted to an exposure rate (by dividing by the monitoring period time) for comparison with previous measurements.

Distinguishing a Facility Dose To demonstrate compliance with public radiation dose limits, environmental monitoring programs must be capable of detecting a facility component on top of the naturally varying radiation background. To address this issue, it is useful to look at data from the long-term monitoring of natural background radiation.

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Figure 1 shows PIC and TLD data from 14 years of simultaneous monitoring at a rural location with no local sources of pollution and undisturbed soil. [10] For the PIC data, each point represents the average of thousands of readings; the associated statistical uncertainty is small (much less than 1%). For TLD measurements, the uncertainty tends to be much higher (about 5 to 10%), because of poorer statistics, so larger variations are observed in the TLD data. Figure 1 shows good agreement between the TLD and PIC data, and it illustrates that while the monthly average background dose rate can vary by as much as almost 40%, the yearly average tends to be more stable, varying only a few percent from year to year. The largest monthly variations are low dose rates corresponding to winter months with greater snow cover. One way to test whether this type of monitoring is adequate to demonstrate compliance with public dose limits is to consider the minimum hourly dose rate that would result in an accumulated annual dose at the regulatory limit. The overall PIC average for this data is 87 nSv/h and is marked with a solid line in the figure. The dashed lines show the hourly dose rate levels that would correspond to an additional dose, above the PIC average, equal to that of some of the annual public dose limits shown in Table 1. The dashed lines show that an additional external dose corresponding to an annual dose of 1 mSv (i.e., 114 nSv/h) above the average background dose would be clearly beyond the range of natura1 measurement variations, and, therefore, easily detectable. The EPA limit of 0.25 mSv and the State of Vermont limit of 0.20 mSv, while closer, are still above the maximum data variation also. However, since the total dose, including the internal component due to effluents, must be considered for compliance, this illustrates that in some cases the external dose of interest could be near to natural background variations. The EPA limit of 0.15 mSv for long-term storage is close to the highest variations observed in TLD data. Thus a closer look at routine direct radiation monitoring data analysis is warranted. 220 200

1 mSv/yr

180 160 140 nSv/h 120

0.25 mSv/yr

100

0.15 mSv/yr

80

Average PIC

60 40 1976 1977 1978 1979

1980

1981 1982 1983

1984 1985

1986

1987 1988

1989

1990

Year

Figure 1. Fourteen years of monthly TLD and PIC monitoring of environmental background radiation. PIC data are shown as dashes, and TLD data are open diamond shapes. For clarity, error bars are shown only for the minimum and maximum TLD data points. Dashed lines indicate the hourly dose rates that correspond to the annual dose limits from Table 1. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

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Interpreting Direct Radiation Monitoring Data Most nuclear power plants in the United States have a network of TLD monitoring stations to demonstrate compliance with dose limits for the public. TLDs are inexpensive, reusable, and rugged, and can therefore be widely deployed and used in locations that are subject to potential loss from vandalism or weather. NRC guidance documents [11,12] describe how to locate about 40 monitoring networks stations in an inner ring around the site boundary, an outer ring 6 to 8 km from the site, and other stations in special interest areas such as population centers, nearby residences, schools, and one or two areas to serve as controls. These are incorporated into each reactor licensee's Offsite Dose Calculation manual (ODCM), and the NRC license Technical Specifications require conformance with the ODCM. Results of TLD measurements are contained in site environmental reports that are published annually and are available on the Internet. [13] Data analysis and interpretation are performed by each facility, and the methods used by each facility can vary. Some report the results as an hourly exposure rate, while others report the integrated exposure for the quarter. To interpret the results, some facilities may group the results by monitoring site locations and take an average for that group, such as inner ring, outer ring, boundary, indicator sites, or controls. The averages may then be compared with previous years’ measurements in the same category, or across categories. Recently updated NRC guidance [14] notes that trend graphs may be appropriate to determine whether there is a component from facility operations. As described above, according to NRC guidance, estimates of background levels of radiation may be subtracted on the basis of selected control locations. Because of the expected variability in the natural background radiation and also in TLD data, subtracting a numerical value for the radiation background may be problematic (e.g., could result in negative numbers). Graphical analysis is an alternative approach, where background TLD data are shown on the same plot as indicator locations. Error bars on the data would be helpful to quantify expected variability. The graphical analysis of Figure 1 illustrates a lower bound on how TLD data could be used, but key differences in routine site monitoring should serve to improve this further. First, most environmental monitoring programs use a quarterly monitoring cycle (rather than monthly), which should result in a lower range of variations than those seen in Figure 1. Secondly, it is important to note that for comparison with annual dose limits, dose rate measurements near the limiting value would have to be present for more than one quarter to result in a dose in excess of the annual limit. Thirdly, a dose large enough to exceed annual limits in a single quarter would be well beyond the range of natural data variations and should be easily detectable in the TLD data. Thus routine TLD monitoring data is expected to be reliable to demonstrate compliance with public dose limits.

Conclusion Regulatory limits for the radiation dose to the public range from 0.15 mSv/yr to 1 mSv/yr and include both internal and external dose. Quarterly TLD measurements are used for direct radiation monitoring to assess the external dose. Methods of analysis of these measurement

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data vary across sites. On the basis of long-term measurements of the natural background radiation, assessing an additional external dose on the order of 0.15 mSv or more would be possible by using TLD data. However, interpretation of environmental monitoring data requires knowledge of the natural background radiation field and its variations. Additional guidance on the analysis and interpretation of TLD direct radiation monitoring data is expected to be addressed in consensus standards currently under development.

Acknowledgments Thanks to Ronald Nimitz and Steven Garry (U.S. Nuclear Regulatory Commission) for helpful comments and discussions and to Elizabeth Hocking (Argonne National Laboratory) for technical insights. Argonne National Laboratory's work was supported by the U.S. Department of Energy under contract DE-AC02-06CH11357.

References

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[30] [31] [32] [33] [34] [35] [36] [37] [38]

[39] [40]

[41]

[42] [43]

40 CFR Part 190. 10 CFR 20.1301(e). 40 CFR 191.03 and 191.04. 40 CFR 191.15. 40 CFR 197. 10 CFR 20.1301(a)(1). DOE Order 5400.5, Radiation Protection of the Public and the Environment, Change 2, dated 1-7-93. Vermont Radiological Health Regulations, Section 5-305, Dec. 10, 1977, available at http://healthvermont.gov/regs/radio. U.S. Nuclear Regulatory Commission Regulatory Guide 1.21, “Measuring, Evaluating, and Reporting Radioactive Material in Liquid and Gaseous Effluents and Solid Waste,” available at (http://www.nrc.gov/reading). P. Shebell, K. Miller, G. K1emic, J.L. Kuiper, M.L. Maiello, USOOE Report EML-538, New York (1991). NRC NUREG 1301 (PWR), “Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Pressurized Water Reactors,” available at http://www.orau.org/PTP/PTP%20Library/library/NRC/NUREG/NUREGS.htm. NRC NUREG 1302 (BWR), “Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Boiling Water Reactors,” available at http://www. orau.org/PTP/PTP%20Library/library/NRC/NUREG/NUREGS.htm. http://www.nrc.gov/reactors/operating/ops-experience/tritium/plant-info.html. Regulatory Guide 4.1, “Radiological Environmental Monitoring for Nuclear Power Plants,” June 2009, at www.nrc.govor.http://adamswebsearch2.nrc.gov/idmws/ doccontent.dll?library=PU_ADAMS^PBNTAD01andID=091630162.

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In: Radiation Exposure in Medicine and the Environment ISBN: 978-1-61209-827-2 Editor: Nicole E. Parnell © 2012 Nova Science Publishers, Inc.

Chapter X

Mobile Telephony Radiation Effects on Living Organisms Dimitris J. Panagopoulos* and Lukas H. Margaritis Department of Cell Biology and Biophysics, Faculty of Biology, University of Athens, Panepistimiopolis, 15784, Athens, Greece

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Abstract A number of serious non thermal biological effects, ranging from changes in cellular function like proliferation rate changes or gene expression changes to cell death induction, decrease in the rate of melatonin production and changes in electroencephalogram patterns in humans, population declinations of birds and insects, and small but statistically significant increases of certain types of cancer, are attributed in our days to the radiations emitted by mobile telephony antennas of both handsets and base stations. This chapter reviews briefly the most important experimental, clinical and statistical findings and presents more extensively a series of experiments, concerning cell death induction on a model biological system. Mobile telephony radiation is found to decrease significantly and non thermally insect reproduction by up to 60%, after a few minutes daily exposure for only few days. Both sexes were found to be affected. The effect is due to DNA fragmentation in the gonads caused by both types of digital mobile telephony radiation used in Europe, GSM 900MHz, (Global System for Mobile telecommunications), and DCS 1800MHz, (Digital Cellular System). GSM was found to be even more bioactive than DCS, due to its higher intensity under equal conditions. The decrease in reproductive capacity seems to be non-linearly depended on radiation intensity, exhibiting a peak for intensities higher than 200 μW/cm2 and an intensity “window” around 10μW/cm2 were it becomes maximum. In terms of the distance from a mobile phone antenna, the intensity of this “window”corresponds under usual conditions to a distance of 20-30 cm. The importance of different parameters of the radiation like intensity, carrier frequency and pulse repetition frequency, in relation to the recorded effects are discussed. Finally, this chapter describes a plausible biophysical and

* E-mail address: [email protected]. Fax: +30210 7274742, Phone: +30210 7274117.

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Dimitris J. Panagopoulos and Lukas H. Margaritis biochemical mechanism which can explain the recorded effects of mobile telephony radiations on living organisms.

Keywords: mobile telephony radiation, GSM, DCS, RF, ELF, electromagnetic fields, non-ionizing electromagnetic radiation, biological effects, health effects, Drosophila, reproductive capacity, cell death, intensity windows

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Introduction As mobile telephony becomes more and more a necessary tool in our daily life enabling modern man to communicate easily with everyone at any place and any moment, serious threats arise from the exposure of all living organisms and the environment to a type of radiation unknown until now. Man made electromagnetic fields and radiations differ substantially from natural electromagnetic radiations like natural light, mainly because artificial ones are polarised, able to induce coherent forced vibrations to any electric charge in their space. All living organisms are made of cells and all cellular functions are of electrical nature, involving movements of electrical charges like clouds of free ions or charged macromolecules. Certain movements of certain type of charges within the cells induce or interrupt corresponding cellular functions. Any wrong, synchronized net movement of charge within the cell, would induce a wrong cellular function. The cell as a highly organized unit of life, has protective mechanisms against wrong cellular function, for example by activating certain genes and consequently producing certain proteins like the “heat shock” ones, made to protect the cell from excessive heat. But if the cell fails to protect itself from an external disturbance, a malfunction may start which can be transferred to a whole tissue or the whole organism. Electromagnetic fields (EMFs) are perceived by the cells as external disturbances or external stress but the cells don’t seem to have special genes to be activated for protection against electromagnetic stress. This might be the reason why in response to electromagnetic stress, cells activate heat shock genes and produce heat shock proteins very rapidly (within minutes) and at a much higher rate than for heat itself, (Weisbrot et al, 2003). It seems to be for the same reason why electromagnetic stress from mobile telephony radiation induces cell death to the reproductive cells much more than other types of external stress examined before like food deprivation or chemicals, (Panagopoulos et al 2007a). Thus it seems that cells are much more sensitive to man-made electromagnetic fields (EMFs) than to other types of stress previously known. This is probably due to the fact that man-made EMFs constitute a new and perhaps more intense type of external stress, against which, cells have not developed defensive mechanisms. If cells activate heat shock genes to protect themselves from electromagnetic stress and this happens at a much higher rate than for heat itself, this might be dangerous, since repetitive stress leading to continuous expression of heat shock genes may result to cancer induction, (French et al, 2001). A number of biological effects induced by man-made (EMFs) and radiations of different frequencies including digital mobile telephony and microwave radiations, have already been reported and documented by many research groups. These include changes in intracellular ionic concentrations, changes in the synthesis rate of different biomolecules, changes in cell proliferation rates, changes in the reproductive capacity of animals, changes in gene expression and even DNA damage and cell death,, (Aitken et al 2005; Bawin and Adey 1976;

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Bawin et al. 1975; 1978; Barteri et al 2005; Belyaev et al 2005; Blackman et al 1980; 1989; Caraglia et al 2005; Diem et al 2005; Dutta et al 1984; Kwee and Raskmark 1998; Velizarov et al 1999; Magras and Xenos 2001; Xenos and Magras 2003; Panagopoulos et al 2004; 2007a; 2007b; Lai and Singh 1995; 1996; 1997; 2004; Remondini et al 2006; Nylund and Leszczynski 2006; Diem et al 2005; Salford et al 2003). At the same time, some epidemiological studies are starting more and more to indicate a connection between the use of cellular mobile phones and certain types of cancer, (Hardell et al 2007a; Hardell et al 2006; Hardell and Hansson-Mild, 2006; Kundi 2004). In several cases, melatonin, a hormone which controls the daily biological cycle and has an oncostatic action, produced by the epiphysis (pineal gland) in mammals, mainly during the night, is found to reduce the action of EMR exposure, but the synthesis of melatonin itself seems to be reduced by EMR, (Burch et al, 2002; Ozguner et al, 2006; Oktem et al, 2005).

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Technical Characteristics of Digital Mobile Telephony Radiation Both systems of Digital Mobile Telephony Radiation used in Europe, GSM 900 MHz and DCS 1800 MHz and also the system used in USA, GSM 1900 MHz, use different carrier frequencies, (900, 1800, and 1900 MHz respectively), but the same pulse repetition frequency of 217 Hz, (Hillebrand 2002; Clark 2001; Hyland 2000; Hamnerius and Uddmar 2000; Tisal 1998). As is obvious, the signals of Digital Mobile Telephony Radiation, combine “radio frequencies” (RF) and “extremely low frequencies” (ELF). All three systems use the “Time Division Multiple Access” (TDMA) code to increase the number of people that can simultaneously communicate with a base station. The radiation is emitted in frames of 4.615 msec duration, at a repetition rate of 217 Hz. Each frame consists of eight “time slots” and each user occupies one of them. Within each time slot the microwave radiation uses a type of phase modulation called “Gausian Minimum Shift Keying” modulation (GMSK) to carry the information, (Tisal 1998; Hamnerius and Uddmar 2000). The transmitted frames by both handsets and base stations are grouped into multi-frames of 25 by the absence of every 26th frame. This results to an additional multi-frame repetition frequency of 8.34 Hz. Finally, handsets emit an even lower frequency at 2 Hz whenever the user is not speaking, for energy saving reasons, (“non-modulated” or “non-speaking” emission or “discontinuous transmission mode”- DTX), (Hyland 2000). Of course, when the handsets operate at DTX mode, the average emitted power is much less (about one tenth of the emitted power when they operate at “speaking” mode, (Panagopoulos et al, 2000a; 2004). Except of the carrier frequency, another important difference between the three systems of digital mobile telephony radiation is that GSM 900MHz antennas of both mobile phones and base stations operate with double the output power than the corresponding DCS 1800MHz ones or the GSM 1900 MHz ones. GSM 900 MHz handsets operate with 2 W peak power output, while DCS 1800 MHz and GSM 1900 MHz ones operate with 1 W peak power output. Radiation from base station antennas is almost identical to that from mobile phones of the same system (GSM or DCS), except that it is about 100 times more powerful, or to be more accurate, from several tens up to several hundred times more powerful. Thereby, effects

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produced by mobile phones at certain distances, can be extrapolated to represent effects from base station antennas at about 100 times longer distances. Another difference is that handset signals include one pulse per frame occupying one time slot, whereas base station signals include again one pulse per frame but this pulse may occupy 1-8 time slots depending on the number of subscribers each moment. In other words the ratio between pulse peak power and time-averaged power is usually higher for the handset signals compared to the base station signals, (Hillebrand 2002; Clark 2001; Hyland 2000; Hamnerius and Uddmar 2000; Tisal 1998).

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Established Exposure Criteria for Mobile Telephony Radiations The most stringent international exposure limits in the western world for RF radiation used by digital mobile telephony were set by the International Radiation Protection Association (IRPA) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). These criteria were established to protect biological tissue from temperature increases, (thermal effects). The ICNIRP exposure limits are given either in terms of Radiation Intensity (Power Density) usually in mW/cm2, either in terms of Specific Absorption Rate (SAR) which is defined as the radiation power, absorbed by the unit mass of tissue, in W/kg. Only the radiation intensity in air outside the body can be readily and objectively measured in exposed individuals. The SAR is difficult to be determined for every single tissue as is different for different tissues and radiations. The best way for determining SAR is by computational approximate methods like the Finite Difference Time Domain (FDTP) method, the Finite Element Method (FEM), or the Method of Moments (MoM), (Meyer and Jacobus, 2003). According to the ICNIRP exposure criteria, the maximum permitted radiation intensity (in mW/cm2) for the general population exposure, is given according to radiation frequency and it is f/2 (f in GHz). Therefore, at 900MHz, the intensity limit according to these criteria is 0.45mW/cm2. At 1800 MHz the corresponding limit is 0.9 mW/cm2, e.t.c). In terms of SAR the ICNIRP limits for the general population are 0.08 W/Kg (for whole-body average absorbed power) and 2 W/Kg (for the head and trunk). All the above values are to be averaged over any 6min period during the 24-h day. (IRPA 1988; ICNIRP 1998). For the frequency 25-800 Hz, the IRPA-ICNIRP limits for the general population are for electric field intensity E, the value 250/f and for magnetic induction B, the value 50/f, (E in kV/m, B in G, f in Hz). Therefore, at 217 Hz, (the pulse repetition frequency of digital mobile telephony radiations), the ICNIRP limits are 1.15kV/m and 0.23 G for up to 24h exposure during the day, (IRPA 1990; ICNIRP 1998). As we shall see, during the years after the establishment of the IRPA-ICNIRP exposure criteria, it has been shown that the vast majority of health effects of digital mobile telephony radiations are non-thermal and a lot of biological effects were recorded at radiation intensities much lower than the values of these criteria. This is the reason why several countries in Europe have established much more stringent national exposure criteria, like Italy, Poland, Russia (10 μW/cm2), or Salzburg (Austria), (0.1 μW/cm2), (“EMF World Wide Standards”).

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A Review of Biological, Clinical and Epidemiological Data There is already a very large number of published studies regarding research on possible health risks from cellular mobile telephony radiations. While a large and increasing number of studies (biological, clinical and epidemiological) have recorded a variety of nonphysiological changes with increased probabilities for health hazards including several types of cancer, a lot of other studies find no connection between exposure to mobile telephony radiations and health risks. Inconsistencies observed between studies are partly expected since no identical conditions can ever be attained between different studies and different labs, but also they are explained by some authors to be due to biased samples. According to a recent article in which possible secret ties between industries and University researchers are discussed, (Hardell et al, 2007b). Since a large number of studies are funded by companies, a matter arises on how much independent these studies can be. In the present review we shall emphasize on the studies that indicate different possible effects on living organisms, since we consider that we must take most seriously and focus the most on the possibility that is worse for living organisms and the natural environment. Additionally because of the large number of studies relating RF-microwave radiations in general, we shall concentrate on those that regard to radiations with frequencies and intensities close to those utilized by digital mobile telephony radiations (800-2450 MHz).

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A. Biological Effects Microwaves are found to produce thermally and non-thermally a large number of biological effects, in many cellular and animal studies, (Banik et al, 2003). In the case of radiations emitted by mobile telephony antennas at intensities that people are normally exposed, the effects are non-thermal as verified by different experimenters, (Diem et al, 2005; Panagopoulos et al, 2004; 2007a; 2007b; Leszczynski et al, 2002; Schirmacher et al, 2000; Velizarov et al, 1999) Regarding non-thermal effects of RF radiations, it is a must to refer to the pioneer works of Bawin et. al. and Blackman et. al. back in the seventies and eighties although these works were relating lower frequency RF radiations. In those pioneer experiments, RF radiation with carrier frequencies 147 and 450 MHz, modulated by sinusoidal ELF signals 0-40 Hz, was found to decrease Ca2+ concentration in chicken brain cells. The effect was found to become maximum at modulation frequencies 6-20 Hz and at intensities 0.6-1 mW/cm2, (Bawin et al 1975; 1978). Non-modulated RF signals were not found to be as bioactive as modulated ones by ELFs and additionally, these effects were found to be non-linearly depended on radiation intensity and frequency, exhibiting “windows” within which the phenomena appeared and then disappeared for values outside, (Blackman et al, 1980; 1989). Repairable DNA damage and increased expression of heat shock protein Hsp 70 without changes in cell proliferation rates was detected in human lens epithelial cells after 2h exposure to 1.8GHz RF field, amplitude modulated at 217 Hz with 3 W/kg SAR. The DNA damage was determined by use of the comet assay, (Lixia et al, 2006).

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Increased expression of genes encoding ribosomal proteins and consequently upregulating the cellular metabolism in human cell types, was found after in vitro exposure to 900 and 1800MHz mobile phone radiation, (Remondini et al, 2006). In an other study, gene and protein expression were altered in human endothelial cell lines, after 900 MHz GSM mobile phone radiation exposure at an average SAR of 2.8 W/kg. Genes and proteins were differently affected by the exposure in each of the cell lines, suggesting that cell response to this type of radiation might be genome and proteome- dependent which in turn might explain to some extend the discrepancies in replication studies between different laboratories, (Nylund and Leszczynski, 2006). Exposure of human endothelial cells in vitro, to GSM 900 MHz mobile phone radiation for 1h at non-thermal levels, average SAR 2 W/kg, caused transient increase in heat shock protein hsp27 phosphorylation and transient changes in protein expression levels, (Leszczynski et al, 2002). Rapid (within minutes) induction of heat shock protein hsp70 synthesis, was found in the insect Drosophila melanogaster, after in vivo exposure to GSM 1900 MHz mobile phone radiation, (Weisbrot et al, 2003). According to a theoretical report, repetitive stress caused by mobile phone radiation, leading to continuous expression of heat shock genes in exposed cells and tissues may result to cancer induction, (French et al, 2001). Two hours of exposure by a cellular mobile phone, changed the structural and biochemical characteristics of acetylcholinesterase, an important central nervous system enzyme, resulting to a significant alteration of its activity. The enzyme was exposed within an aqueous solution at 5 cm distance from the mobile phone, (Barteri et al, 2004). Exposure of myoglobin solution to 1.95 MHz microwave radiation for 3h at non-thermal levels was found to affect the folding of the protein and thereby changing its biochemical properties, (Mancinelli et al, 2004). In vitro exposure for 1h of human skin fibroblasts to GSM radiation, induced alterations in cell morphology and increased the expression of mitogenic signal transduction genes, cell growth inhibitors and genes controlling apoptosis, (Pacini et al, 2002). In an earlier study, 960 MHz GSM-like signal at SAR 0.021, 0.21 and 2.1 mW/cm2 with exposure times 20, 30 and 40 min respectively, was found to decrease the proliferation rate of transformed human epithelial amnion cells. The maximum effect was reached at lower power level with a longer exposure time than at higher power level, (Kwee and Raskmark, 1998). In another study, in vitro exposure of human peripheral blood lymphocytes to continuous 830 MHz radiation, with average SAR 1.6-8.8 W/kg, was found to produce losses and gains of chromosomes (aneuploidy), a somatic mutation leading to cancer. The effect was found to be activated via a non-thermal pathway, (Mashevich et al, 2003). Long term exposure of rats to 900 MHz mobile phone radiation produced oxidative stress (increased oxidant products of free radicals) in retinal tissue. Melatonin and caffeic acid phenethyl ester (CAPE)- component of honeybee propolis administered daily to the animals prior to their EMR exposure, caused a significant reduction in the levels of the oxidant products, (Ozguner et al, 2006). In a previous study of the same group, melatonin was found to reverse oxidative tissue injury in rat kidneys, after 10 days exposure-30 min per day, to 900 MHz GSM radiation emitted by mobile phone, (Oktem et al, 2005). Male mice were exposed to 1800 MHz GSM-like microwaves, 0.1 mW/cm2 for two weeks on workdays, 2h per day. Then mice were anesthetized and blood samples were taken

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for hematology, serum chemistry and serum testosterone determinations. Additionaly, testicles, epididymes, adrenals, prostates and pituitary glands were removed for histology. Red blood cell count and serum testosterone level were found to be significantly higher in the exposed groups but no significant alterations were found in the other investigated variables, (Forgacs et al, 2005). Mice prone to the development of lymphomas, exposed for two 30 min periods per day for up to 18 months, to 900 MHz pulsed microwave radiation with a 217 Hz pulse repetition frequency at SAR ranging from 0.007 to 4.3 W/kg, developed twice the number of tumors than the unexposed ones, (Repacholi et al, 1997). Male Wistar 35-day-old rats were exposed to 2.45 GHz radiation for 2 h/day for a period of 35 days at a power density of 0.344 mW/cm2, (SAR 0.11 W/kg). After 35 days the rats were sacrificed and whole brain tissue was isolated for protein kinase C (PKC) assay. The study revealed a decrease in PKC activity. Electron microscopy study showed an increase in the glial cell population in the exposed group. The results indicated that chronic exposures may affect brain growth and development, (Paulraj and Behari, 2006a). In another study of the same group, single strand DNA breaks were measured as tail length of comet. Fifty cells from each slide and two slides per animal were observed. The study showed that chronic exposure to microwave radiation at non-thermal levels (SAR 1 and 2 W/kg) causes statistically significant increase in DNA single strand breaks in rat brain cells, (Paulraj and Behari, 2006b). In another study mice placed within an RF antenna park were repeatedly mated for five times while they were continuously exposed at very low levels of RF radiation (0.168-1.053 μW/cm2). A progressive decrease in the number of newborns per maternal mouse was observed after each mating, which ended to irreversible infertility, (Magras and Xenos, 1997). In a more recent study of the same group, it was found that exposure of pregnant rats to GSM-like 940 MHz radiation at 5 μW/cm2, resulted in aberrant expression of bone morphogenetic proteins (BMP)-(major endocrine and autocrine morphogens known to be involved in renal development), in the kidneys of newborn rats, (Pyrpasopoulou et al, 2004). Increase in the number of micronuclei in rat bone marrow erythrocytes, a sign of genotoxicity, was observed after 30 days exposure for 2h daily, to 910 MHz microwave radiation, (Demsia et al, 2004). In several other mammal studies, no effects were found, in regards to genotoxicity of second generation mobile telephony (GSM, DCS) and third generation, “universal mobile telecommunication system” (UTMS) radiations, (Sommer et al 2007; Oberto et al 2007; Juutilainen et al 2007;Tillmann et al 2007; Gatta et al 2003). The mortality of chicken embryos was found to increase to 75% from 16% in the control group, after exposure to radiation from a GSM mobile phone, (Grigor’ev, 2003). This result is in agreement with the increased mortality of fertilised chicken eggs that was recorded after irradiation by low power 9.152 GHz pulsed and continuous-wave microwaves, (Xenos and Magras, 2003). Several studies have reported that microwave exposures increase the permeability of the blood-brain barrier (BBB), an hydrophobic barrier made by endothelial cells to protect the mammalian brain from harmful compounds in the blood. A Swedish group has reported that 915 MHz microwaves at non-thermal intensities causes leakage of albumin into the brain through the BBB in rats, accumulating in the neurons and glial cells which surround the capillaries in the brain, (Salford et al, 1994). The same group reported that GSM mobile

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phone radiation from a test mobile phone with a programmable constant power output, opens the BBB for albumin, resulting to damage of brain cells in rats. The power density and SAR were within the ICNIRP limits, (Salford et al 2003). These were the first experiments that indicated cell damage caused by mobile phone radiation although this radiation was not a real mobile phone signal. However in an earlier study of the same group, continuous-wave and pulsed 915 MHz radiation at relatively high intensities, 1 W and 2 W respectively, was not found to damage brain or promote brain tumour development in rats, (Salford et al. 1993). Exposure of an in vitro BBB model, consisted by rat brain cells growing in a culture with pig blood cells, exposed to 1800 MHz microwave radiation pulsed at 217 Hz repetition rate (DCS-like), at SAR 0.3-0.46 W/kg, increased the permeability to sucrose of the BBB twice compared to the control culture. No significant temperature rise was detected during the exposures, (Schirmacher et al, 2000). In a latter study of the same group, in vitro exposure of three other BBB models with distinctly higher barrier tightness than the previously used one, did not cause any effect on the permeability of the BBB of the models, (Franke et al, 2005). In regards to DNA damage or cell death induction due to microwave exposure, in a series of early experiments, rats were exposed to pulsed and continuous-wave 2450 MHz radiation for two hours at an average power density of 2 mW/cm2 and their brain cells were subsequently examined for DNA breaks by “comet” assay. The authors found a dosedependent (0.6 and 1.2 W/kg whole body SAR) increase in DNA single-strand and doublestrand breaks, four hours after the exposure to either the pulsed or the continuous-wave radiation, (Lai and Singh 1995; 1996). The same authors found that melatonin and PBN (Ntert-butyl-alpha-phenylnitrone) both known free radical scavengers, block the above effect of DNA damage by the microwave radiation, (Lai and Singh 1997). Although these experiments were the first to report DNA damage by microwaves, the radiation intensity (2mW/cm2) was relatively high, exceeding the international exposure limits (ICNIRP 1998) and additionally the radiation frequency was the same as in microwave ovens. This is why the authors of this review cannot be sure on whether the reported effects were thermal or non-thermal. In vitro exposure of mouse fibroblasts and human glioblastoma cells to 2450 MHz, (Malyapa et al, 1997a), 835.62 MHz and 847.74 MHz (Malyapa et al, 1997b), radiations at SAR 0.6 W/kg, was not reported to damage DNA as measured by comet assay. A number of recent studies have reported DNA damage, or cell damage, or cell death, induced by mobile telephony or similar RF radiations at non-thermal intensity levels, (Aitken et al, 2005; Diem et al 2005; Panagopoulos et al 2007; Salford et al, 2003; Markova et al, 2005; Caraglia et al, 2005; Nikolova et al, 2005), while some other studies did not find any such connection, (Hook et al, 2004; Capri et al, 2004a; 2004b; Meltz 2003; Cranfield et al, 2003). Aitken et al 2005, reported damage to mitochondrial genome and the nuclear betaglobin locus in the spermatozoa of mice exposed to 900 MHz, 0.09 W/kg SAR, for 7 days, 12h per day. Diem et al 2005, reported single and double-strand DNA breakage in cultured human and rat cells exposed to 1800 MHz mobile phone-like radiation. Panagopoulos et al 2007a, found DNA fragmentation at a very high degree, caused in the reproductive cells of female Drosophila insects only by few min daily exposure to a real mobile phone signal for only few days. These were the first experiments that showed extensive DNA damage and cell death by real digital mobile phone GSM and DCS signals. Previous experiments of the same group had shown a large decrease in the reproductive capacity of the same insect, caused by real mobile phone similar exposures, (Panagopoulos et al, 2004).

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B. Clinical Studies on Humans. Effects on Eeg, Eda, Melatonin, Etc. Mobile telephony radiation is found in several studies to affect electroencephalograms (EEG), electrodermal activity (EDA) and the synthesis rate of hormones like melatonin, in humans. In a series of early experiments performed by a Finish group, GSM mobile phone exposure was found to alter the EEG oscillatory activity of healthy adult subjects, in the 6-8 and 8-10 Hz frequency bands during cognitive (visual memory) tasks, (Krause et al, 2000). In more recent experiments of the same group, exposure of 10-14 year old children to mobile phone GSM field while performing an auditory memory task, induced changes in their brain oscillatory EEG responses in the frequencies 4-8 Hz and 15 Hz, (Krause et al, 2006). Exposure for 30 min to pulse modulated 900 MHz mobile phones-like EMF, increased waking regional cerebral blood flow (rCBF) and enhanced EEG power in the alpha frequency range (8-12 Hz) prior to sleep onset and during sleep. Exposure to the same field without pulse modulation did not enhance power in waking or sleep EEG, (Huber et al, 2002). In another set of experiments of the same group, 30 min exposure to the same 900 MHz GSMlike field during waking period preceding sleep, increased the spectral power of the EEG in non-rapid eye movement sleep. The maximum increase occurred in the 9.75-11.25 Hz and 12.5-13.25 Hz frequency ranges during the initial part of the sleep. Since exposure during waking, modified the EEG during subsequent sleep, the changes in the brain function induced by mobile telephony radiation are considered to outlast the exposure period, (Huber et al, 2000). Mobile phone exposure prior to sleep was found to decrease rapid eye movement sleep latency and to increase EEG spectral power in the 11.5-12.5 Hz frequency, during the initial part of sleep following exposure, (Loughran et al, 2005). Some other studies have failed to find any effects of mobile phone-microwave exposures on EEG during cognitive testing, or to replicate earlier findings, (Röschke and Mann, 1997; Wagner et al., 1998). Mobile phone radiation was found to affect the evoked neuronal activity of the central nervous system (CNN) as represented by EDA, an index of the sympathetic nervous system. Mobile phone exposure was found to lengthen the latency of EDA (Skin Resistance Response), irrespectively of the head side next to mobile phone, (Esen and Esen, 2006). Therefore, mobile phone exposure may increase the response time of users with different negative consequences, like for example the increase in the risk of phone-related driving hazards, e.t.c. A statistically significant increase of chromosomal damage was found in blood lymphocytes of people who used GSM 900 MHz mobile phones, compared to a control group of non-users, matched according to age, sex, health status, drinking and smoking habits, working habits, and professional careers. The increase was even greater for users who were smoker-alcoholic, (Gadhia et al, 2003) In another type of clinical study, exposures of humans to GSM 900 MHz and DCS 1800 MHz mobile phones fields for 35 min, were not found to change significantly arterial blood pressure or heart rate during or after the exposure, (Tahvanainen et al, 2004). Prolonged use of mobile phone, (more than 25 min per day), was found to induce a reduction in melatonin production among male users. The effect was enhanced by additional exposure to 60 Hz ELF magnetic field, (Burch et al, 2002).

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Two studies about possible immediate- short term effects of GSM and UTMS (third generation of mobile networks)-like exposure on well being and cognitive performance in humans based on questionnaires, found contradictive results. The first (Zwamborn et al, 2003) reported no effects of GSM-like exposure, while the UTMS-like exposure was found to reduce well-being and cognitive performance. The second, (Regel et al, 2006) reported no effects at all from either type of radiation. The opinion of the authors of this review is that studies based on questionnaires cannot be as much objective as studies based on measurable indexes like EEG or EDA. Besides, it would be unlikely that subjects would report themselves immediate effects on their well-being.

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C. Epidemiological Studies According to the Swedish Prof. L. Hardell and his research group, the concluding results of up to date epidemiological studies among users for more than ten years use of mobile phones indicate consistently an increased risk for acoustic neuroma and glioma, especially for ipsilateral exposure, (Hardell et al, 2007a). Earlier work of the same research group had found a connection between digital (2nd generation) and analogue (1st generation) mobile phones use and malignant brain tumors, highest for more than ten years latency period, (Hardell et al, 2006). Another review study of the Austrian Prof. M.Kundi conducted few years ago, states as the resume from several epidemiological and experimental studies, that long term exposure to mobile phone emissions (analogue and digital) constitutes a small to moderate increased risk for developing certain types of cancer, (Kundi, 2004). Several other studies had not found any association between mobile phone use and cancer, (Inskip et al, 2001; Johansen et al, 2001; Muscat et al, 2002). A major difficulty in epidemiological studies among mobile phone users is the variation of parameters governing the exposure from hand held mobile phones, i.e. the distance from the nearest base station which can considerably change the intensity of the radiation emitted by the phone, the actual duration of daily use, e.t.c. Nevertheless, the studies done on habitants living close to base stations are more consistent since the station emits a more constant radiation level on a daily basis and therefore a person residing nearby, receives a measurable radiation at least for several hours per day. A recent Egyptian study (Abdel-Rassoul et al, 2007) found that inhabitants living nearby mobile telephony base stations may develop a number of neuropsychiatric problems like headaches, memory changes, dizziness, tremors, depression, sleep disturbances, reported also in previous studies as “microwave syndrome” (Navarro et al 2003), plus changes in the performance of neurobehavioral functions. Similar results were found by other studies in different countries like in France, (Santini et al 2003), Poland (Bortkiewicz et al 2004), Spain (Navarro et al 2003), Austria (Hutter et al 2006). Other epidemiological studies have reported diminishes in the populations of birds around mobile telephony base stations at distances 100-600m from the masts in Belgium, (Everaert and Bauwens 2007) and within 200m from the masts in Spain (Balmori 2005). These studies are in agreement with earlier biological studies which had reported increased mortality of avian embryos, exposed to low levels (5-120 μW/cm2) of RF antennae radiation, (Xenos and Magras, 2003).

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The Design of Bioelectromagnetic Experiments and a Reason for Inconsistencies

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As described in the previous paragraphs, there are frequently contradictory results in the bioelectromagnetic experiments performed by different labs. One factor that we have found to be very important and able to completely change the results of a biological experiment is the influence of the stray electromagnetic fields that exist inside any lab. Within a usual room inside a house or laboratory there are 50-60 Hz fields due to the electric wirings and electrical appliances. Close to the walls, near to sockets or close to electrical appliances one can measure electric fields up to 50 V/m and magnetic fields up to 10 mG. Such fields are found to affect biomolecules, cells and whole organisms in different ways and therefore to affect the outcome of any biological experiment, (Goodman E. et al. 1995; Panagopoulos et al. 2002; Weaver and Astumian 1990). Prior to the design of any biological experiment, a careful scanning of stray fields inside the lab is necessary. The experiments should be performed at the place with the minimum stray fields and special care should be taken in having the control under identical conditions with the exposed groups except only for the factor studied. Temperature, light and humidity are additional important factors that should be identical between exposed and control groups. Before the relatively recent evolution of knowledge in the field of Bioelectromagnetism, ambient electromagnetic fields within the labs were not taken into account in biological experiments. But living organisms are very sensitive to external electromagnetic fields, natural or artificial ones. Rooms or devices used as incubators, are constructed to keep a constant temperature, humidity, e.t.c. in their internal space, but usually are sources of EMFs from their own electrical circuits. A specialized physicist should always be member of any experimental team for taking good care of such factors.

Effects of Mobile Telephony Radiation on a Model Organism Introduction In order to study the ability of the electromagnetic signals emitted by cellular mobile telephony antennas to affect the biological function of living organisms, we used a biological model, the reproductive capacity of the insect Drosophila melanogaster, a well studied experimental animal with many advantages, including its short life cycle and the good timing of its metamorphic stages and developmental processes, (King 1970). Especially the good timing of this insect’s early developmental stages (oogenesis, spermatogenesis, embryogenesis, larval and pupal stages), under certain environmental conditions (i.e. temperature, humidity, food e.t.c.), is a very important feature, on which our experimental protocols were based. In order to study the effects of mobile telephony radiation on the reproductive capacity, we exposed the insects to real mobile phone signals, emitted by commercially available handsets.

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The basic cellular processes are identical in insect and mammalian cells. In addition, insects (particularly Drosophila) are much more resistant, at least to ionizing electromagnetic radiation, than mammals, (Koval and Kazmar 1988, Koval et al 1979, 1977, Abrahamson et al 1973). Therefore, a proper experimental protocol relating Drosophila can be very useful in assessing the bioactivity of electromagnetic radiation in general, (including non-ionizing radiation and electromagnetic fields). Our experiments, regarding few minutes daily exposure of this model organism for only few days, to cellular mobile phone signals, have shown a large decrease in the reproductive capacity, affecting both sexes (Panagopoulos et al 2004). Both systems of digital mobile telephony radiation used in Europe, GSM 900 MHz and DCS 1800 MHz were found to decrease the insect’s reproductive capacity, but GSM 900 MHz was found to be even more bioactive than DCS 1800 MHz, mainly due to the higher intensity of GSM 900 MHz antennas compared to DCS 1800 MHz ones, (Panagopoulos et al 2007b; 2007a). The decrease in the reproductive capacity was found to be due to induced cell death (DNA fragmentation) in the gonads, caused by both types of mobile telephony signals, (Panagopoulos et al 2007a). Unpublished experiments of ours presented here for the first time, show that the bioactivity is strongly and non-linearly dependent on the intensity of the radiation, becoming maximum for intensities higher than 200 μW/cm2 and within an “intensity window” around 10 μW/cm2.

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Materials and Methods Experimental Animal We used Drosophila melanogaster flies, wild-type strain, Oregon R, held in glass bottles with standard food, kept in incubator at 25 °C, with 12-h periods of light and darkness and 70% relative humidity, cultured according to standard methods, (Panagopoulos et al 2004). The food consisted of 450ml water, 4g agar, 13g yeast, 32g rice flour, 16g sugar, 25g tomato pulp. The mixture was boiled for over 10min to ensure sterility, which was preserved by the addition of 2ml propionic acid and 2ml ethanol. This food quantity was enough for 2530 glass vials which were sterilized before the food was added. In each experiment, we collected newly emerged adult flies from the stock early in the afternoon, anesthetized them lightly with diethyl ether and separated males from females. We divided the collected flies in groups of ten in standard laboratory cylindrical glass vials, with 2.5cm diameter and 10cm height, with standard food, which formed a smooth plane surface, 1cm thick at the bottom of the vials. The vials were closed with cotton plugs. Exposure System Before each set of experiments we measured the mean power density of the radiation emitted by the mobile phone handset in the RF range at 900MHz and/or 1800MHz, with the field-meter, “RF Radiation Survey Meter, NARDA 8718”, with its probe inside a glass vial similar to the ones we used for the insects in our experiments. In addition, we measured in the same way the mean electric and magnetic field intensities at the Extremely Low Frequency (ELF) range, with the field-meter, “Holaday HI-3604, ELF Survey Meter”. The experimenter’s position in relation to the mobile phone during the measurements was the same as during the exposures. The mobile phone was held close to the experimenter’s

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head with its antenna facing downward. The exposures and the field measurements, took place in a quiet but not sound-isolated room to simulate the actual conditions to which a user is subjected during a normal conversation on the mobile phone. The room conditions and the positions of all items around the experimental bench were always the same. Exposures and measurements of mobile phone emissions were always conducted at the same place where the mobile phone had full perception of both GSM and DCS signals. The handset was fully charged before each set of exposures or measurements. In the most new digital cell phone handsets, the antenna is in the back and upper side of the device. This can be easily verified by measuring the emitted radiation holding the probe of the field meter in contact with different parts of the handset’s surface. The measured exposure values were in general within the established exposure limits, (ICNIRP 1998). We used commercially available digital mobile phone handsets in all the sets of our experiments, in order to analyze effects of real mobile telephony exposure conditions. As far as we know, we were the first to use a commercially available mobile phone handset itself in biological experiments, (Panagopoulos et al 2000a). The obvious reason was that these devices are the most powerful RF transmitters in our immediate daily environment. Thus, instead of using simulations of digital mobile telephony signals with constant parameters (frequency, intensity etc), or even “test mobile phones” programmed to emit mobile telephony signals with controllable power or frequency, we used real GSM, DCS signals which are never constant, since there are continuous changes in their intensity and frequency. Electromagnetic fields with changing parameters are found to be more bioactive than fields with constant parameters, (Goodman E.M. et al 1995; Diem et al 2005), probably because it is more difficult for living organisms to get adapted to them. Experiments with constant GSM or DCS signals can be performed, but they do not simulate actual conditions. Later other experimenters also started to use mobile phone handsets as exposure devices apparently for the same reasons, (Weisbrot et al 2003; Barteri et al 2005). We exposed the flies within the glass vials by placing the antenna of the mobile phone outside of the vials, in contact with or at different distances from the glass wall and parallel to the vial’s axis. The total duration of exposure was 6min per day in one dose and we started the exposures on the first day of each experiment (day of eclosion). The exposures took place for a total of 2 to 6 days in each experiment depending on the kind of the experiment, as described below. The daily exposure duration of 6min, was chosen in order to have exposure conditions that can be compared with the established exposure criteria, (ICNIRP 1998). Besides, early experiments had shown that only few minutes of daily exposure were enough to produce a significant effect on the insect’s reproductive capacity (Panagopoulos et al, 2000a). The experimenter could speak on the mobile phone during connection (this we called, “modulated” or “speaking” emission), or could just stay silent, (“non-modulated” or “nonspeaking” emission, or DTX mode). The intensity of the emitted radiation increases about ten times when the user speaks during connection, than when there is no speaking, (Panagopoulos et al, 2000a). Exposure Procedures We carried out six sets of experiments: In the first set, we exposed the insects to the mobile phone’s GSM 900 MHz field while the mobile phone was operating in non-speaking mode, (non-modulated emission or DTX). In the second set of experiments, the mobile phone

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was operating in speaking mode, (modulated emission) during the exposures. In the third set of experiments we investigated the effect of the mobile phone signal on the reproductive capacity of each sex separately. In the fourth set of experiments we compared the bioactivity between GSM 900 MHz and DCS 1800 MHz types of mobile telephony signals. In the fifth set of experiments we exposed the insects to different distances (intensities), from the mobile phone antenna from 0 to 100 cm, for both types of radiation. Finally, in the sixth set of experiments we tested the ability of GSM and DCS fields to induce DNA fragmentation (cell death) in the ovarian cells of the female insects during oogenesis. In every single experiment we separated the newly emerged collected adult flies to exposed (E) and sham-exposed (SE)/control (C) groups. Each one of the groups consisted always of ten female and ten male, newly emerged flies. The sham exposed groups had identical treatment as the exposed ones, except that the mobile phone during the 6-min “exposures”, was turned off. Every time before each exposure, the cotton plugs were pushed down in the glass vials in order to confine the flies to a small area of about 1cm height between the cotton and the food so as to provide roughly even exposure to all flies. After the exposure, the cotton plugs were pulled back to the top of the vials, and the vials were put back in the culture room. In every group of insects in all the sets of experiments, we kept the ten males and the ten females for the first 48h of the experiment in separate glass tubes. At eclosion, adult female flies have already in their ovaries eggs at the first preyolk stages and oogenesis has already started. The eggs develop through 14 distinct stages, until they are ready to be fertilized and laid, and the whole process of oogenesis lasts about 48h. By the end of the second day of their adult life, the female flies have in their ovipositors the first fully developed egg chambers of stage 14th, ready to be fertilized and laid, (King 1970; Panagopoulos et al 2004). At the same time, the first mature spermatozoa, (about 6h after eclosion) and the necessary paragonial substances (about 12h after eclosion) in male flies have already been developed (King 1970; Stromnaes and Kvelland 1962; Connolly and Tully 1998). Keeping males separately from females for the first 48h of the experiment ensures that the flies are in complete sexual maturity and ready for immediate mating and laying of fertilized eggs. After the first 48h of each experiment, the flies were anesthetized very lightly again and males and females of each group were put together (ten pairs) in another glass tube with fresh food, allowed to mate and lay eggs for 72h. During these three days, the daily egg production of Drosophila is at its maximum (from the 3rd to 5th day of its adult life), then stays at a plateau or declines slightly for the next 5 days and diminishes considerably after the 10th day of adult life (Bos and Boerema 1981; Shorrocks 1972; Ramirez et al 1983). On the sixth day of each experiment in all six sets of experiments, the flies were removed from the glass vials and the vials were maintained in the culture room for six additional days, without further exposure. After the last six days, most F1 embryos (deriving from the laid eggs) are in the stage of pupation, where they can be clearly seen with bare eyes and easily counted on the walls of the glass tubes, as at the last stages before pupation, the larvae leave the food, crawling up the walls of the glass vials. There may be a few embryos still in the last stages as larvae, which are big enough and ready for pupation (on the surface or already away from the food), so that they can be easily counted. [If the remaining larvae are still many and the counting is imprecise, the experimenter can wait an additional day and recount the pupae]. There may be also already a few newly emerged F1 adult flies, which can also be counted easily.

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During the last six days, we inspected the surface of the food within the glass vials under the stereo-microscope for any non-developed laid eggs or dead larvae, something that we did not see in our experiments (empty egg-shells can be seen after hatching). The number of observed exceptions (non-developed eggs or dead larvae), both in exposed and control groups (less than 5%) was within the Standard Deviation of progeny number. [The insignificant percentage of F1 egg and larvae mortality is due to the fact that the paternal-maternal flies were newly emerged during the first 2-5 days of their adult lives]. Therefore the number of pupae in our experiments corresponded to the number of laid eggs (oviposition). Furthermore, the counting of pupae can be done without any error at all, whereas the counting of laid eggs under a stereo-microscope is subject to considerable error. The oviposition of Drosophila is influenced by many factors, like temperature, humidity, prior anesthesia, crowding, food, (King 1970). Special care must be taken to keep all these factors constant. Experience in handling the flies is necessary to prevent accidental deaths. This number of F1 pupae under the above described conditions, during the insect’s three days of highest oviposition, is that we have defined as the Insect’s Reproductive Capacity and this is the biological index we have used to examine the bioactivity of electromagnetic radiation-field. The temperature during the exposures was monitored within the vials with a mercury thermometer with an accuracy of 0.05°C. In the sixth set of experiments, after the additional last exposure in the morning of the sixth day from the beginning of each experiment, the flies were removed from the glass vials, and the ovaries of females were dissected into individual ovarioles and fixed for TUNEL assay. The vials were then maintained in the culture room for six additional days, without further exposure, in order to count the F1 pupae as in all the sets of experiments. Tunel Assay A widely used method for identifying cell death is TUNEL assay. By use of this method, fluorescein dUTP is bound through the action of terminal transferase, onto fragmented genomic DNA which then becomes labelled by characteristic fluorescence. The label incorporated at the damaged sites of DNA is visualized by fluorescence microscopy, (Gavrieli et al, 1992). Each Drosophila ovary consists of 16 to 20 ovarioles. Each ovariole is an individual egg assembly line, with new egg chambers in the anterior moving toward the posterior as they develop, through the 14 successive stages as described, until the mature egg reaches the oviduct. To determine the ability of GSM and DCS radiation to act as possible stress factors able to induce cell death during early and mid oogenesis, we used TUNEL assay, as follows: Ovaries were dissected in Ringer’s solution and separated into individual ovarioles from which we took away egg chambers of stages 11-14. In egg chambers of stages 11-14 programmed cell death takes place normally in the nurse cells and follicle cells. Thereby we kept and treated ovarioles and individual egg chambers from germarium up to stage 10. Samples were fixed in PBS solution containing 4% formaldehyde plus 0.1% Triton X-100 (Sigma Chemical Co., Germany) for 30min and then rinsed three times and washed twice in PBS for 5 min each. Then samples were incubated with PBS containing 20 μg/ml proteinase K for 10 minutes and washed three times in PBS for 5 min each. In situ detection of fragmented genomic DNA was performed with Boehringer Mannheim kit containing

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fluorescein dUTP for 3h at 37°C in the dark. Samples were then washed six times in PBS for 1h and 30 min in the dark and finally mounted in antifading mounting medium (90% glycerol containing 1.4-diazabicyclo (2.2.2) octane (Sigma Chemical Co., Germany) to prevent from fading and viewed under a Nikon Eclipse TE 2000-S fluorescence microscope.

Results and Discussion In the first two sets of experiments, we separated the insects into two groups: a) the Exposed group (E) and b) the Sham Exposed group (SE). The 6-min daily exposures took place for the first five days of each experiment. In the first three sets of experiments, the exposures were performed by GSM 900 MHz mobile phone radiation-field. Before the exposures, we measured radiation and field intensities, as described above. In the RF range, the measured mean power density for 6min of modulated emission (M), with the antenna of the mobile phone outside of the glass vial in contact with the glass wall and parallel to the vial’s axis was 0.436±0.060 mW/cm2. The non-modulated (NM) corresponding measured mean value, was 0.041±0.006 mW/cm2. In the ELF range, the measured values for modulated field, excluding the ambient electric and magnetic fields of 50Hz, were 6.05±1.62 V/m electric field intensity and 0.10±0.06 mG magnetic field intensity. The corresponding non-modulated values were 3.18±1.10 V/m and 0.030±0.003 mG. All given values are average from eight separate measurements of each kind ± Standard Deviation (SD). These values are typical for all commonly used GSM 900 MHz mobile phone handsets.

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1. Effect of Non-Modulated GSM Radiation-Field on the Reproductive Capacity We carried out four experiments (1.1-1.4) with non-modulated field, (non-speaking emission). The exposure parameters in this case simulate the situation when a user listens through the mobile phone during connection. Results are listed in Table 1. Table 1 shows the mean number of F1 pupae (corresponding to the number of laid eggs) per maternal fly in the groups E(NM) exposed to Non-Modulated (NM), GSM 900 MHz mobile phone field and in the corresponding sham exposed (control) groups SE(NM) during the first three days of the insect’s maximum oviposition. The Non-Modulated GSM 900 MHz signalss, decreased the insect’s reproductive capacity by up to 20% in relation to the unexposed groups with six min daily exposure for five days. No temperature increases were detected within the vials during the exposures. Statistical analysis, (single factor ANOVA test) shows that the probability that mean oviposition differs between the exposed and the sham exposed groups, owing to random variations, is P < 5×10-4. Therefore, the decrease in the reproductive capacity is due to the effect of the GSM field.

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Table 1. Effect of Non-Modulated GSM field on the Reproductive Capacity of Drosophila melanogaster Experiment No

Groups

1.1

E(NM) SE(NM) E(NM) SE(NM) E(NM) SE(NM) E(NM) SE(NM) E(NM) SE(NM)

1.2 1.3 1.4 Average ± SD

Mean Number of F1 Pupae per Maternal Fly 9.7 11.6 10 11.9 9.8 12.4 10.4 12.9 9.975 ± 0.31 12.2 ± 0.57

Deviation from Control -16.38% -15.96% -20.16% -19.38% -18.24%

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2. Effect of Modulated GSM Radiation-Field on the Reproductive Capacity We carried out four experiments (2.1-2.4), with modulated emission (the experimenter was speaking close to the mobile phone’s microphone, during the exposures). The exposure parameters in this case simulate the situation when a user speaks on the mobile phone during connection. Results are listed in Table 2. Table 2 shows the mean number of F1 pupae (corresponding to the number of laid eggs) per maternal fly in the groups E, exposed to “Modulated” GSM field and in the corresponding sham exposed groups, SE, during the first three days of the insect’s maximum oviposition. The Modulated GSM 900 MHz signals induced a large decrease in the insect’s reproductive capacity up to 60% as compared to the unexposed groups. No temperature increases were detected during the exposures and thus these effects are considered as nonthermal. Table 2. Effect of Modulated GSM field on the Reproductive Capacity of Drosophila melanogaster Experiment No

Groups

2.1

E(M) SE (M) (Control) E SE (M) (Control) E SE (M) (Control) E SE (M) (Control) E (M) SE (M) (Control)

2.2 2.3 2.4 Average ± SD

Mean Number of F1 Pupae per Maternal Fly 6.7 13.1 5.1 11.8 5.6 12.1 6 12.8 5.85 ± 0.67 12.45 ± 0.6

Deviation from Control -48.85% -56.78% -53.72% -53.125% -53.01%

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The reproductive capacity was much more decreased by modulated emission, (50-60%), than by non-modulated emission, (15-20%). Thus the effect is strongly dependent on radiation-field intensity. At the same time, the intensity of the modulated signal, is about ten times more powerful than the non-modulated signal. Thereby, the effect is not linearly dependent on radiation intensity. The results from the first two sets of experiments are represented, in Figure 1. The statistical analysis shows that the probability that mean oviposition differs between the exposed and the sham exposed groups, owing to random variations, is very small, P < 10-5. Thus the recorded effect is due to the GSM signal.

Number of F1 pupae per maternal insect

R e p ro d u c tiv e C a p a c ity o f E x p o s e d a n d S h a m E x p o s e d G ro u p s 14 12 10 8 6 4 2 0

S E (N M )

E (N M )

S E (M )

E (M )

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G ro u p s

Figure 1. Reproductive Capacity of the groups exposed to non-modulated and modulated GSM 900 MHz field [E(NM), E(M)] and the corresponding sham exposed, [SE(NM), SE(M)], groups. [The error bars correspond to Standard Deviation].

3. Effects on the Reproductive Capacity of Each Sex A third set of experiments (C) was carried out in order to record the effect of the GSM 900 MHz field on the reproductive capacity of each sex separately. The mobile phone was operating in speaking mode during the 6 min exposures, and the insects were separated into four groups (each one consisting again 10 male and 10 female insects): In the first group (E1), both male and female insects were exposed. In the second group (E2), only the females were exposed. In the third group (E3), we exposed only the males and the fourth group (SE) was sham exposed (control). Therefore in this third set of experiments, the 6-min daily exposures took place only during the first two days of each experiment while the males and females of each group were separated and the total number of exposures in each experiment was 2 instead of 5. The results from this set of experiments are listed in Table 3 and represented graphically in Figure 2. The results of this set of experiments show that the GSM field affects the reproductive capacity of both female and male insects. The female insects (E2) were more affected than males (E3) in these experiments. This is expected to be due to the fact that, by the time we

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started the exposures, spermatogenesis was already almost completed in male flies, while oogenesis had just started, (King 1970; Panagopoulos et al 2004). Statistical analysis (single factor ANOVA test) shows that the probability that mean oviposition differs between the four groups because of random variations is P < 10-7. Table 3. Effect of “Modulated” GSM field on the Reproductive Capacity of each sex Experiment Νο 3.1

Groups SE(Control) E1 E2 E3 SE (Control) E1 E2 E3 SE (Control) E1 E2 E3 SE (Control) E1 E2 E3 SE (Control) E1 E2 E3

3.2

3.3

3.4

Deviation from Control -35.61% -28.79% -11.36% -44.93% -35.51% -12.32% -39.53% -27.91% -14.73% -48.89% -42.22% -9.63% -42.32% -33.71% -11.985%

Effect of GSM field on the R eproductive Capacity of each sex Number of F1 pupae per maternal insect

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Average ±SD

Mean Number of F1 Pupae Per Maternal Fly 13.2 8.5 9.4 11.7 13.8 7.6 8.9 12.1 12.9 7.8 9.3 11 13.5 6.9 7.8 12.2 13.35 ± 0.39 7.7 ± 0.66 8.85 ± 0.73 11.75 ± 0.54

14 12 10 8 6 4 2 0

SE

E1

E2

E3

G roups

Figure 2. Effect of Modulated GSM field on the reproductive capacity of each sex of Drosophila melanogaster. Average mean number of F1 pupae ±SD per maternal insect. SE: sham exposed groups, E1: groups that both sexes were exposed, E2: groups in which only the females were exposed, E3: groups in which only the males were exposed.

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In the following fourth, fifth and sixth set of experiments, we used a dual band cellular mobile phone that could be connected to either GSM 900 or DCS 1800 networks simply by changing SIM (“Subscriber Identity Module”) cards on the same handset. The highest Specific Absorption Rate (SAR), given by the manufacturer for human head, was 0.89 W/Kg. The exposure procedure was the same. The experimenter spoke on the mobile phone’s microphone during the exposures. The GSM and DCS fields were thus “modulated” by the human voice, (“speaking emissions” or “GSM basic”).

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4. Comparison of Bioactivity between GSM 900 MHz and DCS 1800 MHz In this set of experiments we separated the insects into four groups: a) the group Exposed to GSM 900MHz field with the mobile phone antenna in contact with the glass vial containing the flies (named as “900”), b) the group exposed to GSM 900MHz field with the antenna of the mobile phone at 1cm distance from the vial (named as “900A”), c) the group exposed to DCS 1800MHz field with the mobile phone antenna in contact with the glass vial (named as “1800”), and d) the Sham Exposed (Control) group (named as “SE”). The comparison between first and third group represents comparison with the usual exposure conditions between GSM 900 and DCS 1800 users, while comparison between second and third group represents comparison between possible effects of the RF frequencies of the two systems under equal radiation intensities. Therefore the second group (900A) was introduced for better comparison of effects between the two types of radiation. Measured mean power densities in contact with the mobile phone antenna for six min of modulated emission, were 0.407 ± 0.061 mW/cm2 for GSM 900 MHz and 0.283 ± 0.043 mW/cm2 for DCS 1800 MHz. As was expected GSM 900 MHz intensity at the same distance from the antenna and with the same handset was higher than the corresponding DCS 1800 MHz. For the better comparison between the two systems of radiation we measured the GSM power density at different distances from the antenna and found that at 1cm distance, the GSM 900 MHz intensity was 0.286± 0.050 mW/cm2, almost equal to DCS 1800 MHz at zero distance. Measured electric and magnetic field intensities in the ELF range for modulated field, excluding the ambient electric and magnetic fields of 50Hz, were 22.3±2.2 V/m electric field intensity and 0.50±0.08 mG magnetic field intensity for GSM at zero distance, 13.9±1.6 V/m, 0.40±0.07 mG correspondingly for GSM at 1 cm distance and 14.2 ±1.7 V/m, 0.38±0.07 mG correspondingly for DCS at zero distance. All these values are averaged over ten separate measurements of each kind ± standard deviation (SD). Except for the power density - field measurements of the mobile phone emissions, we obtained the spectra of both types of radiation, plus the background spectrum in our lab, (Figure 3). Each one of the two types of radiation gave a unique frequency spectrum. While GSM 900MHz gives a single peak around 900MHz, (Figure 3b), DCS 1800MHz gives a main peak around 1800MHz and a smaller one around 900MHz, (Figure 3c). The spectra were obtained by a Hewlett Packard 8595 E, (9 kHz-6.5 GHz), spectrum analyzer (USA). We carried out ten replicate experiments. Results are listed in Table 4 and represented graphically, in Figure 4.

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Figure 3. Background, GSM 900 MHz and DCS 1800 MHz spectra. Radiation Exposure in Medicine and the Environment: Risks and Protective Strategies : Risks and Protective Strategies, Nova Science Publishers,

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The results from this set of experiments show that the reproductive capacity in all the exposed groups is significantly decreased compared to the sham exposed groups. The decrease is maximum in the 900 groups, (48.25% compared to SE) and smaller in the 900A and the 1800 groups, (32.75% and 31.08% respectively), (Table 4). Although the decrease was even smaller in the 1800 groups than in 900A, differences between the 900A and 1800 groups were found to be within the standard deviation, (Table 4, Figure 4). The statistical analysis shows that the probability that the reproductive capacity differs between groups, owing to random variations, is negligible, P < 10-18. Again, we did not detect any temperature increases, within the glass vials during the exposures. The differences in the reproductive capacity between the groups were greater between 900 and 900A (owing to intensity differences between the two types of radiation) and much smaller between 900A and 1800, (owing to frequency differences between GSM and DCS), (Table 4). This set of experiments shows that there is a difference in the bioactivity between GSM 900 MHz and DCS 1800 MHz and this difference is mainly due to the higher intensity of GSM 900 under the same exposure conditions, (differences between groups 900 and 900A) and not due to the different RF carrier frequencies, (differences between 900A and 1800 groups). Intensity differences between the two types of cellular mobile telephony radiation depend also on the ability of communication between the antennas of the mobile phone and the corresponding base station. Even if GSM 900 usually has a higher intensity than DCS 1800, this situation can be reversed in certain places if GSM 900 has a much better signal perception between its antennas than DCS 1800, (Tisal 1998). Our results count for equal signal perception conditions between the two types of radiation.

Number of F1 pupae per maternal insect

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Effect of GSM, DCS fields on Reproductive Capacity 14 12 10 8 6 4 2 0

SE

900

900A

1800

Groups Figure 4. Reproductive Capacity (mean number of F1 pupae per maternal fly) of exposed (900, 900A, 1800) and sham exposed (SE) groups.

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Table 4. Effect of Modulated GSM and DCS fields on the Reproductive Capacity of Drosophila melanogaster Experiment No

Groups

1

900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control) 900 900A 1800 SE (Control)

2

3

4

5

6

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7

8

9

10

Average ± SD

Mean Number of F1 Pupae per Maternal Fly 7.7 8.9 9.2 13.4 5.8 8.1 7.9 11.9 6.8 7.9 8.7 12.6 7.4 9.7 9.9 14.1 6.2 8.5 8.2 13 6.1 8.2 7.8 10.8 6.7 8.3 9 12.8 6 7.9 8.4 11.7 6.7 8.8 9.1 13.2 5.7 8.3 8.5 12.3 6.51 ± 0.67 8.46 ± 0.55 8.67 ± 0.65 12.58 ± 0.95

Deviation from Control -42.54% -33.58% -31.34% -51.26% -31.93% -33.61% -46.03% -37.30% -30.95% -47.52% -31.21% -29.79% -52.31% -34.62% -36.92% -43.52% -24.07% -27.78% -47.66% -35.16% -29.69% -48.72% -32.48% -28.21% -49.24% -33.33% -31.06% -53.66% -32.52% -30.89% -48.25% -32.75% -31.08%

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5. Radiation Bioactivity According to its Intensity (or According to the Distance from the Antenna) The aim of this set of experiments was to investigate the dependence of GSM 900 MHz and DCS 1800 MHz bioactivity on their intensity, at different intensity levels that people are exposed to, from mobile phones and base station antennas. The radiation from base station antennas is almost identical to that of corresponding mobile phones but it is about 100 times stronger. Thus distances from mobile phones antennas correspond to about 100 times longer distances from base station antennas of the same type of radiation. It is difficult to set up experiments regarding exposures from base station antennas since there is no way to have a sham exposed group of experimental animals under identical environmental conditions but without being exposed to the radiation at the same time. Thus we thought that the only way to simulate the reality of the exposure by a base station antenna is to expose the animals at different distances from a mobile phone within the lab. Biological effects of mobile telephony signals at different intensities- distances from the antenna of a mobile phone handset, resembling effects from base station signals within residential areas, were not performed until now. In each single experiment of this set, we separated the collected insects into thirteen groups: The first group (named “0”) was exposed to GSM 900 MHz or to DCS 1800 MHz field with the mobile phone antenna in contact with the glass vial containing the flies. The second (named “1”), was exposed to GSM 900 MHz or to DCS 1800 MHz field, at 1cm distance from the mobile phone antenna. The third group (named “10”) was exposed to GSM 900 MHz or to DCS 1800 MHz field at 10 cm distance from the mobile phone antenna. The fourth group (named “20”) was exposed to GSM 900 MHz or to DCS 1800 MHz field at 20 cm distance from the mobile phone antenna, etc, the twelveth group (named “100”) was exposed to GSM 900 MHz or to DCS 1800 MHz field at 100 cm distance from the mobile phone antenna. Finally, the thirteenth group (named “SE”) was the sham exposed. Each group consisted of ten male and ten female insects as previously. Radiation and field measurements in contact and at different distances from the mobile phone antenna, for six min of modulated emission, for GSM 900 MHz and DCS 1800 MHz in the RF and ELF ranges excluding the background electric and magnetic fields of 50 Hz, are given in Table 5. All the values shown in Table 5, are averaged over ten separate measurements of each kind ± standard deviation (S.D.). The measurements reveal that although ELF electric and magnetic fields fall at almost zero levels for distances longer than 50 cm from both GSM 900 and DCS 1800 mobile phone antennas, the RF components of the signals are still evident for distances up to 100 cm, (Table 5). The Average mean values of reproductive capacity (number of F1 pupae) from six identical experiments with each kind of radiation are shown in Table 6 and represented in Figures 5, 6. The statistical analysis (single factor Anova test) shows that the probability that the reproductive capacity differs between groups, owing to random variations, is negligible, P < 10-8. Once again there was no temperature increases within the vials during the exposures. The results show that the effect of mobile telephony radiation is maximum at zero distance (intensities higher than 200 μW/cm2) and then becomes maximum at a distance of 20-30 cm from the antenna, depending on the intensity of radiation (GSM or DCS). This distance corresponds to an intensity around 10 μW/cm2 for both types of radiation in regards to the RF components.

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Table 5. Radiation and Field Intensities in the Microwave and ELF regions Distance from Antenna (cm)

GSM Radiation Intensity at 900 MHz, (mW/cm2)

GSM Electric Field Intensity at 217 Hz, (V/m)

GSM Magnetic Field Intensity at 217 Hz, (mG)

DCS DCS Radiation Electric Intensity at 1800 Field Intensity MHz, (mW/cm2) at 217 Hz, (V/m)

0 1 10 20 30 40 50 60 70 80 90 100

0.380 ±0.058 0.260 ±0.047 0.062 ±0.020 0.032 ±0.008 0.010 ±0.002 0.006 ±0.001 0.003 ±0.0006 0.002 ±0.0003 0.0017 ±0.0002 0.0012 ±0.0002 0.0010 ±0.0001 0.0004 ±0.0001

19 ±2.5 12 ±1.7 7 ±0.8 2.8±0.4 0.6 ±0.09 0.2 ±0.03 0.1 ±0.02 0 0 0 0 0

0.9 ±0.15 0.7 ±0.13 0.3 ±0.05 0.2 ±0.04 0.1 ±0.02 0.05 ±0.01 0 0 0 0 0 0

0.250 ±0.048 0.068 ±0.015 0.029 ±0.005 0.012 ±0.002 0.007 ±0.001 0.004 ±0.0007 0.002 ±0.0003 0.0016 ±0.0002 0.0014 ±0.0002 0.0008 ±0.0002 0.0005 ±0.0001 0.0002 ±0.0001

13 ±2.1 6 ±0.8 2.9 ±0.48 0.7 ±0.12 0.3 ±0.06 0.1 ±0.04 0 0 0 0 0 0

GSM Magnetic Field Intensity at 217 Hz, (mG) 0.6 ±0.08 0. 4 ±0.07 0. 2 ±0.05 0. 1±0.02 0.06 ±0.01 0 0 0 0 0 0 0

Table 6. Effect of Modulated GSM and DCS radiation-fields on the Reproductive Capacity at different Distances-Intensities from the antenna

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Groups -Distance from mobile phone antenna, (cm) 0 1 10 20 30 40 50 60 70 80 90 100

Average Mean Number of F1 Pupae per Maternal Fly, for GSM 900 MHz 7.45 ± 0.72 9.38 ± 0.61 11.29 ± 0.80 11.52 ± 0.79 7.33 ± 0.58 12.88 ± 0.98 13.48 ± 0.81 13.61 ± 0.84 13.70 ± 0.91 13.97 ± 0.77 13.74 ± 0.96 14.02 ± 1.01

Deviation from Sham Exposed Group

Average Mean Number of F1 Pupae per Maternal Fly, for DCS 1800 MHz

Deviation from Sham Exposed Group

-46.01 % -32.03 % -18.19 % -16.52 % -46.88 % -6.67 % -2.32 % -1.38 % -0.72 % +1.23 % -0.43 % +1.59 %

9.26 ± 0.68 11.36 ± 0.54 11.93 ± 0.71 9.19 ± 0.62 13.03 ± 0.83 13.76 ± 0.85 13.85 ± 0.74 14.00 ± 0.91 14.21 ± 0.89 14.07 ± 0.79 14.02 ± 1.03 14.31 ± 1.08

-34.00 % -19.03 % -14.97 % -34.50 % -7.13 % -1.92 % -1.28 % -0.21 % +1.28 % +0.29 % -0.07 % +2.00 %

The effect on the reproductive capacity diminishes considerably for distances longer than 50 cm from the mobile phone antenna and disappears for distances longer than 80-90 cm, corresponding to radiation intensities smaller than 1 μW/cm2. For distances longer than 50 cm where the ELF components fall within the background, the decrease in reproductive capacity is within the standard deviation. This might suggest that the ELF components of digital mobile telephony signals, play a key role in their bio-activity, alone or in conjunction with the RF carrier wave. We have recorded the existence of an “intensity window” around 10 μW/cm2 (in regards to the RF intensity) where the bio-effect becomes even more intense than at intensities higher than 200 μW/cm2. This intensity window appears at a distance of 20-30 cm from a mobile phone antenna, which corresponds to a distance of about 20-30 meters from a base station antenna.

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Since mobile telephony base station antennas are usually located within residential areas, at distances 20-30 m from such antennas there are often houses and work places where people are exposed up to 24 hours per day.

Mean number of F1 pupae per maternal insect

In te n s ity E ffe c t o f G S M 9 0 0 M H z R a d ia tio n 16 14 12 10 8 6 4 2 0

SE

0

1

10

20

30

40

50

60

70

80

90

100

G ro u p s

Mean number of F1 pupae per maternal insect

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Figure 5. Reproductive Capacity in relation to the Distance from a GSM 900 MHz mobile phone antenna. The decrease in reproductive capacity is maximum at zero distance and at 30 cm distance from the antenna, corresponding to RF intensities 380μW/cm2 and 10μW/cm2 (Table 5).

Intensity Effect of DCS 1800 MHz Radiation 16 14 12 10 8 6 4 2 0

SE

0

1

10

20

30

40

50 60

70 80

90 100

Groups Figure 6. Reproductive Capacity in relation to the Distance from a DCS 1800 MHz mobile phone antenna. The decrease in reproductive capacity is maximum at zero distance and at 20 cm distance from the antenna, corresponding to RF intensities 250 μW/cm2 and 12 μW/cm2 (Table 5).

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Although intensity windows on the bio-effects of RF radiations have been recorded since many years, (Bawin et al 1975; 1978; Blackman et al, 1980), there is still no widely accepted explanation for their existence.

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6. The Decrease in Reproductive Capacity is Due to Cell Death in the Gonads In each experiment of this final sixth set, we separated the collected insects into five groups. The first four groups were the same just as in the No 4 experiments: The first group (named “900”) was exposed to GSM 900 MHz field with the mobile phone antenna in contact with the glass vial containing the flies. The second (named “900A”), was exposed to GSM 900 MHz at 1cm distance from the mobile phone antenna. The third group (named “1800”) was exposed to DCS 1800 MHz field with the mobile phone antenna in contact with the glass vial. The fourth group (named “SE”) was sham-exposed. Finally there was an additional fifth group (named “C”) which was the control. While sham-exposed animals were treated exactly as the exposed ones except that the mobile phone was turned off during the “exposures”, control animals were never exposed in any way or even taken out of the culture room. Each group consisted as always of ten male and ten female insects. In this set of experiments, there was an additional 6 min exposure in the morning of the sixth day, and one hour later female insects from each group were dissected and prepared for TUNEL assay. This additional exposure time was the only difference in the exposure procedure from the previous sets of experiments. Since we were studying the effect on early and mid oogenesis during which the egg chambers develop from one stage to the next within few hours, (King, 1970), an additional exposure, one hour before dissection and fixation of the ovarioles, was proven to be important in recording immediate effects on DNA fragmentation. The most anterior region of the ovariole is called the germarium. The most sensitive developmental stages during oogenesis for stress-induced apoptosis, are region 2 within the germarium referred to as “germarium checkpoint” and stages 7-8 just before the onset of vitellogenesis, referred to as “mid-oogenesis checkpoint”, (Drummond-Barbosa and Spradling, 2001; McCall 2004). The nurse cells (NC) and follicle cells (FC) of both checkpoints, were found to be very sensitive to stress factors like poor nutrition, (DrummondBarbosa and Spradling, 2001; Smith et al., 2002), or exposure to cytotoxic chemicals like etoposide or staurosporine, (Nezis et al., 2000). Apart from these two check points, egg chambers were not observed before to degenerate during other provitellogenic or vitellogenic stages, (germarium to stage 10), (Drummond-Barbosa and Spradling, 2001; McCall 2004). To determine the ability of GSM and DCS radiation to act as possible stress factors able to induce cell death during early and mid oogenesis, we used TUNEL assay, as described above. The samples from different experimental groups were blindly observed under the fluorescence microscope (i.e. the observer did not know the origin of the sample) and the percentage of egg chambers with TUNEL positive signal was scored in each sample. Statistical analysis was made by single factor Analysis of Variance test. In Table 7 the summarised data from 8 separate experiments are listed. The data reveal that both GSM 900 and DCS 1800 mobile telephony radiations strongly induce cell death, (DNA fragmentation) in ovarian egg chambers of the exposed groups, (63.01% in 900,

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45.08% in 900A and 39.43% in 1800), while in the SE and C groups the corresponding percentage of cell death was only 7.78% and 7.75% respectively. Ovarian cell death between the control group and the sham exposed group did not differ significantly, (differences were within standard deviation) and this is why the data from the C group are omitted in Table 7. Electromagnetic stress from mobile telephony radiations was found in our experiments to be much more bioactive than previously known stress factors like poor nutrition or cytotoxic chemicals, inducing cell death to a higher degree not only to the above check points but to all developmental stages of early and mid oogenesis and moreover to all types of egg chamber cells, i.e. nurse cells, follicle cells and the oocyte (OC), (Panagopoulos et al, 2007a).

a

S8 G

S4

S1 S2 S3

S1

b

G

S8 2a

S8 2b

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c

G S4

c S8

S4

FC

S3 G

S7

S2 S1 NC OC

Figure 7. a) Ovariole of a sham exposed female insect with TUNEL negative egg chambers at all the developmental stages from germarium (G) to stage 8. b) Ovariole of exposed female insect with TUNEL positive signal at both check-points, germarium and stage 8 and TUNEL negative signal at the intermediate stages. c) Ovarioles of exposed female insects with TUNEL positive signals at all the developmental stages and in all types of egg chamber cells, nurse cells (NC), follicle cells (FC) and the oocyte (OC).

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Table 7. Effect of GSM, DCS fields on Ovarian Cell Death

Groups

SE

900

900A

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1800

Germarium 1-6 7-8 9-10 Germarium 1-6 7-8 9-10 Germarium 1-6 7-8 9-10

Ratio of TUNEL Positive to Total Number of Eggchambers of each dev. stage 37/186 32/1148 78/364 7/282 165/189 675/1252 310/384 165/262 116/184 484/1248 213/374 117/257

Germarium 1-6 7-8 9-10

101/169 388/1202 196/358 91/239

Dev. Stages

Sum Ratio of TUNEL Positive to Total Number of Egg-chambers of all stages

Percentage of TUNEL Positive Egg chambers

Deviation from Sham Exposed Groups

154/1980

7.78%

0%

1315/2087

63.01%

+55.23%

930/2063

45.08%

+37.30%

776/1968

39.43%

+31.65%

Figure 7a, shows an ovariole from a sham exposed female insect, containing egg chambers from germarium to stage 8, all TUNEL negative. This was the typical picture in the vast majority of ovarioles and separate egg chambers from female insects of the sham exposed and control groups. In the SE groups, only 154 egg chambers (including germaria) out of a total of 1980 in 8 replicate experiments (7.78%), were TUNEL positive (Table 7), a result that is in full agreement with the rate of spontaneously degenerated egg chambers normally observed during Drosophila oogenesis, (Nezis et al., 2000; Baum et al., 2005). Figure 7b shows an ovariole of exposed female insect (group 900A), with a TUNEL positive signal in the nurse cells at both checkpoints, germarium and stage 8, while egg chambers of intermediate stages are TUNEL negative. Corresponding pictures from 900 and 1800 (data not shown) had identical characteristics. The two checkpoints in all groups (exposed and SE/C) had the highest percentages of cell death compared to the other developmental stages 1-6 and 9-10, (Table 7). While in the SE groups the sum ratio of TUNEL positive to total number of egg chambers was slightly higher in stages 7-8 (78/364) than in the germarium (37/186), in all three exposed groups this ratio was higher in the germarium than in stages 7-8, (Table 7). Figure 7c, shows ovarioles of exposed female insects (group 900A), with a TUNEL positive signal at all developmental stages from germarium to 7-8 and in all the cell types of the egg chamber, (nurse cells, follicle cells and the oocyte). Although in most pictures the TUNEL positive signal was most evident in the nurse cells, in the majority of the egg chambers in all the exposed groups, a TUNEL positive signal was detected in all three kinds of egg chamber cells, (figures 1c). In the SE groups the ratio of TUNEL positive egg chambers of stages 9-10 was very small (7/282). In contrast, the corresponding ratio in all three exposed groups was significantly higher, (165/262 in 900, 117/257 in 900A and 91/239 in 1800).

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Number of TUNEL Positive to Total Number of Egg Chambers

Ovarian Cell Death induced by GSM and DCS Radiations 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0

SE

900

900A

1800

Groups

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Figure 8. Mean ratio of Ovarian Cell Death (Number of TUNEL Positive to Total Number of Egg Chambers), in each experimental group ± SD, (0.078± 0.0335 in SE, 0.630± 0.0898 in 900, 0.451± 0.0574 in 900A and 0.394± 0.0777 in 1800).

The summarised data of Table 7 are represented in Figure8. The statistical analysis, (single factor Analysis of Variance test), showed that the probability that groups differ between them because of random variations, is negligible, P or =10 years. Occup. Environ. Med. 64(9):626-32. Review. Hardell L, Carlberg M and Hansson Mild K, (2006): Pooled analysis of two case-control studies on use of cellular and cordless telephones and the risk for malignant brain tumours diagnosed in 1997-2003, Int. Arch. Occup. Environ. Health. 2006 Sep;79(8):630-9. Hardell L. and Hansson Mild K. (2006) Mobile phone use and risk of acoustic neuroma: results of the interphone case-control study in five North European countries. Br. J. Cancer. 94(9):1348-9. Hardell L, Walker MJ, Walhjalt B, Friedman LS, Richter ED. (2007b): Secret ties to industry and conflicting interests in cancer research. Am. J. Ind. Med. 50(3):227-33. Hillebrand F. (Ed), GSM and UTMS, Wiley, 2002.

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Hook GJ, Zhang P, Lagroye I, Li L, Higashikubo R, Moros EG, Straube WL, Pickard WF, Baty JD, Roti Roti JL. (2004): Measurement of DNA damage and apoptosis in Molt-4 cells after in vitro exposure to radiofrequency radiation. Radiat. Res. 161(2):193-200. Hutter H-P, Moshammer H, Wallner P Kundi M, (2006): Subjective symptoms, sleeping problems, and cognitive performance in subjects living near mobile phone base stations. Occupational and Environmental Medicine; 63:307-313. Hyland G.J., (2000): Physics and Biology of Mobile Telephony, Lancet, 356, 1833-36. Huber R, Treyer V, Borbely AA, Schuderer J, Gottselig JM, Landolt HP, Werth E, Berthold T, Kuster N, Buck A, Achermann P. (2002): Electromagnetic fields, such as those from mobile phones, alter regional cerebral blood flow and sleep and waking EEG. J. Sleep Res. 11(4):289-95. Huber R, Graf T, Cote KA, Wittmann L, Gallmann E, Matter D, Schuderer J, Kuster N, Borbély AA, Achermann P. (2000): Exposure to pulsed high-frequency electromagnetic field during waking affects human sleep EEG. Neuroreport. 11(15):3321-5. ICNIRP (1998), “Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300GHz)”, Health Phys. 74, 494-522. Inskip PD, Tarone RE, Hatch EE, Wilcosky TC, Shapiro WR, Selker RG, Fine HA, Black PM, Loeffler JS, Linet MS. (2001): Cellular-telephone use and brain tumors. N. Engl. J. Med. 344(2):79-86. IRPA (1988), “Guidelines on limits of exposure to radiofrequency electromagnetic fields in the frequency range from 100kHz to 300GHz”, Health Phys., 54, 115-123. IRPA, (1990): “Interim Guidelines on Limits of Exposure to 50 / 60 Hz Electric and Magnetic Fields”, Health Physics, Vol.58, No 1, 113-122. Johansen C, Boice J Jr, McLaughlin J, Olsen J. (2001): Cellular telephones and cancer--a nationwide cohort study in Denmark. J. Natl. Cancer Inst. 93(3):203-7. Juutilainen J, Heikkinen P, Soikkeli H, Mäki-Paakkanen J. (2007): Micronucleus frequency in erythrocytes of mice after long-term exposure to radiofrequency radiation. Int. J. Radiat. Biol. 83(4):213-20. King R.C. (1970), Ovarian Development in Drosophila Melanogaster. Academic Press. Koval T.M., Hart R.W., Myser W.C. and Hink W.F. (1977), “A comparison of survival and repair of UV-induced DNA damage in cultured insect versus mammalian cells”, Genetics 87, 513-518. Koval T.M. and Kazmar E.R. (1988), “DNA double-strand break repair in eukaryotic cell lines having radically different radiosensitivities”, Radiat. Res. 113, 268-277. Koval T.M., Hart R.W., Myser W.C. and Hink W.F. (1979), “DNA single-strand break repair in cultured insect and mammalian cells after x-irradiation”, Int. J. Radiat. Biol. Relat. Stud. Phys. Chem. Med. 35, 183-188. Krause CM, Sillanmäki L, Koivisto M, Häggqvist A, Saarela C, Revonsuo A, Laine M, Hämäläinen H. (2000): Effects of electromagnetic fields emitted by cellular phones on the electroencephalogram during a visual working memory task. Int. J. Radiat. Biol. 76(12):1659-67. Krause CM, Björnberg CH, Pesonen M, Hulten A, Liesivuori T, Koivisto M, Revonsuo A, Laine M, Hämäläinen H. (2006): Mobile phone effects on children's event-related oscillatory EEG during an auditory memory task. Int. J. Radiat. Biol. 82(6):443-50.

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Mobile Telephony Radiation Effects on Living Organisms

223

Kundi M, (2004): Mobile phone use and cancer, Occup. Environ. Med., 61, 560-570. Kwee S. and Raskmark P., (1998), “Changes in cell proliferation due to environmental nonionizing radiation: 2. Microwave radiation”, Bioelectrochemistry and Bioenergetics, 44, 251-255. Lai H, Singh NP. (1995): Acute low-intensity microwave exposure increases DNA singlestrand breaks in rat brain cells, Bioelectromagnetics, 16(3): 207-10. Lai H, Singh NP. (1996): Single- and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency electromagnetic radiation. Int. J. Radiat. Biol. Apr;69(4): 513-21. Lai H, Singh NP. (1997): Melatonin and a spin-trap compound block radiofrequency electromagnetic radiation-induced DNA strand breaks in rat brain cells. Bioelectr omagnetics. 18(6): 446-54. Lai H, Singh NP. (2004): Magnetic-field-induced DNA strand breaks in brain cells of the rat. Environ. Health Perspect. 112(6): 687-94. Leszczynski D, Joenväärä S, Reivinen J, Kuokka R. (2002): Non-thermal activation of the hsp27/p38MAPK stress pathway by mobile phone radiation in human endothelial cells: molecular mechanism for cancer- and blood-brain barrier-related effects. Differentiation. 70(2-3):120-9. Lin - Liu S. and Adey W. R. (1982), “Low frequency amplitude modulated microwave fields change calcium efflux rates from synaptosomes”, Bioelectromagnetics, (N.Y.), 3,309-322. Lixia S, Yao K, Kaijun W, Deqiang L, Huajun H, Xiangwei G, Baohong W, Wei Z, Jianling L, Wei W. (2006): Effects of 1.8 GHz radiofrequency field on DNA damage and expression of heat shock protein 70 in human lens epithelial cells. Mutat. Res. 602 (12):135-42. Loughran SP, Wood AW, Barton JM, Croft RJ, Thompson B, Stough C. The effect of electromagnetic fields emitted by mobile phones on human sleep. Neuroreport. 2005 Nov 28;16(17):1973-6. Magras, I.N.; Xenos, T.D. RF radiation-induced changes in the prenatal development of mice. Bioelectromagnetics 1997, 18, 455–461. Malyapa RS, Ahern EW, Straube WL, Moros EG, Pickard WF, Roti Roti JL, (1997a): “Measurement of DNA damage after exposure to 2450 MHz electromagnetic radiation”, Radiation Research, 148(6), 608-617. Malyapa RS, Ahern EW, Straube WL, Moros EG, Pickard WF, Roti Roti JL, (1997b): “Measurement of DNA damage after exposure to electromagnetic radiation in the cellular phone communication frequency band, (835.62 and 847.74 MHz)”, Radiation Research, 148(6), 618-627. Mancinelli F, Caraglia M, Abbruzzese A, d'Ambrosio G, Massa R, Bismuto E. (2004): Nonthermal effects of electromagnetic fields at mobile phone frequency on the refolding of an intracellular protein: myoglobin. J. Cell Biochem. 93(1):188-96. Markova E, Hillert L, Malmgren L, Persson BR, Belyaev IY. (2005): Microwaves from GSM mobile telephones affect 53BP1 and gamma-H2AX foci in human lymphocytes from hypersensitive and healthy persons. Environ. Health Perspect. 113(9): 1172-7.

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224

Dimitris J. Panagopoulos and Lukas H. Margaritis

Mashevich M, Folkman D, Kesar A, Barbul A, Korenstein R, Jerby E, Avivi L. (2003): Exposure of human peripheral blood lymphocytes to electromagnetic fields associated with cellular phones leads to chromosomal instability. Bioelectromagnetics. 24(2):82-90. McCall K., (2004): Eggs over easy: cell death in the Drosophila ovary, Developmental Biology, 274(1), 2004, 3-14. Meltz ML, (2003): Radiofrequency exposure and mammalian cell toxicity, genotoxicity, and transformation, Bioelectromagnetics, suppl. 6, 196-213. Meyer FJC and Jakobus U, (2003): Numerical Techniques in RF Dosimetry for Mobile Phone Technology, In: Stavroulakis P. (Ed.), Biological Effects of Electromagnetic Fields, Springer, 171-237. Muscat JE, Malkin MG, Shore RE, Thompson S, Neugut AI, Stellman SD, Bruce J. (2002): Handheld cellular telephones and risk of acoustic neuroma. Neurology. 58(8):1304-6. Navarro Enrique A., Segura J., Portolés M., Claudio Gómez- Perretta de Mateo, (2003): The Microwave Syndrome: A Preliminary Study in Spain, Electromagnetic Biology and Medicine, 22 (2-3), 161-169. Nezis IP, Stravopodis DJ, Papassideri I, Robert-Nicoud M, Margaritis LH. (2000). Stagespecific apoptotic patterns during Drosophila oogenesis. Eur. J. Cell Biol. 79:610-620. Nylund R, Leszczynski D. (2006): Mobile phone radiation causes changes in gene and protein expression in human endothelial cell lines and the response seems to be genome- and proteome-dependent. Proteomics. 6(17): 4769-4780. Oberto G, Rolfo K, Yu P, Carbonatto M, Peano S, Kuster N, Ebert S, Tofani S. (2007): Carcinogenicity study of 217 Hz pulsed 900 MHz electromagnetic fields in Pim1 transgenic mice. Radiat. Res. 168(3):316-26. Oktem F, Ozguner F, Mollaoglu H, Koyu A, Uz E. (2005): Oxidative damage in the kidney induced by 900-MHz-emitted mobile phone: protection by melatonin. Arch. Med. Res. 36(4):350-5. Ozguner F, Bardak Y, Comlekci S. (2006): Protective effects of melatonin and caffeic acid phenethyl ester against retinal oxidative stress in long-term use of mobile phone: a comparative study. Mol. Cell Biochem. 282(1-2):83-8. Paulraj R, Behari J. (2006a): Protein kinase C activity in developing rat brain cells exposed to 2.45 GHz radiation.Electromagn. Biol. Med. 25(1):61-70. Paulraj R, Behari J. (2006b): Single strand DNA breaks in rat brain cells exposed to microwave radiation. Mutat. Res. Apr 11;596(1-2):76-80. Pacini S, Ruggiero M, Sardi I, Aterini S, Gulisano F, Gulisano M.( 2002): Exposure to global system for mobile communication (GSM) cellular phone radiofrequency alters gene expression, proliferation, and morphology of human skin fibroblasts. Oncol. Res. 13(1):19-24. Panagopoulos DJ, Chavdoula ED, Nezis IP and Margaritis LH, (2007): Cell Death induced by GSM 900MHz and DCS 1800MHz Mobile Telephony Radiation, Mutation Research, 626, 69-78. Panagopoulos DJ, Chavdoula ED, Karabarbounis A, and Margaritis LH, (2007): Comparison of Bioactivity between GSM 900 MHz and DCS 1800 MHz Mobile Telephony Radiation, Electromagnetic Biology and Medicine 26(1).

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Mobile Telephony Radiation Effects on Living Organisms

225

Panagopoulos D.J., Karabarbounis A., and Margaritis L.H., (2004), Effect of GSM 900-MHz Mobile Phone Radiation on the Reproductive Capacity of Drosophila melanogaster, Electromagnetic Biology and Medicine, 23(1), 29-43. Panagopoulos D.J., Messini, N., Karabarbounis, A., Philippetis A.L., and Margaritis L.H., (2000a), “Radio Frequency Electromagnetic Radiation within “safety levels” Alters the Physiological Function of Insects”, In: Kostarakis P, Stavroulakis P, (ed), Millennium International Workshop on Biological Effects of Electromagnetic Fields, Proceedings, Heraklion, Crete, Greece, 17-20 October, 2000, 169-175, ISBN: 960-86733-0-5. Panagopoulos D.J, Margaritis L.H, (2003a): “Effects of electromagnetic fields on the Reproductive Capacity of Drosophila melanogaster, In: Stavroulakis P. (ed.), Biological Effects of Electromagnetic Fields, Springer, 545-578. Panagopoulos DJ, Messini N, Karabarbounis A, Filippetis AL, and Margaritis LH, (2000b): “A mechanism for Action of Oscillating Electric Fields on Cells”, Biochemical and Biophysical Research Communications, 272(3), 634-640. Panagopoulos D.J., Karabarbounis, A. and Margaritis L.H., (2002), “Mechanism for action of electromagnetic fields on cells”, Biochem. Biophys. Res. Commun., 298(1), 95-102. Panagopoulos D.J. and Margaritis L.H., (2003b), Theoretical Considerations for the Biological Effects of Electromagnetic Fields, In: Stavroulakis P. (Ed.) “Biological Effects of Electromagnetic Fields”, Springer, 5-33. Penafiel L.M., Litovitz T., Krause D., Desta A., Mullins J.M., (1997), Role of Modulation on the effects of microwaves on ornithine decarboxylase activity in L929 cells, Bioelectromagnetics, 18, 132-141. Port M, Abend M, Romer B, Van Beuningen D. (2003): Influence of high-frequency electromagnetic fields on different modes of cell death and gene expression. Int. J. Radiat. Biol. 79(9): 701-8. Pyrpasopoulou A, Kotoula V, Cheva A, Hytiroglou P, Nikolakaki E, Magras IN, Xenos TD, Tsiboukis TD, Karkavelas G. (2004): Bone morphogenetic protein expression in newborn rat kidneys after prenatal exposure to radiofrequency radiation. Bioelectromagnetics. 25(3):216-27. Ramirez E., Monteagudo J.L., Garcia-Gracia M., Delgado J.M.R., (1983), “Electromagnetic Effects in Drosophila”, Bioelectromagnetics, 4, 315-326. Regel SJ, Negovetic S, Röösli M, Berdiñas V, Schuderer J, Huss A, Lott U, Kuster N, Achermann P. (2006): UMTS base station-like exposure, well-being, and cognitive performance. Environ. Health Perspect. 114(8):1270-5. Remondini D, Nylund R, Reivinen J, Poulletier de Gannes F, Veyret B, Lagroye I, Haro E, Trillo MA, Capri M, Franceschi C, Schlatterer K, Gminski R, Fitzner R, Tauber R, Schuderer J, Kuster N, Leszczynski D, Bersani F, Maercker C. (2006): Gene expression changes in human cells after exposure to mobile phone microwaves. Proteomics. 6(17):4745-4754. Repacholi MH, Basten A, Gebski V, Noonan D, Finnie J, Harris AW. (1997): Lymphomas in E mu-Pim1 transgenic mice exposed to pulsed 900 MHZ electromagnetic fields. Radiat. Res. 147(5):631-40.

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226

Dimitris J. Panagopoulos and Lukas H. Margaritis

Röschke J.and Mann K., (1997): No short-term effects of digital mobile radio telephone on the awake human electroencephalogram, Bioelectromagnetics 18, pp. 172–176. Salford LG, Brun A, Persson BR, Eberhardt JL,. (1993): Experimental studies of brain tumor development during exposure to continuous and pulsed 915 MHz radiofrequency radiation, Bioelectrochemistry and Bioenergetics, 27(6):535-42. Salford LG, Brun A, Sturesson K, Eberhardt JL, Persson BR. (1994): Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz. Microsc. Res. Tech. 27(6):535-42. Salford LG, Brun AE, Eberhardt JL, Marmgren L, and Persson BR, (2003): Nerve Cell Damage in Mammalian Brain after Exposure to Microwaves from GSM Mobile Phones, Environmental Health Perspectives, 111(7), 881-883. Santini MT, Ferrante A, Rainaldi G, Indovina P, Indovina PL. (2005): Extremely low frequency (ELF) magnetic fields and apoptosis: a review. Int. J. Radiat. Biol. 81(1):1-11. Review. Santini R, Santini P, Danze JM, Le Ruz P, Seigne M. (2003): Symptoms experienced by people in vicinity of base stations: II/ Incidences of age, duration of exposure, location of subjects in relation to the antennas and other electromagnetic factors, Pathol. Biol. (Paris). 51(7):412-5. Sheikh MS, Huang Y. (2004): TRAIL death receptors, Bcl-2 protein family, and endoplasmic reticulum calcium pool. Vitam. Horm.67:169-88. Review. Smith J.E. III, Cummings C.A. and Cronmiller C., (2002), Daughterless coordinates somatic cell proliferation, differentiation and germline cyst survival during follicle formation in Drosophila, Development 129, pp. 3255–3267. Sommer AM, Bitz AK, Streckert J, Hansen VW, Lerchl A. (2007): Lymphoma development in mice chronically exposed to UMTS-modulated radiofrequency electromagnetic fields. Radiat. Res. 168(1):72-80. Schirmacher A, Winters S, Fischer S, Goeke J, Galla HJ, Kullnick U, Ringelstein EB, Stögbauer F. (2000): Electromagnetic fields (1.8 GHz) increase the permeability to sucrose of the blood-brain barrier in vitro. Bioelectromagnetics. 21(5):338-45. Shorrocks B., (1972), “Drosophila”, Ginn, London. Stromnaes O. and Kvelland I., (1962): “Sexual activity of Drosophila melanogaster males”, Hereditas, 48, 442-470. Tahvanainen K, Nino J, Halonen P, Kuusela T, Laitinen T, Lansimies E, Hartikainen J, Hietanen M, Lindholm H. (2004). Cellular phone use does not acutely affect blood pressure or heart rate of humans. Bioelectromagnetics,25(2):73-83. Tillmann T, Ernst H, Ebert S, Kuster N, Behnke W, Rittinghausen S, Dasenbrock C. (2007): Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice. Bioelectromagnetics. 28(3):173-87. Tisal J., (1998), “GSM Cellular Radio Telephony”, J.Wiley and Sons, West Sussex, England. Velizarov S, Raskmark P, Kwee S, (1999): “The effects of radiofrequency fields on cell proliferation are non-thermal”, Bioelectrochemistry and Bioenergetics, 48, 177-180. Wagner P., Roschke J., Mann K., Hiller W. and C. Frank, (1998): Human sleep under the influence of pulsed radiofrequency electromagnetic fields: a polysomnographic study using standardized conditions, Bioelectromagnetics 19, pp. 199–202.

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Mobile Telephony Radiation Effects on Living Organisms

227

Copyright © 2011. Nova Science Publishers, Incorporated. All rights reserved.

Weaver JC and Astumian RD, (1990): “The response of living cells to very weak electric fields: The thermal noise limit”, Science, 247, 459-462. Weisbrot D, Lin H, Ye L, Blank M, Goodman R. (2003), Effects of mobile phone radiation on reproduction and development in Drosophila melanogaster. J. Cell Biochem. 89(1): 48-55. Xenos T.D, Magras I.N, (2003): Low Power Density RF Radiation Effects on Experimental Animal Embryos and Foetuses, In: Stavroulakis P. (Ed.), Biological Effects of Electromagnetic Fields, Springer, 579-602. Zhou YP, Teng D, Dralyuk F, Ostrega D, Roe MW, Philipson L, Polonsky KS. (1998): Apoptosis in insulin-secreting cells. Evidence for the role of intracellular Ca2+ stores and arachidonic acid metabolism. J Clin Invest. 101(8):1623-32. Zwamborn APM, Vossen SHJA, van Leersum BJAM, Ouwens MA, Mäkel WN. (2003). Effects of Global Communication System Radio-Frequency Fields on Well being and Cognitive Functions of Human Subjects with and without Subjective Complaints. FEL-03-C148. The Hague, the Netherlands: TNO Physics and Electronics Laboratory. Available: http: //home.tiscali.be/milieugezondheid/dossiers/gsm/TNO_rapport_Nederland_sept_2003.pdf.

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Index

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A acetylcholinesterase, 188, 217 acid, 116, 188, 194, 222, 225 acoustic neuroma, 192, 219, 222 activation energy, 112 active radicals, 61 activity level, 8 acute myeloid leukemia, 17, 20, 21, 23 adaptation, 37 additives, 112 adenocarcinoma, 35, 36 adsorption, viii, 31, 32 adults, 163 advancement, x, 155, 156 aerosols, vii, viii, 31, 52 aerospace, 64 aetiology, 70 agar, 194 age, 13, 20, 21, 23, 39, 70, 71, 157, 158, 163, 191, 224 agencies, 176, 177 AIDS, 22 Air Force, 20, 26 air temperature, 37, 138 aircrews, vii, 1, 2, 11, 12, 16, 19, 23, 64, 72, 98 airports, 10, 12, 67 airways, 34, 35, 37, 38, 39, 41, 42, 45, 47, 49, 50, 51, 54, 55 albumin, 189 algorithm, viii, 31, 141 alkali aggregate reactivity, viii, 75, 76 alters, 222 alveolar macrophage, 38 alveoli, 35, 39, 52 ambient air, 138 ambient air temperature, 138 American Heart Association, 170

amino acid, 94 amnion, 188 amplitude, 187, 214, 221 anatomy, 165 aneuploidy, 188 aneurysm, 164, 166, 172 angiogram, 161, 162 angiography, 161, 162, 163, 164, 165, 166, 167, 170, 171, 172, 173 angioplasty, 159, 161 angulation, 169 aniline, 113, 115, 116 ankles, 158 anorexia, 157 ANOVA, 198, 201 ANS, 80, 94 antimony, 108 apoptosis, 188, 209, 213, 215, 216, 218, 220, 224 arrhythmia, 172 arsenic, 108 arteries, 165, 172 arteriography, 173 artery, 161, 165, 166, 171 Asia, 152 assessment, ix, 64, 70, 98, 104, 143, 149, 219 astrocytoma, 17 asymmetry, 40, 55 atmosphere, viii, ix, 6, 7, 8, 9, 10, 11, 13, 16, 29, 43, 51, 57, 58, 59, 60, 67, 73, 74, 97, 98, 112, 127 atmospheric pressure, 114 atoms, 6, 11, 58, 59, 60, 81, 108, 111, 146 atrial fibrillation, 172 atrophy, 157 Austria, 31, 103, 186, 192 authorities, 176, 177 automation, ix, 107 avian, 192 avoidance, 71

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Index

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B background radiation, x, 63, 69, 98, 142, 175, 176, 177, 179, 180, 181, 182 bacteria, 43, 218 baggage, 67 barriers, 168 base, x, 26, 28, 33, 41, 68, 70, 73, 74, 77, 101, 112, 135, 154, 183, 185, 192, 204, 206, 207, 208, 216, 217, 218, 219, 220, 223, 224 batteries, 109 BBB, 189, 190 beams, 53, 108 benefits, x, 107, 156 beryllium, 80 beta particles, 58, 156 bias, 70, 71 biochemical processes, 213 biological systems, 25, 61 biomolecules, 184, 193 biotechnology, 108, 117 birds, x, 183, 192 birthweight, 22 bladder cancer, 20, 21 blast furnace slag (BFS), viii, 75, 76 blends, 110 blindness, 18 blood, 23, 32, 35, 37, 74, 188, 189, 190, 191, 218, 219, 220, 221, 222, 224 blood flow, 191, 220 blood pressure, 191, 224 blood-brain barrier, 189, 219, 221, 224 body mass index, 160 body size, 39, 162, 165 Boltzmann constant, 123 bonds, 33, 108, 111 bone, 22, 157, 158, 168, 189, 218 bone marrow, 157, 158, 168, 189, 218 brain, 21, 157, 187, 189, 190, 191, 192, 216, 217, 219, 220, 221, 222, 224 brain cancer, 21 brain growth, 189 brain tumor, 157, 192, 220, 224 branching, 39, 40, 41, 42 breakdown, 27 breast cancer, 22, 23, 25, 27, 70, 71, 74 breathing, viii, 31, 32, 45, 46, 47, 48, 49, 50, 51, 52 breeding, 219 bromine, 108 bronchial airways, 34, 41, 42, 47, 50 bronchial epithelium, 53 bronchial tree, 54, 55 bronchial/alveolar tissues, vii, viii, 31

bronchioles, 36, 37, 38, 39, 50, 52 Brownian motion, 41, 42, 45, 46, 50 building code, 144 Bulgaria, 20, 28 burn, 130, 131, 140, 143 bypass graft, 161

C Ca2+, 187, 225 CAD, 165, 166 Cairo, 75 calcium, 158, 165, 217, 218, 221, 224 calibration, 67, 100 cancer, vii, x, 1, 2, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 29, 30, 31, 32, 34, 35, 36, 52, 53, 54, 61, 64, 66, 69, 70, 71, 72, 74, 111, 155, 157, 163, 169, 174, 183, 184, 185, 187, 188, 192, 218, 219, 220, 221 candidates, 34, 35 carbohydrates, 93 carbon, 37, 98, 111, 142 carbon atoms, 111 carbon dioxide, 37 carcinogenesis, 157 carcinoma, 34, 35, 36 cardiac catheterization, 156, 161, 163, 170, 171, 173 cardiologist, 156, 159, 164 cardiovascular system, 173 careless laser-pointer user, vii, 1 cartilage, 37 catalyst, 112 cataract, x, 29, 70, 74, 155, 157, 159, 170 cataractogenesis, vii, 1 catheter, 165, 172 cation, 109 CBS, 94 CEC, 6, 24 cell culture, 53 cell death, x, 61, 183, 184, 190, 194, 196, 197, 209, 210, 211, 212, 213, 215, 216, 217, 219, 222, 223 cell line, 188, 220, 222 cell membranes, 215, 216 central nervous system, 188, 191, 217 cerebral blood flow, 191, 220 challenges, 171 chemical, ix, 32, 34, 76, 77, 78, 82, 83, 95, 107, 109, 110, 111, 112, 114, 116, 117, 132, 176, 213 chemical bonds, 111 chemical reactions, 132 chemical structures, 109 chemicals, 184, 209, 210

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Index Chicago, 13, 14, 15 chicken, 187, 189 childhood, 21 children, 15, 66, 163, 191, 220 chloroform, 114 chromosomal instability, 222 chromosome, 19, 30, 62, 63, 73 cilia, 35 circadian rhythm, 23, 70 clarity, 180 classes, 50, 52 cleavage, 113 cleft palate, 22 climate, 149 closure, 150, 164 clusters, 33, 53 CNN, 191 CO2, viii, 75, 93, 133 cobalt, 3 coding, 101 cognitive performance, 192, 220, 223 cognitive testing, 191 collaboration, 21, 169 collateral, 161 collisions, 6 colon cancer, 21 color, 19, 153 combined effect, 60 combustion, 120, 129, 132, 134, 143 commercial, vii, 1, 2, 11, 13, 16, 17, 19, 20, 21, 23, 26, 28, 29, 58, 59, 60, 67, 69, 70, 72, 73, 74, 100, 176 commercial aircraft, vii, 1, 2, 11, 13, 16, 19, 23, 28, 58, 60, 67, 100 communication, 71, 105, 171, 204, 218, 221, 222, 224 community, 52 complexity, 101, 173 compliance, x, 169, 175, 176, 178, 179, 180, 181 complications, 168 composites, ix, 77, 81, 107, 112, 117 composition, ix, 8, 76, 77, 82, 83, 93, 95, 108, 146 compounds, 77, 81, 82, 91, 92, 93, 94, 117, 189 computation, 41, 42, 43, 62, 141 computational fluid dynamics, 142 computed tomography, 166, 172, 173 computer, ix, 10, 68, 80, 82, 91, 97, 100, 141, 153 computer software, 141 computing, 77 conception, vii, 1, 14 condensation, 109 conditioning, 37, 149 conduction, 37, 124, 130, 147

231

conductivity, 109, 110 conductor, 108 configuration, 124, 135, 136, 137, 138, 139, 146, 149 conflict, 169 conflict of interest, 169 conformity, 69 congenital heart disease, 163 connective tissue, 37 consensus, 182 conservation, 142 constituents, 59, 92, 93 construction, 143, 144, 152 consumption, viii, 75, 93, 101 contamination, 112 contour, 141 control group, 20, 21, 22, 189, 191, 193, 197, 210, 211, 212 convention, 164 cooking, 120 copper, 161, 163 coronary arteries, 165, 172 coronary artery bypass graft, 161 coronary artery disease, 165 correction factors, 41, 43 correlation, 140, 173 cosmic rays, ix, 59, 60, 72, 97, 98, 103, 105 cost, 18, 60, 67, 76, 93, 163, 167 cost-benefit analysis, 67 cotton, 194, 196 Council of the European Union, 65 counseling, 168 covering, 38 CPC, ix, 107, 117 criminal acts, 18 critical value, 132, 146, 214 CRP, 170 crystalline, 113, 116 crystals, 160 CT scan, 64, 164 culture, 190, 196, 197, 209, 218 cycles, 7, 9, 111 cyst, 224 cytology, 38, 39 cytoplasm, 214

D damages, 27, 33, 34, 150 damping, 214 danger, 52, 73, 103, 143 data analysis, 180 database, 80, 91, 92 deaths, 13, 16, 197

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232 decay, 6, 9, 54, 63 decomposition, 112 defects, vii, 1, 2, 14, 15, 22, 66, 108, 157, 158 defence, 213 defibrillator, 160, 162 degenerate, 209 degradation, 108 dehydration, 71 Denmark, 21, 220 density values, 82 Department of Commerce, 26 Department of Defense, 30 Department of Energy, 176, 182 Department of Homeland Security, 175 Department of Transportation, 25 deposition, vii, viii, 31, 32, 33, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 deposits, 110, 111 depression, 192 deprivation, 184 depth, ix, 32, 35, 59, 76, 80, 87, 92, 93, 103, 104, 140, 148 detectable, 99, 180, 181, 213 detection, x, 94, 119, 142, 143, 153, 154, 197 detection system, 143 developmental process, 193 deviation, 202, 204, 206, 207, 210, 216 diastole, 165 dicentric chromosome, 23 diffraction, 115, 116 diffusion, 41, 42, 120, 179 direct action, 215 direct measure, 67 discharges, 27, 177 discomfort, 131 discontinuity, 147 dispersion, 121 displacement, 51, 122, 214 distortions, 109 distribution, viii, 31, 42, 61, 121, 127, 146, 147 diversity, 37 dizziness, 192 DNA, x, 3, 27, 32, 33, 34, 61, 72, 183, 184, 187, 189, 190, 194, 196, 197, 209, 212, 213, 215, 216, 217, 218, 219, 220, 221, 222 DNA breakage, 190, 218 DNA damage, 27, 32, 34, 72, 184, 187, 190, 213, 215, 220, 221 DNA strand breaks, 221 donors, 218 dopants, 108 doping, 108 dosage, 29

Index DOT, 26, 28, 29, 72 double bonds, 108 Down syndrome, 22 Drosophila, 184, 188, 190, 193, 194, 196, 197, 199, 201, 205, 211, 213, 215, 218, 220, 222, 223, 224, 225 drug delivery, 109 dusts, 43

E editors, 169 effluents, 177, 178, 180 egg, 5, 196, 197, 209, 210, 211, 212, 213, 218 elderly population, 163 electric charge, 99, 184 electric field, 16, 25, 27, 108, 186, 193, 198, 202, 214, 215, 217, 225 electrocardiogram, 173 electroencephalogram, x, 183, 220, 224 electromagnetic, 2, 8, 10, 11, 14, 16, 17, 18, 23, 27, 58, 61, 110, 111, 121, 156, 184, 193, 194, 197, 212, 213, 216, 217, 218, 219, 220, 221, 222, 223, 224 electromagnetic fields, 23, 27, 184, 193, 194, 217, 219, 220, 221, 222, 223, 224 electromagnetic waves, 110, 121 electron, ix, 2, 3, 13, 25, 27, 57, 58, 76, 79, 83, 84, 86, 93, 94, 108, 111, 115, 116, 214 embryogenesis, 193 emergency, 150 emission, viii, 2, 24, 25, 75, 93, 99, 108, 166, 173, 185, 195, 198, 199, 200, 202, 206 emitters, 133 employees, 68 employment, 19, 21 encapsulation, 102 encoding, 188 endocrine, 38, 189 endothelial cells, 188, 189, 221 energy, viii, ix, 2, 3, 4, 6, 7, 8, 10, 11, 13, 16, 24, 25, 30, 33, 57, 59, 60, 61, 62, 65, 66, 67, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 99, 100, 102, 103, energy transfer, ix, 3, 34, 61, 79, 97 engineering, x, 76, 94, 95, 119, 125, 126, 132, 138, 141, 143, 148, 149 environment, vii, 12, 44, 64, 74, 127, 132, 147, 184, 187, 195 environmental conditions, 99, 193, 206 Environmental Protection Agency, 176 environmental radon, vii, 31, 32 enzyme, 188

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Index EPA, 176, 177, 178, 180 epidemiology, 24 epiphysis, 185 epithelial cells, 35, 52, 187, 221 epithelium, 32, 34, 35, 37, 53, 54, 218 equipment, x, 60, 66, 67, 99, 155, 159, 161, 162, erythrocytes, 189, 220 ester, 188, 222 ethanol, 112, 194 EU, 65, 170 eukaryotic cell, 220 Europe, xi, 69, 70, 72, 74, 102, 183, 185, 186, 194 European Commission, 24, 67, 72, 104, 170, 174 European Union, ix, 6, 65, 71, 97 evacuation, 144, 150 evidence, vii, 1, 23, 63, 71, 216, 217 evolution, 193 excitation, 61 exclusion, 161 excretion, 218 expertise, 16, 168 extinction, 119, 126, 133, 134, 142 eye movement, 191

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F FAA, 5, 10, 11, 15, 17, 25, 26, 28, 29, 64, 65, 67, 69, 72 fabrication, 176 family history, 21 fatal cancer, vii, 1, 13, 15, 16, 66, 157 fatty acids, 93 federal government, 176 FEM, 186 fetus, 164 fibers, 44, 55, 115, 116 fibrillation, 172 fibroblasts, 188, 190, 218, 222 fibrosis, 157 filled polymers, 110 films, 116, 117, 162 filters, 163 filtration, 160, 161 Finland, 21, 22 fire detection, 143, 153 fire fighting, x, 119, 134, 145 fires, x, 119, 120, 123, 127, 130, 132, 134, 140, 142, 144, 145, 146, 148, 153 fission, 4, 26, 62, 77 fixation, 209 flame, 119, 123, 129, 130, 132, 133, 134, 135, 136, 137, 138, 140, 141, 142, 143 flaws, 146, 147

233

flexibility, 150 flight, vii, ix, 1, 7, 10, 11, 12, 13, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 28, 29, 30, 58, 60, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 97, 98, 99, 100, 101, 102, 103 flight attendant, 12, 22, 24, 25, 29, 30, 70, 74 flights, ix, 10, 11, 12, 25, 66, 67, 73, 97, 98, 101, 102, 103, 104 fluid, 42, 55, 142 fluorescence, 197, 198, 209 fly ash (FA), ix, 76 follicle, 197, 209, 210, 211, 213, 218, 224 food, 108, 111, 184, 193, 194, 196, 197, 218 force, 45, 214 forecasting, 103 formaldehyde, 197 formation, 33, 34, 35, 109, 111, 112, 113, 116, 157, 224 formula, 39, 43, 78, 80, 81, 82, 94, 159 fragments, 4, 59, 62, 108, 112 France, 17, 30, 66, 103, 192 free radicals, 33, 34, 108, 112, 188 FTIR, 116 fuel consumption, 101 funding, 176

G galactic cosmic ionising radiation (GCR), viii, 57 galactic cosmic radiation, vii, 1, 6, 9, 10, 66, 67, 74 gamma radiation, viii, 2, 3, 62, 73, 76, 114, 177 gamma ray, viii, 13, 30, 58, 62, 75, 76, 92, 94, 103, 111, 115, 156 gamma rays, 13, 30, 58, 62, 76, 92, 103, 115, 156 GAO, 151 gastrointestinal tract, 32 gene expression, x, 183, 184, 222, 223 genes, 184, 188 genetic defect, vii, 1, 2, 14, 15, 66 genome, 23, 188, 190, 222 geometry, viii, 31, 32, 38, 41, 43, 54, 136 germ cells, 157 Germany, 74, 105, 197 gestation, 159, 164, 168 gland, 185 glasses, 145, 146, 159, 168 glial cells, 189 glioblastoma, 190 glioma, 192 global warming, viii, 75, 93 glottis, 35 glycerol, 198 goblet cells, 38

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Index

gonads, xi, 158, 163, 168, 183, 194 governor, 177 grades, 33 gravity, 39, 40, 41, 42, 138, 169 greenhouse, 176 growth, 35, 54, 110, 112, 142, 143, 147, 188, 189 guidance, 26, 177, 178, 181, 182

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H hazardous airborne materials, vii, 31 hazardous materials, 55 hazards, x, 76, 103, 119, 130, 141, 155, 156, 169, 187, 191 HDPE, 130 health, vii, x, 1, 2, 3, 13, 16, 17, 18, 19, 23, 32, 57, 61, 64, 65, 72, 73, 155, 156, 159, 168, 170, 184, 186, 187, 191, 217 health care, x, 155, 156 health effects, vii, 1, 2, 3, 16, 18, 19, 23, 57, 164, 184, 186, 217 health risks, 16, 23, 32, 64, 65, 72, 187 heart rate, 165, 166, 172, 191, 224 heat release, 134, 135, 138, 148 heat shock protein, 184, 187, 188, 218, 219, 221 heat transfer, x, 119, 124, 126, 128, 129, 135, 142, 144, 146, 147, 148 height, 39, 50, 119, 135, 138, 140, 194, 196 helium, 58 hematology, 189 hemisphere, 68, 98 hexane, 148 high-temperature ratio (HTR), ix, 97 histogenesis, 54 histology, 189 history, 21, 23, 70, 110 homolytic, 113 hormone, 185, 191 hospitalization, 19 host, 6 House, 217 HRTEM, 116 human, vii, ix, 2, 3, 16, 19, 27, 30, 31, 34, 35, 36, 37, 38, 40, 41, 43, 44, 46, 51, 52, 53, 54, 55, 57, 58, 61, 74, 98, 103, 107, 108, 120, 123, 129, 130, 131, 133, 156, 157, 187, 188, 190, 202, 217, 218, 220, 221, 222, 223, 224 human body, 2, 16, 36, 37, 57, 103, 108, 129, 130, 131 human exposure, 27, 30, 74 human health, 61 human resources, ix, 107 humidity, 37, 193, 194, 197

Hungary, 103 hybrid, 164, 171 hydrogen, 34, 58, 81 hydrogen peroxide, 34 hydroxide, 34 hydroxyl, 34, 112, 113 hyperthermia, 130 hypospadias, 22 hypothesis, 157

I Iceland, 20, 21, 70, 74 ideal, 34, 42, 43, 123, 142 ignition source, 129 illumination, 18 image, 18, 116, 160, 161, 162, 165, 166, 167, 168, 171 improvements, 101 impurities, 110 in utero, vii, 1, 15, 26 in vitro, 188, 190, 213, 218, 219, 220, 224 in vivo, 41, 188, 213, 219 incidence, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 54, 66, 69, 70, 71, 74 incubator, 194 indirect effect, 34 individuals, 16, 17, 18, 19, 158, 166, 186 induction, x, 21, 53, 63, 183, 184, 186, 188, 190, 213 industries, 187 industry, viii, 32, 64, 75, 93, 95, 115, 145, 169, 219 infants, 163 infertility, 189 initiation, 112, 135 injuries, 33, 150, 162, 170, 172, 173 injury, 32, 61, 129, 157, 165, 188 insects, x, 183, 190, 193, 194, 195, 196, 198, 200, 202, 206, 209, 210, 211, 212, 216 insulators, 108 insulin, 225 integration, 123, 164, 172 integrity, 145, 148, 217 interaction process, 83, 87, 91 interference, 18, 163 International Commission on Radiological Protection, ix, 5, 27, 52, 64, 73, 97, 104, 173, 174, 177 intervention, x, 155, 158, 160, 161, 162, 164, 166, 167, 168, 170, 171 iodine, 108, 177 ion channels, 215, 216 ionization, 34, 111, 160, 179

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Index ionizing radiation, vii, 1, 2, 3, 5, 7, 11, 12, 13, 16, 21, 32, 70, 72, 73, 74, 108, 111, 156, 170, 194, 221 ions, 2, 4, 14, 33, 34, 53, 58, 59, 61, 62, 108, 109, 111, 113, 184, 213, 214, 215 ipsilateral, 192 Ireland, 103 iron, 80, 98 irradiation, vii, ix, 15, 31, 32, 36, 52, 99, 107, 108, 110, 112, 113, 115, 116, 117, 159, 189, 220 ischemia, 172 issues, x, 35, 73, 156, 159, 175, 176 Italy, 186

J Japan, 73 Jordan, 25 jurisdiction, 176

K kidneys, 21, 188, 189, 222, 223 kill, 111, 216 kinetics, 74

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L labeling, 219 larvae, 196, 197 larynx, 35, 36 laser radiation, 18 latency, 166, 191, 192, 219 laws, 5, 125 layering, 142 lead, 11, 19, 60, 61, 87, 100, 109, 159, 163, 164, 167, 168, 169, 173, 176, 215 leakage, 189 learning, 102 legislation, 6 leisure, 70 lens, 5, 71, 158, 159, 163, 168, 187, 221 lesions, 159, 161, 163, 165, 171 leukemia, vii, 1, 17, 20, 21, 23, 24 life cycle, 193 lifetime, 13, 15, 16, 66, 157, 158, 163 light, vii, 1, 2, 11, 18, 19, 25, 45, 71, 99, 110, 111, 122, 133, 143, 144, 176, 184, 193, 194 light transmittance, 19 liquids, 142 lithium, 160 localization, 165 locus, 190

235

low birthweight, 22 luminescence, 179 lung cancer, vii, 20, 21, 31, 32, 35, 36, 52, 53 Luo, 24, 135 lying, 23 lymph, 32 lymphocytes, 23, 74, 188, 191, 217, 218, 219, 221, 222 lymphoma, 21, 22

M macromolecules, 184 magnet, 7, 163 magnetic field, vii, viii, 1, 6, 7, 8, 11, 16, 17, 28, 30, 57, 58, 60, 163, 179, 191, 193, 194, 198, 202, 206, 216, 217, 224 magnetic resonance imaging, 165 magnitude, 3, 39, 60, 108 majority, 34, 186, 211, 217 malignancy, 157, 158, 159, 164 malignant melanoma, 20, 21, 22, 70, 71 mammalian cells, 53, 194, 189, 220 mammals, 54, 185, 194, 216 man, x, 5, 54, 175, 176, 177, 184 management, 5, 6, 65, 162, 164, 176 manual movement, 162 manufacturing, x, 107, 111, 117, 120, 147 mapping, 165 marrow, 157, 158, 168, 189, 218 mass, viii, 2, 6, 39, 57, 60, 78, 79, 80, 81, 82, 90, 91, 92, 93, 94, 110, 134, 142, 156, 157, 160, 186, 214 massive particles, 61 materials, vii, viii, x, 17, 31, 55, 63, 75, 76, 77, 78, 80, 81, 82, 83, 84, 85, 86, 87, 90, 92, 93, 94, 107, 108, 109, 110, 114, 115, 117, 119, 120, 124, 125, 126, 129, 130, 144, 176, 178 matrix, 110, 112, 117 matter, 2, 3, 9, 10, 16, 32, 35, 44, 48, 76, 77, 94, 129, 147, 187 measurement, ix, x, 55, 63, 67, 68, 72, 97, 100, 104, 108, 119, 126, 127, 148, 171, 178, 180, 181 measurements, vii, ix, x, 7, 11, 12, 13, 17, 40, 41, 55, 67, 71, 72, 73, 74, 97, 98, 100, 101, 102, 169, 175, 176, 177, 178, 179, 180, 181, 194, 198, 202, 206 mechanical properties, viii, 75, 76 mechanical stress, 146 media, 26, 28, 77, 125, 133, 135 median, 17, 162, 163, 164

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236 medical, vii, 5, 6, 21, 23, 26, 28, 31, 35, 51, 61, 64, 73, 76, 92, 95, 108, 130, 156, 157, 158, 162, 167, 168, 170, 172, 173, 176, 177 medical goods, 108 medical history, 21, 23 medicine, vii, 76, 108, 117, 145, 156, 172, 173 meiosis, 213 melanoma, 20, 21, 22, 23, 70, 71 melatonin, x, 183, 185, 188, 190, 191, 222 membranes, 215, 216 memory, 109, 191, 192, 216, 220 mental retardation, 15, 66, 159, 168 mercury, 197 meta-analysis, 20, 21, 22, 24, 30, 172 metabolism, 188, 225 metal ion, 112, 113 metal ions, 113 metal nanoparticles, 116 metals, 77, 108, 110, 112 meter, 17, 111, 127, 128, 160, 194, 195 methanol, 120, 121 Miami, 14 mice, 26, 188, 189, 190, 219, 220, 221, 222, 223, 224 micrometer, 3 microscope, 197, 198, 209 microscopy, 189, 197 microspheres, 112 microwave radiation, vii, 1, 24, 108, 184, 185, 187, 188, 189, 190, 222 microwaves, 2, 111, 188, 189, 190, 217, 223 military, 20, 23, 24, 27 miscarriage, 28 missions, 166, 192, 202 mitochondria, 215 mitral stenosis, 164, 172 mixing, 42, 110 mobile communication, 222 mobile phone, xi, 183, 185, 188, 189, 190, 191, 192, 193, 194, 195, 196, 198, 199, 200, 202, 204, 206, 207, 208, 209, 216, 217, 218, 219, 220, 221, 222, 223, 225 mobile telecommunication, 189 mobile telephony, vii, x, 183, 184, 185, 186, 187, 189, 190, 191, 192, 193, 194, 195, 196, 204, 206, 207, 208, 209, 210, 212, 213, 215, 216 modelling, 142 models, 23, 40, 43, 63, 101, 102, 103, 134, 141, 142, 148, 190, 219 modifications, 108 mole, 79 molecular structure, 133 molecular weight, 108, 112

Index molecules, 3, 32, 34, 44, 59, 61, 81, 108, 111, 215 morbidity, 27 morphology, 37, 53, 115, 188, 222 morphometric, 38, 40, 54 mortality, 24, 26, 52, 69, 70, 71, 73, 189, 192, 197, 218, 219 mortality rate, 219 MTI, 118 mucous membrane, 37 multiplication, 80 muons, 3, 4, 6, 8, 10, 14, 62 mutation, 157, 188, 217 mutation rate, 217 mutations, 34, 157, 213 myoglobin, 188, 221

N nanocomposites, 110, 112, 114 nanofibers, 115, 116 nanomaterials, 112 nanometer, 110 nanometers, viii, 31 nanoparticles, 45, 110, 113, 116 nanostructured conductive polymer composites (NCPC), ix, 107, 117 nanostructured materials, 114 nanostructures, 112, 115 nanotechnology, 117 nanowires, 114 nasopharynx, 35 National Aeronautics and Space Administration, 26 National Research Council, 28 natural zeolite (NZ), ix, 76 navigation system, 163, 165, 171 necrosis, 157, 158, 213, 215, 216 negative consequences, 191 nervous system, 21, 188, 191, 217 Netherlands, 225 neural network, ix, 98, 101, 102, 103, 104 neuroblastoma, 218 neuroma, 192, 219, 222 neurons, 189 neutron attenuation, viii, 75 neutrons, viii, ix, 2, 4, 6, 8, 10, 14, 26, 58, 59, 61, 62, 73, 75, 76, 77, 81, 82, 92, 98, 99, 100, 103, 104, 111, 156 New South Wales, 121 New Zealand, 145 nitrogen, 6, 58, 59, 108 non-Hodgkin’s lymphoma, 22 nonsmokers, 36 Norway, 21, 22

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Index nuclear weapons, 32 nucleation, 110 nuclei, 6, 35, 53, 58, 59, 62, 98 nucleus, 2, 3, 57, 63, 82, 111 nutrients, 212 nutrition, 209, 210, 213

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O obstruction, 164 occlusion, 159, 171 occupational groups, 32 Oceania, 152 octane, 198 Oklahoma, 1 oocyte, 210, 211, 213 oogenesis, 157, 193, 196, 197, 201, 209, 210, 211, 213, 218, 222 operations, vii, 18, 31, 32, 68, 69, 72, 73, 176, 177, 181 ophthalmologist, 17, 18 optical properties, x, 109, 119, 133, 144, 145 organ, 2, 3, 4, 5, 62, 157, 176, 178 organic polymers, 108, 109 organism, 3, 184, 194, 213 ornithine, 223 oscillation, 214 oscillatory activity, 191 ovaries, 196, 197 oversight, 176 oviduct, 197 oxidation, 109 oxidative stress, 188, 222 oxygen, 6, 37, 44, 58, 59

P pain, 130, 131 palate, 22 palliative, 164 parallel, 59, 77, 195, 198 parents, vii, 1, 14, 15 pathology, 53 pathways, 40, 161, 165, 177 percentile, 132 perfusion, 158, 166 perinatal, 22 peripheral blood, 23, 74, 188, 218, 222 peripheral blood mononuclear cell, 218 permeability, viii, 75, 76, 189, 190, 219, 224 permission, 114, 115, 116 peroxide, 34, 112

237

personal communication, 71 PET, 166 pharmaceutical, 108, 160 pharynx, 36 Philadelphia, 27, 53, 73 phosphorous, 109 phosphorylation, 188 photons, 2, 3, 4, 6, 8, 10, 14, 16, 58, 62, 76, 77, 78, 79, 87, 92, 111 physical properties, 146, 147 physics, 64, 74, 94, 154 Physiological, 165, 223 pineal gland, 185 pions, 3, 4, 6, 10, 14 pituitary gland, 189 plasma membrane, 215 plastics, 134 playing, 213 PMMA, 130 Poland, 103, 186, 192 polar, 58, 59, 68, 103 pollen, 43 pollution, 180 polycarbonate, 19 polymer, ix, 107, 108, 109, 110, 112, 114, 117 polymer matrix, 110, 112, 117 polymerization, ix, 107, 110, 112, 114, 116, 117 polymers, ix, 107, 108, 109, 110, 114, 115, 117 population, vii, x, 1, 2, 13, 15, 16, 17, 19, 20, 21, 22, 26, 28, 31, 32, 41, 66, 70, 73, 74, 132, 156, 163, 181, 183, 186, 189, 217 positron, 166 positron emission tomography, 166 positrons, 3, 6, 8, 10, 14, 58, 98 power plants, 76, 92, 176, 177, 178, 181 precipitation, 179 pregnancy, 5, 6, 22, 28, 64, 65, 69, 157, 159, 172 premature death, 158 prenatal development, vii, 1, 15, 16, 66, 221 prevention, 144 principles, 126, 141, 167 probability, 3, 35, 41, 71, 77, 81, 147, 198, 200, 201, 204, 206, 212 probability distribution, 41 probe, 194, 195 process control, 117 professional careers, 191 progenitor cells, 32, 34, 35, 36, 53 project, 74, 219 proliferation, x, 34, 183, 184, 187, 188, 218, 221, 222, 224 propagation, 73, 92, 130 prostate cancer, 20, 21

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238

Index

protection, viii, x, 5, 19, 52, 57, 60, 64, 65, 72, 74, 99, 104, 119, 135, 143, 144, 148, 149, 150, 155, 159, 162, 163, 164, 167, 168, 169, 170, 171, 174, 176, 184, 222 protective mechanisms, 184 protein family, 224 protein kinase C, 189 protein structure, 71 proteinase, 197 proteins, 184, 188, 189, 214, 219 proteome, 188, 222 protons, 2, 3, 4, 6, 8, 10, 11, 14, 53, 58, 60, 62, 98, 103, 111, 156 prototype, 173 public concern, 176 pulp, 194 purity, 112 PVC, 130

Q quality control, 168, 169 quartz, 128, 145 query, 174

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R race, 39 radar, vii, 1, 17 radiation detectors, 161 radicals, 33, 34, 61, 108, 112, 188 radio, 2, 12, 27, 60, 110, 160, 163, 165, 168, 177, 182, 185, 217, 224 radioactive isotopes, 76, 92 radioactive waste, 176, 177 radionuclides, vii, viii, 31, 32, 33, 34, 36, 43, 44, 177, 179 radiotherapy, 64 radius, 42, 119 radon, vii, 31, 32, 63, 177, 179 random walk, 40, 41 rapid eye movement sleep, 191 rat kidneys, 188, 223 raw materials, viii, 75, 93 reactions, ix, 34, 103, 107, 132 reactivity, viii, 75, 76 reading, 67, 182 real time, 161, 165 reality, 146, 206 reasoning, 166 receptors, 224 recombination, 34, 100

recommendations, 5, 7, 54, 62, 66, 68, 72, 73, 177 recovery, 61, 157 reflectivity, 120, 125 refraction index, 125 registries, 21 Registry, 172 regression model, 23 regulations, x, 64, 99, 149, 175, 176, 177 reliability, 117, 148 remedial actions, 177 repair, 57, 61, 62, 164, 172, 213, 220 reparation, 34 replication, 188 reprocessing, 176 reproduction, x, 183, 216, 225 reproductive cells, 61, 184, 190, 216 requirements, 6, 176, 178 researchers, 92, 109, 112, 187 resistance, 145, 150, 152 resolution, 161, 165, 166 resources, ix, 107, 173 respiration, 45 response, 21, 23, 63, 70, 77, 100, 105, 130, 142, 184, 188, 191, 212, 213, 222, 225 response time, 191 restaurants, 111 restoration, 34, 214 restrictions, 176 retardation, 15, 66, 159, 168 reticulum, 215, 224 rheumatic heart disease, 164 rhythm, 23, 70 rights, iv rings, 37, 63, 108, 109 risk, vii, 1, 3, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 31, 52, 60, 61, 64, 66, 70, 71, 74, 98, 149, 156, 157, 158, 159, 163, 164, 165, 167, 170, 191, 192, 219, 222 rodents, 54 roentgen, 2, 5 room temperature, 110, 112, 116 routes, 66, 68, 69, 72, 74, 171 routines, 99 rubber, 150 Russia, 105, 186

S safety, x, 18, 27, 65, 72, 74, 119, 132, 138, 143, 149, 150, 155, 156, 164, 167, 170, 223 Saudi Arabia, 107 savings, 143 scaling, 39, 42

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Index scatter, 7, 160, 161, 167, 168 scattering, 7, 76, 81, 82, 83, 87 scavengers, 190 school, 181 science, 25, 30, 95, 145, 170, 174 sea level, 8, 59, 101, 179 second generation, 189 secondary radiation, ix, 3, 4, 97 secretin, 225 security, 67 selenium, 112 self-repair, 57, 61, 62 semiconductors, 99, 109, 110,112 senses, 142 sensing, 128, 142 sensitivity, 5, 19, 32, 67, 99, 163, 165 sensors, 128, 143, 214 serum, 189 sex, 5, 191, 196, 200, 201 shape, 7, 43, 45, 49, 51, 80, 124 shock, 10, 184, 187, 188, 218, 219, 221 showing, 70 side effects, x, 155, 157, 159, 163 signal transduction, 188 signals, 143, 185, 186, 187, 190, 193, 194, 195, 196, 199, 206, 207, 210, 215, 216, 224 silica, ix, 76, 94, 145, 146 silicon, 109, 116 silver, 113, 114 simulation, 44, 54, 101, 102, 104, 134, 195 Singapore, 105, 152 skin, 5, 18, 20, 21, 22, 23, 29, 58, 70, 71, 130, 131, 132, 157, 158, 160, 162, 164, 165, 166, 167, 168, 171, 172, 188, 222 skin cancer, 18, 20, 21, 22, 23, 29, 70, 71 slag, viii, 75, 76, 90, 93, 94 sleep disturbance, 192, 216, 220 Slovakia, 103 smoking, 21, 23, 32, 70, 71, 191 smooth muscle, 37 society, 167 software, 102, 141, 142 solar cells, 109 solar cosmic radiation, vii, 1, 11 solar particle events (SPEs), viii, 57 solar system, viii, 6, 57, 58 sol-gel, 110 solubility, 108 solution, 110, 112, 113, 114, 115, 188, 197, 214 solvents, 93, 110 somatic cell, 224 space technology, 76 Spain, 192, 222

239

species, 38, 43, 108, 113, 133, 142, 217, 218 specific heat, 138 specifications, 178 sperm, 157 spermatogenesis, 157, 193, 201 spin, 116, 221 spontaneous abortion, vii, 1, 17 squamous cell, 21, 35, 36 stability, 110, 177 stabilizers, 110 standard deviation, 202, 204, 206, 207, 210, 216 stars, viii, 6, 57 state, 22, 72, 87, 176, 177 states, 6, 65, 177, 178, 192 statistics, 26, 41, 99, 101, 180 stenosis, 162, 164, 166, 172 stent, 164 stochastic lung geometry, viii, 31 stochastic model, 40, 41 storage, 161, 176, 180 storms, 7, 24 stress, 120, 145, 146, 149, 150, 184, 188, 197, 209, 210, 212, 213, 221, 222 stress factors, 197, 209, 210, 212 structural defects, 108 structure, x, 34, 40, 41, 53, 54, 61, 71, 74, 77, 93, 108, 110, 116, 117, 119, 147, 148 subscribers, 186 substitutes, viii, 75 substitution, 162 substrates, 112 sucrose, 190, 219, 224 sulfur, 112 Sun, vii, 1, 7, 8, 10, 11, 122 supernovae, vii, viii, 1, 6, 57, 98 supervision, 167 suppression, 151, 157 supraventricular tachycardia, 172 surface area, viii, 31, 38, 43, 140, 147, 163 surface modification, 108 surfactant, 37, 38 surveillance, ix, 6, 97 survival, 15, 26, 61, 218, 220, 224 survivors, 54 sustainable development, 95 Sweden, 21, 22, 27, 28, 73, 219 sympathetic nervous system, 191 symptoms, 18, 218, 220 syndrome, 22, 164, 192, 216 synthesis, 110, 112, 184, 185, 188, 191 synthetic polymers, 115

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240

Index

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T target, 32, 35, 52, 61, 135, 136, 142 techniques, ix, x, 53, 99, 107, 112, 113, 114, 117, 119, 165, 168, 173 technologies, x, 108, 119, 175, 176 technology, ix, x, 12, 76, 107, 110, 115, 163, 167, 175 telecommunications, xi, 111, 183 telephones, 219, 220, 221, 222 TEM, 114, 115, 116 temperature dependence, 125, 147 testicular cancer, 19, 20 testing, 32, 191 TGF, 13 therapeutic interventions, 123,124, 221, 145, 146, 147, 150, 156, 163 thermoluminescence, 99 thermoluminescent dosimeters (TLDs), ix, 97, 178 thyroid, 158, 159, 163, 168, 176 tissue, viii, 2, 3, 4, 5, 17, 31, 32, 37, 57, 58, 61, 62, 157, 184, 186, 188, 189, 213, 217 trachea, 35, 36, 38, 39, 40, 41, 50, 53 training, 72, 98, 168 transducer, 127, 128 transformation, vii, 31, 52, 108, 222 transformations, 6 translocation, 23, 32, 62 transmission, 120, 121, 125, 185 transport, viii, 10, 31, 40, 41, 42, 43, 45, 51, 54, 60, 66, 67, 68, 72, 105, 142 transportation, 74, 176 treatment, 43, 44, 64, 147, 164, 196 tumor, 35, 157, 224 tumor development, 224 tumors, 22, 34, 35, 189, 192, 220 turbulence, 58, 179

V valence, 112, 214 variables, 43, 58, 189 variations, 7, 29, 40, 64, 82, 83, 87, 100, 131, 142, 146, 179, 180, 181, 182, 198, 200, 204, 206, 212 vector, 136, 137 velocity, 42, 46, 50, 93, 214 ventilation, 140 vibration, 62, 213, 214 videos, 153 viscosity, 42 vision, 18, 19, 153, 154 visual impression, 161 visualization, 163 VSD, 164

W waking, 191, 220 Washington, 22, 25, 26, 28, 30, 72, 150, 151, 153, 173, 175 waste, 93, 176, 177, 212 water, 33, 34, 76, 110, 113, 120, 125, 126, 128, 148, 150, 176, 194, 215 wavelengths, 111, 122, 130, 133, 144 wear, 19, 150, 167 weather radar, vii, 1, 17 well-being, 192, 223 windows, 19, 143, 149, 184, 187, 209, 217 workers, vii, x, 6, 17, 23, 30, 31, 32, 64, 65, 67, 72, 155, 156, 157, 159, 168, 170 workplace, x, 155, 169 worldwide, ix, 67, 71, 107, 156, 163, 164

X U UK, 13, 14, 15, 27, 64, 68, 69, 71, 151, 158, 169, 172 uniform, 33, 42, 44, 45, 112, 133, 139 United Kingdom, 12, 63 United States, x, 12, 26, 27, 29, 30, 175, 176, 181 upper airways, 41, 55 uranium, 52, 110, 176, 178 urinary bladder, 20, 21 USA, 63, 64, 69, 71, 94, 95, 141, 152, 153, 154, 165, 175, 185, 202 UV, 18, 19, 108, 142, 143, 220

x-rays, 33

Y yeast, 194 yield, 61, 134

Z ZnO, 113, 116 zygote, 26

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