Environmental Pollution and Health [1 ed.] 9788179936009, 9788179934616

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Environmental Pollution and Health V K Ahluwalia

Pollution as we know is an undesirable change in the physical, chemical, and biological characteristics of the environment. Environmental Pollution and Health expounds the three main types of environmental pollution—air, water, and land—and their effects on human health. It also focuses on photochemical air pollution, marine pollution, thermal pollution, noise pollution, and radioactive pollution and their effects on human health. The book also discusses the impact on the health of the human beings by factors other than pollutants. These factors include occupation of a person, stress, global warming, and ozone layer depletion. Finally, the author has dealt with various types of wastes generated in different establishments and how they should be managed.

Environmental Pollution and Health V K Ahluwalia

Key Features • Describes the measures to be taken to control industrial wastes • Explains effects of radioactive pollutants on health • Elaborates the different types of wastes • Discusses how various types of wastes can be managed

ISBN 978-81-7993-461-6

The Energy and Resources Institute

9 788179 934616

The Energy and Resources Institute

Environmental Pollution and Health

Environmental Pollution and Health

V K Ahluwalia

The Energy and Resources Institute

© The Energy and Resources Institute, 2015

ISBN 978-81-7993-461-6

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher. All export rights for this book vest exclusively with The Energy and Resources Institute (TERI). Unauthorized export is a violation of terms of sale and is subject to legal action. Suggested citation Ahluwalia, V. K. 2015. Environmental Pollution and Health. New Delhi: TERI

Published by The Energy and Resources Institute (TERI) TERI Press Tel. 2468 2100 or 4150 4900 Darbari Seth Block Fax 2468 2144 or 2468 2145 IHC Complex, Lodhi Road India +91 • Delhi (0) 11 New Delhi – 110 003 Email [email protected] India Website www.teriin.org

Printed in India

Preface Pollution as we know is an undesirable change in the physical, chemical, or biological characteristics of the environment. Various agents that pollute the environment are called pollutants. These pollutants have extremely hazardous effect on the health. This book titled Environmental Pollution and Health deals with the effects various pollutants have on the health of a person. The pollutants are present in various segments of the environment, viz., air, water, and soil. Besides these pollutants, thermal, noise, and radioactive pollutions affect the health of living beings. Radioactive pollution is the worst type of pollutant encountered and is responsible for the destruction of life. The health of a person is also adversely affected by hazards due to factors other than pollutions. These factors include occupation of a person, stress, global warming, and ozone layer depletion. All these have been discussed in detail in the present book. The waste generated in various establishments is responsible for the health of a person. Its management is very important and has also been discussed. The book is divided into eight chapters. Chapter 1, Introduction, discusses various forms of pollution. In Chapter 2, Air Pollution, the author discusses major types of air pollutants, sources of air pollutants, and effects of air pollutants. Chapter 3, Water Pollution, deals with major types of water pollution, water pollution in various water bodies, sources of marine pollution among others. Chapter 4, Soil Pollution, examines sources of soil pollution, harmful effects of soil pollution, and effects of improper disposal of hazardous wastes. In Chapter 5, Thermal and Noise Pollution, effects of thermal pollution, sources of noise, and effect of noise pollution are discussed. Chapter 6, Radioactive Pollution, examines sources of radioactive pollution, effect of radioactive pollution on health, and control of radioactive pollution. Chapter 7, Health Hazards due to Factors other

vi

PREFACE

than Pollution, discusses occupation and health, stress and health, and global warming and health. Chapter 8, Management of Wastes, explains municipal wastes, industrial wastes, and hazardous wastes. Any suggestion from the readers is most welcome and will be gratefully acknowledged. The author wishes to express his sincere gratitude to Anupama Jauhry, TERI Press for the help rendered for the publication of the book.

Contents Preface

v

1. INTRODUCTION

1

Pollution Sources of Pollution Nature of Pollutants Pollution Monitoring Pollutant Stability Pollution Reduction Pollution and Health

2. AIR POLLUTION Introduction Major Air Pollutants Sources of Air Pollutants Effects of Air Pollution Air Pollution in India Air Pollution and Health Control of Air Pollution

3. WATER POLLUTION Introduction Major Water Pollutants Water Pollution in Various Water Bodies Status of Coastal and Estuarine Pollution in India Water Pollution and Health Control of Water Pollution River Water Pollution in India Lake Water Pollution

2 2 4 5 7 7 11

13 13 14 22 24 24 25 36

39 39 40 41 49 50 59 60 65

CONTENTS

viii 4. SOIL POLLUTION

Introduction Sources of Soil Pollution Environmental Concerns of Soil Pollution Harmful Effects of Soil Pollution Soil Pollution and Health Measures to Control Industrial Wastes Effects of Improper Disposal of Hazardous Wastes

5. THERMAL AND NOISE POLLUTION Thermal Pollution Noise Pollution

69 69 70 73 73 74 76 79

81 81 82

6. RADIOACTIVE POLLUTION

87

Introduction Sources of Radioactive Pollution Radioactive Pollution and Health Control of Radioactive Pollution

87 87 91 94

7. HEALTH HAZARDS DUE TO FACTORS OTHER THAN POLLUTION Introduction Occupation and Health Stress and Health Global Warming and Health Ozone Layer Depletion and Health

8. MANAGEMENT OF WASTES Municipal Wastes Industrial Wastes Biomedical Waste Radioactive Wastes

95 95 95 97 98 98

99 99 101 106 108

Index

113

About the Author

121

CHAPTER

1

Introduction

E

nvironment is the surroundings of an organism consisting of all living (biotic) and non-living (abiotic) components. It has the conditions suitable for the existence and growth of plants, animals, and microorganisms. These conditions have been continuously changing since life evolved, which have been beneficial to some organisms, while harmful to others. New species came into existence due to changes beneficial to them, and a number of existing species, which could not adapt to the same changes, became extinct from earth. A typical example is the extinction of dinosaurs due to hostile conditions. One of the causes attributed to their extinction is the appearance of many primitive mammals that fed on dinosaur eggs. Although the earth’s environment has been continuously changing due to natural reasons for millions of years, it has been subject to extreme and harmful changes since human population increased and their activities expanded. Some activities that have degraded the environment are as follows: • Deforestation has been occurring for thousands of years, which involves cutting of trees in forests for farming or other requirements such as building residential areas. • Hunting of wild animals for food and game has been responsible for the extinction of many species such as the Tasmanian tiger. • Industrialization has led to pollution of air, water, and land because of harmful materials and effluents released from industries. • Man-made environmental disasters have profoundly affected the environment. Some such incidents include the Great Smog of London; the nuclear bombing of Hiroshima and Nagasaki during World War II; nuclear accidents such as those in Chernobyl (Ukraine); Three Mile Island (USA), Fukushima (Japan), and the Bhopal Gas Tragedy of India.

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POLLUTION Pollution is an undesirable change in the physical, chemical, or biological characteristics of the environment. It adversely affects the life support system of the biosphere. The agents that pollute the environment are called pollutants. Sometimes, even the normal constituents of the atmosphere become pollutants when their concentration increases to abnormal limits. For example, carbon dioxide (CO2) is not normally considered a pollutant, but its increased concentration has been responsible for global warming. Pollutants are of two types—non-degradable and biodegradable pollutants. Non-degradable pollutants are not decomposed by bacteria, and so they persist for a long time in the environment, get accumulated, and biomagnify to dangerous levels. Examples of nondegradable pollutants include pesticides, heavy metals, rubber, plastic, and nuclear waste. Biodegradable pollutants such as paper, domestic sewage, garden waste, and fertilizers are broken down into simple components by bacterial decomposition.

SOURCES OF POLLUTION In this section, we will discuss the sources of pollution in all segments of the environment—air, water, and land.

Sources of Air Pollution • Natural sources of pollution include volcanic eruptions [releasing poisonous gases such as sulphur dioxide (SO2), hydrogen sulphide (H2S), and carbon monoxide (CO)], forest fires, decay of organic matter, marsh gases, pollen grains, fine sand particles, and fungal spores. • Man-made sources of pollution include increase in population, deforestation, burning of fossil fuels, vehicular emissions, rapid industrialization, and agricultural activities (use of agrochemicals such as fertilizers, pesticides, insecticides, and herbicides). Some other sources include wastes from nuclear reactors.

Sources of Water Pollution Water is essential for all living organisms. However, most of the drinking water has been polluted. Some significant sources of water pollution are as follows:

INTRODUCTION

3

• Sewage and domestic wastes: Almost 75% of water pollution is caused by discharge of sewage and domestic wastes into water sources. • Industrial effluents: Toxic materials are discharged into water bodies from industries, which contain chemicals and harmful compounds such as phenols, aldehydes, ketones, amides, cyanides, metalloids, corrosive alkalis, acids, and oils. • Agricultural discharges: Mostly agrochemicals such as fertilizers, pesticides, insecticides, and herbicides are discharged into water bodies as agricultural run-offs. • Detergents: Household detergents contain a number of pollutants that severely affect water bodies. These detergents contain surfaceactive agents containing phosphates of sodium and sodium silicate. • Toxic metals: Industrial processes are responsible for releasing toxic metals such as mercury, cadmium, lead, arsenic, cobalt, manganese, iron, and chromium. • Siltation: Silt from higher regions is brought down by rains and flash floods and deposited in water bodies such as rivers and lakes. The soil particles in the silt make the water turbid, thus hindering the free movement of aquatic organisms. • Thermal pollutants: Unutilized heat from thermal power plants is released into water bodies, which adversely affect the aquatic environment. • Radioactive materials: Radioactive wastes enter water bodies from sources such as nuclear power plants, nuclear tests, and fission reactions. Extremely toxic radioactive elements such as plutonium, uranium, thorium, and radium are produced from neutron bombardment of atomic fuel. Once they enter the water bodies, they disrupt the ecosystem and find way into the food chain.

Sources of Soil Pollution Soil is the uppermost layer of the earth that supports almost all living systems. Plants and trees grow on this layer, which provide two fundamental necessities of life—food and shelter. Human activities have a profound impact on the quality of soil and its role in the

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ecosystem. Some sources of soil pollution due to human beings are as follows: • Industrial wastes: Disposal of industrial wastes is mainly responsible for soil pollution. The industries that discharge wastes on land include paper mills, chemical industries, oil refineries, sugar-manufacturing factories, tanneries, textile, steel, distilleries, agrochemical industries, coal and mining industries, metal polishing, drugs, glass, cement, and engineering industries. • Urban wastes: Both commercial and domestic wastes are dumped on land. These wastes, particularly in urban areas, contain garbage and materials such as plastic, glasses, metallic cans, fibres, paper, fuel residues, leaves, and other discarded manufactured products. • Radioactive pollutants: Nuclear fallout, or Black Rain, from overground tests and explosions in nuclear power plants deposit on land and get mixed with soil. Radioactive wastes produced in laboratories are also buried in land. Radionuclides such as strontium-90, iodine-129, caesium-137, and isotopes of iron are most injurious to living beings. • Agricultural practices: Green Revolution resulted in the use of large quantities of agrochemicals to increase food production. These chemicals are mostly responsible for soil pollution. Besides these wastes, manual slurry, debris, and soil erosion also cause soil pollution. • Biological agents: The major biological agents that pollute soil come from human and animal excreta.

NATURE OF POLLUTANTS As already stated, pollutant are agents (chemical or physical) that pollute the environment. A pollutant can be of any of the following kinds: • Gaseous pollutants [oxides of carbon (C), nitrogen (N2), and sulphur (S)] • Metallic pollutants (toxic metals) • Particulate matter (fine particles of carbon, cement, asbestos, and metallic dust) • Radioactive substances (radionuclides and radiations)

INTRODUCTION

5

• Biological agents (viruses, bacteria, and protozoa) • Miscellaneous agents [chlorofluorocarbons (CFCs), dioxins, and benzene] Environmental pollution may be of six types—air pollution, water pollution, soil/land pollution, noise pollution, pollution by radioactive substances, and thermal pollution. Depending on the nature of pollutants, they can belong to three major categories—biological (pathogenic organisms, products of biological origin), chemical (toxic metals, agrochemicals, gaseous pollutants, particulates, hazardous chemicals, carcinogenic substances, petroleum products, acidic or basic substances), and physical [thermal (heat), radiation (ionizing and non-ionizing), radioactive substances, sound waves, foul odours]. Due to rapid growth of population and industrialization, environmental pollution is increasing at an alarming rate. Thus, water is getting polluted by sewage and domestic effluents, industrial effluents, agricultural discharges, detergents, toxic metals, and radioactive materials. Even underground water has been polluted by leaching of various pollutants from the surface.

POLLUTION MONITORING As a large number of pollutants pollute the environment, it is essential to monitor them. This helps to know the nature of the pollution, its source of origin, and remedial measures to prevent it. The monitoring of pollutants can be carried out by two general methods—chemical methods and instrumental methods. Chemical methods include volumetric methods, gravimetric methods, colorimetric methods, and turbidimetric methods. • Volumetric methods include acid–base titrations (which are used for acidic and basic substances), oxidation and reduction methods (iodometric titration is used for determining chloride, aldehydes, and oxidizing agents), and precipitation methods (used for the determination of HCl). • Gravimetric methods are useful for determining SO2, dust, soil, and other particulate matter in the air. • Colorimetric methods are best suited and commonly used for the estimation of metallic vapours, oxides of nitrogen (NOx), fluorine,

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chlorine, CO, CO2, formaldehyde, and numerous other inorganic and organic compounds. A number of chemical systems absorb light and are coloured, hence the name colorimetric analysis. Colorimeters are used for the measurement of such systems. In fact, the variation of the colour of a system due to a change in concentration of some component is the basis of colorimetric analysis. It is based on the determination of the concentration of a substance by measurement of the relative absorption of light with respect to known concentration of the substance. • Turbidimetric methods are commonly used for the determination and estimation of particulate matter in the atmosphere. In this method, a turbid solution (a suspension of solid particulate matter in a liquid) is brought in the path of light of a photometer. Less radiant power reaches the photodetector. In fact, turbidimetric analysis is based on the measurement of a collimated beam due to scattering. Instrumental methods are efficient and give accurate results when other methods do not give satisfactory results. So these methods are commonly used. Some of the important instrumental methods are—infrared spectroscopy, non-dispersive infrared spectroscopy, atomic absorption spectroscopy, emission spectrometry, gas chromatography, high-performance liquid chromatography, and chemiluminescence. Table 1 gives a summary of various pollutants analysed by instrumental procedures.

TABLE 1 Various pollutants analysed by instrumental methods Pollutant

Instrumental technique

CO

Non-dispersive infrared spectroscopy, gas chromatography

NO2

Chemiluminescence, infrared spectrometry

SO2

Volumetrically, spectrophotometry

Hydrocarbons

Infrared spectrometry, gas chromatography

Aromatic hydrocarbons Gas chromatography Metals

Atomic absorption spectrometry

Ozone and oxidants

Visible and ultraviolet spectrometry

Sulphates

Gravimetrically

Particulate matter

Gravimetrically

INTRODUCTION

7

POLLUTANT STABILITY Most of the pollutants in the environment have different degrees of stability. Some pollutants undergo degradation by chemical or microbial degradation. However, there are pollutants which are non-biodegradable and stay in the environment for a much longer time. Some examples of such pollutants include polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and chlorofluorocarbons (CFCs). Table 2 gives the resident time of some major pollutants.

POLLUTION REDUCTION The reduction or control of pollution depends on the following factors: • Recognizing the source of origin • Type of pollutant • Controlling at the source • Removal of pollutant from the environment The measures/techniques for the reduction/control of pollution also depend on the pollutant. Some typical examples are discussed as follows:

Oxides of Sulphur A major oxide of sulphur is SO2. It is a hazardous pollutant, and thus it is necessary to check its emission into the atmosphere. There are two approaches for the reduction and prevention of SO2 in the

TABLE 2 Resident time of major pollutants Pollutant

Resident time

CO2

About four years

CO

1–4 months

CFCs and other halocarbons

>20 years

SO2

3–10 days

H2S

2–3 days

NOx

4–5 days

Ammonia

2 days

Particulates

Variable

PCBs

2–3 years

CFCs – chlorofluorocarbons; PCBs – polychlorobiphenyls

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atmosphere—(1) desulphurization of coal, which is a major source of SO2, and removal of SO2 from flue gases. The emission of SO2 from automobile exhausts can be prevented by using catalytic converter in vehicles.

Desulphurization of coal Sulphur is invariably present in coal either in inorganic form (as iron pyrites) or in organically bound form. The inorganic sulphur is removed from coal by the hydraulic washing of powdered coal. In this process, iron pyrites settle down (being heavier) and sulphur floats on the surface and is collected. For removing organically bound sulphur, hydrogen (H2) gas is passed over coal in the presence of a catalyst. This converts the organically bound sulphur into H2S, which is absorbed in a solution of diethanolamine. Finally, H2S is oxidized to sulphur. H2S + [O] Æ H2O + S

Desulphurization of flue gases Flue gases can be desulphurized by heating powdered coal with powdered limestone. CaCO3

D

CaO + CO2

CaO + SO2 Æ CaSO3 CaO + SO2 + O Æ CaSO4 The resultant CaSO3 and CaSO4 are removed by washing with lime water, which is obtained by hydrolysis of lime.

Oxides of Nitrogen Nitrogen is emitted in the atmosphere mainly by automobiles and power plants using fossil fuels.

Fitting of catalytic converters Automobiles fitted with catalytic converters in the exhaust system do not produce NOx. The exhaust gases, on passing through catalytic converters, release only harmless gases such as CO2, H2O, and N2.

INTRODUCTION

2CO + O HC + O2

Catalyst Catalyst

2NO + 2CO 2NO + 2CO 2N2O

Catalyst

NO + HC

9

2CO2 H2O + CO2

Catalyst Catalyst

2N2 + 2CO2 N2O + CO2

N2 + O2

Catalyst

N2 + CO2 + H2O

As seen, in the catalytic converter: • CO is converted to CO2; • Hydrocarbons are oxidized to CO2 and H2O; • Nitric oxide, on reaction with CO, gives N2 and CO2; • Nitric oxide is partially reduced to N2O, which decomposes to N2 and O2; • Nitric oxide and hydrocarbons are converted to N2, CO2, and H2O.

Treatment of coal On reaction with steam, sulphur-free coal gives water gas (a mixture of CO and H2). The water gas is sprayed with water and burnt. Due to the presence of water, the combustion temperature is lowered and so N2 and oxygen (O2) do not combine to produce NOx.

Carbon Monoxide Carbon monoxide is formed in the atmosphere due to the combustion of all carbon-containing components, especially in automobile engines, industrial furnaces, cigarette smoking, and volcanic eruptions. In automobiles, emission of CO, as well as NOx and unburnt hydrocarbons, can be prevented by fitting catalytic converters. However, as there is no mechanical way of controlling cigarette smoke, the best approach is to encourage people to quit smoking. There are also ways of checking emission of CO from eruption of volcanoes and industrial furnaces.

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Particulate Matter Particulate matter is emitted into the atmosphere from power plants using coal. Although there is no way to control their formation, they can be prevented from escaping into the atmosphere by collecting them with electrostatic precipitators.

Asbestos The fibres of asbestos find their way into the atmosphere from rocks and minerals and from mining and fabrication of asbestos sheets used as building material. Airborne asbestos is extremely harmful to health. Like particulate matter, emission of asbestos fibres can be prevented by using electrostatic precipitators.

Industrial Pollution Industries are responsible for the development of a nation as they manufacture products essential for growth in day-to-day life. However, wastes from manufacturing industries are a major cause of environmental (air, water, and land) pollution. These wastes include unutilized starting materials, end products, intermediate products, and by-products. Industries also discharge gaseous effluents by using coal or oil for heating purposes. The following are some useful measures for reducing and preventing the formation of waste: • Process modification: Industrial processes should be suitably modified or altered in such a way that the amount of waste generated is reduced to minimum. This can be achieved by making sure that most of the starting materials are incorporated into the final product and thus no waste is generated. The by-products generated should be used and converted into other useful products. • Use of green solvents: Most of the industries need solvents for their processes. Use of volatile organic solvents should be avoided, and only green solvents should be used, which include water, supercritical CO2, ionic liquids, polyethylene glycol and its solution, and perfluous liquids. • Catalysts: As far as possible, catalysts should be used to get better yields. These catalysts include phase-transfer catalysts, biocatalysts, green ethers, or other green catalysts.

INTRODUCTION

11

• Waste processing: All industries should process their wastes and not dispose them off on land or in water bodies. For example, industries using water should purify the discharged water and reuse it. Even after taking the aforementioned measures, some waste will be generated, which should be properly disposed.

POLLUTION AND HEALTH Being healthy means absence of diseases and prolongation of life. Physical well-being also depends on the quality of life and sound health. According to the World Health Organization (WHO), health is defined as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” In fact, health is the ability to function effectively within a given environment. Good heath involves the process of continuous adaptation to changes in the physical, biological, and social environment. Therefore, it is important to take care of “environment health”. If the environment is healthy, human beings will be healthy too. The basic measures that can be taken to keep the environment healthy are as follows: • Maintenance of a clean environment • Control of communicable diseases • Early diagnosis and prevention of diseases • Awareness about personal hygiene • Development of a social machinery to improve standard of living Environment has a profound influence on health, and elements such as air, water, and food are essential for the survival of human beings. Apart from their availability, their quality must also be assured. Progress in industrialization has increased environmental hazards and resulted in air, water, noise, and radiation pollution, which have caused many health problems and diseases. Worms, insects, and other organisms thriving in the polluted environment become disease-causing parasites, carriers of diseases, and intermediate hosts. Although it is not possible to completely eradicate disease-causing agents, various measures can be taken to prevent their proliferation. The physiological environment has certain ill effects on humans. For example, it has been proved that carcinogens present in cigarettes

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TABLE 3 Food-borne diseases and their agents Agent

Food-borne disease

Virus

Viral hepatitis, gastroenteritis, polio

Bacteria

Typhoid, paratyphoid, botulism, infantile diarrhoea, shigellosis, bacterial dysentery, staphylococcal infections, cholera, salmonella

Worms

Pork tapeworms, whipworms, pinworms, hookworms, roundworms

Chemicals

Pesticides, food additives, adulterants

Metals

Mercury, lead, cadmium, tin, zinc

cause lung cancer. A number of chemical substances are present in the environment, which have toxic effects on living organisms. These effects can be of short duration (for example, exposure to CO released by automobiles) or of long duration (for example, smoking cigarettes and chewing tobacco can cause cancer of lungs and mouth, respectively). Food is also a potential source of infection. It can be contaminated by microorganisms, microbial and non-microbial toxins, and added chemicals. It can also get contaminated at any point during its journey from the producer to the consumer. Table 3 lists some food-borne diseases caused by various biological agents, toxins, and metals. According to WHO estimates, poor quality environment contributes to about 25% of all preventable health problems in the world. The Centre for Science and Environment (CSE) states that at least a million people die in India every year because of water pollution and another 50,000 to 100,000 die because of air pollution. According to a World Bank study, the cost of environmental damages in India is more than ` 340,000 million. It is estimated that respiratory infections, diarrhoeal diseases, tuberculosis, and malaria affect about 5 million, 3 million, 2 million, and 1.5 million people in India, respectively. In the subsequent chapters, the causes of air, water, and land pollutions and their effects on human health have been discussed. In addition, photochemical pollution and thermal pollution have also been dealt with. There are health hazards caused by factors other than pollution, which include occupation, stress, global warming, and ozone layer depletion.

CHAPTER

2

Air Pollution INTRODUCTION Air pollution is an undesirable change in the physical, chemical, or biological characteristics of air that adversely affects its life support system. Pollution is caused by the addition of harmful substances that unfavourably alter the quality of air. Normally, carbon dioxide is not considered a pollutant. However, its presence in excessive amounts leads to global warming, which is responsible for health hazards. Pollutants can be of two types—non-degradable and biodegradable. Non-degradable pollutants remain unchanged in the environment for a very long period. For example, pesticides, heavy metals, rubber, plastic, and nuclear waste. Such substances cannot be decomposed or broken down by bacteria. They persist for a very long time in nature, get accumulated, and often bio-magnify to dangerous levels. On the other hand, pollutants such as paper, domestic sewage, garden wastes, and fertilizers are broken down into simple products by bacteria. Such products are referred to as biodegradable pollutants. For the sake of convenience, pollutants can be classified into the following three types: (1) Natural pollutants, (2) Primary pollutants, and (3) Secondary pollutants.

Natural Pollutants Natural pollutants find their way into the atmosphere as a result of natural phenomenon. Natural pollutants have been known to cause atmospheric pollution since time immemorial. Some examples of natural pollutants are as follows: • Forest fires started by lightening

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• Pollen, soil eroded by natural causes, and lava and debris released by volcanic eruptions • Volatile organic compounds discharged from leaves and trees • Decomposed or putrefied organic matter • Natural radioactive material • Natural Pollutants have been know to cause atmospheric pollution since time in immemorial

Primary Pollutants Primary pollutants enter the atmosphere directly as a result of activities such as burning of coal, oil, natural gas, and wood and release of carbon dioxide and carbon monoxide. Automobile exhausts are also responsible for contributing considerable amounts of sulphur dioxide and carbon monoxide. Other primary pollutants include oxides of nitrogen, hydrocarbons, and suspended particulate matter (SPM).

Secondary Pollutants Secondary pollutants are formed when primary pollutants undergo reaction with substances present in the atmosphere. For example, sulphur dioxide reacts with oxygen in the atmosphere to form sulphur trioxide, which further reacts with water vapour to form sulphuric acid. 2SO2 + O2 Æ 2SO3 SO3 + H2O Æ H2SO4 In this example, both sulphur trioxide and sulphuric acid are secondary pollutants.

MAJOR AIR POLLUTANTS Major air pollutants are produced in significant amounts and are responsible for a variety of environmental and health problems.

Gaseous Pollutants Carbon monoxide Carbon monoxide is a highly poisonous gas. It reduces the oxygencarrying capacity of blood and can be fatal in concentrations exceeding 100 parts per million (ppm). It is known as a silent killer because of its colourless, odourless, and tasteless properties. Victims can thus

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inhale carbon monoxide without any realization. The major sources of carbon monoxide are as follows: • Incomplete combustion of all carbon-containing fuels in the presence of insufficient quantity of oxygen. Such combustion takes place in automobile engines. • Industrial furnaces (for example, blast furnace) used at high temperature. • Smoking cigarettes • Industrial gases such as coal gas (obtained by destructive distillation of coal; contains 5%–10% carbon monoxide) and water gas (obtained by passing steam over red hot coke) contains 30%–40% carbon monoxide). • Volcanic eruptions • Forest fire • Controlled oxidation of methane • Decomposition or degradation of chlorophyll, the green pigment present in green plants. • Marine algal and marine siphonophores.

Carbon dioxide The major sources of carbon dioxide are as follows: • Burning of fossil fuels such as coal, natural gas, and petroleum, contributing more than 6000 million tonnes (MT) of carbon dioxide per year. • Cultivation of soil releases large amounts of carbon dioxide, contributing more than 10,000 MT of carbon dioxide per year. • Industrial processes, such as manufacture of lime and alcohol, contribute more than 10,000 MT of carbon dioxide per year. • Decay of dead organisms, respiration by living organisms, volcanic eruptions, and forest fires.

Oxides of nitrogen Nitrogen forms a number of air-polluting oxides such as nitrous oxide, nitric oxide, and nitrogen dioxide. Nitrous oxide is a greenhouse gas and plays an important role in the destruction of the ozone layer. The major sources of oxides of nitrogen are as follows:

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• Formation of nitric oxide and nitrogen dioxide during thunder storms and lightening. N2 + O2

Electric discharge

2NO

2NO + O2 Æ 2NO2 • • • •

Exhaust gases released from automobiles. Manufacture of explosives like trinitrotoluene (TNT). Bacterial decay of organic matter by soil microorganisms. Action of aerobic and anaerobic bacteria in the soil on nitrogenbased fertilizers.

Oxides of sulphur Sulphur forms two oxides—sulphur dioxide and sulphur trioxide. Sulphur trioxide is a secondary pollutant because it is obtained by the oxidation of sulphur dioxide in the atmosphere. Suphur dioxide is an important atmospheric pollutant. The main sources of sulphur dioxide are as follows: • Volcanic eruptions • Burning of oil and coal • Extraction and roasting of sulphide ores such as pyrites, copper pyrites, copper glance, zinc blende, and galena. • Power plants (oil or coal based), oil refineries, and sulphuric acid manufacturing plants. • Hydrogen sulphide discharged into the air by natural processes.

Suspended Particulate Matter Finely divided suspended solid particles present in the atmosphere are called particulates. An important characteristic of SPM is the extremely small size of particles ranging from 0.5 µm to 100 µm. Particles less than 2.5 µm in diameter are called fine particulate matter (80% of the particles are less than 2 µm). On the other hand, particles above 2.5 µm in diameter are called coarse particulate matter. Heavy particulate matter settles down quickly due to the gravitational force and rain. However, small particles keep floating in the air with wind. Fine SPM has an adverse impact on health causing

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respiratory disorders when inhaled. These particulates are called respirable suspended particulate matter (RSPM). SPM can adversely affect the photosynthetic process in plants by covering the leaves and plugging the stomata. This reduces absorption of carbon dioxide and sunlight, and photosynthesis is hampered. In the atmosphere, reaction of gases and solids or mixing of solid and liquid particles can produce secondary particles. Smog is formed due to the mixing of gases and solids. Some important sources of particulates are as follows: • • • • • • • • •

Meteorites Volcanoes Pollens and spores Mining of coal, asbestos, mica, and ores of metals Cement dust from cement factories Insecticide dust Fly ash generated from power units Milled flour Exhaust gases of automobiles

Metallic Pollutants Metallic pollutants such as zinc, chromium, arsenic, beryllium, boron, manganese, nickel, vanadium, selenium, mercury, lead, and cadmium are released into the air by various metallurgical processes.

Hydrocarbons and Other Volatile Organic Compounds Hydrocarbons Hydrocarbons are compounds made up of carbon and hydrogen. They are the most important constituents of petroleum and natural gas. They are also present in the exhaust gases of automobiles. Methane is a major naturally occurring hydrocarbon emitted in the atmosphere. It constitutes 90%–95% of natural gas. It is also produced by bacteria during the anaerobic decomposition of organic matter in soil, water, and sediments. Methane is a greenhouse gas and, thus, contributes to global warming. The hydrocarbons, particularly methane, along with oxides of nitrogen contribute to the formation of photochemical smog.

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Some polycyclic hydrocarbons (hydrocarbons having multiple ring structure) can be carcinogenic to humans. Benzopyrene is a carcinogenic hydrocarbon produced by burning of coal.

Volatile organic compounds Volatile hydrocarbons escape into the atmosphere during petroleum production. Hydrocarbons and oxides of nitrogen from automobile exhausts react to form photochemical oxidants such as ozone, peroxyacetyl nitrate, and acrolein in the presence of sunlight. Chlorofluorocarbons (CFCs) are another group of volatile organic compounds composed of chlorine, fluorine, and carbon. Dichlorodifluoromethane (CCl 2 F2) and trichlorofluoromethane (CCl3F) are two important CFCs, which absorb infrared radiation and thus contribute to global warming. They are non-flammable, water insoluble, and inert, thus remaining intact in the atmosphere. Ultimately, they reach the stratosphere, where they are decomposed by high energy ultraviolet radiation, breaking the carbon–chlorine bonds and releasing free chlorine atoms. It is estimated that one chlorine atom on an average can destroy 100,000 molecules of ozone. One can rightly imagine how the protective layer of ozone is destroyed due to the presence of trace CFCs in the stratosphere.

Photochemical Pollutants Pollutants arising from photochemical reactions are referred to as photochemical air pollutants. A photochemical reaction requires a lot of energy. Certain pollutants in the atmosphere, such as oxides of nitrogen and hydrocarbons, undergo photochemical reactions. These reactions produce new pollutants, including ozone, aldehydes, and toxic organic compounds such as peroxyacetyl nitrate. Ozone, the main photochemical oxidant, is formed in the atmosphere in the following two ways: 1. Higher up in the atmosphere, oxygen molecules absorb ultraviolet light and split into two oxygen atoms (O2 Æ 2O), which combine with oxygen molecules to ultimately form ozone (O2 + O Æ O3). 2. Short ultraviolet radiations do not reach the earth’s surface. However, they are absorbed by nitrogen dioxide, which breaks into nitric oxide and oxygen through photolysis. The oxygen atom

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Figure 1

19

Basic chemical reactions leading to the formation of ozone in the atmosphere

so produced combines with oxygen molecule (O2) to give ozone (Figure 1). Hydrocarbons released from automobile exhausts also help in the accumulation of ozone (Figure 2). Ozone is a powerful oxidizing agent, which can damage crops and other vegetation. It can also harm human beings and damage fabric

Figure 2

Accumulation of ozone via hydrocarbons

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and rubber. Even in concentrations of 0.001 ppm, ozone can affect some people. It is ironic that although ozone is harmful, it is an important and necessary constituent of the atmosphere. The ozone layer in the stratosphere protects life on earth from harmful ultraviolet radiations having wavelengths shorter than 340 nanometres. However, certain pollutants resulting from human activities tend to remove ozone from the stratosphere. The depletion of ozone in the stratosphere has created a hole in the layer, referred to as the ozone hole. The steps involved in the formation of photochemical smog have been explained by the following reaction (Figure 3): 1. Hydrocarbons from automobiles interact with ozone to form a hydrocarbon free radical RCH*2 (1). This free radical may also be formed by the reaction of hydrocarbons with atomic oxygen (evolved from nitrogen dioxide by ultraviolet radiation from the sun; NO2+ UV radiation Æ NO + O). 2. The free radical RCH*2 (1) reacts rapidly with oxygen to form another free radical RCH2O* (2). 3. The second free radical (RCH2O*2) in turn reacts with nitric oxide present in the atmosphere (either from nitrogen and oxygen in the presence of sunlight or by the irradiation of nitrogen dioxide) to produce another free radical RCH2O* (3) (the nitric oxide is converted into nitrogen dioxide). 4. The third free radical (RCH2O*) subsequently reacts with oxygen yielding an aldehyde (RCHO) and generating a hydroperoxyl radical (HO*2).

Figure 3

Steps involved in the formation of photochemical smog

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5. The hydroperoxyl radical (HO*2) reacts with nitric oxide to give nitrogen dioxide and a hydroxyl radical (HO*). 6. The hydroxyl radical (HO*), being extremely reactive, reacts with hydrocarbons (RCH3) regenerating the hydrocarbon free radical (RCH*2) (1). The above cycle is repeated a number of times leading to a rapid build-up of photochemical smog. 7. The aldehyde (RCHO) formed in step 4 reacts with the hydroxyl radical (HO*) producing an acyl radical (RCO*), which in turn reacts with oxygen to give peroxyacyl radical (RCOO*2). The generated peroxyacyl radical finally reacts with nitrogen dioxide to generate peroxyacyl nitrate. The Figure 4 shows formation of peroxyacyl nitrate.

Figure 4

Steps involved in the formation of peroxyacyl nitrate

Effects of photochemical pollutants on health Photochemical pollutants are responsible for increased frequency of attacks in asthmatics. Individuals with chronic lung diseases are also affected by photochemical pollutants. These pollutants also cause irritation in eyes, nose, and throat. Peroxyacyl nitrate, a constituent of smog, causes irritation in eyes. The components of smog affect the respiratory tract of human beings. They also cause nose and throat irritation and lead to several problems of eyes, lungs, and heart.

Control of photochemical pollutants Photochemical pollutants result from air pollutants such as oxides of nitrogen and hydrocarbons. Therefore, these pollutants can be controlled by following procedures similar to that used for controlling air pollutants.

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SOURCES OF AIR POLLUTANTS Air pollution is caused by gaseous pollutants such as oxides of carbon, nitrogen, and sulphur, SPM, metallic pollutants, and hydrocarbons. Besides these, pollutants arise from industries, petroleum exploration and refining, mining, power production, and agriculture.

Pollutants from Industries Industries dealing with the manufacture of explosives (such as various nitro compounds) using concentrated nitric acid release thousands of tonnes of oxides of nitrogen into the atmosphere. Fermentation industries emit thousands of tonnes of carbon dioxide, caustic soda manufacturing units release chlorine, and metallurgical processes discharge carbon monoxide, carbon dioxide, hydrogen sulphide, and metal particles into the atmosphere. Some of the specialized industries that release pollutants into the atmosphere are discussed in the subsequent sections.

Polymers and Plastic The non-biodegradability of polymers and plastic has caused serious waste disposal problems. In addition, some toxic chemicals used in the manufacture of polymers and plastic are released into the atmosphere, including n-pentane, trichlorofluoromethane (Cl3CF), toluene-2, 4-diisocyanate (commonly used as a foaming agent), plasticizers such as di-(2-ethylhexyl) phthalate and di-(2-ethylhexyl) adipates, polychlorinated biphenyls (used to increase the flexibility of polymers), and antioxidants such as 2-hydroxybenzophenone. Other chemicals discharged into the atmosphere include 2-chloro-1, 3-butadiene (chloroprene), bis(chloromethyl) ether, toluene-2, 4-diisocyanate, and vinyl chloride.

Asbestos Being fibrous in nature, asbestos is an environmental hazard. Asbestos is spun into yarn, which can be reinforced with other fibres such as nylon. This yarn can be used to make garments for firefighting, thermal insulators, electrical insulators, brake lining in automobiles, and building materials. Most asbestos fibres are released into the atmosphere during mining and disposal of articles made of asbestos.

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Tobacco Tobacco smoke has been found to contain over 2500 chemical substances hazardous to health. Tobacco chewing is also a serious health hazard.

Petroleum exploration and refining During drilling, some low-boiling fractions escape into the atmosphere and also spill onto land. Spilling or leakage of petroleum also takes place during transportation. Even during fractional distillation, a number of fractions, such as gas and hydrocarbon, find their way into the atmosphere due to leaks or poor recovery.

Mining industries A number of minerals are extracted out of the earth. Many mining industries such as coal mining, mica mining, and asbestos mining pollute the atmosphere by injecting fine particles of coal dust, mica, and asbestos into the atmosphere.

Power plants Power is generated in most power plants by using coal as the source of energy. Besides gaseous pollutants, power plants inject fine carbon particles and fly ash into the atmosphere.

Automobiles Automobiles are mostly run on petrol or diesel. The exhausts from automobiles inject a number of gaseous pollutants such as oxides of carbon, nitrogen, and sulphur into the atmosphere. Aeroplanes use large quantities of gasoline and are the major contributors of exhaust gases into the higher atmosphere.

Agrochemical-based industries Agro-industries include industries manufacturing fertilizers, insecticides (or pesticides), fungicides, and herbicides. All these industries inject various toxic chemicals into the atmosphere. Nitrogen fertilizers such as sodium nitrate or potassium nitrate result in the accumulation of nitrate ion in leafy vegetables. In the human body, nitrate is reduced to nitrite, which is a probable factor for

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the occurrence of cancer. Excessive amounts of nitrates may lead to the blue baby syndrome or methaemoglobinaemia in infants. The nitrites formed from the nitrate react with haemoglobin (in the bloodstream) and reduce the oxygen-carrying capacity of blood, leading to a blue complexion in the affected babies. The symptoms of blue baby syndrome include diarrhoea and vomiting, which can be fatal. One of the worst environmental disasters related to industrialization happened in Bhopal (Madhya Pradesh) on 3 December 1984 when methyl isocyanate gas used for manufacturing insecticides leaked by accident. It killed thousands of people and disabled millions. Mercurial fungicides are also responsible for poisoning of food and deaths. Mercury poisoning happens when flour and wheat seeds treated with organomercury fungicides are ingested. This type of poisoning has been recorded in Iraq (1956, 1960, and 1972), Guatemala (1965), and Pakistan (1969). Herbicides 2, 4-D (2, 4-dichlorophenoxyacetic acid) and 2, 4, 5-T (2, 4, 5-trichlorophenoxyacetic acid) are harmful to the health and survival of human beings. Both 2, 4-D and 2, 4, 5-T were used to defoliate forests in the Vietnam War. It was observed that children born to people in these regions had birth defects such as deformed or missing limbs, which was attributed to the damage of male sperm cells caused by the herbicides.

EFFECTS OF AIR POLLUTION The pollutants in the atmosphere are responsible for many changes in the environment that have a profound effect on the health and well-being of humans. Some of the effects of these pollutants include acid rain, greenhouse effect, global warming, depletion of ozone layer, and formation of smog.

AIR POLLUTION IN INDIA India has made great technological and industrial advances since independence. However, all this progress has come at a cost for the environment because of the release of toxic gases, particulate matter, and radioactive nuclides. According to a survey conducted in 2000, Delhi was the most polluted city followed by Kolkata and Ahmedabad. Automobiles are one of the primary sources of pollution. In Delhi, the

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number of vehicles increased from 285,000 to over 8,448,000 from 1972 to 1992. This number has tripled now. However, implementation of stringent measures during the last few years, such as introduction of Euro II standards, lowering of the sulphur content of gasoline, use of unleaded gasoline, and introduction of compressed natural gas (CNG) as fuel for taxis and trucks, has helped change the situation. A recent Central Pollution Control Board (CPCB) report stated that Ahmedabad has replaced Delhi as the city with the most polluted air, followed by Kanpur, Sholapur, and Lucknow. The report finds that Indian cities have high particulate pollution with 14 cities in the critical list. To make matters worse, air quality has been evaluated only on the basis of pollutants such as sulphur dioxide, nitrogen dioxide, and particulates. The threat posed by other air toxins such as benzene, ozone, and dioxins is not known. India has to do much more to improve the quality of air. Some attempts made in this direction include the following: • Use of CNG as fuel for automobiles • Creating awareness among people about the pollution created by automobiles • Reducing the use of fossil fuels • Increasing the use of nuclear energy

AIR POLLUTION AND HEALTH The threat of air pollution to health became apparent only when some severe disasters caused human causality in the USA and the UK. In 1880, about 2200 people died in London when coal smoke emitted from domestic heating and industry combined to form a toxic smog of sulphur dioxide gas and airborne combustion particles. In 1948, about 50 people died in Denora, Pennsylvania (USA), and thousands became ill when pollutants emitted from steel mills and zinc smelter plants were trapped in the atmosphere. In 1952, about 4000 people died in London when sulphuric acid vapours, particulate matter, and sulphur dioxide enveloped the city. As stated earlier, the worst environmental disaster in history occurred on 3 December 1984 in Bhopal. Approximately 33 tonnes of methyl isocyanate, an extremely poisonous gas used in the synthesis

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of the pesticide Sevin, escaped from a storage tank of the Union Carbide India Ltd factory in Bhopal and spread mist and cloud over the city. The people were exposed to the poisonous gas in their sleep. It is estimated that about 10,000 people died and more than 2000 were severely affected. Even the survivors of the gas tragedy suffered from one or more problems such as permanent respiratory illness; impairment of vision; damaged lungs, kidneys, and muscle, gastrointestinal and reproductive problems; and impairment of the immune system. Menstrual abnormalities and abortions were also reported in a number of women. Air pollution affects young children more than adults. According to a US agency, air pollution is responsible for about 50 million cases of chronic coughing in children below 14 years of age all over the world per year. A World Bank study estimated that the largest share of money spent on health issues (approximately $7 billion/year) globally is due to the growing air pollution. Urban air pollution has worsened in most of the large cities in India because of population growth, industrialization, and increased vehicle use. The health hazards due to various major pollutants have been discussed in the subsequent sections.

Effects of Major Gaseous Pollutants on Health Gaseous pollutants produced in significant amounts adversely affect human health. Over a billion tonnes of pollutants are released into the atmosphere from human activities. The most common and acute health problems caused by gaseous pollutants include bronchitis and congestion in chest and wheezing. These effects can be reduced if the exposure to pollutants is reduced.

Sulphur dioxide Sulphur dioxide is a major cause of lung diseases. It is responsible for irritation in nose and mucous lining, shortness of breath, accumulation of fluids in tissues, oedema, and bronchospasm. Longterm exposure can result in respiratory diseases such as chronic bronchitis, aggravated asthma, emphysema, pulmonary fibrosin, and increased stress on heart.

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Oxides of nitrogen Oxides of nitrogen released from the exhausts of buses, trucks, and two-wheelers cause irritation of eyes and lungs. Inhalation of these oxides in large amounts may lead to gum inflammation, internal bleeding, pneumonia, and even cancer. In fact, oxides of nitrogen oxidize lipids thereby disrupting cell membranes leading to respiratory oedema. Most of the nitrogen dioxide inhaled is quickly absorbed by the lining of the respiratory tract. It has been found that exhausts from diesel-operated vehicles cause chromosomal mutations, a factor responsible for cancer. Individuals with chronic respiratory diseases such as emphysema and asthma and individuals with heart disease are more sensitive to nitrogen dioxide, which is responsible for many short-term respiratory diseases. They may develop complications such as pneumonia from short-term infections.

Carbon monoxide Carbon monoxide is known to be an extremely toxic gas. On entering the bloodstream, it completely inhibits the combining capacity of oxygen with haemoglobin. In fact, the affinity of carbon monoxide is more than 240 times that of oxygen. It combines with haemoglobin to form carboxyhaemoglobin, thus reducing the amount of oxygen in the blood. Even low concentrations of carbon monoxide are not safe. In higher concentrations, carbon monoxide slows down physical and mental activities and may cause asphyxiation, heart problems, brain damage, and even death. Hb

(Haemoglobin)

+ O2

HbO2 + CO

Æ

HbO2 (Oxyhaemoglobin) HbCO (Carboxyhaemoglobin)

+ O2

Table 1 summarizes the effects of gaseous pollutants on human health.

Effects of Suspended Particulate Matter on Health Suspended particulate matter consists of solid and low-vapour-pressure liquid particles that float around in the atmosphere. Short- and long-

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TABLE 1 Effects of gaseous pollutants Gaseous pollutant

Environmental effect

Health effect

Combustion of Oxides of carbon coal, oil, and • Carbon dioxide a other fuels for • Carbon monoxide the production of energy; manufacturing and transport; biomass burning

Carbon dioxide has a major role in the greenhouse effect; it produces weak carbonic acid adding to acid rain.

Carbon monoxide causes headache, weakness, fatigue, drowsiness, and asphyxiation; fatal in large doses; decreases the oxygen-carrying capacity of blood; increases resistance to blood flow; aggravates health disorders; affects the perception and reflexes of the central nervous system; causes vision and brain damage.

Oxides of sulphurb • Sulphur dioxide • Sulphur trioxide

Combustion of sulphurcontaining fuels such as coal; petroleum extraction and refining; paper manufacturing; smelting of ore for metal extraction.

It is an important precursor to acid rain which corrodes paints, metal, and causes injury or death to animals and plants.

Sulphur dioxide has maximum deleterious effects as it can cause severe damage to lungs in humans and animals. It also causes the following: • Irritation in eyes, nose, and mucous lining • Shortness of breath, cough, and choking • Accumulation of tissue fluid known as Oedema. • Chronic bronchitis, pulmonary fibrosis, acute and chronic asthma • Aggravation of preexisting heart and lung diseases

Oxides of nitrogenb • Nitric oxide • Nitrogen dioxide • Nitrous oxide

Burning of fuels; biomass burning; by-product in the manufacture of fertilizers; by-product during nitration process, such as manufacture of TNT.

Forms secondary pollutants such as peroxyacetyl nitrate and nitric acid; suppresses plant growth

Causes tissue damage and irritation in eyes; nitrogen dioxide causes irritation in eyes and respiratory tracts; oedema of respiratory tract; reduction in lung function and the oxygen-carrying capacity of blood; diminished pulmonary function; slow immune response; prone to viral infection

a

Source

Carbon monoxide is described as a silent killer.

b

Oxides of sulphur and nitrogen are responsible for acid rain. They are also responsible for the formation of smog.

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term exposure to SPM can lead to chronic respiratory problems. It can also increase the risk of cardiac arrest and premature death. Particles smaller than 10 µm in size, known as PM10, are RSPM. Fine particles of size less than 2.5 µm are known as PM2.5. These particles can penetrate deep into the lungs and cause severe problems. Gaseous pollutants, particularly sulphur dioxide, settle on the particles and reach the interior parts of the respiratory system. Hence, the toxicity of even low concentrations of sulphur dioxide can increase significantly. About 40% of SPMs are RSPM. Diesel-operated vehicles and electricity generators contribute much of the PM10 and PM2.5 (which are more lethal than the larger particulate matter) present in the atmosphere. These particles are coated with carcinogens and polyaromatic hydrocarbons and can be fatal to humans. Diesel vehicles emit three to four times more particulates than other vehicles. Fine dust particles generated by construction activities, coal, cement, asbestos, and mica industries contribute more SPM. Severe respiratory problems are caused by coal dust, asbestos fibres, mica fibres, and even fibres of sugar cane, cotton, flax, and hemp. Long-term inhalation of SPM results in respiratory diseases known as pneumoconiosis. The effect of SPM on human health is summarized in Table 2.

TABLE 2 Effect of SPM on human health Suspended particulate matter

Source

Environmental effects

Health effects

SPM includes dust, soil, sulphate salts, particles of carbon (soot), silicon, asbestos.

Fuel combustion; building construction; mining; thermal power stations; stone crushing; industrial processes; forest fires; refuse incineration

Deposition on the surface of green leaves thus interfering with the absorption of carbon dioxide and release of oxygen; blocking of sunlight; forms photochemical smog.

Causes irritation in throat, respiratory tract, affects lungs (particles of size in the range 0.1–10 μm cause the greatest damage to lungs); decrease in pulmonary function; stress on heart; carcinogenic effect; children with small heads and bodies are born; damage. DNA of the growing foetus; premature mortality, death from respiratory illness and cardiovascular failure.

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Effects of Metallic Pollutants on Health The particulates released during the extraction of metals from ores have extremely adverse effects on health. Table 3 lists some metallic particulate pollutants along with their source and harmful effects.

TABLE 3 Sources of metallic pollutants and their effects Metallic pollutant

Major source

Harmful effect

Zinc

Zinc refineries; galvanizing processes; brass manufacture; metal plating, and plumbing

Zinc fumes have a corrosive effect on the skin and can cause irritation and damage mucous membranes.

Chromium

Metallurgical and chemical industries; processes using chromate compounds; cement and asbestos units

Toxic to body tissues, can cause irritation, dermatitis, ulceration of skin, perforation of the natal septum; carcinogenic action suspected.

Arsenic

Arsenic-containing fungicides, pesticides, and herbicides; metal smelters; by-product of mining activities; chemical wastes

Inhalation, ingestion, or absorption through skin can cause mild bronchitis, nasal irritation, or dermatitis; carcinogenic activity is also suspected; they attack the SH groups of enzymes and coagulate proteins.

Beryllium

Coal, nuclear power, and space industries; production of fluorescent lamps; motor fuels and other industrial activity

Damage to skin and mucous membranes, pulmonary damage, perhaps carcinogenic.

Boron

Boron-producing units; production and use of petroleum fuel and additives; burning coal and industrial wastes; detergent formulations

Ingestion or inhalation as dust causes irritation and inflammation; boron hydrides can damage the central nervous system and may result in death.

Manganese

Absorption, ingestion, inhalation, Ferromanganese production; organomanganese fuel additives; or skin contact may cause manganic pneumonia. welding rods; incineration of manganese-containing substances

Nickel

Respiratory disorders, dermatitis, Metallurgical industries using cancer of lungs and sinus nickel; combustion of fuels containing nickel additives; burning of coal and oil; electroplating units using nickel salts; incineration of nickel salts; incineration of nickelcontaining substances; vanaspati manufacture Contd...

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Contd...

Metallic pollutant

Major source

Harmful effect

Vanadium

Vanadium refining; production of vanadium-containing alloys; power plants; burning of oil rich in vanadium

Gastrointestinal and respiratory disorders; inhibition of synthesis of cholesterol; heart disease and cancer in the case of chronic exposures

Selenium

Burning of fuels and residual oils; fumes and gases from refinery wastes; incineration of paper and other wastes; natural sources

Irritation of gastrointestinal and respiratory tracts; irritation of eyes, nose, and throat; damage to lungs, liver, and kidneys

Mercury

Metallurgical and chemical processes for chlor-alkali industries

Produces heaviness, headache, nervousness, fatigue, and a number of other problems; prolonged exposure causes breakdown of the central nervous system

Lead

Metallurgical processes; lead pipes used for water supply; exhausts of automobiles

Impairs enzyme functions; affects the nervous system; causes hypertension; a cumulative poison accumulating in the tissues of humans and plants; in humans, accumulation of lead causes malfunctioning of red blood cells. leading to anaemia; lead is known to damage liver, kidneys, and intestines.

Cadmium

Metallurgical processes of zinc, Causes lung irritation, vomiting, and lead, and copper hypertension

Effects of Hydrocarbons on Health Hydrocarbons such as benzene, benzopyrene, chlorinated hydrocarbons, polyvinyl chloride (PVC), and many other compounds are carcinogenic. The World Health Organization (WHO) has listed some the most toxic dioxins carcinogenic to humans (Table 4). During the Vietnam War, the US military aerially sprayed 42 million litres of Agent Orange, a herbicide, to deny the communist fighters forest cover. This herbicide was contaminated with dioxins. It created havoc in the lives of millions of war victims and other civilians in the area. Dioxins are the most carcinogenic compound tested so far. Children born to people affected by dioxins were deformed with low Intelligent Quotient (IQ). Many children were mentally disabled. People also suffered from skin tumours. In 1976, Roche Holding Ltd, a chemical factory, released dioxins into the atmosphere in Seveso, Italy. People exposed to dioxins suffered

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TABLE 4 Sources of some hydrocarbons and their effects on human health Hydrocarbon

Source

Environmental effect

Health effect

Hydrocarbons, also called volatile organic compounds, include methane, butane, ethylene, benzene, benzopyrene, and propane

Evaporation from gasoline tanks, carburetors; burning of fuels, biomass; microbial activity of sewage; industrial processes involving solvents

Higher concentrations are toxic to plants and animals; some are more reactive and produce photochemical smog on reaction with sunlight.

Hydrocarbons such as methane and ethane cause coughing; eye irritation; drowsiness; polycyclic aromatic hydrocarbons, including benzene and benzopyrene, are carcinogenic and can be fatal.

Dioxins

By-product of industrial processes; burning of chlorinated compounds in garbage and medical waste

Cause cancer in humans

skin injuries, which took a few weeks to heal. A number of people also developed cases of chloracne, a condition characterized by dark skin blotches.

Effects of Other Pollutants on Health Polymer and plastic industries Chloroprene (2-chloro-1,3-butadiene) used for the production of synthetic rubber (neoprene) can cause liver damage. Toluene-2,4diisocyanate is responsible for acute respiratory problems. Vinyl chloride used in the manufacture of PVC polymers results in a rare form of liver cancer. Polychlorinated biphenyls released into the atmosphere when plastic wastes are burnt in incinerators are responsible for an ailment called Yusho disease. Symptoms of this disease include headache, fatigue, pain in the joints, and anaemia. A concentration above 12 ppm can cause blindness. Besides polychlorinated biphenyls, incineration of waste plastic material also releases carbon dioxide responsible for the greenhouse effect, oxides of nitrogen (responsible for acid rain), carbon monoxide (a deadly poisonous gas), and particulate matter.

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Asbestos mining Penetration of asbestos fibres in lung tissues causes a lung disease known as asbestosis. Over a period of time, the outer lining of the victim’s lungs thickens, thereby decreasing the oxygen–carbon dioxide exchange capacity and the elasticity of the lungs. The victim suffers from breathlessness and eventually dies of heart failure. Workers engaged in asbestos industries (mining, cleaning, and weaving) are more prone to suffer from asbestosis, which is incurable. These workers can also develop lung cancer and mesothelioma (a rare cancer of the thin membrane lining the chest and abdomen). Certain varieties of asbestos contain appreciable amounts of iron (25%–30%). Although iron is essential for life, excessive built-up of iron in the body is harmful. It forms chelate with citrate ion. These chelates enter the cells, and ferrous iron reacts with molecular oxygen radicals. These radicals create havoc by oxidizing Deoxyribonucleic acid (DNA) and proteins and damaging proteins leading to carcinogenesis.

Tobacco industries Tobacco smoke is found to contain more than 2500 chemical substances, including carbon monoxide, carbon dioxide, ammonia, nitrosamines, oxides of nitrogen, hydrogen cyanide, sulphur compounds, nitriles, ketones, alcohols, and acrolin. The tar contains carcinogenic hydrocarbons, which include nitrosamine, benzo(a)pyrene, anthracene, acridine, quinoline, benzene, naphthol, naphthalene, cresols, and insecticides, as well as radioactive compounds such as potassium-40 and radium-226. Some of the compounds are known to increase the risk of cancer in humans (such as cancer of lungs, larynx, mouth, oesophagus, urinary bladder, kidneys, and prostrate). Smoking adversely affects fertility in females. Children born to mothers who smoke are more prone to various abnormalities. Even passive cigarette smoking is equally harmful.

Petroleum industries Petroleum finds its way into the atmosphere during drilling, transportation, and fractional distillation. Some of the fractions, particularly benzene, are known to be carcinogenic.

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Coal mining During coal mining, fine particles of coal dust are released into the atmosphere. Inhalation of these fine coal dust particles leads to wheezing and shortness of breath. It finally leads to a black lung disease, which is incurable. Power plants using coal as a source of energy release gaseous pollutants, fine particles of carbon, and fly ash. All these pollutants are extremely harmful to humans.

Mica mining During mining of mica, small fine particles of mica are released into the atmosphere. Inhalation of these particles causes a number of health hazards.

Acid rain Acid rain is produced from the oxides of nitrogen and sulphur in the presence of oxygen and moisture. Acid rain has been found to be dangerous to human health. In fact, acidic conditions can play havoc with the human nervous system, respiratory system, and digestive system by making the person an easy prey to various neurological diseases.

Global warming An increase in the average temperature of the earth’s atmosphere due to greenhouse effect has led to global warming. This can have far-reaching effects on the climate and consequently on the key life support systems of the planet. The accelerated heating of the atmosphere can influence human health in a number of ways. Excessive heat, floods, and droughts claimed 154,000 deaths due to malaria, dengue, and diarrhoea. Fierce heat waves compounded with lack of night-time cooling are expected to double the number of deaths due to heat waves in the years to come. Due to high temperature, the dispersal of allergens in the atmosphere is enhanced; this puts large population at risk of exposure. Global warming will melt all the glaciers, flooding the low-lying areas and raising the level of water in the oceans. Floods are known

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to cause devastation of life and property; floods also lead to scarcity of food and drinking water. These disasters promote the spread of infectious diseases. Global warming will increase manifold the incidence of water-borne infections such as cholera and jaundice. Diseases spread by mosquitoes such as malaria, dengue fever, yellow fever, and several kinds of encephalitis are likely to increase as a result of global warming. Vector-borne diseases affecting more than 700 million people in a year are considered most sensitive to climate and environmental conditions.

Depletion of ozone The ozone layer protects life on earth by absorbing high-energy ultraviolet radiations from the sun before they reach the earth. However, certain man-made substances such as CFCs, which are widely used as refrigerants and cleaning agents, liberate reactive chlorine atoms on exposure to ultraviolet radiation. The chlorine atoms then break the ozone molecules, creating a hole in the ozone layer. As a result, ultraviolet radiations from the sun reach the earth, which cause skin cancer and other skin ailments.

Effects of Indoor Air Pollution on Health Indoor air pollution occurs mainly due to the use of gas, kerosene, coal, wood, and tobacco, which release gaseous pollutants or particulate matter into the air. More than 50% of Indian households and about 40%–45% of the world population use traditional fuels such as wood, crop residues, dried animal dung for daily cooking. These biofuels are the major source of indoor air pollution. They generate 20–100 times more RSPM than cleaner fuels. The pollutants emitted from these biofuels contain carbon monoxide, SPM, polycyclic aromatic hydrocarbons, formaldehyde, and oxides of nitrogen and sulphur. It has been shown that indoor air pollution contributes to a higher prevalence of ailments in households using biomass fuels compared to households using cleaner fuels. In fact, India bears the largest number of health problems related to indoor air pollution in the world. Approximately 500,000 women and children die each year, which is approximately 25% of the deaths due to indoor air pollution worldwide. Women and children in rural areas suffer the most since

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they spend more time indoors in inadequately ventilated houses. They inhale large quantities of pollutants released from burning of biofuels. The health effects of indoor air pollution are as follows: • Cough, breathlessness, chest ailments, and chronic bronchitis • Pulmonary hypertension and cardiac enlargement resulting in cor pulmonale (abnormal enlargement of the right side of the heart), decreased ventilatory capacity • Certain types of cataracts, which may lead to blindness • Adverse effects during pregnancy such as stillbirth, neonatal death, and low birth weight • Lower immune response in neonates • Increased susceptibility to gastrointestinal and respiratory infection in neonates • Acute respiratory infection in children, including cough, running nose, noisy respiration, and wheezing • Tuberculosis and cancer

CONTROL OF AIR POLLUTION Air pollutants constitute a grave danger to all. The harmful effects of various pollutants have already been discussed. Air pollution can be best described as a time bomb, which may explode at any time, any place causing severe, undetermined problems. There are basically two approaches to control air pollution—effluent control and preventive techniques. Some important measures to control air pollution are as follows: • Coal is a basic raw material for a number of industries, such as power plants and metal-extraction units. Coal contains sulphur as an impurity. So it is best to desulphurize coal before using. Inorganic sulphur can be removed by subjecting ground coal to hydraulic washing. Organically bound sulphur can be removed by passing hydrogen gas over the fuel in the presence of a catalyst (mixed cobalt–molybdenum oxide). The organically bound sulphur is converted into hydrogen sulphide, which is absorbed in a solution of diethanolamine. Subsequently, hydrogen sulphide is oxidized to sulphur.

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H2S + [O] Æ H2O + S • Exhaust gases (particularly sulphur dioxide) can be removed by using scrubbers. In this process, exhaust gases are passed through slurry of calcium carbonate or magnesium hydroxide. • Oxides of nitrogen are obtained from fossil-fuel-based power plants and automobile exhausts. The formation of oxides of nitrogen can be prevented by passing steam over sulphur-free coal (obtained by desulphurization of coal). In this process, water gas is formed (coal + steam Æ CO + H2). The water gas is sprayed with water and burnt. The presence of water lowers the combustion temperature, and so nitrogen and oxygen do not combine to form oxides of nitrogen. The pollution caused by oxides of sulphur and nitrogen from exhaust gases of automobiles is removed by using catalytic convertors. Even carbon monoxide gets converted into carbon dioxide by catalytic convertors. • Particulate matter is generally discharged into the atmosphere from powerhouses operating on coal. Fine carbon particles are removed by instillation of industrial filters. It is said that prevention is better than cure. So alternative sources of energy should be used as far as possible. • Use of hydroelectric power in place of power generated from coal. • Use of nuclear power (which has its own problems, see Chapter 6). • Electric cars powered by batteries seem to be a completely pollution-free alternative. However, their use might shift the environmental concern from one source to another. The electricity required for charging batteries would have to be met by existing or new electric power generation units, which itself may be an environmental concern.

CHAPTER

3

Water Pollution INTRODUCTION Water pollution is the degradation of the quality of water making it harmful to human, animal, and aquatic life. Any physical, biological, or chemical change that degrades the quality of water results in water pollution. Polluted water is a threat to the survival of all life forms. Water is a universal solvent; almost all chemicals can be dissolved in it. Due to this property, water gets polluted easily. Water covers about 75% of the earth’s surface in the form of oceans, seas, rivers, and lakes. Oceans contain about 97% of all the water on earth. Of the remaining water, a sizeable amount is locked in the frozen form in the polar regions and glaciers. Only about 1% is available as freshwater (potable water). The distribution of water on earth is described in Table 1. Water found in rivers, lakes, streams, and wetlands is known as surface water. Water that percolates into the ground is called groundwater, which constitutes about 0.31% of the total water on earth. Porous saturated layers of sand and gravel through which groundwater flows are called aquifers. Most groundwater and aquifers are replenished naturally by rainfall.

TABLE 1 Distribution of water on earth Location/source

Percentage of total water

Oceans

97.2

Atmosphere

0.001

Rivers and streams

0.0001

Groundwater (up to a depth of 0.8 km)

0.31

Lakes (freshwater)

0.009

Ice caps and glaciers

2.15

Source US Geological Survey

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MAJOR WATER POLLUTANTS Most of the pollutants responsible for air pollution are washed from the atmosphere by rains. The substances that pollute land are also drained into water bodies during rainfall. The industries that pollute water bodies include polymer and plastic, tobacco, petroleum and mining industries, power plants, and agrochemical-based industries. Water pollutants are of three types: (1) biological (disease-causing organisms such as virus, bacteria, protozoan, and worm), (2) chemical (nitrates, phosphates, acids, salts, toxic heavy metals, oil, gasoline, pesticides, dyes, paints, plastic, detergents, organic wastes, domestic wastes, animal manure, and radioactive substances), and (3) physical (suspended solids, insoluble particles of silt, and heat).

Biological Agents Pathogenic organisms such as virus, bacteria, and protozoa are serious water pollutants. Some water-borne diseases include cholera, bacterial and amoebic dysentery, gastroenteritis, typhoid, polio, viral hepatitis, worm infections, and flu. Malaria, dengue, yellow fever, and filariasis are usually transmitted by insects that have aquatic larvae. In India, the onset of the rainy season is accompanied by water-borne epidemics. In populated areas, unplanned industrial and human settlements (slums) are some of the contributory factors. Water gets contaminated due to human wastes, domestic sewage, and wastewater discharges from tanneries and slaughterhouses.

Chemical Agents Chemical pollutants can be soluble or insoluble in water or oxygen demanding. They can be inorganic in nature such as nitrates, phosphates, acids, salts, and toxic heavy metals. Organic chemical pollutants include oil, gasoline, pesticides, dyes, paints, plastic, cleaning solvents, detergents, domestic sewage, and animal wastes. Radioactive substances are released into water bodies as a result of processing of uranium ore and wastes generated from nuclear research laboratories.

Physical Agents Physical agents such as suspended and sedimentary solids affect the quality of water. Some of the adverse effects of suspended solids

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include silting, clogging, filling of dams, and murkiness of water. Suspended organic and mineral solids can absorb metals and other toxins and pass them into the food chain. Thermal pollution occurs when hot water enters the water body. Major water pollutants, their sources and effects are given in Table 2

WATER POLLUTION IN VARIOUS WATER BODIES There are two types of sources responsible for water pollution—point source and non-point source. A point source discharges effluents through a channel such as a pipe, sewer, or tunnel. Examples of point source include factories, sewage treatment plants, power plants, and coal mines. Point sources can be easily identified, and so measures to

TABLE 2 Major water pollutants, their sources and effects Pollutant

Source

Biological agents— Human sewage, animal and bacteria, parasitic plant wastes, organic matter, fungi, and protozoa industrial wastes (paper mill, food-processing units), natural land, and urban run-offs

Effect Decomposition of oxygenconsuming bacteria depletes dissolved oxygen in water; fish die, plant life is destroyed; foul odour emanates; livestock are poisoned.

Chemical agents— acids, salts, metals, plant nutrients like phosphates and nitrates

Natural run-offs from land; industrial wastes; acid deposition; leaded gasoline, lead smelting, pesticides, agricultural run-offs; mining, domestic sewage; food-processing units; detergents

Toxic to various life forms and humans through the food chain; can cause genetic and birth defects; water becomes unfit for domestic, agricultural, and industrial uses; upsets ecosystems of water bodies, causes eutrophication.

Organic chemicals—agro chemicals, detergents, chlorine compounds, oil, grease, and plastic

Agriculture, forestry; pest control industries; home and industrial wastes; paper industry; bleaching process; machine and pipeline wastes; oil spills

Toxic to aquatic life forms as well as organisms depending on such water bodies; eutrophication of water bodies

Radioactive substances

Nuclear wastes from research laboratories and hospitals; processing of uranium, nuclear plants

Radionuclides enter the food chain and cause birth and genetic defects; causative agents for cancer

Physical agents

Run-off from agricultural activities, mining, forestry, construction activities, power plants, industrial cooling

Increase in temperature lowers the solubility of oxygen in water; reduces biotic life in water bodies.

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control discharge from these sources can be easily adopted. A nonpoint source is a scattered source and discharges pollutants over a large area. For example, run-offs from agricultural fields and acid rain. Water pollution can occur in freshwater as well in marine water.

Freshwater and Groundwater Pollution Freshwater (or surface water) in the form of rivers, streams, and lakes constitutes only 0.0091% of the total water on earth. All segments of the society are responsible for surface water pollution. Various processes and materials may also pollute freshwater bodies. Some sources of freshwater pollution are listed in Table 3. Siltation and sedimentation is a common problem of most water bodies. The natural deposition of silt in the form of sediments results from sharp fluctuations in the flow of water within a short span of time ranging from no flow to flash floods. Sewage and industrial effluents sometimes bring silt into rivers, lakes, and ponds. They then turn them into swampy, marshy stretches of foul-smelling land. Groundwater is considered a gift of nature. More than 98% of freshwater lies below the earth in the form of underground water. It is the main source of drinking water for about half of the world’s population. Groundwater gets polluted due to seepage of wastes from domestic households, industries, and agricultural land. Contamination of groundwater is generally irreversible. It leads to degradation of water quality such as objectionable taste, odour, and excessive hardness. Table 4 describes the sources of groundwater pollution along with the pollutants mixed in groundwater through seepage.

TABLE 3 Sources of freshwater pollution Source of contamination

Contamination discharged into freshwater

Agricultural run-offs

Agrochemicals (pesticides, herbicides, fungicides)

Accidental spill of chemicals

Different chemicals

Leakage from surface storage tanks or pipeline

Gasoline, oil

Run-offs from industrial sites such as factories, refineries, mines

Solvents, chemicals

Radioactive material processing units

Radioactive material

Air fall out in rivers, lakes

Particulates, metals, pesticides

WATER POLLUTION

TABLE 4

43

Sources of contamination of groundwater

Source of contamination

Contaminant discharged into groundwater

Domestic wastes

Pathogenic organisms, nutrients, and solids

Industrial wastes

Toxic heavy metals along with hazardous organic and inorganic effluents

Agricultural wastes

Fertilizers, pesticides, insecticides, herbicides. Leaches from agricultural land containing nitrates, phosphates, and potash pollute groundwater.

Note Groundwater can also be polluted by septic tanks and refuse dumps.

Contamination of groundwater occurs due to the seepage of industrial effluents, agricultural run-offs, refuse dumps, septic tanks, sewer, and fuel tanks. It should be noted that soil cannot filter out viruses, hazardous organic chemicals, and toxic heavy metals.

Marine Pollution Oceans are believed to be the ultimate sink of pollutants. Wastes are either directly dumped into them, or they reach there as run-offs through rivers, streams, and canals. Pollution of oceans and seas due to these reasons is called marine pollution. A sizeable amount of marine pollution occurs near the coastlines where large cities, harbours, and industrial centres are situated. The pollutants generated in coastal areas include sewage, municipal discharges, agricultural run-offs, industrial effluents, and waste heat from industries during cooling of products.

Sources and nature of marine pollutants Dredged material and mine tailings • More than 80% of all materials dumped in the sea are the result of dredging. About 10% of the dredged materials contain materials from a number of sources such as shipping, municipal and industrial discharges, and run-offs from land. Different types of contaminants are present in dredged materials. These include heavy metals, organic chlorine compounds, and oil and are bioaccumulated in marine organisms. • Mine tailings are of particular concern because it has been found that all waste materials from coastal mines get dumped into the sea during flooding. Some materials are chemically inert and their environmental effects are due to blanketing. One such material

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is waste generated from china clay mining. The mining of metal ores produces toxic wastes resulting from processes such as initial extraction. Concentrated toxic wastes are discharged into oceans either directly or indirectly by washings from the mines. The metals injected into the sea include aluminium, copper, iron, lead, mercury, molybdenum, tin, and zinc.

Sewage sludge and industrial wastes The sludge obtained by the treatment of sewage can be used on agricultural land as fertilizers. It should, however, be ascertained that the sewage is not contaminated with organic chemicals, oils, and metals. Usually municipal sewage sludge does not contain such contaminants in high concentration. However, excessive dumping in lakes is harmful and is responsible for depletion of oxygen and eutrophication. Health risks also arise if pathogens are present. In some developed countries, it has been decided to phase out the dumping of sewage sludge. So sewage disposal at sea is decreasing gradually. However, in underdeveloped countries, the sludge or municipal wastes is directly discharged into the sea.

Incineration at sea Incineration of certain types of organic materials in liquid form is considered least damaging. The products of incineration are mostly nitrites of oxygen and carbon dioxide. In the case of halogen-containing compounds, chlorine is also formed. Remote sites are selected for incineration at sea. Liquid organohalogen compounds can be incinerated at sea. It is estimated that about 100,000 tonnes of organics are incinerated per year in the North Sea. However, adequate precautions have to be taken for transporting the organics to the incineration site so as to avoid any possible accident leading to spillage. Dumping by ships and aircraft has been prohibited by all countries party to the Convention for the Protection of Marine pollution (1988). It was also agreed to phase out incineration at sea by 1994.

Disposal of plastic litter Most of the plastic are not biodegradable, and they persist for a long time. The discarded plastic are extremely harmful to the ocean

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environment. The discarded plastic from urban locations find their way into the oceans. The plastic wastes may come from fishing gear, nets, synthetic ropes, plastic bags, and bottles. The plastic nets, which are lost or discarded, continue to trap marine creatures and are, thus, harmful to marine life. It is best to use alternative materials that are not harmful to the environment. If possible, the discarded plastic can be recycled. As per the International Convention for the Prevention of Pollution from Ships (1973), dumping of plastic is prohibited.

Oil spills Crude petroleum oil is a complex mixture of paraffins (25%), cycloparaffins (20%), aromatics (5%), and a large number of toxic organic compounds. About 10 million tonnes of petroleum oil is discharged into oceans per year. Oil pollution is mainly due to spillage during transportation of crude oil for processing. The spilled oil is spread mainly by winds, currents, waves, and tides. It persists in the sea water, and its dispersal depends on its type, chemical composition, specific gravity, temperature, and the state in which it is discharged into the sea. The oil is subjected to natural processes such as evaporation, dissolution, emulsification, and oxidation. The volatile components of the discharged oil, such as low-boiling aromatics (benzene, phenanthrene), paraffins (n-hexane, 2,3-dimethyl hexane), and cycloparaffins (cyclohexane, 2,3-bicyclo octane) readily evaporate. Some of the highly soluble aromatics are removed by dissolution. The less resistant paraffins are degraded by bacteria. Heavy oils disintegrate as tar lumps and get washed into the beaches. Massive marine pollution in the seas results due to accidents of oil tankers and other means. A few such accidents are as follows: • A Liberian tanker Torrey Canyon was shipwrecked off the coast of UK in 1967, resulting in the discharge of more than 100,000 tonnes of oil into the sea. The oil spread along the 160-km coastline and killed a large number of fishes, birds, and aquatic fauna. • Another major oil spill occurred in January 1969 off the coast of Santa Barbra in the USA due to an off-shore blow-out resulting in the discharge of oil at the rate of 1000 gallons per hour. Around

ENVIRONMENTAL POLLUTION

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•

•

•

• • •

•

•

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HEALTH

10,000 tonnes of oil spread over water surface causing extensive destruction of the coastal marine fauna. An oil tanker MT Cosmos Pioneer shipwrecked near Porbandar in Gujarat, India, in 1973 due to rough weather resulting in the release of about 18,000 tonnes of light diesel oil. An American oil tanker Transhuron collided off the Kiltan Island in Lakshadweep Sea in 1974 discharging about 5000 tonnes of furnace oil on the beaches. An oil tanker Urquiola met with an accident in 1976 near the Spanish coast of La Coruna and discharged 100,000 tonnes of crude oil. The much publicized Amoco Cadiz disaster occurred in 1978 spilling 68 million gallons of oil along the French coast. The oil tanker Exxon Valdez crashed in Prince William Sound, Alaska, in 1989, discharging about 11 million gallons of oil. During the Iran–Iraq war, a massive discharge of oil happened in February 1990. The oil (330 million gallons) covered an area of about 80 × 20 km2 and moved towards Saudi shores and also shores of Bahrain, Qatar, Kuwait, and United Arab Emirates. The oil spill disrupted the fragile ecosystem of the region and resulted in the death of about 2 million birds. A massive oil spill occurred in May 1993 in Mumbai when a feeder pipeline in Bombay High ruptured, spilling about 3000– 6000 tonnes of oil across a 10 mile × 2 mile area. World’s worst marine pollution occurred in 2010 off the US coast when the millions of litres of oil were discharged during a drilling operation by IBP Company. The company had to pay millions of dollars to the US Government as compensation for damages.

Effects of oil pollution Oil pollution has an adverse effect on the physical state of sea water and on the marine ecosystem, birds, and human beings. The layer of oil retards the uptake of oxygen by water, thus reducing dissolved oxygen. The oil slick also considerably reduces the penetration of light, which interferes with the photosynthesis of aquatic life. In addition, the layer of oil also kills lichens and algae along the coastline.

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47

Oil pollution affects the floating plantation and causes damage to fisheries. Large heaps of dead fish washed up along the shore of Goa. Subsequently, it was found that dangerous effluents discharged from the Zuari Agro Chemicals Ltd were responsible for the death. Aromatic hydrocarbons in oil get accumulated in aquatic plant tissue in low concentration. Being carcinogenic, these hydrocarbons adversely affect plant metabolism. Naphthalene and phenanthrene are very toxic to marine biota. Benzopyrene is known to accumulate in food chain in fish, which is responsible for causing cancer in human beings and animals. Oil spills close to sea shore are responsible for the massive destruction of marine life such as fish, worms, crabs, and lobsters. After reaching the bottom of the sea, the emulsified oil damages aquatic animals and plants. Birds are most vulnerable to damage from oil coating. The spilled oil breaks down the natural insulating oils and waxes on feathers of birds that protect them from water. As a result, the birds lose insulation, start shivering, and die in winter. About 25,000 birds died during the Torrey Canyon incident. Due to oil spilling, the temperature of birds dips abnormally, resulting in hypothermia. After the Exxon Valdez accident, about 150 rare species of eagles were killed. Oil pollution in marine water is harmful to human beings in the following ways: • Being asphyxiants, paraffins such as methane and ethane cause suffocation. Some paraffins depress the central nervous system. Liquid paraffins are responsible for causing dermatitis and pneumonia in lung tissue. • Breathing unsaturated cycloparaffins in high concentration results in irritation and anaesthesia. • Aromatic heterocycles such as aromatic thiophene, benzothiophenes, and mercaptans damage liver and kidneys. • Crude petroleum oil contains compounds of sulphur, nitrogen, olefins, and metals such as iron, nickel, and vanadium. Carbonyl sulphide is extremely poisonous and is toxic to rats at 2900 ppm. In fact, it dissociates into hydrogen sulphide, which acts on the central

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nervous system, and in turn results in death due to respiratory paralysis. Effects of oil pollution on marine biota The ocean has a stable environment having relatively constant pH, temperature, and chemical composition. The oxygen dissolved in water and derived from photosynthesis by aquatic organisms is sufficient to support biomass. The effects of oil pollution on various organism are discussed as follows: • Phytoplankton: Oil spills adversely affect phytoplankton. A number of sensitive phytoplankton species suffer retarded cell division or even death at very low concentrations of oil (0.1–0.00001 ml/l). The species of Coscinodiscus, Skeletonema, Chlorella, and Chlamydomonas showed considerable sensitivity to oil pollution in marine environment. • Zooplankton: Species such as Acartia clausi and Oithona sora are adversely affected by oil pollution. The young species die after 3–4 days due to exposure at a low concentration of 10 µg/l. Adults die at a concentration of 10 µg/l after exposure for a long time; however, they die after 5–60 min at a concentration of 1000 µg/l. • Marine grasses: It has been found that Spartina sp., Suaeda maritima, and Salicornia spp. are sensitive to oil pollution. However, Oenanthe lachenalii is a tolerant perennial marsh plant. It has also been found that some marsh grasses are stimulated by oil pollution. • Macroscopic algae: The growth and survivability of some seaweeds such as Macrocystis, Fucus, Ascophyllum, and Sargassum are affected by oil spills. It was found after various oil spills the sporelings of Polysiphonia sp. did not survive. The photosynthetic activities of some green algae such as Enteromorpha (sea lettuce) are considerably affected by oil pollution. Certain algal forms, especially the blue–green algae, are found to be resistant to oil pollution. • Benthic and inter-tidal organisms: These organisms spend most of their lives at the bottom of the sea and include a number of species such as molluscs, crustaceans, echinoderms, polychaetes, and coelenterates. Some of these species, particularly lobsters,

WATER POLLUTION

49

oysters, and scallops, are also amenable to mariculture. All these creatures are susceptible to oil pollution. Molluscs suffer heavy mortalities in larger spills in coastal areas. However, certain creatures such as Black Sea mussels and oysters can withstand oil pollution. The larvae of some marine bivalve molluscs are severely affected by oil pollution. However, common blue mussel (Mytilus edulis) is tolerant to oil pollution. Mobile creatures such as crustaceans and lobsters suffer heavy mortalities due to oil pollution. It was found that some varieties of benthic invertebrates were killed by the diesel oil spill in the Puget Sound in 1971. The mortalities of about 50 species of inter-tidal invertebrates ranged from 30% to 100%. Most of the creatures adversely affected belong to brittle stars, hermit crabs, and limpets. • Fish: Fish are adversely affected by spilled petroleum resulting in their death. Maximum harm is caused to eggs and larval stages. The death of young fish has serious long-term consequence. • Coral reefs: It has been found that the branched corals are sensitive to oil. The effect is more when exposed to air. Many reefs in the Pacific Ocean and the Indian Ocean protrude above the water surface at low tide.

STATUS OF COASTAL AND ESTUARINE POLLUTION IN INDIA India, with a coastline of 6000 km, has more than 40 heavily polluted areas. All the coastal towns have been facing serious problems due to marine pollution. The marine environment is degraded by pollutants generated from human settlements, industries, and oil fills. These pollutants have posed serious problems for Porbandar, Mumbai, Thiruvananthapuram, Tuticorin, Chennai, Kakinada, Kolkata, and Visakhapatnam. Pollutants also get accumulated in marine sediments; for example, in Kochi Backwaters and in Ennore Estuary. The enormous pollution from the ever-expanding population is affecting marine organisms. Some of the important coastal areas in India affected by pollution are as follows: • Gujarat: A number of seaweed species have been wiped out due to the caustic soda industry. There are high levels of nitrites.

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• Tamil Nadu: Low levels of dissolved oxygen in Chennai and high bacteria and mercury levels in Tuticorin. • Odisha: Low levels of dissolved oxygen and much higher levels of lead and mercury in sediments of Gopalpur. • Maharashtra: Low levels of dissolved oxygen (almost zero in 1991) of Thane and Mahim creeks; contamination of cadmium and mercury of Mumbai. • West Bengal: Low levels of dissolved oxygen and high levels of bacteria in the Ganga delta and of Kolkata. • Andhra Pradesh: Considerable sewage pollution of Kakinada and Visakhapatnam. • Karnataka: Reduction in dissolved oxygen level of Bengaluru attributed to domestic sewage. • Kerala: Petroleum hydrocarbons from fishing vessels of Kannur; timber and industrial wastes from rayon factories, mercury, and copper of Kozhikode; copper of Kochi and Kollam; and effluents of titanium factory of Thiruvananthapuram. Sea sediments of Vizhinjam and Kozhikode are mostly contaminated by sewage.

WATER POLLUTION AND HEALTH Globally, more than 1 billion people do not have access to safe drinking water, and double the number of people do not have safe sanitation facilities. On an average, about 3 million people die every year due to water-related diseases, most of which are avoidable. In India, major health problems are due to water-related diseases since a majority of the population does not have access to safe drinking water. Even groundwater is polluted in a number of districts due to contaminants such as arsenic and fluorine, which seep into underground water. Water is generally contaminated by sewage containing organic matter and pathogenic agents. Industrial and agricultural wastes contain a mixture of toxic chemicals and heavy metals, most of which are non-biodegradable and are responsible for long-term health hazards. The effects of various types of water pollutants on health are discussed in the subsequent sections.

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Toxic Chemicals and Health A number of toxic chemicals such as polyphenols, phenols, fertilizers, pesticides, dyes, solvents, and detergents that get into natural water reservoirs or into public water supply have hazardous effects on health. Besides water, one may come in contact with toxic chemicals by other means. For example, chemicals may get accidentally mixed with food. Such a case was reported in Japan in 1968 when cooking oil was accidentally contaminated with polychlorinated biphenyls. This resulted in thousands of people suffering from enlarged liver and disorders of the intestines and lymphatic system. Table 5 lists some common toxic chemicals, their sources and effect on health.

TABLE 5 Toxic chemicals, their sources, and effect on health Toxin

Source of exposure

Effect on health

Polychlorinated biphenyls

• Used for manufacturing transformers and other electric appliances • Used in the production of plastic containers, epoxy resins, various types of walls and upholstery covering • Ingredients in soap, cream, paint, glue, paper, waxes, and many other products

• • • • •

Vinyl chloride

• Used in plastic as polyvinyl chloride

• Birth anomalies • Damage to liver, bone, and circulatory system • Cancer of liver, brain, and lymphatic system

Benzene

• Used in art and craft supplies, detergents, mouldings, fibres • Used as insecticide and gas additives

• Anaemia • Bone marrow damage, leukaemia

Phthalates

• Used as plasticizers (added to plastic resins)

• Damage to central nervous system

DDT

• Pesticide

• Causes tremors, convulsions • Damage to kidneys • Suspected carcinogen

Fatigue, vomiting Temporary blindness Skin blemishes Abdominal pain Disorders of the intestines • Stillbirths • Suspected carcinogen

Contd...

ENVIRONMENTAL POLLUTION

52 TABLE 5

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HEALTH

Contd...

Toxin

Source of exposure

Effect on health

Aldrin/dieldrin

• Pesticide

• Causes tremors, convulsions • Damage to kidneys • Suspected carcinogen

Dioxin

• By-product of industrial processes • Causes persistent and severe form of acne and • Contaminant in herbicide other adverse health • Released mostly from burning effects. of chlorinated compounds, for • Powerful carcinogen example, from garbage, medical wastes and toxic chemicals. • Contaminants of some herbicides such as Agent Orange.

Chlorinated organic compounds

• Produced by the chlorination of wastewater to use as drinking water.

Nitrates and nitrites

• Nitrites combine with • Nitrates originate from septic haemoglobin and reduces tanks, farn yards, heavily its oxygen-carrying fertilized crops, and sewage capacity. treatment plants • Nitrates are used for curing meat, • Nitrite causes the fatal disease salami, and also in smoked fish. methaemoglobinaemia • Nitrates get converted to nitrites in infants younger than in the intestines of humans, three months. particularly infants. • Long-term exposure causes diuresis, increases starchy deposits, and haemorrhaging of the spleen.

Nitrosamine

• Produced by the chemical reaction of nitrates with other amines present in food.

• Carcinogenic

Mercury

• Industrial wastes

• Affects brain

Cadmium

• Industrial wastes

• Osteomalacia

• Carcinogens

Effects of pesticides Most pesticides, including dichlorodiphenyltrichloroethane (DDT), are insoluble in water but soluble in fats. Therefore, they accumulate in organisms for a long period of time, by a process called bioaccumulation. Moreover, their concentration increases as they pass from one organism to another in the food chain. This increase in concentration along the food chain at the higher levels is called

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biomagnification. Thus, human beings, who are at the highest level of the food chain, end up imbibing huge concentration of pesticides posing severe health hazards.

Effects of nitrate: methaemoglobinaemia Intake of nitrate in excessive amounts through drinking water, food, drugs, or other sources leads to reduction in the oxygen-carrying capacity of blood and damages the alveolar tissues of lungs. Although nitrate by itself is relatively non-toxic, it gets converted by bacteria into nitrite during metabolism in the digestive canal under high pH conditions (alkaline conditions of the intestine). The nitrite, once it reaches the blood, oxidizes iron in the haemoglobin of red blood cells to form methaemoglobin, which lacks oxygen-carrying capacity. During nitrate metabolism, free radicals of nitric oxide and oxygen are also formed. This leads to alveolar damage in lungs. The intake of nitrate is severe for infants under six months, since their digestive track has a high pH because of low secretion of gastric juices. The nitrate gets converted into nitrite, leading to shortage of oxygen in the infant’s system. This condition is called methaemoglobinaemia, also known as the blue baby syndrome.

Effects of mercury: Minamata disease In the 1950s, more than 50 people were killed and a number of people were affected in Minamata, a village along the sea coast of Japan. The reason attributed to this casualty was the consumption of fish contaminated with mercury. Investigations revealed that the water of the Minamata Bay had been polluted for more than 30 years (1932–68) by the dumping of an estimated 27 tonnes of mercury compound. Chisso Corporation, a chemical company located at Kumamoto, Japan, was responsible for this act. It was found that Chisso used mercuric chloride as a catalyst for the production of acetaldehyde and that only non-toxic mercury was released as effluents. However, the sediments of the Minamata Bay were found to be rich in methylmercury(II) chloride. Microorganisms in the sediments of the lake helped in the biomethylation of mercury to form methylmercury(II) chloride. Being lipid soluble, it found its way into the tissues of fish. Consumption of this contaminated fish caused birth defects and affected neural tissues, mainly in the brain.

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Effects of cadmium poisoning: itai-itai disease Around 1912, an unusual disease was reported in Toyama Prefecture in Japan. The disease termed itai-itai resulted from the pollution of the Jinzu river basin due to cadmium. The victims, mostly women, suffered acute pain in their entire body; more critical victims reported broken bones when they tried to move. They cried out “itai-itai” (Japanese for ouch ouch) due to pain and so the disease was termed itai-itai. It was found after investigation that this disease was caused by cadmium poisoning. About 200 people were officially declared to have the disease till 1969.

Effects of fertilizers: eutrophication Organic wastes and inorganic nutrients enrich water bodies resulting in eutrophication. Organic wastes such as sewage, effluents from milk plants, tanneries, slaughterhouses, paper mills, and fish-processing plants, and run-offs from agricultural lands, and inorganic wastes such as nitrate and phosphate reach water bodies and cause an increase in its nutrient concentration. Aerobic bacteria release nutrients from organic wastes in the presence of oxygen. These nutrients act like fertilizers and cause an increase in the population of microscopic plants such as algae. Such an abundant growth of algae is called algal bloom. The more the plants grow in number, the more they die, adding to the wastes in the water body. More waste means more population of decomposers, which release nutrients, and the cycle is repeated. Bacterial activity and respiration by algae and larger green plants consume a lot of dissolved oxygen. This leads to a decrease in the oxygen available to fish, finally causing their death. Ultimately, eutrophication causes the water body to disappear. Such a phenomenon does not occur in flowing water.

Effects of Microorganisms on Health A number of microorganisms such as bacteria, viruses, protozoa, insects, and helminths present in polluted water can cause infectious diseases. Water polluted with sewage gives foul smell, creates unhygienic conditions, and adversely affects health. Diseases caused by microorganisms include cholera, dysentery, typhoid, jaundice, guinea worm disease, Japanese encephalitis, malaria, filariasis, and

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TABLE 6 Diseases caused by microorganisms in drinking water Organism

Disease

Remark

Ascaris sp.

Nematode worms

Dangerous to humans from polluted water and when dried sludge is used as a fertilizer.

Bacillus anthracis

Anthrax

Found in wastewater; spores are resistant to treatment

Brucella sp.

Brucellosis; Malta fever in humans; contagious abortion in sheep, goat, and cattle

Transmitted through infected milk by contact and wastewater.

Entamoeba histolytica

Amoebic dysentery

Spread by contaminated water

Leptospira sp.

Leptospirosis (Weil’s disease)

Caused by sewer rats

Mycobacterium tuberculosis

Tuberculosis

Isolated from wastewater

Salmonella paratyphi

Paratyphoid fever

Common in wastewater

Salmonella typhi

Typhoid fever

Common in wastewater

Salmonella sp.

Food poisoning

Common in wastewater

Shigella spp.

Bacillary dysentery

Polluted water

Vibrio cholerae

Cholera

Polluted water

Virus

Poliomyelitis, hepatitis

Wastewater treatment plants

Escherichia coli

Diarrhoea

Polluted water

knock knees. Disposal of human excreta in water is the main cause of contamination of rivers, wells, and lakes. This contamination results in the spread of diseases. According to the World Health Organization (WHO), more than 5000 people die everyday worldwide from infectious diseases. Table 6 lists the diseases caused by microorganisms commonly found in polluted water.

Harmful Effects of Water Pollution Polluted water is a major cause of epidemics and chronic diseases such as typhoid, jaundice, dysentery, diarrhoea, tuberculosis, and hepatitis. The use of polluted water for irrigation damages crops and decreases the yield of agricultural products. Polluted water affects the fertility of soil by killing bacteria and microorganisms. It has already been discussed that contamination of mercury, cadmium, and nitrate in drinking water causes Minamata disease, itai-itai disease, and methaemoglobinaemia, respectively.

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Besides mercury, cadmium, and nitrate, other chemicals that might pose a threat to human health include fluoride, arsenic, lead, chromium, and cobalt. • Fluoride: It is known that fluoride present in water in small amounts (0.8 ppm) protects gums and teeth. However, an excess concentration of fluoride causes fluorosis (Table 7). High fluoride intake results in a humped back. Continuous consumption causes weakening of bone joints, particularly the spinal cord. It may also cause bending of legs from the knee called knock-knee syndrome. Fluorosis is classified as skeletal fluorosis, non-skeletal fluorosis, and dental fluorosis. High fluoride concentration in groundwater is a natural phenomenon in several countries such as China, Sri Lanka, West Indies, Spain, Holland, Italy, Mexico, and India. It is believed that a fluoride belt stretches across the Middle East, through Pakistan and India, and then to South East Asia and south of China. The bedrock of the Indian peninsula consists of a number of fluoride-bearing minerals. In India, the problem is severe in Odisha, Rajasthan, and Karnataka where people depend on groundwater. The prevalence of fluoride has caused joint pain, irregular growth of limbs and spinal cord, and formation of lumps on the body, resulting in the inability to even stand up. When the bedrock containing fluoride weathers, the fluoride leaches into groundwater. Fluoride enters the human body by drinking underground water. It combines with bones since it has an affinity for calcium phosphate present there. Excess intake causes

TABLE 7 Concentration of fluoride and its impact on human health Concentration (ppm) 0.8 1

Effect Protects gums and teeth Mild dental fluorosis in children

1.0–1.9

Mottled teeth in children

1.9–2.0

Tooth disorder

2.0–3.0

Tooth decay

3–12.0

Bone disorders

15–100 Above 100

Skeletal disorder, dangerous to life Poisonous, fatal to life

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dental, skeletal, or non-skeletal fluorosis, depending on the amount of fluoride imbibed. Dental fluorosis results in discoloration of teeth. In skeletal fluorosis, bone joints become deformed. Nonskeletal fluorosis is responsible for gastrointestinal problems and neurological disorders. Fluoride can also damage the foetus and effect the normal development of the child. Various technologies are available for defluorination, yet none of the technologies used in India are foolproof. The available household water treatment kits are also not foolproof. • Arsenic: Arsenic finds its way into water by dissolution of minerals and ores and from industrial effluents. The arsenic concentration in groundwater in some areas is elevated as a result of erosion from natural sources. The average daily intake of inorganic arsenic through water is estimated to be similar to that through food. It has been established that the maximum level of arsenic in drinking water should not exceed 0.01 mg/l. The world’s worst arsenic-affected areas are located in the India– Bangladesh border. More than 3 million people are affected in India and Bangladesh. Arsenic poisoning is detected late because distinctive symptoms appear only at the final stage of infection. The WHO has asked Indian Government and Bangladesh Government to put arsenic poisoning under immediate national surveillance, giving it a status similar to that of cancer. In animals, arsenic affects liver, kidneys, and lungs leading to toxicity of the biological system. In human beings, arsenic gets absorbed through lungs and skin. At higher concentrations, As(III) compounds coagulate protein, possibly by attacking the S-bond that retains the secondary and tertiary structures of proteins. Thus, the main reaction in the biological system involves the formation of complexes of arsenic compounds with coenzymes, coagulation of biological protein, and uncoupling of phosphorylated sites. Table 8 shows the effects of different levels of arsenic dosage on the biological system. Arsenic in water is carcinogenic in nature. A number of cases of arsenic contamination of groundwater have been reported from all over the world. In 1988, it was found that people in West

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TABLE 8 Effects of arsenic dosage on the biological system Dosage

Effect

Mild dose

Nausea, fainting, salivation, vomiting, burning sensation in stomach

Higher dose

Diarrhoea, peripheral neuritis, hyperketosis, conjunctivitis

Chronic dose

Severe gastroenteritis, loss of weight, skin lesions, loss of hair, black foot disease

Lethal dose

Death due to shock and vascular failure

Bengal who drank arsenic-contaminated groundwater suffered serious health problems such as keratosis, dermatitis, conjunctivitis, bronchitis, melanosis, and malignant neoplasm. After investigation, it was found that about 320 villages in six districts of West Bengal (800,000 people) were drinking arsenic-contaminated water and that more than 150,000 people had symptoms of late-stage arsenic poisoning. It was found that the arsenic concentration in water from tube wells was 30 times higher than the permissible level of 0.05 mg/l stipulated by the WHO. In West Bengal, arsenic occurs naturally as insoluble salt in the bedrock in an area of about 88,000 km2. It is believed that this natural source is the reason for arsenic contamination in West Bengal. The state government and the Central Government must immediately take appropriate steps to protect the public health and environment. This is especially important since 80% of irrigation in the affected areas is done using groundwater. • Lead: Some of the important sources of lead include mining, smelting, extraction of metals, and automobiles. A serious outbreak of lead poisoning occurred in the Western world a number of years ago. When present in concentrations above 40 mg/100 ml of blood, it is considered normal. A level beyond 100 mg/100 ml of blood is considered excessive and is unacceptable. Lead is a toxicant that accumulates in the skeleton. It has been observed that lead deposited in bones works like a cumulative poison. Young children absorb four to five times more lead than adults. In fact, children up to six years of age and pregnant women are most susceptible to its adverse health effects. Lead also interferes with calcium metabolism by interfering with vitamin D metabolism. Lead is toxic to both the central and the peripheral nervous systems, bringing about subencephalopathic neurological and behavioural effects.

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Most of the lead in drinking water arises from plumbing in buildings. The remedy for this problem consists in principally removing plumbing and fittings containing lead and replacing them with plastic pipes. • Chromium: Chromium salts are used in a number of industrial operations. For example, as a tanning agent in tanneries. It is also used as a corrosion inhibitor. Chromium in its hexavalent form is highly toxic to aquatic organisms and human beings. A number of diseases such as hypertension, heart attack, and lung and skin cancers are attributed to chromium. • Cobalt: Cobalt causes nausea, vomiting, and various physiological abnormalities. Its toxic effects include loss of weight and appetite, dysentery, diarrhoea, conjunctivitis, and discoloration of the skin. In higher concentrations, there is an increase in coproporphyrin in the urine, pathological changes in the retina, colloid, and optic nerves, and damage of retinal and ganglion cells. Table 9 summarizes some toxic elements in water, their sources, and effects.

CONTROL OF WATER POLLUTION As water is generally polluted by wastes generated by various industries, this can be checked and controlled by the following measures: • All wastewater from industries must be treated at the point of origin before being discharged into water bodies. • Water used in any industrial operation should be suitably treated and reused.

TABLE 9 Some toxic elements in water Element

Source

Effect

Fluorine (fluoride ion)

Natural geological sources, industrial wastes, water additive

Prevents tooth decay at about 1 mg/l concentrations; causes mottled teeth and bone damage at about 5 mg/l

Arsenic

By-product of mining, pesticides, chemical wastes

Toxic, possibly carcinogenic

Lead

Industry, mining, plumbing, coal, gasoline

Toxic (anaemia, kidney disease, nervous disorder), destruction of wildlife

Chromium

Found as Cr(VI) in polluted water

Essential trace elements; possibly carcinogenic as Cr(VI)

Cobalt

Mining and industrial effluents

Physiological abnormalities

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RIVER WATER POLLUTION IN INDIA Rivers are the main source of usable water in India. However, good quality water is not easily available. The rivers are getting heavily polluted due to discharge of municipal wastes and industrial discharge. The problem has been compounded due to increasing population, industrialization, urbanization, and a host of human activities. As a result, water resources of industrialized cities in India (such as Mumbai, Pune, Kanpur, Chennai, Durgapur, Kolkata, and Delhi) are highly polluted. According to survey reports of various environmental agencies, most rivers in India are severely polluted. Most of the major rivers such as Ganga, Yamuna, Gomti (near Lucknow), Damodar (between Bokaro and Panchet, Bihar), Hooghly (Kolkata), Sone (Dalmianagar, Bihar), Godavari (Andhra Pradesh), Cauvery (Tamil Nadu), Periyar (Kerala), and Mahanadi and Katjari (Odisha) are giant reservoirs for India’s urban population. River Gomti has been polluted by paper mills located near the banks and also by sewage. In Kanpur a number of textile mills, tanneries, jute mills, and other chemical and pharmaceutical units are located on its river bank, which have been the cause of pollution. River Damodar has been polluted by fertilizers, fly ash from steel mills, and suspended coal particles from thermal power stations and washeries. The river is being continuously polluted by the discharge of effluents from iron and steel mills and paper mills located in West Bengal’s Asansol–Raniganj and Durgapur regions. Industries located at a distance from River Damodar discharge their untreated wastes through storm water drains. The Durgapur Steel Plant also discharges its wastes via storm water drains. Thus, it is clear that River Damodar, which is the source of water supply for the entire Asansol–Durgapur region for domestic and industrial needs, has become a sink for municipal and industrial wastes, rendering the water highly polluted. The water treatment plants located in Asansol and Durgapur find it impossible to treat such a high load of pollution. The liquid chlorine used for the treatment of water reacts with ammonia and phenols, and forms very toxic chloramines and chlorophenols, which impart bad odour and taste to water.

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River Hooghly in Kolkata is polluted with huge quantities of sewage. Power stations, paper and pulp mills, jute, textile, and chemical units, steel, varnishes, rayon, and soap factories located on its banks discharge untreated wastes into the river. The area surrounding River Hooghly is polluted due to more than 150 industries on both sides of the river. The quality of water in Hooghly is highly degraded. River Sone in Dalmianagar, Bihar, is polluted due to the location of cement, paper and pulp mills. Even River Godavari in Andhra Pradesh is polluted due to discharges from paper mills. River Cauvery in Tamil Nadu has been polluted by the discharges of tanneries, distilleries, paper, pulp and rayon mills, and also due to the discharge of sewage. It is also heavily polluted with chlorides of zinc and manganese. River Periyar in Kerala receives effluents from more than 15 chemical industries. The water of River Mahanadi and River Katjari in Odisha is unfit for human consumption. People consuming such polluted water suffer from waterborne diseases. River Yamuna in Delhi has been described as an open sewer. The water of this river is unfit even for irrigation. The river is highly polluted in the Okhla Industrial Area covering a stretch of about 50 km. Industrial effluents from more than 16 industries, including Mother Dairy, Delhi Milk Scheme, Hindustan Insecticides, and more than 500 units, are discharged in Yamuna. Electroplating works release highly poisonous cyanide into the river. Municipal sewage to the extent of 320 million gallons enters the river daily. A large number of open drains pollute the river. The pollutants in Yamuna include untreated toxic wastes consisting of more than 500 tonnes of dissolved solids, 150 tonnes of organic materials, and 120 tonnes of suspended solids on a daily basis. It is estimated that about 515,000 kl of sewage wastes is discharged in River Yamuna daily. The three water treatment plants located at Wazirabad, Chanderwal, and Hyderpur are inadequate for the supply of drinking water needs of Delhi. The government has spent millions of rupees to prevent the pollution of Yamuna but with no result so far. A large number of people have suffered from infective hepatitis, and a number of deaths have been reported. Studies have found that the coliform count of water, when it enters Delhi at Wazirabad, is about 7500/100 ml, and when it leaves Okhla, the count is about

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24 million/100 ml. This shows the extent of pollution of Yamuna water in Delhi. Any person drinking such water will be prone to waterborne diseases such as jaundice, diarrhoea, and dysentery. Although such diseases have been controlled in developed countries, these diseases assume epidemic proportions in India. As many as 40–50 thousand people in Delhi become victims of these diseases every year, especially infective hepatitis. The Government of India had initiated a ` 10,000 million National River Action Plan in order to check the pollution of about 20 major rivers, including their cleaning. However, the results are not visible.

Attempts to control River Yamuna pollution A number of steps have been taken by the Delhi Water Supply and Sewage Disposal Undertaking to prevent and control the pollution of River Yamuna. These steps include the following: • Augmentation and construction of sewage treatment plants for processing domestic wastes • Repairs and maintenance of sewer line and construction of new lines • Prevention of wastes from major drains leading into Yamuna to reduce pollution load • Controlling pollution from industries and preventing effluent discharge into the river In spite of all these measures, Yamuna is still critically polluted. The Government of Delhi, on the basis of a large number of reports on checking the pollution of River Yamuna, has decided to divert the flow of drains and nullahs carrying sewage. The wastewater will be treated by various plants to be set up and then discharged into the river. A number of urban centres along River Yamuna, which cause maximum pollution, have been identified. Attempts will be made to recycle and use the waste material for other purposes to generate revenue. The waste material will be used to generate biogas. Under the Indo–Dutch Bilateral Programme, automatic water quality monitoring stations have been installed on Yamuna at Okhla and Wazirabad. These would warn against sudden change in water quality due to discharge of effluents upstream.

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Ganga Action Plan Ganga is a sacred river in India and one of the 10 mighty rivers of the world. It covers a distance of 2525 km and passes through Uttar Pradesh, Bihar, and West Bengal, supporting more than 50 million people. Once Ganga water was known as the purest water and was used in all religious functions. However, it is now polluted at a large number of places by domestic and industrial wastes. During the past two–three decades, a large number of industrial units have been established along its route from the Himalayas to the Bay of Bengal and discharging their poisonous wastes into River Ganga. There are more than 35 big cities situated along the bank of River Ganga. Practically all the garbage and other waste materials are injected into the river. More than 80 big industries are located near River Ganga, which release unlimited amount of industrial wastes into the river. In fact, Ganga has become a dumping ground for them. Varanasi is a holy Indian town where millions of people take bath every year. Large amounts of biological and chemical filth from millions of people find way into the river. Besides about 100 million litres of untreated sewage is dumped in the river everyday. The ashes of more than 40,000 human bodies and about 15,000 incompletely burnt bodies of people and animals are dumped annually into the river at Varanasi. River Ganga at Kanpur (UP) is polluted by industrial effluents from jute, chemical, metal, and surgical industries; tanneries; and textile mills besides domestic sewage. A survey conducted at Garhmukteshwar (Meerut) found that, the Ganga water is heavily contaminated with salts such as nitrates and fluorides, which are found to be present in amounts more than the prescribed standards. The sewage from the city and nearby places is discharged into the river. Agricultural fields are responsible for discharging pesticides into the river water. River Ganga, which was a source of drinking water, has become poisonous. According to the Central Board for the Prevention and Control of Water Pollution (CBPCWP), the biochemical oxygen demand (BOD) reached more than 9.7 mg/l against the prescribed limit of 3.0 mg/l.

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River Ganga water has been severely polluted by industrial discharges from a large number of mining, iron and steel, chemical, pharmaceutical, soap and detergent, food processing, and pulp and paper industries located in the vicinity of the river at various places. A summary of various inorganic and organic pollutants discharged from various industries is given in Table 10. The consequences of pollution of Ganga attracted the attention of the Government of India. A project known as the Ganga Action Plan was prepared and adopted in 1985 under the chairmanship of then Prime Minister, Rajiv Gandhi, involving a cost of nearly ` 2920 million. The Government of India established the Ganga Project Directorate in 1985 under the Ministry of Environment and Forests to coordinate activities of the action plan. Another government agency, the Central Ganga Authority (CGA), was established in 1985 to guide and oversee the implementation of the action plan for improving the quality of water and reverting to its original state.

TABLE 10 Inorganic and organic pollutants Industry

Organic pollutant

Inorganic pollutant

Iron and steel

Oil, phenols, naphtha

Suspended solids; iron; sulphides; oxides of copper, cadmium, and mercury; cyanide and thiocyanide

Mining

Paper and pulp

Chlorides, various metals, ferrous sulphate, sulphuric acid, hydrogen sulphide, heavy metals, suspended solids, surface wash-offs. Cellulose fibres, wood, bark, sugars, organic acids

Sulphides, sulphites, bleaching liquids

Soaps and detergents Fats, fatty acids, glycerol, polyphosphates, sulphonated hydrocarbons

Tertiary ammonium compounds, alkalis

Chemicals

Aromatic solvents, nitro compounds, dyes, organic acids

Alkalis, acids, sulphates, nitrates of metals, silicon, fluorine, and suspended particles

Food processing

Putrescible organic matter, pathogens

Pharmaceuticals

Proteins, carbohydrates, drugs, antibiotics, by-products, organic solvents

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The Ganga Action Plan covers about 27 cities (6 in Uttar Pradesh, 4 in Bihar, and 17 in West Bengal). The main aim of the Ganga Action Plan is to improve the quality of river water by reducing the load of pollution and by establishing sewage treatment plants. In the first phase of Ganga Action Plan, it was proposed to cover the following tasks: • Prevention of the outflow of sewage into River Ganga; for this, renovation of all existing sewers to be done. • Diversion of the flow of sewage and other liquid wastes away from the river; for this, interceptors, drains, and sewers to be constructed. • Installation of new sewage treatment plants and renovation of the existing plants; the objective is to recover resources such as methane gas, which could be used for generation of power. The treated water could be used for irrigation and agriculture. • Construction of low-cost sanitation in areas adjoining the river. • Development of river front and afforestation on the banks of the river. • Prevention and control of industrial pollution. • Regular monitoring of the quality of water at different places. • Construction of electric crematoria. New technologies have been introduced in collaboration with the Dutch Government for the treatment of sewage. The Upflow Anaerobic Sludge Blanket Technology has been developed in collaboration with the Dutch Government. This technology is used in Kanpur, Mirzapur, and Chapra. Another technology for the treatment of sewage has been developed by the National Environmental Engineering Research Institute (NEERI), Nagpur. Most of the industrial units in the Ganga Basin have been told to set their house in order or face prosecution and closure. It is believed that about one-third of River Ganga pollution is due to industrial effluents. Commitment by the newly elected Modi government at the centre is to clean all rivers of pollution (inculding checking for pollutions). The results are yet to be seen.

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LAKE WATER POLLUTION A number of lakes in India are coastal lakes and cover about 2.5 million hectare of water area. Lakes are considered valuable water resource. Most of the lakes are severely polluted due to industrial discharges and urbanization. The known sources of pollution of lake water are as follows: • Discharge of toxic effluents and organic wastes from hills and urban areas; this has resulted in enhanced mortality of fish. • The discharge of waste sludges from industries as well as washing and dumping of tailings. • Plants meant for sewage treatment also discharge toxic organic matters in lake. • Dumping of large quantities of sediments in lakes result in siltation of lakes. • Run-offs from agricultural lands into lakes discharge excessive amounts of nitrates and phosphates leading to eutrophication, thereby disturbing the aquatic environment. Some well-known lakes in India include Dal and Nagin Lakes (Kashmir), Loktak Lake (Manipur), Hussain Sagar (Hyderabad, Andhra Pradesh), Bhopal Lake (Madhya Pradesh), Chilika Lake (Odisha), and Kolleru Lake (Andhra Pradesh). All these lakes are polluted. A typical example is the pollution of the Hussain Sagar Lake in Hyderabad. This lake has been polluted to such an extent that the gases emitted from the surface cause irritation of skin and eyes. The water of the lake has become oily, highly coloured, and stinking. A number of industries such as chemicals, paints, textile printing, and electroplating discharge their effluents in the Hussain Sagar Lake. It has been found that the water of the lake is highly acidic and contains dissolved solids and heavy metals in quantities more than the permissible limits. The fluoride content is 10–14 parts per million (ppm) against the permissible limit of 12 ppm. The Kolleru Lake in Andhra Pradesh, which was India’s biggest natural freshwater lake, is virtually disappearing and is reduced to a small stream. The fish catch has been considerably reduced. Pollutants enter the lake in large quantities due to excessive use of fertilizers and pesticides in the Krishna and Godavari deltas.

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The Dal Lake in Srinagar is a tourist attraction. Tourists like to stay in wooden boats especially built for the lake. Wastes from the houseboats, hotels, and homes are discharged into the lake. The lake has been heavily polluted, and according to reports, the future of the lake is bleak. Special measures have to be taken to save the lake. In addition, the Telbal Nallah, a major source of its water, discharges about 8000 tonnes of silt into the lake every year. The species of phytoplankton far exceeds 200 plankton and are responsible for severe pollution of the lake. In the Kumaon region, Sukha Tal (dry lake) and Saria Tal (rotten lake) have high pollution level. A number of lakes have disappeared due to increased rate of weathering and erosion.

CHAPTER

4

Soil Pollution INTRODUCTION Soil is the topmost layer of the earth (lithosphere). All living organisms, including human beings, depend on soil for survival and basic necessities of life. Soil is the costliest natural resource available on earth and it has no substitute. It takes centuries to form 10 mm of soil. On an average, the depth of soil is only 6 inches. Besides natural causes, human beings are responsible for diminishing the quality of the land surface. They deplete it by using it for agriculture and by extracting minerals from it. Soil is the dumping ground of most waste products from domestic, industrial, and agricultural sources. All over the world, the amount of solid wastes, including hazardous chemicals, dumped onto the soil every year is increasing at an alarming rate. Soil pollution is compounded by the use of agrochemicals such as pesticides, fungicides, bactericides, insecticides, biocides, fertilizers, and manure. Soil is also polluted by deadly pathogenic organisms. Some of the major effects of soil pollution have been discussed in the subsequent sections.

Loss of Biodiversity Cutting of vast areas of forests to use the land for agricultural and development needs, and the desires and greed of the ever-growing human population have led to destruction of the natural flora and fauna. According to the International Union for Conservation of Nature (IUCN), it is estimated that by 2050, about 50,000 plant species will become extinct or threatened.

Soil Erosion Soil erosion is the process of loosening, detachment, and removal of soil components, especially the topsoil. It is caused by the flow of water (during rains) and wind (particularly storms). These forces are

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particularly effective if the land surface is devoid of vegetation cover. Excessive soil erosion from the top surface reduces soil fertility and results in slitting of water bodies due to deposition of eroded soil in riverbeds.

Acidity, Alkalinity, and Salinity Acid rain is responsible for making the soil acidic. The excess use of fertilizers such as ammonium sulphate also makes the soil acidic, rendering it unfit for the growth of plants. The ammonium ions are used by successive crops, but sulphate ions, which cause acidity, get accumulated in the soil. When sodium nitrate or potassium nitrate is used as fertilizers, the nitrate ions are used by successive crops, but sodium and potassium ions get accumulated in the soil. These cations render the soil alkaline, making it unfit for growing. Sometimes, the soil is saturated with excess fertilizers and water to increase crop production. In the absence of a proper drainage system to remove excess water, the soil becomes saline due to accumulation of salts, rendering it unfit for growing crops.

SOURCES OF SOIL POLLUTION The main sources of soil pollution include industrial wastes, urban and domestic wastes, radioactive materials, agrochemicals, chemical and metallic pollutants, biological agents, and acid rain.

Industrial Pollution A major cause of soil or land pollution is the wastes and by-products generated by various industries such as textile, paper and pulp, leather and tanning, petrochemical, food processing, soap and detergent, dairy, polymers and plastic, asbestos, tobacco, petroleum, and mining industries. A notable case of soil pollution by an industry is the Love Canal episode in Niagara Falls, New York. For many years up to 1952, Hooker Chemical packed some of its wastes in drums and buried them in Love Canal, a neighbourhood of Niagara Falls. After the burial area was filled, the canal was covered with clay. This land was subsequently acquired by the Board of Education of Niagara

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Falls. Later, residential houses and a school were developed on this land. After about 25 years, the wastes from the buried drums started leaching out. Soon the residents of the locality and school children complained of foul odour, and a number of cases of illnesses were reported. Children playing near the site suffered chemical burns; some even died. It was found that a number of women suffered from miscarriages and children were born with birth defects. Cases of asthma, urinary infection, ear infection and sinus infection increased. People also reported respiratory diseases, rashes, and headaches. On investigation, about 26 toxic organic compounds were identified, including chloroform, benzene, toluene, perchloroethylene, and chlorotoluene. Some of these compounds are potential human carcinogens. As a result of these findings, the New York State declared a health emergency in the area and evacuated 300 families. The school was also shifted to a safer place.

Urban and Domestic Wastes Urban and domestic wastes (together called municipal wastes) consist of garbage, organic waste from kitchens, sewage, industrial effluents, domestic effluents, hospital wastes, and waste materials such as plastic, glass, metallic containers, fibres, and a number of other discarded products. It is estimated that in India about 400,000 tonnes of solid wastes are produced daily, which is an alarming situation. The landfill sites used for more than 25 years cannot take any more refuse. A large portion of the urban and domestic wastes is nonbiodegradable and is extremely harmful. Some items such as paints, varnish, and oils are the worst type of soil pollutants. Leaches from dumping sites or open dumping are very harmful as they pollute groundwater and rivers. If the waste is incinerated, the ash obtained contains a high concentration of dangerous toxins and heavy metals, thus polluting the surrounding land.

Radioactive Material Radioactive fallouts Radioactive fallouts result from the testing of nuclear weapons. Considerable amounts of fission products, particularly C-14, Sr-90,

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I-131, Cs-137, are dispersed in the atmosphere after nuclear weapons are tested. These nuclides spread all over the world. They finally settle on the earth’s surface from where they find their way into the food chain.

Radioisotopes Radioisotopes are used in research, industry, and the production of medicine. They are also generated during the operation of nuclear reactors.

Natural radioactive nuclides The earth’s crust contains some radioactive materials such as U-238, Th-234, and Ra-226, which emit radiations continuously. These enter the body through the food chain.

Agrochemicals Agrochemicals such as fertilizers and pesticides (insecticides, fungicides, and herbicides) are commonly used for agricultural crops. It has already been stated that the use of excess fertilizers makes the soil acidic or alkaline (depending on the nature of the fertilizer used); these fertilizers are also responsible for eutrophication. Pesticides are used to kill pests that damage crops. According to the World Health Organization (WHO), about 750,000 people are poisoned by pesticides every year resulting in about 14,000 deaths. Agrochemicals find their way into the food chain and are responsible for a variety of health hazards.

Chemical and Metallic Pollutants Chemical and metallic pollutants result from industries producing textiles, agrochemicals, paints, dyes, soaps, synthetic detergents, drugs, batteries, cement, asbestos, petroleum, paper and pulp, leather, steel, glass, and processed metals. In fact, most industrial effluents are responsible for pollution of air, water, and soil.

Biological Agents Biological agents are responsible for the contamination of soil and crops. They include pathogenic organisms present in contaminated

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soil or discharged onto it by faulty sanitation, municipal garbage, and excreta of birds, animals, and humans. Intestinal parasites can be considered the most serious soil pollutant.

Acid Rain Air pollutants, especially oxides of sulphur and nitrogen, are responsible for acid rain. They damage crops and plants and make the soil acidic, which is harmful for crops.

ENVIRONMENTAL CONCERNS OF SOIL POLLUTION Once they enter any component of the biosphere, pollutants can cycle through all the components, that is, air, water, and soil. For example, pesticides are sprayed on plants or mixed with soil in the fields. Spraying enables pesticides to spread in the atmosphere, and rainfalls bring these chemicals back to land and water bodies. Runoffs from agricultural fields also bring pesticides into water bodies. These pesticides are generally non-biodegradable and enter the food chain through water and vegetables. They can bioaccumulate and biomagnify at higher levels of the food chain. Bioaccumulation refers to the entry of a pollutant in a food chain and the increase in its concentration level from the environment to the first organism in the food chain. Biomagnification is the phenomenon of increase in the concentration of a pollutant from one link in a food chain to another. Water-soluble pollutants can be excreted by the organism, but fat-soluble pollutants are retained in the body for a long time, leading to biomagnification.

HARMFUL EFFECTS OF SOIL POLLUTION Hazardous pollutants reach human beings via several routes such as ingestion, skin absorption, and inhalation resulting in allergies, sensory loss, and cancer. Problems become more acute when the pollutants enter the placenta to mutate the genes, resulting in birth defects. Studies have confirmed that pollutants have toxic effects on the foetus. Thus, expectant mothers must take all possible precautions to avoid contact with pollutants. Some inorganic elements such as arsenic, cadmium, mercury, lead, nickel, fluorine, boron, copper, manganese, chromium, and

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molybdenum are of public health concern due to their potential risk to humans. These elements tend to accumulate in living tissues via the food chain and bioaccumulate in the system. Metals such as mercury, cadmium, arsenic, lead, chromium, and cobalt are very harmful. Organic solvents, which are common constituents of pesticides, are responsible for health hazards due to absorption. Being volatile, these solvents evaporate at room temperature and reach the entire blood circulatory system in a very short time when inhaled. Absorption through skin is also very high. The foetus experiences severe toxic effects due to the presence of these volatile organic solvents. These affect the central nervous system, kidney, liver, and heart.

SOIL POLLUTION AND HEALTH The threat of soil pollution to health becomes apparent only when some severe disasters occur. One such case of contamination has already been discussed in the section ‘Sources of Soil Pollution’.

Industrial Pollutants and Health Industries are responsible for the discharge of metallic pollutants such as zinc, chromium, arsenic, beryllium, boron, manganese, nickel, vanadium, selenium, mercury, lead, and cadmium into the soil. These metals have extremely harmful effects on human health. Once heavy elements enter the food chain, they tend to accumulate in living tissues, resulting in biomagnification. They reach a toxic level by the time they reach human beings. It has already been stated that problems become acute when pollutants enter the placenta to mutate the genes resulting into birth defects. This may have a lifelong effect or even carried over to successive generations. Lead and mercury are the most toxic of all metals. Lead has been reported to effect neurological functions, and mercury may cause severe brain damage. Cadmium is also associated with hypertension and other neurological problems. Arsenic damages skin and causes genetic changes. Manganese alters the endocrine pathway. Molybdenum is responsible for producing certain bone abnormalities. Besides metallic pollutants, some industries such as leather tanneries discharge a number of microorganisms into the soil, which are responsible for a number of diseases.

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Radioactive Pollutants and Health Radioactive pollutants cause skin cancer, eye cataract, and mutation in cells by breaking one or both strands of DNA. The damage depends on the nature of the radiation such as a-particles, b-particles, and X-rays. Ionizing radiation causes cancer, has a mutagenic effect (changes in genetic material, which can pass on to subsequent generations), and has teratogenic effects (defects in the developing foetus resulting in birth defects in newborns).

Agrochemicals and Health Fertilizers such as sodium nitrate or potassium nitrate are responsible for methaemoglobinaemia in children. Other fertilizers such as ammonium sulphate, if used in excess, are responsible for eutrophication. Well-known pesticides such as DDT cause tumours and damage the central nervous system. Aldrin and dieldrin are known to damage the kidney and are suspected carcinogens. Mercuric fungicides are also responsible for human poisoning and deaths. The harmful effects of the herbicide Agent Orange—a mixture of 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 2, 4, 6-trichlorophenoxyacetic acid (2, 4, 6-T) have already been mentioned in Chapter 2. The effects of pesticides on human health are very severe. Individuals exposed to higher levels of pesticides suffer from headache, dizziness, irritability, nausea, impairment of nervous system, and even death. Chronic effects include development of long-term complications such as cancer.

Waste Disposal and Health As already stated, industrial solid and liquid wastes are traditionally dumped on land, endangering human health. Biomedical waste, due to its improper disposal, also poses a threat to health. It is dumped along with municipal wastes in dustbins, open space, and water bodies. Small health-care units (such as nursing homes and private clinics) do not dispose biomedical waste properly. Biomedical wastes include blood, fluids, and body sections, which harbour many viruses, bacteria, and parasites that can cause severe and fatal infections. A

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number of ragpickers collect used syringes and blades. They are prone to human immunodeficiency virus (HIV) infection on being pricked by infected needles. Other diseases resulting from improper waste management include tuberculosis, pneumonia, diarrhoea, tetanus, and whooping cough.

MEASURES TO CONTROL INDUSTRIAL WASTES A large number of industries such as petroleum refineries, paper mills, smelters, and metallurgical units produce large quantities of hazardous wastes. A waste is considered hazardous if it has one of the following characteristics: • Catches fire easily • Wears away other materials • Reacts with water or explodes on reaction with other chemicals • Releases ionizing radiation • Produces symptoms of metabolic disorder, poisoning, or malformations Toxic wastes have the capacity to produce injury after entering the metabolic process of the consumer. These are poisonous even in small or trace amounts and have an immediate effect on humans or animals causing various illnesses and even death. All countries need to manage hazardous wastes. The following control measures might be taken: • Producing less waste • Recycling of industrial waste • Treatment of hazardous waste • Proper disposal of hazardous waste

Waste Minimization Waste minimization is the most important aspect of waste management. It can be achieved by the following ways: • Process modification: Industrial processes can be modified or altered in such a way that the amount of hazardous wastes is reduced to the minimum. This can be achieved by incorporating most of the starting materials into the final product so that no waste is generated.

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• Concentration of waste: The amount of hazardous wastes can be reduced considerably by evaporation and precipitation. • Segregation of waste: It is useful to separate non-hazardous wastes from hazardous wastes. This can be done at the source of generation, which decreases the volume of hazardous wastes, making it easier to handle and treat.

Recycling Industrial Wastes Recycling and reuse can also eliminate hazardous wastes. For example, certain solvents and acids can be recovered and recycled. Baghouse dust from scrap steel processors, containing up to 25% zinc oxide, can be reacted with waste sulphuric acid to make galvanizer’s acid pickle. The spent pickle liquor containing up to 10% zinc sulphate and some iron salt can be used as a fertilizer. Certain industries can also mutually benefit each other by taking wastes from one industry and using them as raw materials in another.

Treatment of Hazardous Wastes The toxicity of hazardous wastes can be reduced by physical, chemical, or biological methods. Physical methods such as phase separation (including lagooning, prolonged storage in tanks, and sludge drying in beds) and use of charcoal or resin filters can be used. Distillation is also helpful. Precipitation and immobilization are useful in making wastes suitable for long-term storage. Chemical methods such as neutralization, oxidation, reduction, and ion exchange are useful for breaking down hazardous wastes and detoxifying them. Biological methods involve the use of bacteria and soil microorganisms to reduce the hazardous characteristics of the waste. Biodegradation can be accomplished by aerobic and anaerobic procedures. Besides the aforementioned procedures, incineration can also be used to detoxify and minimize wastes.

Disposal of Hazardous Wastes The physical characteristics of the waste must be determined before disposal. These properties can be found from the place where the waste is generated. They must be kept in mind during the different stages of collection, interim storage, transport, and disposal. Waste

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is a complex mixture, and mixing of non-compatible wastes for convenience in transit could create acute hazards, either immediately or on treatment and disposal. For example, a mixture of water and waste containing sodium residues will explode. Thus, there should be proper collection, transport, and storage for the safe disposal of hazardous wastes. Non-compatible wastes should be dealt with separately. The final disposal of hazardous wastes must be done very carefully. The procedures used for the final disposal include landfill disposal, incineration, and dumping at sea.

Landfill disposal Dumping in open space is a poor method of waste disposal because it causes environmental problems. Hazardous wastes should be disposed in properly operated sanitary landfills causing least damage to the environment. The area or site to be filled must be lined with nonporous substances such as clay or high density polyethylene plastic membrane to prevent the wastes from leaking into the surrounding areas or polluting the underground water. The wastes should be packed and dumped at the site and covered with earth every day. This prevents insects from getting into the refuse. After the site is full, it should be covered properly, and the area can be used for recreational purposes. A new concept consists in placing hazardous wastes in landfill sites constructed on a structure consisting of concrete cells.

Incineration Incineration detoxifies the waste and reduces its quantity. The flue gases produced during burning are released into the atmosphere, and the slag or ash can be deposited in a landfill. Generally, wastes having inflammable characteristics are incinerated. Such wastes include wasted mineral oil, varnish, paints, plastic, rubber, latex, emulsions, phenolic wastes, resins, grease and wax, pesticides, and organic wastes containing halogen, sulphur, or phosphorus compounds. Wastes having high chlorine, sulphur, and phosphorous contents, polychlorinated biphenyls, heavy metals, and carcinogenic substances need special incineration technologies and precautions.

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Dumping at sea The notion that the enormous volume of water in the seas will have dilution effect and so can be used for dumping anything is an erroneous conviction. Hazardous wastes have to be put in sealed containers before dumping them into the deep seas. All precautions have to be taken to prevent contamination of sea water. Disposal of waste at sea is governed by international and national legislation. Accordingly, the direct dumping of waste into the sea is prohibited, particularly wastes containing organic silicon compounds, halogenated organic mercury and its compounds, cadmium, carcinogenic wastes, and plastic. The aforementioned procedures are used for the disposal of hazardous wastes. Besides these, another method involves disposal of nuclear waste (one of the worst type of hazardous wastes) by underground disposal. Nuclear wastes are generated in all operations associated with the use of nuclear energy and other processes involving testing of nuclear weapons. For such wastes, salt mines are used because salt deposits prevent the interaction of wastes with other geological formations. Salt also absorbs moisture, which reduces the risk of rusting of metallic containers.

EFFECTS OF IMPROPER DISPOSAL OF HAZARDOUS WASTES Improper disposal of wastes causes adverse effects on the environment and human health. The usual practice of waste disposal on land or unsanitary open dumps leads to the contamination of groundwater from leaching waste. Once groundwater is polluted, it is rather impossible to reverse the damage. Pesticides have been used to destroy harmful organisms with a view to increase food production. These pesticides are not biodegradable and keep on accumulating. During rain, they find their way into underground water or other water bodies. Pesticides are responsible for a number of health hazards. Improper and uncontrolled dumping of hazardous wastes has brought about a number of environmental problems. It has killed livestock and made human beings ill; Minamata disease and itai-itai

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disease are just a few examples. The following measures should be taken to control soil pollution: • Industrial units should not dump their wastes on land or in water bodies. These industries must ensure that minimum waste is generated. As far as possible, waste products should be recycled or used to make other useful products. • Domestic and urban garbage should be properly managed by municipalities. • Animal refuse and agricultural wastes can be utilized as manure and for the production of biogas, which can be used for generating electricity. • Paper, glass, metal scraps, and certain types of plastic can be recycled. • Biological methods of pest control can also reduce the use of pesticides, which in turn will minimize soil pollution.

CHAPTER

5

Thermal and Noise Pollution THERMAL POLLUTION Thermal pollution occurs when waste heat is released into a water body or the atmosphere. For example, thermal power plants, heat generators, metal smelters, processing units, petroleum refineries, paper mills, food-processing factories, and chemical-manufacturing plants use water for cooling. The resultant heated water is released into the water bodies, thereby raising their temperature. Natural causes such as forest fires and volcanic eruptions also heat up the environment.

Effects of Thermal Pollution If the temperature of the ocean increases even by 1°C, the environment becomes lethal to sensitive organisms. The release of heated water into a water body changes its temperature. This leads to decrease in the concentration of dissolved oxygen, which has detrimental effects on aquatic animals. Rise in temperature can also harm the reproductive ability of marine organisms.

Control Measures Heated water discharged by power plants and industrial units should be retained in a holding unit and cooled before being discharged into a water body. However, it is best to reuse the cooled water. Heat generated from industries can also be used for warming buildings in the cold season. A cooling tower can also be used to control thermal pollution. In a cooling tower, most of the heat transfer occurs through evaporation. The warm water is sprayed downwards over vertical shafts or baffles, where the water flows in films. A natural draft of air is maintained to cool the water. The excess heat is dissipated.

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NOISE POLLUTION Sound is a medium of communication without which it would be impossible to lead our daily life. However, it becomes noise when its level increases beyond certain limits. Although the environment does not become unclean, noise renders it unlivable by having psychological effects on human beings. Any unwanted, disturbing or harmful sound capable of impairing or interfering with our normal hearing has the capacity to cause stress. It can adversely affect the concentration and efficiency of a person leading to abnormal behaviour and accidents. Increased use of technology has led to noise pollution.

Measurement of Intensity of Sound Sound travels in the form of waves through compression and refraction exerting pressure on the atmosphere. Sound intensity is measured by the sound pressure on a scale called the decibel (dB) scale. The instrument used for this measurement is called a decibel meter. The pressure volume is converted into loudness level with the help of a mathematical equation. Sound also has pitch in addition to pressure. A high-pitch sound seems louder than a low-pitch sound of the same pressure. It is also more annoying than a low-pitch sound of the same intensity. Thus, the sound pressure is weighed for high-pitch sounds to which humans are more sensitive. The unit of measuring sound is dBA. A sound becomes annoying when it reaches a pressure level of 75 dBA and becomes painful when it goes above 120 dBA. The decibel scale is logarithmic, that is, each rise of 10 dB means a tenfold increase in sound pressure. Even a low-level noise may be damaging if encountered for longer durations. The noise levels of common sounds in dBA are given in Table 1

Sources of noise Traffic Noise Traffic is a major source of noise pollution in Indian cities. Motor vehicles, particularly heavy and commercial vehicles, are not properly maintained. Their engines and bodies rattle and their horns (particularly pressure horns) honk loudly, producing considerable noise. Even high-level tyre pressure contributes to noise pollution.

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TABLE 1 Sound levels and their effect on humans Activity

Sound pressure(dBA) Perceived loudness

Rocket engine

180

Jet take-off (25 m away) Aircraft carrier deck Jet take-off (100 m away)

Effect

Painful

Eardrum rupture

150

Painful

Eardrum rupture

140

Painful

120

Uncomfortably loud

Thunderclap, textile loom, 120 live rock music, jet takeoff (161 m away), siren (in close range), chainsaw

Uncomfortably loud

110

Uncomfortably loud

100 Jet take-off (305 m away), subway, outboard motor, power lawnmower, motorcycle (8 m away), farm tractor, printing plant, jackhammer, garbage truck

Uncomfortably loud

Serious hearing damage (8 h)

Steel mill, riveting, automobile horn (1 m away), stereo held close to ear

Human pain threshold

Busy urban street, diesel truck, food blender, cotton-spinning machine

90

Very loud

Hearing damage (8 h), speech interference

Garbage disposal, washing clothes, average factory noise, freight train (15 m away), dish washer

80

Very loud

Positive hearing damage

Freeway traffic (15 m away), vacuum cleaner, noisy office or party

70

Moderately loud

Annoying

Conversation in restaurant or office, background music

60

Moderately loud

Intrusive

Quiet subway (daytime), conversation in living room

50

Moderately loud

Quiet

Library, soft background music

40

Quiet

Quiet

Quiet area (night time)

30

Quiet

Quiet

Whisper, rustling leaves

20

Quiet

Quiet

Breathing

10

Quiet

Quiet

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The Motor Vehicle Rules 1989 (Sections 119 and 120) have been enacted to reduce noise from vehicles. According to these rules, the horn should be of normal intensity, the body of the vehicle should not rattle, and the vehicle should be properly maintained.

Industrial noise Industries produce a high level of noise through their equipment such as boilers, generators, hammers, cutters, cranes, and grinders. Loading or unloading of materials also causes noise pollution. Some industries have loud sirens, which produce noise at regular intervals.

Community noise Community noise results from various sources such as audio and video equipment inside homes, construction activities, use of loudspeakers during meetings and religious functions, processions, and household appliances and gadgets. Generator sets produce high level of noise pollution. Community noise is responsible for disturbed sleep, reduced performance, and impact on learning.

Effects of Noise Pollution on Health The effect of noise on human health depends on the quality and duration of the noise, and the sensitivity of the individual. As already stated, noise may rupture the eardrum and cause serious hearing impairment. According to the World Health Organization (WHO), noise can affect human health physically, physiologically, and psychologically. • Physical effects: Prolonged exposure to noise levels above 80 dB may cause high blood pressure, cardiovascular changes, problems associated with digestive systems, and general fatigue. • Physiological effects: Physiological effects include anxiety, stress, insomnia, hypertension, nausea, and giddiness. Noise levels in the range of 120–150 dB can affect the respiratory system. The first response to excessive noise is annoyance. It may make the ears to ring, and the nearby speech might seem muffled. Due to excessive noise, adrenalin is released in the body, resulting in faster heartbeat, high blood pressure, and tense muscles. If the exposure to excessive noise continues for longer durations, it may lead to permanent hearing loss, hypertension, migraine, high cholesterol

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level, gastric ulcer, insomnia, and other physiological disorders, including increased aggressive behaviour. • Psychological effects: Psychological effects include reduced efficiency, absenteeism, and higher rates of accidents and injuries. It can also lead to ill temper, quarrels, or enmity.

Hearing Damage from Noise Exposure Noise affects the hearing capacity of the ear. The damage to the ear can be temporary or permanent depending on the intensity and duration of sound. Maximum damage is caused by continuous exposure to high intensity noise. The auditory sensitivity of ear is reduced if the ear is exposed to noise levels of more than 90 dB in the mid-frequency range for more than a few minutes. It has been found that noise of high-intensity impulse, which can result from an explosion, or a sudden excessive noise of more than 10 dB causes instantaneous damage or acoustic trauma. The hearing damage is a cumulative process. Low-frequency noise is less damaging than noise in the mid-frequency range. All individuals are not equally susceptible to hearing loss by noise of the same intensity. The hearing loss resulting from noise is most pronounced near 4000 Hz. However, it spreads over the frequency range with increased exposure time. Hearing loss due to noise is of two types—temporary and permanent. On being exposed to noise of 100 dB, there is substantial increase in the minimum level one can hear. However, repeated exposures for a longer period will lead to hearing loss. In case of incomplete recovery, there will be permanent hearing loss, which depends on the level of noise, pattern of exposure, and recovery time. Workers in industries in which a lot of noise is produced suffer from hearing loss, the extent of which depends on the age of the worker and the length of service in the industry (Table 2). On being exposed to noise, the sound waves create mechanical motion in the middle ear. This is followed by translation of mechanical motion into nerve impulses. Hearing is affected if the path of motion is interrupted. The overall permissible levels of noise exposure are given in Table 3.

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TABLE 2 Hearing loss by workers Industrial process Printing

Age of worker (years)

Length of service (years)

Loss of hearing (dB)

55.3

21.8

35

Iron moulding

55.4

38.4

43

Drivers (bus)

55.7

21.2

44

Manufacture of boilers

59.8

30.5

52

Weaving industry

55.0

31.5

55

Metal industries

53.5

21.3

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TABLE 3 Permissible noise exposure Sound level dBA

Duration per day (hours)

90

8

95

6

96

4

97

3

100

2

102

1

110

½

115

¼ or less

It has been found that noise level less than 25 dB does not pose any problem in hearing, but noise level greater than 25 dB causes hearing difficulty. In the case of difficulty in hearing sound greater than 50 dB, hearing aid is required.

Control of Noise Pollution The following measures can control noise pollution: • Reduction in noise at source • Interruption in the path of transmission, for example, by planting more trees • Protection of the receiver The government enacted the Environment (Protection) Act, 1986 to regulate noise pollution and defined ambient noise standards for different areas.

CHAPTER

6

Radioactive Pollution INTRODUCTION Radioactivity is the spontaneous disintegration of certain atomic nuclei accompanied by the emission of alpha particles (helium nucleus), beta particles (electrons or positrons), or gamma radiation (short wavelength electromagnetic waves). The rate of radioactive disintegration is not influenced by any change in temperature and pressure, any chemical change, or the effect of magnetic fields. Radioactivity is measured in becquerel (Bq) ( 1 Bq is equal to the quantity of the element producing one disintegration per second). An isotope of a chemical element exhibiting radioactivity is called radioisotope, which can be natural and man-made. Examples of natural isotopes include Th-232 and Ra-226. An example of a manmade radioisotope is Pu-239, which is produced by bombarding a stable atomic nucleus with high-energy particles such as protons and deuterons.

SOURCES OF RADIOACTIVE POLLUTION Natural Sources Natural sources of radioactive pollution include the rocks in the earth’s crust that contain radioactive nuclides such as U-239, Th-234, and Ra-226. These rocks continuously emit radiation, and so buildings made of such rocks are unsafe. The environmental concerns of mining, milling, and processing radioactive materials have been discussed below.

Wastes from mining Uranium used in reactors is extracted from mines as ores. Uranium ores contain a number of toxic metals such as arsenic, cadmium, mercury, and other materials formed from radioactive decay. The

.

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harmful effects of mining are first felt by the miners. They are exposed to constant radiation, which produces severe biological effects in the long run. Adequate precautions should be taken to safeguard the workers. Some of these safeguards include wearing gas masks, spectacles, and gloves. No part of the body should be left exposed to radioactive elements. Mining produces a lot of waste materials known as tailings, which have to be safely disposed or stored. The normal practice is to bury this waste under a 1–3 m thick layer of gravel, sand, or soil. The site is carefully selected to avoid movement of waste inside the ground or across air and water. These sites cannot be used for any other activity for thousands of years. The problem of disposal of radioactive wastes has acquired global concern. Some nations have shipped their radioactive wastes to developing countries for storage. By doing so, they have just transferred the problem somewhere else.

Wastes from refining and fuel fabrication Most of the wastes generated during refining and purification of uranium concentrates can be recycled. Chemical processing generates ammonium nitrate, which can be mixed with commercial fertilizers for use in agriculture. Some wastes are also produced in the fuel fabrication process during pressing, grinding, and operation, which can also be reused in the process.

Man-made Sources Nuclear fission Nuclear fission refers to the splitting of the nuclei of a heavy atom. The total mass of the products in a nuclear reaction is always less than the total mass of the reactants. The lost mass is converted into energy according to Einstein’s equation E = mc2, where E is the energy, m is the mass, and c is the velocity of light. Since velocity of light is very large, even a small loss of mass creates a huge amount of energy. The energy obtained from a nuclear reaction is million times more than the energy obtained from combustion of coal. For example, 1 kg of U-235 releases energy equal to that obtained on burning 3 million tonnes of coal. The conversion of mass into energy releases fission fragments and large amounts of gamma radiation. Figure 1 shows the schematic representation of U-235 fission in which a large

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Figure 1

89

Fission of U-235 and the release of gamma energy and other particles

Note: O is equal to neutron

amount of energy is released. The concept of fission is also used in nuclear reactors where the released energy is used for producing electricity. The release of energy in reactors is slow, whereas it is instantaneous in an atomic explosion.

X-rays X-rays can penetrate the human body. Since exposure to X-rays has a cumulative effect on the body, an X-ray should be taken only on the advice of a physician. A number of cases of diseases due to genetic disorders resulting from exposure to X-rays have been reported.

Testing of nuclear devices Testing of nuclear devices is a major contributor to nuclear radiations. When tested on the ground, considerable quantities of fission products such as C-14, Sr-90, I-131, and Cs-137 are released into the atmosphere. These materials enter the stratosphere and stay there for about 10 years. The nuclides may undergo further disintegration and spread all over the world. Ultimately, they settle on the earth’s surface and find their way into the food chain. This type of nuclear pollution has been considerably reduced because of the Partial Nuclear Test Ban Treaty (1963) signed by the governments of the Soviet Union, USA, and UK. The treaty prohibits all types of nuclear tests in the atmosphere, outer space, or underwater; only underground tests are allowed.

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Radiations Radiations (including alpha-, beta-, and gamma-rays) emitted from nuclear power plants may enter the human body at any stage and transfer their energy to body tissues. The biomolecules in the human system absorb this energy and undergo fragmentation, causing a host of deleterious effects.

Radioisotopes Another source of radioactive pollution is radioisotopes, which are being increasingly used in medicine and research and in nuclear reactors for power generation. Radioisotopes may enter the human body either through direct inhalation or through the food chain. Ra-226 and Xe-133 are readily absorbed by suspended particles in the air. Upon inhalation, these isotopes are deposited in the passage way of lungs where they release energy through radioactive decay. Radioisotopes are also absorbed by the soil and taken up by plants. They enter the human body when affected plants or animals are consumed. Radioisotopes can also enter the body on the consumption of contaminated fish and marine animals. Different human organs are affected by different radioisotopes. Accidental leakage of radiation from nuclear reactors is an additional hazard. A number of nuclear accidents have been recorded, some of which have been discussed as follows: • Chernobyl nuclear disaster: The worst nuclear disaster in history occurred at Chernobyl in Ukraine (in former Soviet Union) on 26 April 1986. The explosion from the nuclear reactor burst through a massive concrete cover. Radioactive debris shot into the air and fell on places as far as 1000 km. Within a few days, the debris and gases drifted over most of Europe. A column of fluorescent blue light emerged from the reactor and reached the upper atmosphere. The accident directly and indirectly killed many people and destroyed vegetation in a large area around Chernobyl. • Three Mile Island accident: The Three Mile Island power plant was located near Harrisburg in Pennsylvania, USA. The accident occurred in one of its units on 28 March 1979. The malfunctioning nuclear plant released radioisotopes into the environment. The emissions were estimated to be low to affect a large area; however,

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TABLE 1 Effects of low level radiation Exposure

Effect observed years later

Radiation therapy for acne, spiral problems, and syphilis

Increased risk of leukaemia

Radiation therapy for inflammatory ailment in breast and lung tuberculosis in women

Breast cancer

X-ray of neck or radiation therapy to shrink tonsils or treat chest ailments in children

Cancer of thyroid gland, salivary gland, tumour

Miners exposed to uranium and fluorspar

Lung cancer

Watch dial and aeroplane instruments (paint containing radium)

Bone cancer, bone marrow disease

Pregnant women exposed to diagnostic X-ray (2–3 rads)

Children born show 50% higher rates of leukaemia, tumours of brain, and cancer

radiation levels were much higher near the site. No casualties were reported. • Fukushima Daiichi nuclear disaster: The Tohoku earthquake and tsunami on 11 March 2011 resulted in the meltdown of three nuclear reactors of the Fukushima Daiichi Nuclear Power Plant. There were explosions due to the accumulation of hydrogen gas in the outer containment buildings of the reactors. A large number of people had to be evacuated from areas near the nuclear plant.

RADIOACTIVE POLLUTION AND HEALTH The ill effects of radiation were discovered only in the beginning of the nineteenth century. Malignant tumours were detected on the hands of radiologists and other scientists using X-ray machines or radium. Subsequently, a high incidence of leukaemia (three to four times higher than in the general population) was detected. Workers who painted the dial of watches with radium paint experienced a high incidence of bone tumour. Table 1 summarizes the effects of low level of radiations. Radioactive pollution consists mainly of alpha particles, beta particles, gamma-rays, and X-rays, all of which affect different parts of the body (Table 2). The radiations from these particles possess enough energy to rip electrons from atoms, resulting in the formation of ions; they are, therefore, called ionizing radiations. When high-energy radiations strike the human body, they penetrate the tissues, transfer

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their energy, and kill the cells. In most cases, a change in DNA occurs and the mutations are passed from generation to generation.

TABLE 2 Different types of radiations and their effect on the body Type of radiation

Effect on body

Alpha particles

Alpha particles can travel only a few centimetres in air. In living tissue, they can travel only up to 30 μm, that is, they can cross only three cells.

Beta particles

Beta particles can travel about 8 cm in air and about 1 cm in tissue. They can penetrate the skin but cannot reach the underlying tissue. They can result in skin cancer and eye cataract.

Gamma-rays

Gamma-rays can travel about 100 m in air and can pass through the body. They can cause mutation of cells.

X-rays

X-rays can travel extremely far and pass through body tissues, except bones. They can cause damage to cell molecules.

The impact of radiation on health depends on a number of factors such as the energy, type, and amount of radiation; the age of the individual; and the body part exposed. Ionizing radiation may cause the following biological effects in human beings: • Carcinogenic effects: Ionizing radiation increases the probability of most forms of cancer. • Mutagenic effects: The genetic material changes due to mutagenic affects, and the mutations get transferred to the offspring. • Teratogenic effects: The development of the embryo is affected, and this results in birth defects. It has been found that cells which undergo rapid division are more sensitive to radiation. The foetus is more sensitive to radiation and so are the children. In view of this, extra precautions must be taken by pregnant women and children. Most of the studies on radiation have been conducted on animals. Although the results gave some idea of the damage caused by radiation, they cannot be extrapolated to human beings. Significant information about the harmful effects of radiation is now being obtained by studying the people affected by the Hiroshima and Nagasaki bombings and the Chernobyl nuclear plant disaster. The results obtained have been summarized in Table 3. Food crops grown on and drinking water obtained from radioactive soil contain some radioactive nuclides such as K-40, C-14, and Rn-222.

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TABLE 3 Effects of high level of radiation Dose (rad)*

Effect

50–200

There is no immediate death, but the victim suffers from radiation sickness, including fatigue, nausea, vomiting, diarrhoea, sore throat, reduction in blood platelets, and loss of hair. Long-term effects include cancer, leukaemia, cataract, and decreased life span. In pregnant women, there is an increase in spontaneous abortion and stillbirths.

300

About 50% of the population exposed dies within two months

650

Sure death within a few hours or a few days.

* 1 rad is equal to 100 ergs of energy deposited per gram of tissue. Rad has now been replaced by the new international unit grey (1 grey = 100 rads).

TABLE 4 Effects of radionuclides on different organs Radionuclide

Organ affected

Radium-226

Bones

Radon-222

Lungs

Iodine-131

Thyroid

Krypton-85

Ovaries

Cobalt-60

Liver

Potassium-42

Muscles

Sulphur-35

Skin

These nuclides enter the human body via the food chain and drinking water. The milk of cows consuming vegetation containing radionuclides is also extremely harmful to humans. Radionuclides affect different organs of the human body (Table 4). High doses of ionizing radiation are the most harmful. Some of the health hazards due to high doses of ionizing radiation are as follows: • Damage to the brain and the central nervous system causing delirium, convulsions, and death within hours or days • Eyes are affected, forming cataracts and impairing sight • Vomiting, bleeding of gums, and formation of mouth ulcers • Infection of the intestinal wall resulting in death after two to three weeks • Unborn children are vulnerable to brain damage

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• Damage to ovaries and testes • Damage to bone marrow

CONTROL OF RADIOACTIVE POLLUTION Radioactive pollution is the worst threat to the environment and the future generations. These pollutants persist in the environment for a long time. Radioactive wastes such as spent fuel from nuclear reactors pose the maximum threat. Radioactive wastes are of two types—low-level wastes and high-level wastes. High-level wastes contain trace amounts of short half-life isotopes such as Sr-90, Cs-137, and U-237. The disposal of low-level wastes is relatively simple. They are packed in drums and placed in trenches (15 m wide and 10 m deep). Alternatively, the sealed drums can be buried under the seabed. High-level wastes include large concentrations of radionuclides. The spent fuel is removed from the reactor, and unused uranium is extracted from it. High-level wastes have to be buried in remote locations. Before burial, they are stored above the ground for about 10 years to reduce their temperature. They can be buried in the following ways: • The wastes can be kept in canisters and then buried in rocky places at a depth of about 700 m from the surface. • They can be buried in salt deposits at a depth of about 600 m. • They can be buried in the red clay deposits of the ocean basin at a depth of about 30 m. • The waste can be stored in a tank made of synthetic rock, which can withstand high temperature, and then buried at a depth of about 500 m.

CHAPTER

7

Health Hazards due to Factors other than Pollution INTRODUCTION The previous chapters dealt with the impacts of air, water, soil, photochemical, marine, noise, and radioactive pollution. Besides these, certain other factors leading to serious health problems include occupation, stress, global warming, and ozone layer depletion.

OCCUPATION AND HEALTH There are many underprivileged people who engage in risky and hazardous jobs and live in unhealthy environments such as slums. As a result, they suffer from severe health problems. Even the privileged people who work in comfortable offices are not free from health problems as they have to deal with physical illness and psychological stress. Health problems associated with work environment are called occupational hazards. The common health problems associated with different occupations have been discussed in the following subsections.

Mining and Factory Work People working in factories and mines inhale chemical particles and dust evolved during various operations. As they are exposed to these particles for several years, they become prone to pneumoconiosis, a disease caused by dust inhalation. Workers inhaling silicon dust suffer from silicosis, which is one of the oldest diseases in the world responsible for the death of thousands of people every year. It is an incurable disease, and its severity depends on the extent of inhalation. The frequent causes of death in the mining industry are lung fibrosis, emphysema, and pulmonary tuberculosis. These diseases are common

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in workers engaged in mining coal, gold, silver, lead, zinc, manganese, and other metals; pottery and ceramic industries; and iron, cement, and steel industries. Table 1 lists various types of lung diseases and their causes, and Table 2 gives health hazards and industries associated with them.

Agriculture Farmers use agrochemicals such as fertilizers and pesticides. The adverse effects of agrochemicals have already been discussed in Chapter 4. In addition, farmers are also exposed to the risk of infection carried by farm animals. Farms are also the breeding ground for mosquitoes due to irrigation activities responsible for malaria, dengue, and filaria, and farmers are exposed to these diseases.

Profession People having white-collar jobs often suffer from spondylosis and backache because of using uncomfortable furniture, improper

TABLE 1 Lung diseases and their causes Lung disease

Cause

Silicosis

Silicon dust

Byssinosis (or brown lung)

Cotton fibre, flax, hemp

Anthracosis (or black lung)

Coal dust

Bagassosis

Sugarcane fibre

Asbestosis

Asbestos fibre

Talcosis

Talc

TABLE 2 Health hazards associated with industries Industry

Health hazard

Welding industries

Early blindness and respiratory diseases

Flour mills

Lung diseases

Paprika industry

Lung disease called paprikosis

Tobacco factories

Lung disease and allergic skin disease

Dyeing, tanning, and paint industries

Cancer

Industries dealing with carcinogenic chemicals

Cancer

Heavy engineering industries producing noise

Deafness

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sitting posture, and lack of movement. Besides these disorders, they also suffer from psychological stress, which is responsible for hypertension, ulcer, and cardiovascular diseases. These problems can be reduced to a great extent by doing regular exercises, walking, yoga, and meditation. Tobacco chewing is also responsible for health hazards. People working in offices generally consume tea and coffee in excessive amounts resulting in acidity. Continuous driving, as in the case of drivers of the public transport system and taxis, increases stress leading to high blood pressure, indigestion, and hyperactivity. Most occupational hazards can be avoided by adopting appropriate safety measures, some of which are as follows: • Workers in factories should use gloves and masks and should wash their hands or take bath after work. • People in white-collar jobs should do regular exercises. • In agricultural practice, water should not be allowed to stagnate except where required. • In industries producing noise, workers must use ear plugs.

STRESS AND HEALTH Humans invariably look forward to achieving some goals in their life. However, these goals vary from person to person. Students want to get high marks in examinations and subsequently pursue a career of their choice, followed by a high-paid job and getting settled. In case any of these goals are not achieved, the person gets stressed. Other factors that cause stress include poverty, unemployment, death of a close relative, and tensions resulting from competitions in life. In fact, all people face stressful situations throughout their lives. Stress is responsible for a number of physical and mental disorders, including neurosis, coronary heart ailments, gastric ulcers, high blood pressure, allergies, asthma, and so on. It also results in heart attack, headache, insomnia, loss of sexual interest, and weakness. Most people deal with stress on a routine basis. However, unmanageable stress causes illnesses. For example, emotional distress activates the immune and endocrine systems. This results in the release of more adrenalin, a hormone responsible for increasing blood pressure. The immune system is affected by long-term activation

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of the nervous and endocrine systems. Unable to cope with stress, the person suffers from anxiety, depression, fatigue, frustration, irritability, bad temper, and low self-esteem leading to drug addiction, alcohol abuse, and smoking. In extreme cases, people even think of committing suicide.

GLOBAL WARMING AND HEALTH An increase in the average temperature of the earth’s atmosphere due to the greenhouse effect can have far-reaching effects on the climate and consequently on the key life-support systems of the planet. Global warming can lead to serious medical problems. A rise in temperature will melt glaciers, resulting in floods and subsequent scarcity of food and drinking water. These disasters promote infectious diseases such as cholera and jaundice. Flooding also increases breeding of mosquitoes leading to the spread of malaria, dengue fever, yellow fever, and encephalitis. Vector-borne diseases, which affect more than 700 million people in a year, are the outcome of climate and environment conditions.

OZONE LAYER DEPLETION AND HEALTH It is now well known that depletion of the ozone layer in the stratosphere by chlorofluorocarbons (CFCs) is responsible for the formation of the ozone hole (see Chapter 2). Due to the depletion of the ozone layer, ultraviolet radiations from the sun reach the earth. These radiations are responsible for causing cataract and skin cancer in humans. It also increases the risk of infectious diseases. Light-skinned people can also develop non-melanoma skin cancer on exposure to ultraviolet radiation.

CHAPTER

8

Management of Wastes

W

aste is produced in enormous quantities in all countries. According to the United Nations Development Programme (UNDP), per capita production of waste in developed countries is higher than that in developing countries because of higher levels of consumption. Municipal solid wastes in developed countries consists mainly of plastic, metals, and paper, whereas organic matter forms half of the waste generated in developing countries. Wastes can be broadly categorized into four types—municipal wastes (including domestic waste), industrial wastes, biomedical wastes, and nuclear or radioactive wastes.

MUNICIPAL WASTES Municipal wastes, including domestic and household wastes, are treated in three stages—primary treatment, secondary treatment, and tertiary treatment. Besides, perishable municipal wastes can be subjected to vermicomposting and production of manure.

Primary Treatment Municipal waste is passed through a number of screens to remove any floating materials, which include all non-biodegradable solids such as rocks, sand, grit, plastic, and metal parts. Subsequently, water is passed through a chamber, which is packed with sand and small stones. By this treatment, dirt is removed. The resulting filtered water is made to enter a sedimentation tank. In the sedimentation tank, the particulate matter settles down in the form of sludge. Addition of certain chemicals such as alum hastens the settling process. The sludge is used as manure after processing.

Secondary Treatment The water from the primary treatment, that is, from the sedimentation tank is aerated in an aeration tank in which air is pumped along with

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some sludge from the sedimentation tank. The aerobic bacteria present in the sludge breakdown the organic pollutants in water. Aeration is continued for 8–10 hours. Subsequently, the aerated water is pumped into a second sedimentation tank, in which most of the remaining sludge settles down. The total sludge from both the sedimentation tanks is used to generate methane by microbial degradation, and the generated methane is used as a fuel. Finally, water from the last sedimentation tank is taken in a disinfection tank and treated with chlorine, which removes diseasecausing organisms. Normally, primary and secondary treatments are enough for the complete purification of water (Figure 1).

Tertiary Treatment It has already been stated that considerable purification is accomplished by primary and secondary treatments. However, sometimes these two treatments are inadequate. The two treatment processes do not remove many pollutants in domestic sewage. Inorganic compounds such as nitrates and phosphates still remain in the treated water. In case excess chlorine has been used in the secondary purification step, it may react with organic solvents and result in the formation of chlorinated products, which are more harmful.

Figure 1

Diagrammatic representation of treatment of water

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In tertiary treatment, the water obtained from the secondary stage is treated with certain chemicals. This helps in removing highly soluble salts as precipitates by adding alum or other flocculating agents. However, such treated water still contains nitrates, nitrites, phosphates, and other non-biodegradable chemicals (such as insecticides and herbicides from agricultural run-offs). Such water is rendered alkaline, and phosphates are precipitated. Finally, metallic hydroxides are added, and phosphates are precipitated as insoluble phosphate salts. Compounds that are soluble in water, such as nitrates, are removed by electrodialysis. These can also be removed by chemical coagulation using alum, ferrous sulphate, and ferric sulphate. The foul smell and taste are removed by aeration. Finally, treatment with chlorine or ozone removes bacteria and viruses.

Vermicomposting It is always advisable to separate perishable wastes from solid wastes and convert them into manure through a process called vermicomposting. This is done by digging a pit (1 × 1 × 1 m3) and lining it with straw, dried leaves, and grass. Organic wastes are put in the pit, and a culture of worms (available commercially) is introduced into it. The pit is covered with twigs and dried leaves every day and watered twice a week to keep moist. After 15 days, the contents of the pit are turned over to ensure complete vermicomposting. It takes about 40–50 days for complete decomposition of wastes by microorganisms. The final product is obtained in the form of soil rich in nutrients, which can be used as manure in place of chemical fertilizers.

INDUSTRIAL WASTES All industries generate wastes, and the nature of the wastes depends on the processes in which they originate. It is best to process the wastes at the source so that valuable by-products can be recovered and used. For example, the wastes from fermentation industries can be evaporated and dried, and the product can be sold as animal feed. In electroplating industries, metals can be recovered from the wastes using ion exchanges. Similarly, ferrous sulphate can be recovered from pickling operations.

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The treatment of wastes at source is easy because the pollutants present are known, and procedures are available for the treatment of different types of pollutants. However, if wastes from different industries are mixed, the resultant is a complex mixture, which is difficult to deal with.

Types of Industrial Wastes There are two types of industrial wastes—process wastes and chemical wastes.

Process wastes Every industry produces its own process wastes from operations such as washing of raw materials and purification of intermediate and final products. Process wastes are of two types: 1. Inorganic process wastes: The effluents from chemical manufacturing industries, metallurgical industries, electroplating units, and petroleum industries contribute to inorganic process wastes. Such wastes may be toxic, but they do not pose biological problems. However, in combination with organic wastes, they create problems of disposal. As an example, fatty acids and a high concentration of sulphate stimulate the sulphate-reducing bacteria producing hydrogen sulphide, which creates problems. 2. Organic process wastes: Such wastes result from wastewaters from industries such as food processing units, dairies, breweries, distilleries, textile mills, paper mills, and industries manufacturing organic chemicals.

Chemical wastes Chemical wastes are obtained from industries involved in the manufacture of acids, bases, detergents, explosives, dyes, agrochemicals, silicon, plastic, and resins. Such wastes are usually acidic or basic, high in biochemical oxygen demand (BOD), and generally inflammable. Chemical wastes obtained from industries manufacturing explosives and agrochemicals are acidic in nature and require neutralization. Certain types of chemical wastes such as cornstarch waste, mixed with domestic waste, require biological oxidation and treatment methods such as trickling filters, activated sludge, or lagooning.

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Treatment and Disposal of Industrial Wastes Industrial wastes are treated in the same way as municipal wastes are treated. All the three steps of treatment—primary, secondary, and tertiary are used. It is, however, possible to select a method most suitable for a particular type of effluent (organic, inorganic, or chemical) since the quality of waste is predictable and the pollutants present are known.

Treatment of wastes with inorganic impurities Inorganic wastes are treated chemically. The pH of the effluents is maintained between 6 and 9. Acidic wastes are neutralized with lime (CaO). Alkaline wastes are also neutralized. If possible, acidic and alkaline wastes can be mixed together so that the pH of the resulting waste ranges from 6 to 9. Such wastes can be discharged into water bodies. Suspended matter and oily substances are removed by coagulation and flocculation by adding flocculating agents. Heavy metals, if present, are precipitated by using appropriate precipitating agents or by adjusting to appropriate pH. Poisonous wastes such as cyanides are removed by chlorination under alkaline conditions. The process, known as chemical oxidation, can also be carried out with ozone as an oxidizing agent. Some wastes such as those containing chromium (from electroplating industries) are removed by chemical reduction by subjecting them to chemical reduction process with sulphur dioxide. In place of sulphur dioxide, ferrous sulphate can also be used in the case of some wastes.

Treatment of wastes with organic impurities Organic effluents in wastewater are subjected to biological treatments. However, before biological treatment, the wastes are subjected to primary treatment. The organic matter is putrescible and is removed by aeration. Acidic or basic wastes are neutralized. In case the wastes contain inorganic toxic metals, they are subjected to chemical treatment. Suspended organic pollutants and colloidal impurities are coagulated, precipitated, or flocculated by the addition of ferrous

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sulphate or alum as flocculating agent. This treatment is necessary before biological treatment. After the primary process, the effluents are subjected to biological treatment using activated sludge and trickling filter treatments. In case the organic content is more, additional amounts of microorganisms, along with organic nutrients, have to be added.

Hazardous Wastes For dealing with hazardous wastes, special practices are followed. These include production of less waste, conversion of hazardous substances into less hazardous substances, and safe disposal of wastes.

Production of less waste Producing less quantities of waste is the best available option. This can be done by suitable changes in raw materials, chemical processes, and the equipment used. Hazardous solvents, if used in the manufacturing process, can be recycled in the same industry. In certain cases, it is possible to use wastes from one industry as raw materials for another industry. In all industries, the formation of wastes can be eliminated or minimized by adhering to the following principles of green chemistry: • It is better to prevent wastes than to treat or clean them up after they are formed. • Synthetic methods should be designed to maximize the incorporation of all materials used into the final product. • Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment. • Chemical products should be designed to preserve efficacy of functions while reducing toxicity. • The use of auxiliary substances (solvents and separation agents) should be made unnecessary whenever possible and innocuous when used.

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• Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure. • A raw material or feedstock should be renewable rather than depleting whenever technically and economically practical. • Unnecessary derivatization (blocking group, protection/ deprotection, and temporary modification of physical/chemical processes) should be avoided whenever possible. • Catalytic reagents (as selective as possible) are superior to stoichiometric reagents. • Chemical products should be designed so that at the end of their function, they do not persist in the environment and instead breakdown into innocuous degradation products. • Analytical methodologies need to be further developed to allow for real-time in-process monitoring and control prior to the formation of hazardous substances. • Substances and the form of a substance used in a chemical process should be chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.

Conversion of hazardous wastes to less hazardous wastes The hazardous characteristics of wastes can be reduced by a number of methods. These include physical, chemical, and biological methods and incineration. • Physical methods: Hazardous constituents are absorbed on charcoal or resin filters. Sometimes distillation is also useful. Precipitation and immobilization are useful for long-term storage. • Chemical methods: Chemical methods involve neutralization, oxidation, reduction, or ion-exchange procedures. • Biological methods: Use of bacteria, microorganisms, and other species reduces the hazardous nature of wastes. Biodegradation can be affected by aerobic and anaerobic methods. • Incineration: Incineration is an important procedure and involves heating the waste to 1200°C. The hazardous waste is degraded to safer products and the volume of waste is also considerably reduced. Incineration reduces volatile, combustible, and organic waste. It is, in fact, a permanent solution to many hazardous wastes.

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Disposal of hazardous wastes Two methods, generally, used for the disposal of hazardous wastes are secure landfills and deep-well injection.

Secure landfills A secure landfill is a specially designed pit (of dimension 50 × 50 × 10 m3) from which hazardous wastes cannot escape into open air or mix with groundwater. The sides of the pit are lined with an impermeable membrane such as plastic. The solid waste is carefully placed in the pit, spread out, and compacted with heavy machinery. The waste is then covered with a layer of compacted soil. The process is repeated till the pit is full. It is then closed by cement concrete.

Deep well injection Deep well injection is a technology of disposing waste, mostly liquid, in which treated or untreated water is poured through pipes running down several thousand feet from the ground level. The water is injected into highly saline regions under the earth having impermeable rocky layer. As a result, contaminants do not migrate to pollute freshwater aquifers. In this technology, concentric pipes are dug into earth. The outermost pipe acts an external cover, which extends below the groundwater table and is cemented back to the surface to prevent contamination of underground sources of water. Inside the outermost pipe is a long string casing, which is also filled with cement back to the surface to seal the waste from the layers above the injection zone. The innermost pipe is the injection tube through which wastewater is pumped to the impermeable zone.

BIOMEDICAL WASTE The wastes generated in hospitals, nursing homes, pathological laboratories, and research institutions are referred to as biomedical waste. These comprise used needles, syringes, blood, blood bags, urine bags, glucose bottles, bandages, chemicals, and body parts. Biomedical wastes are one of the sources of spreading diseases such as Acquired Immunodeficiency Syndrome (AIDS), hepatitis, septicaemia, and other infections.

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According to the Bio-medical Waste (Management and Handling) Rules, 1998, biomedical wastes must be segregated at the source of waste generation. Different categories of waste must be kept in specially made containers (waste bags) having appropriate colour coding and disposed as proscribed in Schedule 1, Rule 5. Table 1 gives the waste category and their treatment and disposal procedure.

TABLE 1 Waste category and treatment/disposal procedure Option

Waste category

Treatment/disposal

Category 1

Human body parts

Incineration, deep burial

Category 2

Incineration, deep burial Animal waste (animal tissues, body parts, carcasses, fluids, blood, experimental animals used in research, veterinary hospitals, and discharges from hospitals and animal houses)

Category 3

Microbiology and biotechnology (wastes from human culture, specimens of microorganisms, live or attenuated vaccines, human and animal cell culture used in research and industrial laboratories)

Autoclaving, microwaving, incineration

Category 4

Waste sharps (needles, syringes, and blades); these include both used and unused sharps

Shredding, disinfection (chemical treatment, autoclaving, microwaving)

Category 5

Discarded medicines and cytotoxic drugs (wastes consisting of outdated, contaminated, and discarded medicine)

Incineration, drug disposal in secure landfills

Category 6

Solid wastes (items contaminated with blood, body fluids, cotton dressing, soiled plaster casts, lines, beddings, and other material stained with blood)

Incineration, autoclaving, microwaving

Category 7

Solid waste (wastes generated from disposal items other than waste sharps such as tubing, catheters, and intravenous sets)

Disinfection by chemical treatment, autoclaving, microwaving, and shredding

Category 8

Incineration ash (ash obtained from the incineration of any biomedical waste)

Landfills

Category 9

Liquid waste (generated from laboratory washing, cleaning, housekeeping, and disinfecting activities)

Disinfection by chemical treatment and discarded into drains

Category 10

Chemical waste (chemicals used in production of biological matter, chemicals used in disinfection, insecticides)

Chemical treatment and discharge into drain for liquids and secure landfills for solids

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Some of the procedures for the disposal of various types of biomedical wastes are as follows: • Incineration: Incineration is a controlled combustion process in which the waste is completely oxidized and microorganisms, if present, are destroyed and denatured at high temperature. • Autoclaving: Autoclaving is a low-heat thermal process in which steam is brought into contact with the waste under pressure for a sufficient duration of time. • Microwaving: Microwave ovens having radiation frequency between 300 MHz and 300,000 MHz are used for treating waste. • Shredding: In shredding, waste is cut into smaller blocks and disinfected. The shredded material is then stored in landfills.

RADIOACTIVE WASTES Radioactive wastes are generated from nuclear power plants, fuel processing plants, hospitals using radioisotopes, and research institutions. In addition, the mining of ores of radioactive elements generate considerable amount of waste. These are special types of wastes and pose serious threat to the environment and to the future generations. Lethal to living beings even in minute amounts, these wastes are persistent for much longer times. Thus, radioactive wastes need immediate and urgent attention for their safe disposal. Depending on the level of radioactivity, nuclear wastes can be divided into two types—low-level wastes and high-level wastes. The procedures for disposing of these two types of nuclear wastes are different.

Low-level Waste Low-level wastes contain trace amounts of radioisotopes having short half-life such as strontium-90, caesium-137, neptunium-236, and uranium-237. These wastes include residuals or solutions from chemical processing. Materials containing low-level wastes include plastic bottles, rubber gloves, glassware, and protective clothing. Low-level wastes can be disposed using simple procedures. The waste is packed in bags or drums and then placed in deep trenches (usually 15 m wide and 10 m deep). Seabeds can also be used for disposal.

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High-level Waste Being extremely toxic, high-level wastes need immediate attention. The spent fuel left after the generation of energy from nuclear plants contains about 1% uranium-235. The splitting of uranium235 generates radioactive isotopes of smaller elements. In addition, heavier elements such as plutonium are obtained from uranium-235 by capture of neutrons. These are heavier than uranium and are known as transuranic elements and take longer time to decay. For example, plutonium-239 has a half-life of 24,000 years compared to smaller fragments such as strontium-90 and caesium-137 having halflife of about 30 years. High-level wastes are most hazardous to human and other forms of life. Direct exposure even for a short time is fatal. These wastes are responsible for serious health risks. The temperature of these wastes is very high, and so they have to be stored for about 10 years to reduce temperature. It has been found that if long-lived isotopes are transmitted to short-lived isotopes, the disintegration of waste becomes faster. For example, a constituent of spent fuel is neptunium237, which takes a long time to disintegrate (Equation 1). However, when is bombarded by neutrons, it gets converted into neptunium-236 (Equation 2), that in turn decays to plutonium-236 (Equation 3), which disintegrates much faster. 237 N 93

t1/2=2.14×106 years

233 Pa + 4 He 2 91

(1)

237 N + 1 n Æ 236 NP + 2 1 n 93 0 0 94

(2)

236 Np 93

(3)

t1/2=22.3 days

236 Pu + 0 b 94 –1

After the high-level waste has been transmuted (Equations 1, 2, and 3), it is ready for burial. It should, however, be ascertained that once the waste is buried, it should not re-enter the biosphere. The total nuclear waste (both liquid and solid) is first converted into a structure such as solid borosilicate glass. In this form, the waste becomes insoluble in water and cannot leach into the groundwater. The resulting borosilicate capsule is enclosed in canisters made of stainless steel

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(which is a high corrosion-resistant alloy). The canisters are encased in a suitable absorbent material. This procedure delays the migration of any ion in the waste, which might have got dissolved in groundwater inadvertently. Finally, the canisters are buried at an appropriate burial site, which can be of the following types explained in the ensuing sections.

Geologic repository High-level nuclear wastes are buried or stored in rock formation at a depth of 400–700 m. It should, however, be ascertained that the rock formation meets the following criteria: • The rocks must have high structural strength, good thermal conductivity, and heat capacity to disperse any heat load from the waste without undergoing damage. • It should be ascertained that groundwater may not seep through it. This is possible if the rocks have low permeability and porosity. • It should have high plasticity to permit healing in case the burial site is fractured. • The location of rocks should be in a zone of low seismicity.

Salt deposits High-level radioactive wastes can be buried in salt deposits. As salt has high thermal conductivity, it disperses the heat of the radioactive waste effectively. Also salt has extremely low permeability and does not permit seepage of water. It also has high plasticity, which increases with depth. This allows the salt to heal any fractures that may develop. The main disadvantage of salt, however, is its solubility in water. Also salt deposits are contaminated with brine fluids having high concentration of dissolved solids. Canisters are likely to get corroded if the brine fluids reach them. So in the case of salt deposits, stainless steel containers should be replaced with containers made of corrosionresistant titanium alloys.

Beneath seabed High-level radioactive wastes can be safely embedded 30 m below the red clay deposits of the ocean basin. The red clay deposits possess high degree of plasticity, low permeability, and high absorptivity.

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Drill holes It has already been stated that high-level wastes can safely be buried in geological repositories at a depth of 400–700 m. On drilling beyond 700 m, the rock formation is completely devoid of groundwater. Permeability also decreases at lower depths. The main drawback of drill holes is that beyond 1 km, the geological temperature of the earth, combined with the radiological heat of the waste canisters, may be enough to melt the borosilicate glass barriers, resulting in leakage of radionuclides. This procedure works satisfactorily if borosilicate glass is replaced with an artificial rock-type material called synthetic rock (Synroc), which is a titanate ceramic and is thermodynamically very stably and can withstand very high temperatures. Synroc is a mixture of minerals Hollandite (BaAl2Ti6O16), Zirconolite (CaZrTi2O7), and Perovskite (CaTiO3). These minerals can take all the radioisotopes present in nuclear wastes into their crystal structure in the form of dilute solid solution. Using Synroc, high-level wastes can be buried at a depth of 4 km. Small drill holes, approximately 1 m in diameter, are suitable for burying the waste.

Index Note: t is for tables and f is for figures.

Asbestos mining, 23, 33 Autoclaving, 107, 108

A Acid rain, 24, 28, 32, 34, 42, 70, 73 Agent orange, 31, 52, 75 Agricultural discharges, 3, 5 Agrochemicals, 2, 3, 5, 42, 69, 70, 72, 75, 96, 102 adverse effects on human health, 75, 96 Agro-industries, 23 Air pollutants, 14, 18, 21, 22, 36, 73 and health, 25–26 in India, 24–25 sources of, 22 Air pollution, 2, 5, 12, 13–37, 40 control of, 36–37 effects of, 24 sources of, 2 Alternative sources of energy, 37 Amoco Cadiz disaster, 46 Arsenic contamination, 57–58 effects on health, 57–58, 58t Asbestos, 4, 10, 17, 22, 23, 29, 30, 33, 70, 72, 96

B Benthic and inter-tidal organisms, 48–49 Benzopyrene, 18, 31, 32, 47 Bhopal gas tragedy, 1, 24–26 Bioaccumulation, 52, 73 Biodegradable pollutants, 2, 13 Biological agents, 4, 5, 12, 40, 41, 70, 72–73 Biomagnifications, 53, 73, 74 Biomedical waste (management and handling) rules, 1998, 106 Biomedical wastes, 75, 99, 106–107 category and treatment, 107, 107t disposal, 107, 107t Black rain, 4 Blue baby syndrome, 24, 53 Bombay High oil spill, 46 C Cadmium poisoning, 54 Carbon dioxide, 2, 13–17, 22, 28, 29, 32, 33, 37, 44 source of, 15–16

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Carbon monoxide, 2, 9, 14–15, 22, 27, 28t, 32, 33, 35, 37 effects on health, 26, 28t a silent killer, 14, 28 sources of, 15 Catalytic converters, 8, 9 Central Ganga Authority (CGA), 64 Central Pollution Control Board (CPCB), 25 Cent re for S c ience a nd Environment (CSE), 12 Chemical, and metallic pollutants, 72 oxidation, 103 wastes, 102 Chernobyl nuclear disaster, 1, 90, 92 Chlorofluorocarbons (CFCS), 5, 7, 18, 35, 98 Chromium poisoning, 59 Coal mining, 23, 34 Coastal and estuarine pollution in India, 49–50 Cobalt poisoning, 59 Colorimetric methods, 5–6 Community noise, 84 D Dal Lake pollution, 66–67 Deep well injection, 106 Deforestation, 1, 2 Desulphurization, 8, 37 of coal, 8, 37 of flue gases, 8

Detergents, 3, 5, 40, 41, 51, 64, 72, 102 Domestic wastes, 3, 4, 40, 43, 62, 70, 71 E Einstein’s equation, 88 Environment (protection) act, 1986, 86 Environmental disasters, 1, 24 Environment degradation, 1–2 Environment health, 11 cost of damages of, 12 measures for, 11 Eutrophication, 41, 44, 54, 66, 72, 75 Extinction of dinosaurs, 1 Exxon Valdez crash, 46, 47 F Fluoride contamination, 56–57 effects on health, 56t, 56–57 Fluorosis, 56–57 classified, 56 Food-borne diseases, 12t Freshwater pollution, 42, 106 sources of, 42t Fukushima Daiichi nuclear disaster, 1, 91 G Gandhi, Rajiv, 64 Ganga Action Plan, 63–65 Ganga project directorate, 64 Gaseous pollutants, 4, 5, 14, 22, 23, 26–29, 34, 35 effects of, 26–28, 28t

INDEX

Geologic repository, 110 and drill holes, 111 and rock criteria, 110 Global warming, 2, 12, 13, 17, 18, 24, 34, 35, 95, 98 effects of, 34–35 and medical problems, 98 Gravimetric methods, 5 Great Smog of London, 1 Green revolution, 4 Green solvents, 10 Green chemistry, 104 Principles of, 104–105 Groundwater pollution (contamination), 42, 43, 50, 56–58, 71, 79 sources of, 43t H Hazardous waste, 76–79, 104–106 characteristics of, 76 control measures for, 76 conversion of, 105–106 disposal of, 77–78, 106 dumping of at sea, 79 improper disposal of, 79–80 treatment of, 77 Herbicides, 2, 3, 23, 24, 30, 42, 43, 52, 72, 101 Hiroshima and Nagasaki bombings, 1, 92 Human immunodeficiency virus (HIV), 76 Hussain Sagar Lake pollution, 66

115

Hydrocarbons, 6, 7, 9, 14, 17–22, 29, 31–33, 35, 47, 50, 64 effects on health, 31–32, 32t sources of, 32t I IBP company, 46 Incineration, 29–32, 44, 77, 78, 105, 107, 108 at sea, 44 Indo-Dutch Bilateral Programme, 62 Indoor air pollution, 35–36 health effects of, 35–36 Industrial health hazard, 96t Industrial pollution, 10, 65, 70 and health, 74 Industrial wastes (effluents), 3–5, 30, 41–44, 50, 52, 57, 59–61, 63, 65, 70–72, 77, 99, 101–103 management of, 101–102 measures to control, 10–11, 76–79 recycling of, 77 treatment and disposal, 103 types of, 102 International Convention for the Prevention of Pollution, 45 International Union for Conservation of Nature (IUCN), 69 Ionizing radiation, 75, 76, 91–93 Iran–Iraq war, 46 Itai-itai disease, 54–55, 79

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K Knock-knee syndrome, 56 Kolleru Lake pollution, 66 L Lake water pollution, 65–66 sources of, 66 Landfill disposal, 78 Lead poisoning, 58–59 Love canal episode in Niagara Falls, 70–71 Lung diseases, 21, 26, 28t, 33, 34, 96t and their causes, 96t M Macroscopic algae, 48 Marine grasses, 48 Marine pollution, 43–46, 49 sources and nature of, 43–44 Metallic pollutants, 4, 17, 22, 30, 70, 72, 74 and their effects, 30, 30t–31t Methaemoglobinaemia, 24, 52, 53, 55, 75 Mica mining, 23, 34 Microorganisms, 1, 12, 53–55, 74, 77, 101, 104, 105, 107, 108 diseases caused by, 55t effects of, 54–55 in drinking water, 55t Microwaving, 107, 108 Minamata disease, 53, 55, 79 Mine tailings, 43, 66, 88 Mining waste, 87–88 Motor Vehicle Rules 1989, 84

Mt Cosmos Pioneer shipwreck, 46 Municipal wastes, 44, 60, 71, 75, 99, 103 treatment of, 99–100 N National River Action Plan, 62 Natural pollutants, 13–14 Natural radioactive nuclides, 72 Nuclear devices testing, 89 Nitrogen fertilizers, 23–24 Noise, permissible limits, 96t Noise pollution, 5, 81–86 by community, 84 effects on health, 84–85 hearing loss from, 85, 86t industrial, 84 measures to control, 86 sources of, 82–83 Non-degradable pollutants, 2, 13 Nuclear accidents, 1, 90–91 Nuclear fission, 88 O Occupational hazards, 95, 97 in industries, 96t safety measures for, 97 Oil pollution, 45–49 effects of, 46–48 Oil spills, 41, 45, 47, 48 Organic pollutants, 64, 100, 103 Oxides of nitrogen, 5, 8, 14, 15, 17, 18, 21, 22, 27, 28, 32–35, 37 effects of, 27, 28t

INDEX

Oxides of sulphur, 7, 16, 28t, 37, 73 Ozone, 6, 12, 15, 18–20, 24, 25, 35, 95, 98, 101, 103 accumulation, 19f formation, 18–20, 19f Ozone hole, 20, 98 Ozone layer, 12, 15, 20, 24, 35, 95, 98 depletion and effects, 12, 20, 24, 35, 95, 98–99 P Partial Nuclear Test Ban Treaty, 89 Particulate matter, 4–6, 10, 14, 16, 17, 24, 25, 27, 29, 32, 35, 37, 99 Pesticides, 2, 3, 12, 23, 30, 40–43, 51–53, 59, 63, 66, 69, 72–75, 78–80, 96 effects of, 52–53 Petroleum, exploration, 22, 23 industries, 33, 102 Photochemical pollutants, 18, 21 control of, 21 effects on health, 21 formation of, 20, 20f Photochemical smog, 17, 20, 21, 32t formation of, 20f Phytoplankton, 48, 67 Plastic litter disposal, 44–45 Pneumoconiosis, 29, 95

117

Pollutants, analysis by instrumental technique, 6t biodegradable, 2, 13 categories of, 5 defined, 2 from industries, 22 inorganic and organic, 6, 64, 64t nature of, 4–5 non-degradable, 2, 13 resident time of, 7t stability, 7 types of, 2, 13 Pollution, defined, 2 sources, 2–3 man-made, 2 natural, 2 reduction, 7 types of, 5 Pollution monitoring, 5–6 chemical methods, 5–6 and health issues, 11–12 volumetric methods of, 5 Polychlorinated biphenyls, 22, 32, 51, 78 Polymers and plastic, 22, 32–33, 70 Primary pollutants, 13, 14 Process wastes, 102 inorganic and organic, 102 types of, 102

118

INDEX

R Radiation effects, 75, 92–93 carcinogenic, 75, 92 on the body, 75, 92t of high level, 92t, 93t of low levels, 91t mutagenic, 75, 92 teratogenic, 75, 92 Radioactive, fallouts, 71–72 materials, 3, 5,14, 42, 70–72, 87 Radioactive pollution, control of, 94 and health, 4, 5, 75, 91–92 man-made sources, 86–87 natural sources, 87–88 sources of, 87–88 Radioactive wastes, 108–110 burial of in salt deposits, 110 and geologic repository, 110 high level waste, 109 low level waste, 108 types of, 94, 108–110 Radioactivity, 87, 108 Radioisotopes, 72, 87, 90, 108, 111 man-made, 87 Radionuclides, 4, 41, 93, 94, 111 effects on human organs, 92–93, 93t Respirable suspended particulate matter (RSPM), 17, 29, 35 River water pollution, 60–65 in India, 60–62

inorganic and organic, 64t reasons of, 60 Roche Holding Ltd, 31 S Santa Barbra oil spill, 45 Secondary pollutants, 13, 14, 28 Secure landfill, 106, 107 Sewage sludge, 44 Shredding, 107, 108 Silicosis, 95, 96 Siltation, 3, 42, 66 Smog, 1, 17, 20, 21, 24, 25, 28, 29, 32 Soil erosion, 4, 69, 70 Soil pollution, 3, 4, 69–80 effects on health, 74 environmental concerns of, 73–74 harmful effects of, 73–74 by industries, 70–71 main sources of, 70–71 measures to control, 80 sources of, 3–4 Sound levels, 82–83 effect on humans, 83t measurement, 82 Stress and health, 97–98 Sulphur dioxide, 2, 14, 16, 25, 26, 28, 29, 37, 103 effects on health, 26, 28t main sources of, 16 Suspended particulate matter, 14, 16, 17, 27, 29

INDEX

119

effects on health, 27, 29, 29t sources of, 17 Synroc, 111

Uranium fission, 88–89, 89f Urban wastes, 4, 70–71 Urquiola accident, 46

T Thermal pollution, 3, 5, 12, 41, 81 control measures, 81 effects of, 81 Three Mile Island accident, 1, 90 Tobacco, 12, 23, 33, 35, 40, 70, 96, 97 chewing, 23, 97 effects on health, 12, 23, 33, 97 indoor pollution by, 35 smoke, 23, 33 Tohoku earthquake, 91

V Vermicomposting, 99, 101 Vietnam war, 24, 31 Volatile organic compounds, 14, 17, 18

Torrey Canyon spill, 45, 46 Toxic chemicals, 22, 23, 50,51t–52t and fertilizers, 54 health effects of, 51, 51t–52t sources and effects of, 51t–52t in water, 59t Toxic metals, 3–5, 87, 103 Traffic noise, 82–83 Transhuron collusion, 46 Treatment of, coal, 9 water, diagram of, 100f Turbidimetric methods, 5, 6 U Union Carbide India Ltd, 26 Upflow anaerobic sludge blanket technology, 65

W Waste, disposal, 22, 75, 78, 79 management, 99–111 minimization, 76–77 processing, 11 Water distribution on earth, 39, 39t Water pollutants, 40–42 source and effects of, 41t types of, 40–41 Water pollution, 2, 3, 5, 12, 39–67 control of, 59 harmful effects of, 55–56 and health, 50–51 in various water bodies, 41–42 sources of, 41, 41t Water treatment, 55, 57, 60, 61 representation of, 100f World Bank, 12, 26 World Health Organization (WHO), 11, 12, 31, 55, 57, 72, 84 World War II, 1 X X–rays, 75, 89, 91, 92

120 Y Yamuna river pollution, 62–63 attempts to control, 62–63 Yusho disease, 32

INDEX

Z Zooplankton, 48 Zuari Agro Chemicals Ltd, 47

About the Author Professor V K Ahluwalia is Professor (Retd) of Chemistry, University of Delhi. His tenure in this university spanned for more than 30 years. For these three decades, he has taught numerous graduate, postgraduate, and MPhil students and has provided guidance to about 70 students for their MPhill and Doctoral degrees. He was also Visiting Professor at Dr B R Ambedkar Centre for Biomedical Research, University of Delhi. Professor Ahluwalia worked as a Post-doctoral Fellow for two years (1960–62), and had the opportunity to work with Professor Harold Shechter at the Department of Chemistry, Ohio State University. He also worked with Professor Herbert C Brown (Nobel Laureate) at the department of Chemistry, Purdue University. Professor Ahluwalia has published more than 250 research papers in national and international journals. He is the distinguished author of a number of books on reaction mechanism, green chemistry, environmental chemistry, and organic synthesis. Some of these include Green Chemistry: Environmentally Benign Reactions, College Practical Chemistry, and Comprehensive Practical Organic Chemistry Qualitative Analysis. His co-authored books include New Trends in Green Chemistry: Organic Reaction Mechanisms; Chemistry of Natural Products: Amino Acids, Peptides, and Enzymes; Comprehensive Practical Organic Chemistry: Preparation and Quantitative Analysis; Comprehensive Practical Organic Chemistry: Quantitative Analysis; Environmental Science; A Textbook of Organic Chemistry; and Organic Synthesis: Special Techniques. His book Green Chemistry: environmentally benign reactions is winner of 2009 Choice Award of Outstanding Title.

Environmental Pollution and Health V K Ahluwalia

Pollution as we know is an undesirable change in the physical, chemical, and biological characteristics of the environment. Environmental Pollution and Health expounds the three main types of environmental pollution—air, water, and land—and their effects on human health. It also focuses on photochemical air pollution, marine pollution, thermal pollution, noise pollution, and radioactive pollution and their effects on human health. The book also discusses the impact on the health of the human beings by factors other than pollutants. These factors include occupation of a person, stress, global warming, and ozone layer depletion. Finally, the author has dealt with various types of wastes generated in different establishments and how they should be managed.

Environmental Pollution and Health V K Ahluwalia

Key Features • Describes the measures to be taken to control industrial wastes • Explains effects of radioactive pollutants on health • Elaborates the different types of wastes • Discusses how various types of wastes can be managed

ISBN 978-81-7993-461-6

The Energy and Resources Institute

9 788179 934616

The Energy and Resources Institute