Health and Safety in the Rubber Industry 1859573010, 1859574149, 9781859573013, 9781859574140

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Report 138

Health and Safety in the Rubber Industry N. Chaiear

Volume 12, Number 6, 2001

RAPRA REVIEW REPORTS A Rapra Review Report comprises three sections, as follows: 1. A commissioned expert review, discussing a key topic of current interest, and referring to the References and Abstracts section. Reference numbers in brackets refer to item numbers from the References and Abstracts section. Where it has been necessary for completeness to cite sources outside the scope of the Rapra Abstracts database, these are listed at the end of the review, and cited in the text as a.1, a.2, etc. 2. A comprehensive References and Abstracts section, resulting from a search of the Rapra Abstracts database. The format of the abstracts is outlined in the sample record below. 3. An index to the References and Abstracts section, derived from the indexing terms which are added to the abstracts records on the database to aid retrieval.

Source of original article Title

Item 1 Macromolecules

33, No.6, 21st March 2000, p.2171-83 EFFECT OF THERMAL HISTORY ON THE RHEOLOGICAL BEHAVIOR OF THERMOPLASTIC POLYURETHANES Pil Joong Yoon; Chang Dae Han Akron,University The effect of thermal history on the rheological behaviour of ester- and ether-based commercial thermoplastic PUs (Estane 5701, 5707 and 5714 from B.F.Goodrich) was investigated. It was found that the injection moulding temp. used for specimen preparation had a marked effect on the variations of dynamic storage and loss moduli of specimens with time observed during isothermal annealing. Analysis of FTIR spectra indicated that variations in hydrogen bonding with time during isothermal annealing very much resembled variations of dynamic storage modulus with time during isothermal annealing. Isochronal dynamic temp. sweep experiments indicated that the thermoplastic PUs exhibited a hysteresis effect in the heating and cooling processes. It was concluded that the microphase separation transition or order-disorder transition in thermoplastic PUs could not be determined from the isochronal dynamic temp. sweep experiment. The plots of log dynamic storage modulus versus log loss modulus varied with temp. over the entire range of temps. (110-190C) investigated. 57 refs.

Location

GOODRICH B.F. USA

Authors and affiliation

Abstract

Companies or organisations mentioned

Accession no.771897

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Volume 4 Report 37

Polymers in Aerospace Applications, W.W. Wright, University of Surrey.

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Advanced Composites, D.K. Thomas, RAE, Farnborough.

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Liquid Crystal Polymers, M.K. Cox, ICI, Wilton.

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CAD/CAM in the Polymer Industry, N.W. Sandland and M.J. Sebborn, Cambridge Applied Technology.

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Polymers in Chemically Resistant Applications, D. Cattell, Cattell Consultancy Services.

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Engineering Thermoplastics, I.T. Barrie, Consultant.

Report 41

Failure of Plastics, S. Turner, Queen Mary College.

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Communications Applications of Polymers, R. Spratling, British Telecom.

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Polycarbonates, R. Pakull, U. Grigo, D. Freitag, Bayer AG.

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Process Control in the Plastics Industry, R.F. Evans, Engelmann & Buckham Ancillaries.

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Polymeric Materials from Renewable Resources, J.M. Methven, UMIST.

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Flammability and Flame Retardants in Plastics, J. Green, FMC Corp.

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Injection Moulding of Engineering Thermoplastics, A.F. Whelan, London School of Polymer Technology.

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Composites - Tooling and Component Processing, N.G. Brain, Tooltex.

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Polymers and Their Uses in the Sports and Leisure Industries, A.L. Cox and R.P. Brown, Rapra Technology Ltd.

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Quality Today in Polymer Processing, S.H. Coulson, J.A. Cousans, Exxon Chemical International Marketing.

Report 47

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Polyurethane, Materials, Processing and Applications, G. Woods, Consultant.

Chemical Analysis of Polymers, G. Lawson, Leicester Polytechnic.

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Polyetheretherketone, D.J. Kemmish, ICI, Wilton.

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Extrusion, G.M. Gale, Rapra Technology Ltd.

Report 49

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Agricultural and Horticultural Applications of Polymers, J.C. Garnaud, International Committee for Plastics in Agriculture.

Blends and Alloys of Engineering Thermoplastics, H.T. van de Grampel, General Electric Plastics BV.

Report 50

Recycling and Disposal of Plastics Packaging, R.C. Fox, Plas/Tech Ltd.

Automotive Applications of Polymers II, A.N.A. Elliott, Consultant.

Report 51

Biomedical Applications of Polymers, C.G. Gebelein, Youngstown State University / Florida Atlantic University.

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Polymer Supported Chemical Reactions, P. Hodge, University of Manchester.

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Weathering of Polymers, S.M. Halliwell, Building Research Establishment.

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Volume 5

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Pultrusion, L. Hollaway, University of Surrey.

Report 21

Materials Handling in the Polymer Industry, H. Hardy, Chronos Richardson Ltd.

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Electronics Applications of Polymers, M.T.Goosey, Plessey Research (Caswell) Ltd.

Report 23

Offshore Applications of Polymers, J.W.Brockbank, Avon Industrial Polymers Ltd.

Report 54

Health and Safety in the Rubber Industry, A.R. Nutt, Arnold Nutt & Co. and J. Wade.

Report 24

Recent Developments in Materials for Food Packaging, R.A. Roberts, Pira Packaging Division.

Report 55

Computer Modelling of Polymer Processing, E. Andreassen, Å. Larsen and E.L. Hinrichsen, Senter for Industriforskning, Norway.

Report 56

Plastics in High Temperature Applications, J. Maxwell, Consultant.

Volume 3 Report 25

Foams and Blowing Agents, J.M. Methven, Cellcom Technology Associates.

Report 57

Joining of Plastics, K.W. Allen, City University.

Report 58

Physical Testing of Rubber, R.P. Brown, Rapra Technology Ltd.

Report 59

Polyimides - Materials, Processing and Applications, A.J. Kirby, Du Pont (U.K.) Ltd. Physical Testing of Thermoplastics, S.W. Hawley, Rapra Technology Ltd.

Report 26

Polymers and Structural Composites in Civil Engineering, L. Hollaway, University of Surrey.

Report 27

Injection Moulding of Rubber, M.A. Wheelans, Consultant.

Report 28

Adhesives for Structural and Engineering Applications, C. O’Reilly, Loctite (Ireland) Ltd.

Report 60

Report 29

Polymers in Marine Applications, C.F.Britton, Corrosion Monitoring Consultancy.

Volume 6

Report 30

Non-destructive Testing of Polymers, W.N. Reynolds, National NDT Centre, Harwell.

Report 61

Report 31

Silicone Rubbers, B.R. Trego and H.W.Winnan, Dow Corning Ltd.

Report 32

Fluoroelastomers - Properties and Applications, D. Cook and M. Lynn, 3M United Kingdom Plc and 3M Belgium SA.

Food Contact Polymeric Materials, J.A. Sidwell, Rapra Technology Ltd.

Report 62

Coextrusion, D. Djordjevic, Klöckner ER-WE-PA GmbH.

Report 63

Conductive Polymers II, R.H. Friend, University of Cambridge, Cavendish Laboratory.

Report 64

Designing with Plastics, P.R. Lewis, The Open University. Decorating and Coating of Plastics, P.J. Robinson, International Automotive Design.

Report 33

Polyamides, R.S. Williams and T. Daniels, T & N Technology Ltd. and BIP Chemicals Ltd.

Report 65

Report 34

Extrusion of Rubber, J.G.A. Lovegrove, Nova Petrochemicals Inc.

Report 66

Report 35

Polymers in Household Electrical Goods, D.Alvey, Hotpoint Ltd.

Reinforced Thermoplastics - Composition, Processing and Applications, P.G. Kelleher, New Jersey Polymer Extension Center at Stevens Institute of Technology.

Report 67

Report 36

Developments in Additives to Meet Health and Environmental Concerns, M.J. Forrest, Rapra Technology Ltd.

Plastics in Thermal and Acoustic Building Insulation, V.L. Kefford, MRM Engineering Consultancy.

Report 68

Cure Assessment by Physical and Chemical Techniques, B.G. Willoughby, Rapra Technology Ltd.

Report 69

Toxicity of Plastics and Rubber in Fire, P.J. Fardell, Building Research Establishment, Fire Research Station.

Report 70

Acrylonitrile-Butadiene-Styrene Polymers, M.E. Adams, D.J. Buckley, R.E. Colborn, W.P. England and D.N. Schissel, General Electric Corporate Research and Development Center.

Report 71

Rotational Moulding, R.J. Crawford, The Queen’s University of Belfast.

Report 72

Advances in Injection Moulding, C.A. Maier, Econology Ltd.

Report 94

Compressive Behaviour of Composites, C. Soutis, Imperial College of Science, Technology and Medicine.

Report 95

Thermal Analysis of Polymers, M. P. Sepe, Dickten & Masch Manufacturing Co.

Report 96

Polymeric Seals and Sealing Technology, J.A. Hickman, St Clair (Polymers) Ltd.

Volume 9 Report 97

Rubber Compounding Ingredients - Need, Theory and Innovation, Part II: Processing, Bonding, Fire Retardants, C. Hepburn, University of Ulster.

Report 98

Advances in Biodegradable Polymers, G.F. Moore & S.M. Saunders, Rapra Technology Ltd.

Report 99

Recycling of Rubber, H.J. Manuel and W. Dierkes, Vredestein Rubber Recycling B.V.

Volume 7 Report 73

Reactive Processing of Polymers, M.W.R. Brown, P.D. Coates and A.F. Johnson, IRC in Polymer Science and Technology, University of Bradford.

Report 74

Speciality Rubbers, J.A. Brydson.

Report 75

Plastics and the Environment, I. Boustead, Boustead Consulting Ltd.

Report 100 Photoinitiated Polymerisation - Theory and Applications, J.P. Fouassier, Ecole Nationale Supérieure de Chimie, Mulhouse.

Report 76

Polymeric Precursors for Ceramic Materials, R.C.P. Cubbon.

Report 101 Solvent-Free Adhesives, T.E. Rolando, H.B. Fuller Company.

Report 77

Advances in Tyre Mechanics, R.A. Ridha, M. Theves, Goodyear Technical Center.

Report 102 Plastics in Pressure Pipes, T. Stafford, Rapra Technology Ltd.

Report 78

PVC - Compounds, Processing and Applications, J.Leadbitter, J.A. Day, J.L. Ryan, Hydro Polymers Ltd.

Report 103

Report 79

Rubber Compounding Ingredients - Need, Theory and Innovation, Part I: Vulcanising Systems, Antidegradants and Particulate Fillers for General Purpose Rubbers, C. Hepburn, University of Ulster.

Report 80

Anti-Corrosion Polymers: PEEK, PEKK and Other Polyaryls, G. Pritchard, Kingston University.

Report 81

Thermoplastic Elastomers - Properties and Applications, J.A. Brydson.

Report 82

Advances in Blow Moulding Process Optimization, Andres Garcia-Rejon,Industrial Materials Institute, National Research Council Canada.

Report 83

Molecular Weight Characterisation of Synthetic Polymers, S.R. Holding and E. Meehan, Rapra Technology Ltd. and Polymer Laboratories Ltd.

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Rheology and its Role in Plastics Processing, P. Prentice, The Nottingham Trent University.

Gas Assisted Moulding, T.C. Pearson, Gas Injection Ltd.

Report 104 Plastics Profile Extrusion, R.J. Kent, Tangram Technology Ltd. Report 105 Rubber Extrusion Theory and Development, B.G. Crowther. Report 106 Properties and Applications of Elastomeric Polysulfides, T.C.P. Lee, Oxford Brookes University. Report 107 High Performance Polymer Fibres, P.R. Lewis, The Open University. Report 108 Chemical Characterisation of Polyurethanes, M.J. Forrest, Rapra Technology Ltd.

Volume 10 Report 109 Rubber Injection Moulding - A Practical Guide, J.A. Lindsay. Report 110 Long-Term and Accelerated Ageing Tests on Rubbers, R.P. Brown, M.J. Forrest and G. Soulagnet, Rapra Technology Ltd.

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Report 111

Polymer Product Failure, P.R. Lewis, The Open University.

Report 85

Ring Opening Polymerisation, N. Spassky, Université Pierre et Marie Curie.

Report 112 Polystyrene - Synthesis, Production and Applications, J.R. Wünsch, BASF AG.

Report 86

High Performance Engineering Plastics, D.J. Kemmish, Victrex Ltd.

Report 113 Rubber-Modified Thermoplastics, H. Keskkula, University of Texas at Austin.

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Rubber to Metal Bonding, B.G. Crowther, Rapra Technology Ltd.

Report 114 Developments in Polyacetylene - Nanopolyacetylene, V.M. Kobryanskii, Russian Academy of Sciences.

Report 88

Plasticisers - Selection, Applications and Implications, A.S. Wilson.

Report 115 Metallocene-Catalysed Polymerisation, W. Kaminsky, University of Hamburg.

Report 89

Polymer Membranes - Materials, Structures and Separation Performance, T. deV. Naylor, The Smart Chemical Company.

Report 116 Compounding in Co-rotating Twin-Screw Extruders, Y. Wang, Tunghai University.

Report 90

Rubber Mixing, P.R. Wood.

Report 117 Rapid Prototyping, Tooling and Manufacturing, R.J.M. Hague and P.E. Reeves, Edward Mackenzie Consulting.

Report 91

Recent Developments in Epoxy Resins, I. Hamerton, University of Surrey.

Report 118 Liquid Crystal Polymers - Synthesis, Properties and Applications, D. Coates, CRL Ltd.

Report 92

Continuous Vulcanisation of Elastomer Profiles, A. Hill, Meteor Gummiwerke.

Report 119 Rubbers in Contact with Food, M.J. Forrest and J.A. Sidwell, Rapra Technology Ltd.

Report 93

Advances in Thermoforming, J.L. Throne, Sherwood Technologies Inc.

Report 120 Electronics Applications of Polymers II, M.T. Goosey, Shipley Ronal.

Volume 11 Report 121 Polyamides as Engineering Thermoplastic Materials, I.B. Page, BIP Ltd. Report 122 Flexible Packaging - Adhesives, Coatings and Processes, T.E. Rolando, H.B. Fuller Company. Report 123 Polymer Blends, L.A. Utracki, National Research Council Canada. Report 124 Sorting of Waste Plastics for Recycling, R.D. Pascoe, University of Exeter. Report 125 Structural Studies of Polymers by Solution NMR, H.N. Cheng, Hercules Incorporated. Report 126 Composites for Automotive Applications, C.D. Rudd, University of Nottingham. Report 127 Polymers in Medical Applications, B.J. Lambert and F.-W. Tang, Guidant Corp., and W.J. Rogers, Consultant. Report 128 Solid State NMR of Polymers, P.A. Mirau, Lucent Technologies. Report 129 Failure of Polymer Products Due to Photo-oxidation, D.C. Wright. Report 130 Failure of Polymer Products Due to Chemical Attack, D.C. Wright. Report 131 Failure of Polymer Products Due to Thermo-oxidation, D.C. Wright. Report 132 Stabilisers for Polyolefins, C. Kröhnke and F. Werner, Clariant Huningue SA.

Titles Available in the Current Volume Volume 12 Report 133 Advances in Automation for Plastics Injection Moulding, J. Mallon, Yushin Inc. Report 134 Infrared and Raman Spectroscopy of Polymers, J.L. Koenig, Case Western Reserve University. Report 135 Polymers in Sport and Leisure, R.P. Brown. Report 136 Radiation Curing, R.S. Davidson, DavRad Services. Report 137 Silicone Elastomers, P. Jerschow, Wacker Chemie GmbH.

Health and Safety in the Rubber Industry Naesinee Chaiear (Khon Kaen University)

ISBN: 1-85957-301-0

Health and Safety in the Rubber Industry

Contents 1 Introduction .................................................................................................................................... 5 2 The Law Affecting Health and Safety ........................................................................................... 5 2.1 The Law Affecting Health and Safety in the United States ................................................................. 5 2.1.1 Federal Regulation of Occupational Health and Safety in the Workplace ............................. 5 2.1.2 Workers’ Compensation ......................................................................................................... 8 2.2 The Law Affecting Health and Safety in the United Kingdom and other European Countries ........... 8 2.2.1 Common Law ......................................................................................................................... 8 2.2.1.1 Standard of Care of Occupational Health Specialist .............................................. 8 2.2.1.2 Duty to Inform and Warn of Risks to Health and Safety ........................................ 8 2.2.1.3 Balancing the Risk .................................................................................................. 8 2.2.1.4 Constructive Knowledge ........................................................................................ 8 2.2.1.5 The State of the Art ................................................................................................. 8 2.2.1.6 Employer’s Responsibility ..................................................................................... 8 2.2.1.7 Duty Owed for Mental Breakdown ........................................................................ 9 2.2.1.8 Stress and Other Mental Disorders ......................................................................... 9 2.2.1.9 Employees’ Duties .................................................................................................. 9 2.2.2 Statutes ................................................................................................................................... 9 2.2.2.1 UK Health and Safety at Work Act 1974 ................................................................ 9 2.2.2.2 Employer’s Statutory Duties................................................................................... 9 2.2.2.3 Employees’ Statutory Duties .................................................................................. 9 2.2.2.4 The Institutions ....................................................................................................... 9 2.2.2.5 UK Control of Substances Hazardous to Health Regulations (COSHH) ............. 10 2.2.2.6 UK Regulations 1992 ........................................................................................... 10 2.2.3 European Law ...................................................................................................................... 10 2.2.3.1 General .................................................................................................................. 10 2.2.3.2 Qualified Majority Voting (QMV) ........................................................................ 10 2.2.3.3 Recommendations ................................................................................................ 10 2.2.3.4 Working Time Directive ........................................................................................11 2.2.4 Other Codes and Regulations on Health and Safety .............................................................11 2.2.4.1 BRMA Code of Practice ........................................................................................11

3 Industrial Safety: Equipment ...................................................................................................... 11 3.1 Industrial Statistics ..............................................................................................................................11

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Health and Safety in the Rubber Industry

3.2 Mill and Calender Safety ....................................................................................................................11 3.2.1 Mill Safety ............................................................................................................................11 3.2.2 Calender Safety .................................................................................................................... 13 3.2.3 Machine Lockout ................................................................................................................. 14

4 Fire and Explosions ...................................................................................................................... 15 5 Solvents .......................................................................................................................................... 15 5.1 Health Effects .................................................................................................................................... 15 5.1.1 Benzene: C6H6 ............................................................................................................................................................................................................ 15 5.1.2 Toluene: C6H5CH3 .................................................................................................................................................................................................. 16 5.1.3 Xylene: C6H4(CH3)2 ............................................................................................................................................................................................. 16 5.1.4 Methylene Chloride (dichloromethane): CH2Cl2 ................................................................................................................. 16 5.1.5 1,1,1-Trichloroethane (Methylchloroform): CH3CCl3 ................................................................................................... 16

6 Epidemiology ................................................................................................................................. 17 7 Natural Rubber Latex Allergy ..................................................................................................... 17 8 Skin Irritation and Dermatitis .................................................................................................... 19 9 Dust and Fume .............................................................................................................................. 19 9.1 Dust .................................................................................................................................................... 19 9.1.1 Carbon Black ....................................................................................................................... 20 9.1.2 Crystalline Silica .................................................................................................................. 21 9.1.2.1 Silicosis ................................................................................................................. 21 9.1.2.2 Cancer ................................................................................................................... 21 9.1.2.3 Autoimmune Diseases .......................................................................................... 21 9.1.2.4 Tuberculosis .......................................................................................................... 21 9.1.2.5 Kidney Disease ..................................................................................................... 22 9.1.2.6 Exposure Control and Personal Protection ........................................................... 22 9.2 Rubber Fumes .................................................................................................................................... 22 9.2.1 Visible Fumes ....................................................................................................................... 22 9.2.2 Gases and Vapours ............................................................................................................... 22 9.3 A Strategy for Dust and Fume Control .............................................................................................. 23 9.3.1 Assessing the Risks to Health from Dust and Fume ............................................................ 23 9.3.2 Selection of Control Methods .............................................................................................. 23 9.3.2.1 Elimination and Substitution ................................................................................ 23

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Health and Safety in the Rubber Industry

9.3.2.2 Containment .......................................................................................................... 23 9.3.2.3 Process Control ..................................................................................................... 24 9.3.2.4 Handling and Working Methods ........................................................................... 24 9.3.2.5 Ventilation Control ............................................................................................... 24 9.3.2.6 Segregation ........................................................................................................... 24 9.3.2.7 Housekeeping and Cleanliness ............................................................................. 24 9.3.2.8 Respirators ............................................................................................................ 24

10 Work-Related Musculoskeletal Disorders ................................................................................ 24 10.1 Prevention ........................................................................................................................................ 25

11 Nitrosamines ................................................................................................................................ 25 12 1,3-Butadiene .............................................................................................................................. 25 12.1 Health Effects .................................................................................................................................. 26 12.1.1 Animal Studies ................................................................................................................... 26 12.1.2 Human Studies ................................................................................................................... 26 12.2 Industrial Exposure and Control ...................................................................................................... 26

13 General Recommendations for Handling Rubber Chemicals ................................................ 27 13.1 Personal Hygiene ............................................................................................................................. 27 13.2 Handling........................................................................................................................................... 27 13.3 General and Local Exhaust Ventilation ........................................................................................... 27 13.4 Skin Protection and Protective Clothing .......................................................................................... 27

14 Conclusion ................................................................................................................................... 28 Acknowledgments ............................................................................................................................ 28 References......................................................................................................................................... 29 References and Abstracts ................................................................................................................ 31 Subject Index ................................................................................................................................. 121

The views and opinions expressed by authors in Rapra Review Reports do not necessarily reflect those of Rapra Technology Limited or the editor. The series is published on the basis that no responsibility or liability of any nature shall attach to Rapra Technology Limited arising out of or in connection with any utilisation in any form of any material contained therein.

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Health and Safety in the Rubber Industry

4

Health and Safety in the Rubber Industry

1 Introduction The rubber industry uses both natural and synthetic rubber. Southeast Asia produces most of the world’s natural rubber, while synthetic rubber is a product of industrialised countries like the United States, Japan and Europe. Brazil is the one developing nation with a significant synthetic rubber industry. Tyres and tyre products account for approximately 60% of the synthetic rubber and 75% of the natural rubber used, and this industry employs about half a million workers worldwide. Important non-tyre uses of rubber include automotive belts and hoses, gloves, condoms and rubber footwear. Table 1 indicates the variety of rubber products made from rubber polymers (a.1). Occupational health and safety in the rubber industry are major concerns. Of the many scientific studies performed on workers in the industry, some have identified a disproportionate mortality from bladder, stomach, lung, haematopoietic and other cancers – deaths correlated to a workplace where long-term exposure to many chemical combinations occurred. Often such long-term exposure injuries, where ill effects are not detected for years, are overlooked so that prevention of dramatic injuries occupies safety agendas instead. In previous guides to health and safety in the rubber industry, the focus was upon the synthetic rubber industry. This guide follows a similar format but with expanded sections on the natural rubber industry. The first section outlines the laws affecting health and safety in the industry whilst the remainder of the guide presents specific health and safety issues of interest to employers and employees.

2 The Law Affecting Health and Safety Occupational health and safety requirements vary around the world. In mainland Europe, occupational health and safety regulations are based on civil law and requirements tend to be more specific than those in the United States.

2.1 The Law Affecting Health and Safety in the United States In the United States, toxic substances in the workplace are primarily controlled through three

federal laws: the Mine Safety and Health Act of 1969, the Occupational Safety and Health Act (OSH Act) of 1970, and the Toxic Substances Control Act (TSCA) of 1976. The OSH Act established the Occupational Safety and Health Administration (OSHA) in the Department of Labor to enforce compliance, and the National Institute for Occupational Safety and Health (NIOSH) in the Department of Health and Human Services (under the Center for Disease Control) to perform research and conduct health hazard evaluations. The Office of Toxic Substances in the Environment Protection Agency (EPA) administers the TSCA. Regulatory laws under the OSH Act have clearly influenced other environmental legislation and will probably affect the implementation of the TSCA (a.2).

2.1.1 Federal Regulation of Occupational Health and Safety in the Workplace The OSH Act requires the OSHA: (1) to encourage employers and employees to reduce hazards in the workplace and to implement new or improved safety and health programs; (2) to develop mandatory job safety and health standards and enforce them effectively; (3) to establish separate but dependent responsibilities and rights for employers’ safety and health conditions; (4) to establish reporting and record keeping procedures to monitor job related injuries and illnesses; and, (5) to encourage states to assume the fullest responsibility for establishing and administering their own occupational safety and health programs (a.2). The OSHA thus: inspects workplaces for violations of existing health and safety standards; establishes advisory committees; holds hearings; sets new or revised standards for control of specific substances, conditions, or use of equipment; enforces standards by assessing fines or by other legal means; and, provides constructive services, training and education for both employers and employees. From the development of standards through to their implementation and enforcement, the OSHA upholds the right of employers and employees to be fully informed, to actively participate, and to appeal its decisions (a.2). The coverage of the OSH Act initially extended to all employers and their employees, except self-employed people, family-owned and -operated farms, and workplaces already protected by other federal agencies or other federal statutes. In 1979, however, Congress exempted approximately 1.5 million businesses (with

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Health and Safety in the Rubber Industry

Table 1 Some important rubber polymers Ty p e o f rubber/elastomer

Production (1000s of tonnes in 1993)

Properties

Common uses

Natural rubber

Thailand Indonesia Malaysia India

General purpose; not oilresistant, swollen by solvents; deteriorates when exposed to oxygen, ozone, UV light

Tyres, shock mounts, seals, couplings, bridge and building bearing, footwear, hoses, conveyor belts, moulded products, linings, rolls, gloves, condoms, medical devices, adhesives, carpet backing, thread, foam

Polyisoprene (IR)

US Western Europe Japan

47 General purpose; 15 synthetic natural rubber, 52 similar properties

Styrene-butadiene

US Western Europe Japan

920 General purpose: Second 1,117 World War natural rubber 620 substitute; poor oil/solvent resistance

Polybutadiene (BR)

US Western Europe Japan Eastern Europe

465 297 215 62 (1996)

Butyl (IIR)

US Western Europe Eastern Europe Japan

130 168 90 83

1 ,5 0 1 1 ,3 5 3 923 426

Same as natural rubber ab o ve Tyres (75%), conveyor belts, sponges, moulded goods, footwear, hoses, roll coverings, adhesives, waterproofing, latex carpet backing, foam products

Poor oil/solvent resistance; subject to weathering; high resilience, abrasion resistance and lowtemperature flexibility

Tyres, shoes, conveyor belts, transmission belts, toy superballs

Low gas permeability: resistant to heat, acid, polar liquids; not resistant to oil, solvents; moderate weathering

Inner tubes, tyre curing bladders, caulking and sealants, cable insulation, vibration isolators, pond liners and roofing membranes, high temperature conveyor belts and hoses

Ethylene-propylene/- US Ethylene-Propylene-- Western Europe Diene Japan

261 Low-temperature 201 flexibility; resistant to 124 weathering and heat but not oil, solvents; excellent electrical properties

Wire and cable jackets; extruded weather stripping and seals; moulded products; isolation mounts; liner sheeting for grain storage, roofing, ponds, ditches, landfill

Polychloroprene (CR) (neoprene)

105 Resistant to oil, flame, 102 heat and weather 74

Wire and cable jackets, hoses, belts, conveyor belts, footwear, wet suits, coated fabrics and inflatable products, extrusions, adhesives, bridge and rail mounts, sheeting, sponge gaskets, latex foam products

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US Western Europe Japan

Health and Safety in the Rubber Industry

Table 1 Continued Ty p e o f rubber/elastomer

Production (1000s of tonnes in 1993)

Properties

Common uses

Nitrile (NBR)

US Western Europe Japan Eastern Europe

Resistant to oil, solvents, vegetable oil; swollen by polar solvents such as ketones

Sealants, fuel-resistant hose linings and gaskets, roll coverings, conveyor belts, shoe soles, gloves, adhesives; oil drilling equipment

Silicone (MQ)

US Western Europe Japan

95 Stable at high/low 107 temperatures; resistant to 59 (1990) oil, solvents, weathering; physiologically and chemically inert

Wire and cable insulation, seals, adhesives, gaskets, specialty moulded and extruded goods, gas masks and respirators, food and medical tubing, surgical implants

Polysulfide (OT)

US Western Europe Japan

20 Resistant to oil, solvents, 0 low temperature, 3 weathering; low gas permeability

Roller covering, hose liner, gaskets, moulded goods, sealants, gas meter diaphragms, glass sealants, solid rocket propellant binder

64 108 70 30

Reclaimed rubber

Shorter polymer chains; easier processing; less mixing time and power consumption; lower tensile strength and low cost

Tyres, inner tubes, floor mats, mechanical goods, adhesives, rubberised asphalt

Source: Reproduced with permission from ILO Encyclopaedia of Occupational Health and Safety, 4th edition, 1998, Volume 3, p 80.2, Copyright © International Labour Organization, 1998 (a.1)

10 or fewer employees) from routine OSHA safety inspections. Since federal agencies, such as the US Postal Service, are not subject to OSHA regulations and enforcement provisions, each agency is required to establish and maintain its own effective and comprehensive job safety and health programme. The OSHA provision does not apply to state and local governments in their role as employers, but does require any state desiring to gain OSHA support or funding for its own occupational safety and health programme to provide a programme to cover its state and local government workers that is as effective as the OSHA programme is for private employees. The OSHA can set standards either on its own or when petitioned to do so by other parties, including: the Secretary of Health and Human Services, NIOSH, state and local governments and nationally recognised standards-producing organisation, employers or labour representatives, or any other interested person. The

standard setting process involves input from advisory committees and from NIOSH. When the OSHA develops plans to propose, amend, or delete a standard, these intentions must be published in the Federal Register. Interested parties can then present arguments and pertinent evidence in writing (or at public hearings) in support of or against the changes. The OSHA is authorised to set emergency temporary standards, which take immediate effect but expire within six months. But in order to do this, the OSHA must first determine that workers are in grave danger from exposure to toxic substances or new hazards and are not adequately protected by existing standards. Standards can be appealed through the federal courts, but filing an appeals petition will not delay the enforcement of the standard unless a court of appeals specifically orders it. Employers may make application to the OSHA for variance from a standard or regulation if they lack the means to comply, or if they can prove that their facilities or methods of operation provide effective employee protection.

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Health and Safety in the Rubber Industry

OSHA requires employers of more than 10 employees to maintain records of occupational injuries and illnesses. Irrespective of company size, the following must be recorded: all occupational injuries and diseases resulting in death, and injuries resulting in one or more lost work days, restriction of work or motion, loss of consciousness, transfer to another job, or medical treatment (other than first aid) (a.2).

2.1.2 Workers’ Compensation Workers’ compensation is a legal system designed to shift some of the costs of occupational injuries and illness from workers to employers. Workers’ compensation is a no fault system with a wider coverage than common law. Workplace injuries and illnesses are compensatable even if they are only in part work related and injured workers do not need to prove that their injuries were caused by employer negligence. Workers’ compensation laws generally require employers or their insurance companies to reimburse part of injured workers’ lost wages and their entire medical and rehabilitation expenses. Workers’ compensation provides income benefits medical payments and rehabilitation payments to workers injured on the job and benefits to survivors of fatally injured workers. There are 50 state and three federal workers’ compensation jurisdictions, each with its own statute and regulations. The law prescribes the benefit formulas. Some large employers pay the benefits themselves, but most pay yearly premiums to an insurance company, which then processes all claims and pays compensation to injured workers.

2.2.1.1 Standard of Care of Occupational Health Specialist The standard of care expected of a professional person, an occupational health specialist, is that he/ she performs well and up to the legislated industry standard.

2.2.1.2 Duty to Inform and Warn of Risks to Health and Safety Employers, with assistance from medical advisers, are obliged to inform and warn their workers, including prospective employees, of the potential dangers and inherent risks of the job.

2.2.1.3 Balancing the Risk The courts have determined that the greater the risk to health and safety, the greater the time and expense an employer must expend to lessen the risk(s) to employees.

2.2.1.4 Constructive Knowledge The courts consider the knowledge base in the industry at the time of an alleged negligence when judging whether an employer acted responsibly or not.

2.2.1.5 The State of the Art 2.2 The Law Affecting Health and Safety in the United Kingdom and other European Countries Common law, statutes, and European Directives and Recommendations can affect the employment of people with health problems, and the services available to them (a.3).

2.2.1 Common Law Common law covers both criminal and civil law. For centuries, common law courts have held employers liable for negligence if they have not taken reasonable care of the health and safety of their workers.

8

Employers should grow in their knowledge of health and safety and take advice and information offered to them by occupational health experts.

2.2.1.6 Employer’s Responsibility Employers have a greater responsibility toward employees with known medical conditions. It is vital that employers take informed advice regarding employee fitness for work. In addition, employers are responsible for any special arrangements, precautions or restrictions for employees with disabilities, which might affect the work or the health and safety of the workers and others.

Health and Safety in the Rubber Industry

2.2.1.7 Duty Owed for Mental Breakdown The courts have extended the principle of the employer’s common law duty to include psychiatric injury and the mental well being of employees.

of his employees. That is, he/she should obtain information not only from the manufacturers and suppliers but, where necessary, from other sources.

2.2.2.2 Employer’s Statutory Duties 2.2.1.8 Stress and Other Mental Disorders The employer must be mindful of the strain and trauma of the job and take steps to compensate employees accordingly. The courts have now recognised that an employer must care for both the physical and mental well being of employees.

2.2.1.9 Employees’ Duties In common law, employees have implied duties, including the duty to work with reasonable care and competence and to loyally and faithfully serve their employer.

The HASWA imposes general duties on employers, in Section 2, to take reasonable care of the health, safety and welfare of their employees at work, and to provide: •

A safe system and place of work;

•

Information, instruction and training on matters of health and safety and adequate supervision;

•

A safe system for the handling, storage and transport of substances and materials;

•

A safe working environment.

2.2.2.3 Employees’ Statutory Duties 2.2.2 Statutes

2.2.2.1 UK Health and Safety at Work Act 1974 The 1974 Health and Safety at Work Act (HASWA) defines the statutory duties UK employers must carry out for the reasonable care of their employees (a.4). The HASWA currently imposes only criminal liability. Companies and individual managers and employees can be prosecuted for breaches of their statutory duties. A provision in the HASWA – Section 47 – extends the jurisdiction of the Act permitting employees injured at work to sue in civil court. The Act covers everyone at work, including independent contractors and their employees, the selfemployed and visitors, but excludes domestic servants in private households. Under Section 6 of the HASW Act the manufacturers and suppliers of industrial chemicals have the responsibility to furnish appropriate information relating to the toxic potential of their products. The employer has a duty to provide such information as is necessary to ensure the health and safety at work

Employees’ duties are outlined in Sections 7 and 8. They are to take reasonable care to ensure their own health and safety and that of others, to co-operate on any matter of health and safety and to avoid behaviour or actions, which would endanger their own health and safety or that of others. This includes the duty to inform employers, when a medical history is requested.

2.2.2.4 The Institutions The Health and Safety Commission (HSC) – set up under HASWA as a tripartite body (Government, Confederation of British Industry (CBI) and Trades Union Congress (TUC)) – is responsible for policy. The Health and Safety Executive (HSE) is responsible for enforcing the Act. There are several divisions, the largest of which is the Factory Inspectorate (HMF). The Employment Medical Advisory Service (EMAS) is the field force of the medical division of HSE. Environmental Health Officers – employed by local authorities – carry out enforcement of the Act. Their powers are the same as the Factory Inspectors. Employment protection legislation includes sections on:

9

Health and Safety in the Rubber Industry

1) Standards of evidence of ill health

•

Health and Safety (Display Screen Equipment) Regulations 1992;

•

Personal Protective Equipment at Work Regulations 1992;

•

Provision and Use of Work Equipment Regulations 1992;

5) Interpreting contracts vis-à-vis health and safety

•

Manual Handling Operations Regulations 1992;

6) Recommended check-lists

•

Workplace (Health and Safety Welfare) Regulations 1992.

2) Standards of medical evidence and medical reports 3) Guidance for conflicting medical advice 4) Guidance for disclosure of medical notes

7) Strategies for dealing with misrepresented medical condition(s).

2.2.2.5 UK Control of Substances Hazardous to Health Regulations (COSHH) COSHH imposes duties on employers to protect employees and other persons who may be exposed to substances hazardous to health, and also responsibilities on employees. Employers are required to prevent or, where this is not practicable, to control the exposure to hazardous substances. To help protect workers against ill-health HSE sets occupational exposure limits. There are two types of limit. Maximum Exposure Limits (MELs) and Occupational Exposure Standards (OESs). A MEL is set for substances which may cause the most serious health effect, such as cancer and occupational asthma; these are substances for which no threshold level of exposure for the key health effect can be determined, or for which exposure thresholds may be identified but at a concentration that is not yet routinely achievable in the workplace. COSHH requires that exposure should be reduced as far below the MEL as possible. An OES is set at a level at which (based on current scientific knowledge) there is no indication of risk to the health of workers who breathe it in day after day. If exposure to a substance that has an OES is reduced at least to that level, then adequate control has been achieved. It is recommended that exposure to all airborne contaminants is kept as low as possible (a.5).

These Regulations require that employers do risk assessments where ‘significant and substantial risks to health or safety’ exist and to appoint ‘competent’ persons to assist in this task. Employers are required to do these risk assessments regularly and to keep records of them. Other related health and safety regulations that affect employment of people in the UK are ‘Pre-employment Medical Examinations’ and the ‘Disability Discrimination Act 1995’ (a.3).

2.2.3 European Law

2.2.3.1 General In principle, when the European Union Council of Ministers adopts Directives, the 15 European Member member states are bound to uphold them. This means that employees may sue an employer for breach of the Directives. Since private sector employers are not directly bound by Directives, it is recommended that member states adopt the Directives into national legislation within a predetermined schedule.

2.2.3.2 Qualified Majority Voting (QMV) The matters which involve workers’ health and safety and product safety, require only QMV, 62 out of the possible 87 votes.

2.2.2.6 UK Regulations 1992 In January 1992, the UK introduced the ‘Six Pack’ •

10

The Management of Health and Safety at Work Regulations 1992;

2.2.3.3 Recommendations The Council of Ministers can make Recommendations although these are not legally binding. European Union

Health and Safety in the Rubber Industry

(EU) resolutions and Recommendations have the effect of law only once national provisions or supplements to existing Community measures are adopted.

3 Industrial Safety: Equipment

3.1 Industrial Statistics 2.2.3.4 Working Time Directive The Working Time Directive, under the QMV system, requires member states to limit working hours to 48 in any 7-day period. Scheduled rest breaks and restrictions on the number of night shifts are set out in detail. Organisation of work patterns must take into account health and safety requirements and the adaptation of work to the worker.

2.2.4 Other Codes and Regulations on Health and Safety

Injuries in the American rubber industry are one-quarter of those in other manufacturing industries. According to a 1999 US Bureau of Labor Statistics Survey of Occupational Injuries and Illnesses, the annual injury and illness rate was 269.4 per 10,000 full-time workers in the rubber and plastics industries. The UK rubber industry has had accident rates well above the ‘all manufacturing’ average in the 1990s and the main reason is the high number of handling accidents, according to the British Rubber Manufacturers’ Association. In 1997/1998 manual handling was responsible for over 40% of accidents reported to the HSE in the new tyres sector, retreading, and general rubber goods (67).

2.2.4.1 BRMA Code of Practice The British Rubber Manufacturers’ Association (BRMA) has prepared a Code of Practice on Rubber Chemicals (38) to help to secure the health and safety of people at work in the rubber industry. The practical points which are made are ‘based on the basic principles of occupational hygiene: (1) An assessment of the risk to health and of the precautions needed. (2) The introduction of appropriate measures to control the risk. (3) Ensuring that control measures are used, that equipment is properly maintained and procedures observed. (4) The monitoring, where necessary, of exposure of workers and the provision of appropriate health surveillance. (5) The information, instruction and training of employees about the risks and the precautions to be taken. The Code defines the recommended working procedures for handling compounding ingredients and other chemicals. If these recommended procedures are carefully followed, a high standard of industrial hygiene will be ensured without introducing unnecessary restrictions into the manufacturing operation.’

In the UK, injuries in the rubber and plastic industries reported to the HSE were the primary cause of ‘over three-day sick leaves’. Major injuries have been increasing since 1997 (Table 2). The fatal and major injury rates in 1999/2000 and 1998/1999 were 280.4 per 100,000 employees and 276.3 per 100,000 employees respectively (a.6).

3.2 Mill and Calender Safety This section is reproduced with permission from the ILO: J.R. Townhills, in Encyclopaedia of Occupational Health and Safety, 4th Edition, 1998, Volume 3, 80.1180.13, copyright © International Labour Organization, 1998.

3.2.1 Mill Safety Mills and calenders are used extensively throughout the rubber industry. Running nip accidents (getting caught in the rotating rolls) are major safety hazards during operation of these machines. In addition, there is a potential for accidents during repair and maintenance of these and other machines used in the rubber industry. This article discussed these safety hazards. In 1973 in the United States, the National Joint Industrial Council for the Rubber Manufacturing

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Health and Safety in the Rubber Industry

Table 2 Numbers of injuries in the rubber industry in the UK reported to the HSE 1994-2000 Fatalities

Non-fatal but major injuries

Over three days sick leave

1994-1995

1

329

3186

1995-1996

0

391

3133

1996-1997

3

606

3256

1997-1998

2

673

3608

1998-1999

5

635

3379

1999-2000

2

640

3438

Year

Source: Health and Safety Executive in the UK

Industry concluded that for in-running nip points, a safety device that depended on action of the operator could not be regarded as an effective method of preventing running nip accidents. This is especially true of mills in the rubber industry. Unfortunately, little has been done to force code changes. Currently there is only one safety device that does not require operator action to activate. The body bar is the only widely accepted automatic device that is an effective means of preventing mill accidents. However, even the body bar has limitations and cannot be used in all cases unless modifications are made to the equipment and work practice. The problem of mill safety is not a simple one; there are several major issues involved: •

mill height,

•

the size of the operator,

•

auxiliary equipment,

•

the way the mill is worked,

•

the tack or stickiness of the stock,

•

stopping distance.

Mill height makes a difference as to where the operator works the mill. For mills less than 1.27 m high, where the height of the operator is greater than 1.68 m, there is a tendency to work too high on the mill or too close to the nip. This allows for a very short reaction time for the automatic safety to stop the mill. The size of the operator also dictates how close the operator needs to get to the mill face to work the mill.

12

Operators come in many different sizes, and often must operate the same mill. The majority of the time on adjustment is made to the mill safety devices. Auxiliary equipment such as conveyors or loaders can often conflict with safety cables and ropes. Despite codes to the contrary, often the safety rope or cable is moved to allow for the operation of the auxiliary equipment. This can result in the operator working the mill with the safety cable behind the operator’s head. While the height of the mill and the auxiliary equipment have a part in the way a mill is worked, there are other factors which enter into the picture. If there is no mixing roll below the mixer to distribute the rubber evenly on the mill, the operator will have to physically move the rubber from one side of the mill to the other by hand. The mixing and moving of the rubber exposes the operator to increased risk of strain or sprain injuries in addition to the hazard of the mill nip. The tack or stickiness of the stock poses an additional hazard. If the rubber sticks to the mill roll and the operator has to pull it off the roll, a body bar becomes a safety hazard. Operators of mills with hot rubber have to wear gloves. Mill operators use knives. Tacky stock can grab a knife, glove or bare hand and pull it toward the running nip of the mill. Even an automatic safety device will not be effective unless the mill can be stopped before the operator reaches the running nip of the mill. Stopping distances must be checked at least weekly and the brakes tested at the beginning of each shift. Dynamic electrical brakes must be checked on a regular basis. If the zero switch is not adjusted properly, the mill will move back and forth and damage to the mill will result. For some situations, disc brakes are preferred. With electrical

Health and Safety in the Rubber Industry

brakes a problem can arise if the operator has activated the mill stop button and then tried an emergency mill stop. On some mills the emergency stop will not work after the mill stop button has been activated.

calender safety, see the two publications by the National Joint Industrial Council for the Rubber Manufacturing Industry (Running Nip Accidents, 1959 and Safe Working of Calenders, 1967).

There have been some adjustments made that have improved mill safety. The following steps have greatly reduced exposure to running nip injuries on the mills:

Unfortunately, when a calender or any other piece of equipment has been transferred from one company to another or one country to another, often the accident history is not included. This had resulted in the removal of guards and in dangerous work practices that had been changed because of a prior incident. This has led to history repeating itself, with accidents that have occurred in the past reoccurring. Another problem is language. Machines with the controls and instructions in a different language from the user country makes safe operation more difficult.

•

A body bar should be used on the working face of each mill, but only if the bar is adjustable for the height and reach of the operator.

•

Mill brakes can be either mechanical or electrical, but they must be checked each shift and the distance checked weekly. The stopping distances should comply with the American National Standards Institute (ANSI) stopping distance recommendations.

Calenders have increased in speed. The braking ability of these machines has not always kept pace with the equipment. This is especially true around the calender rolls. If these rolls cannot be stopped in the recommended stopping distance, an additional method must be used to protect employees. If necessary, the calender should be equipped with a sensing device that will slow the machine when the rolls are approached during operation. This has proven very effective in keeping employees from getting too close to the rolls during the operation of the machine.

•

Where mixer mills have hot, tacky stock, a twomill system has replaced the single-mill system. This has reduced operator exposure and improved the mixing of the stock.

•

Where operators are required to move stock across a mill, a mixing roll should be added to reduce operator exposure.

•

Current mill work practices have been reviewed to ensure that the operator is not working too close to the running nip on the mill. This includes small lab mills, especially where a sample may require numerous passes through the running nip.

Some of the other major areas identified by the National Joint Industrial Council are still a source of injuries today: •

clearing jams and adjusting material,

Mill loaders have been added on mills to load stock. This has eliminated the practice of trying to load a mill using a fork truck, and has eliminated any conflict with the use of a body bar as a safety device.

•

running nip injuries, especially at wind-ups,

•

threading up,

•

communications.

•

Currently technology exists to improve mill safety. In Canada, for example, a rubber mill cannot be operated without a body bar on the working face or front of the mill. Countries receiving older equipment from other countries need to adjust the equipment to fit their workforce.

3.2.2 Calender Safety Calenders have many configurations of machines and auxiliary equipment, making it difficult to be specific on calender safety. For a more in-depth study in

An effective, well understood lockout programme (see below) will do much to reduce or eliminate injuries from the clearing of jams or the adjusting of material while the machine is in operation. Proximity devices that slow the rolls when they are approached may help deter an adjustment attempt. Running nip injuries remain a problem, especially at wind-ups. Speeds at the wind-up must be adjustable to allow for a slow start-up at the beginning of the roll. Safeties must be available in the event of a problem. A device that slows the roll when it is approached will tend to discourage an attempt to adjust a liner or fabric

13

Health and Safety in the Rubber Industry

during the wind-up. Telescoping rolls are a special temptation for even experienced operators. The problem of threading-up incidents has increased with the speed and complexity of the calender train and the amount of auxiliary equipment. Here the existence of a single line control and good communications are essential. The operator may not be able to see all of the crew. Everyone must be accounted for and communications must be clear and easily understood. The need for good communications is essential to safe operation when a crew is involved. Critical times are when adjustments are being made or when the machine is started at the beginning of a run or started after a shut-down which had been caused by a system that audits both. The answer to these problems is a well-trained crew that understands the problems of calender operation, a maintenance system that maintains all safety devices in working condition and a system that audits both.

3.2.3 Machine Lockout The concept of machine lockout is not new. While lockout has been generally accepted in maintenance programmes, very little has been done to gain acceptance in the operating area. Part of the problem is the recognition of the hazard. A typical lockout standard requires that “if the unexpected movement of equipment or release of energy could cause injury to an employee then that equipment should be locked out”. Lockout is not limited to electrical energy, and not all energy can be locked out; some things must be blocked in position, pipes must be disconnected and blanked, stored pressure must be relieved. While the lockout concept is viewed in some industries as a way of life, other industries have not accepted it due to the fear of the cost of locking out. Central to the concept of lockout is control. Where a person is at risk of injury as the result of movement, the power source(s) must be disabled and the person or persons at risk should have control. All situations requiring lockout are not easy to identify. Even when they are identified, it is not easy to change work practices. Another key to a lockout programme which is often overlooked is the ease with which a machine or line can be locked out or the power isolated. Older

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equipment was not designed or installed with a single breaker for several machines. Other machines have multiple power sources, making lockout more complicated. To add to this problem, motor control room breakers are often changed or feed additional equipment, and the documentation of the changes is not always kept current. The rubber industry has seen general acceptance of lockout in maintenance. While the concept of protecting one’s self from the dangers of unexpected movement is not new, the uniform use of lockout is. In the past, maintenance personnel used different means to protect themselves. This protection was not always consistent due to other pressures such as production, and not always effective. For some of the equipment in the industry, the lockout answer is complex and not easily understood. The tyre press is an example of a piece of equipment for which there is little consensus on the exact time and method for lockout. While the complete lockout of a press for an extensive repair is straightforward, there is no consensus about lockout in such operations as mould and bladder changes, mould cleaning and unjamming equipment. The tyre machine is another example of difficulty in lockout compliance. Many of the injuries in this area have not been to maintenance personnel, but rather to operators to operators and tyre technicians making adjustments, changing drums loading or unloading stock or unjamming equipment and to janitorial employees cleaning the equipment. It is difficult to have a successful lockout programme if the lockout is time consuming and difficult. Where possible, the means to disconnect should be available at the equipment, which helps with ease of identification and can eliminate or reduce the possibility of someone being in the danger zone when the energy is returned to the equipment. Even with changes that make identification easier, no lockout can ever be considered complete unless a test is made to be sure the correct power isolation devices were used. In the case of work with electrical wiring, a test should be made after the disconnect is pulled to ensure that all power has been disconnected. An effective lockout programme must include the following: •

The equipment should be designed to facilitate a lockout for all energy sources.

Health and Safety in the Rubber Industry

•

Lockout sources must be identified correctly.

•

Work practices requiring lockout must be identified.

•

All employees affected by lockout should have some training in lockout.

•

Employees who are required to lockout should be trained and advised that lockout is expected and that anything less is unacceptable under any circumstances.

•

The programme needs to be audited on a regular basis to make sure that it is effective.

4 Fire and Explosions In the rubber industry, the risk of fires and explosions is high, and not only during the manufacturing process involving flammable solvents, but also during storage (of raw materials and finished products) and disposal (of flammable wastes). Some liquids such as solvents can give off large volumes of flammable vapours at room temperature. When mixed with air at room temperature, these vapours can ignite, often violently. Therefore, spills on clothing represent a serious risk of injury. To mitigate these risks contaminated materials should be disposed of safely or disposal experts called in, and flammables should be: •

stored in a separate storage area, or a specially designed bin or closet;

•

dispensed and used in a safe place where there is good ventilation and no sparking;

•

kept in closed containers when not in use. If possible, use safety containers which have selfclosing lids;

•

dispensed over a tray with non flammable, absorbent material handy for mopping up spills.

Some solid finished products, like rubber, are also flammable. When ignited they give off plumes of dense black smoke. Consequently: •

keep these materials away from heaters or electrical equipment,

•

keep gangways and exits to and from storage and working areas clear of flammable packaging materials and finished products.

More extensive treatment of this subject can be found in the HSE publication, ‘Safe Working with Flammable Substances’ (a.7).

5 Solvents Solvents are used extensively in the rubber industry during the manufacturing process to prevent tackiness. Solvents are also used to degrease and clean workshops. Users must recognise where particular solvents are likely to occur, namely: that aliphatic hydrocarbons are used for the freshening of rubber surfaces; aromatic hydrocarbons (like toluene and xylene) are likely to be found in rubber solutions; carbon disulfide is used in the traditional cold cure process; and, chlorinated hydrocarbons (like methylene chloride) are used in the production of non-flammable adhesives (a.8, a.9).

5.1 Health Effects The main effects of solvents are irritation to the skin, eyes and lungs, headache, nausea, dizziness and lightheadedness. Exposure can impair coordination making workers prone to falling-type accidents. A person may lose concentration or have a reduced reaction time thus affecting judgment of important or difficult tasks. These effects will vary and can be exacerbated by drinking alcohol. Very high exposure, especially where adhesives are used in unventilated, confined spaces, may cause unconsciousness and even death. A person who has been exposed to solvents and feels their health has been adversely affected should seek medical advice. Other effects vary according to the solvent, several are reviewed here.

5.1.1 Benzene: C6H6 Benzene is a volatile, colorless, clear, flammable liquid used to test the swelling property of rubber (i.e., the swelling index). It has also been used as a solvent in the rubber and shoe industries and in adhesives and paint removers. Benzene is absorbed systemically by inhalation and skin absorption. Acute effects on the nervous system include headache, tiredness, nausea, dizziness, narcosis and loss of consciousness. These

15

Health and Safety in the Rubber Industry

acute symptoms occur at high exposures (i.e., air concentrations of 7,500 ppm for more than 30 minutes cause narcosis leading to death), but there is considerable individual variability in response to benzene. Chronic effects include depression of bone marrow function and an increased risk of aplastic anaemia and leukaemia. It is also suspected of causing multiple myeloma. Haematotoxic effects have also been documented at chronic exposures of more than 50 ppm. Chronic benzene poisoning affecting the nervous system may even result in behavioural and psychomotor changes. Exposure limits for benzene in air vary according to different agencies. The US Occupational Health and Safety Administration (OSHA) has a permissible exposure level (PEL) of 1 ppm; the US National Institute for Occupational Safety and Health (NIOSH) has a threshold limit value (time-weight average; TWA) of 0.1 ppm. The Health and Safety Executive in the UK set the 2000 maximum exposure limit (MEL) for benzene at 3 ppm (TWA) and this current limit will be reduced to 1 ppm in 2003 (a.10). Preventive measures have focused on the elimination or substitution of benzene, and on reduction of exposure. According to the UK Injuries, Disease, and Dangerous Occurrences Regulations (RIDDOR), 1985, cases of poisoning by benzene must be reported by employers.

5.1.2 Toluene: C6H5CH3 Toluene or methylbenzene is a monomethyl derivative of benzene. Toluene is used to indicate the swelling index of rubber. Acute exposure to concentrations >200 ppm may result in headache, dizziness, irritation of the eyes, nose and throat, paresthesia, incoordination, confusion and narcosis. Chronic exposure may give rise to muscle weakness, abdominal pain, impairment of gait/balance, ataxia, peripheral neuropathy and altered mental state. Enlargement of the liver and neurobehavioural effects have been documented. Effects on the blood system similar to benzene have been attributed to benzene being present as a contaminant in some commercial batches of toluene. The 2000 UK occupational exposure limit for toluene was 50 ppm (8-hour TWA reference period) with a short-term exposure limit of 150 ppm (a.10).

5.1.3 Xylene: C6H4(CH3)2 Xylene, or dimethyl benzene, is a volatile flammable liquid. Xylene is used to test the swelling property of

16

rubber, just as benzene and toluene are, and for cleaning rubber surfaces. Acute exposure to xylene irritates the skin, mucous membranes and respiratory tract. Systemic effects are similar to those described for other organic solvents acting on the central nervous system (CNS) including headache, nausea, vomiting, dizziness, drowsiness, confusion and coma. CNS symptoms have been reported at inhalation exposure levels of ~700 ppm (a.11). In rodent experiments, delayed fetal development was related to inhalation of xylene, and increased malformations after ingestion of high doses. In a study of university laboratory employees exposed in the first trimester of pregnancy to a variety of solvents including xylene, miscarriage rates were slightly increased but not significantly different from pregnancies where no solvent exposure occurred. There are no adequate epidemiological data confirming xylene as a reproductive hazard to humans (a.11).

5.1.4 Methylene Chloride (dichloromethane): CH2Cl2 Methylene chloride is a solvent used for surface cleaning before applying an adhesive. It is also used as a blowing agent in foam. Prolonged skin contact with the liquid may produce chemical burns (a.12). The principal action is on the CNS as a narcotic causing headache, giddiness, irritability, and numbness and tingling in the limbs. Higher concentrations may cause light-headedness, drowsiness, unconsciousness and sometimes death. However, it is less toxic to the liver than other chlorinated hydrocarbons.

5.1.5 1,1,1-Trichloroethane (Methylchloroform): CH3CCl3 Methylchloroform is a colourless volatile liquid with a heavy chloroform-like, sweetish smell – the odour threshold being ~100 ppm. It is non-flammable but decomposes to hydrochloric acid and phosgene on heating over 360 ºC. In the rubber industry, it is used for degreasing and cleaning workshops. Acute inhalation at high concentrations has a depressant action on the CNS and may produce narcosis. Early effects are dizziness, lassitude and headaches but very high concentrations may cause a loss of consciousness, even death. Fatalities have occurred among victims in confined spaces where concentrations were between 5,000 and 50,000 ppm (a.13).

Health and Safety in the Rubber Industry

6 Epidemiology In the 1920s and 1930s, reports from the United Kingdom indicated that rubber workers had higher death rates than the general population and that the excess deaths were from cancer. In the late 1940s, British rubber workers had an increased risk of bladder cancer due to exposure to an antioxidant that contained 1-naphthylamine (alphanaphthylamine) and 2-naphthylamine (betanaphthylamine) (a.1). In the United States, early investigations by Mancuso and co-workers (1968) revealed excess cancer deaths among a cohort of Ohio rubber products workers employed in 1938 and 1939. By 1970, the United Rubber, Cork, Linoleum, and Plastic Workers of America (URW) joined with six major American rubber companies to establish a joint occupational health programme. They negotiated a contract with the Schools of Public Health at Harvard and North Carolina Universities to conduct epidemiological studies of rubber workers. The research focused on cancer incidence and mortality (467). The programme was discontinued in 1980. In 1982, the International Agency for Research on Cancer (IARC) published a rubber industry monograph evaluating the available epidemiological, toxicological and industrial hygiene data (467). The principal adverse health effects reported were cancer and respiratory effects (e.g., reductions in pulmonary function, chest tightness, shortness of breath and other respiratory symptoms. The conclusion was that sufficient evidence existed to associate leukaemia with occupational solvent exposure in the rubber industry. No clear evidence indicated the cause of excess bladder cancers in British or American rubber workers. Limited evidence associated stomach, lung and skin cancers with occupational exposures in the rubber industry. There was inadequate evidence to link lymphoma, colon, prostate, brain, thyroid, pancreatic and oesophageal cancers with industry-related exposures. The current risk for cancer and other chronic diseases in rubber product workers are unknown because of the dearth of epidemiological and industrial hygiene research in the past decade. Toxicity data are also lacking for many chemical formulations found in tyre and non-tyre manufacturing. Categories of rubber compounding additives include (467): Accelerators Organic vulcanisers Antioxidants Pigment blends Antiozonants Plasticisers Antitack agents Reinforcing agents Extenders Resins Fillers Solvents. Oils (process and extender)

Workers in the rubber industry are also exposed to chemical by-products and curing fumes. In 1990 NIOSH recommended measures to reduce worker exposures to o-toluidine and aniline (chemicals used as intermediates in the manufacture of rubber antioxidants and accelerators) to the lowest feasible concentrations (a.14). The epidemiological evidence reported by NIOSH (a.15) showed an increased risk of bladder cancer among workers at a plant that manufactured rubber antioxidants and accelerators – an association of occupational exposure to o-toluidine and aniline. However, it is not known whether a similar risk exists for workers involved in the manufacture of rubber products. Most studies of cancer among rubber product workers were conducted as retrospective cohorts, or case control mortality studies, of workers employed in the tyre and non-tyre industries between 1940 and 1975 including those summarised in Table 3. Kogevinas and co-workers reviewed the literature and found an excess risk (1.5 times other studies) of bladder cancer, lung cancer, and leukaemia in 12 cohort studies in nine countries (a.30). By contrast, Straughan and Sorahan and co-workers completed an incidence survey of recent entrants (1982-91) to the UK rubber industry and found no excess deaths from lung and stomach cancer in the workers compared with the national rate. The only statistically significant excess was for cancer of the testis (observed 3, expected 0.51, SMR 589, 95% confidence interval 122 to 1,722) (a.29). Occupational exposure data do not exist for most of these studies so these have had to be estimated. The uncertainty of these exposure estimates is exacerbated by chemical formulations that differ with each plant or process.

7 Natural Rubber Latex Allergy Table 4 lists the uses of natural rubber latex, which is found in a variety of applications. Dipped products account for 75% of latex use. There are three main methods of dipping: (1) straight for thin items such as condoms, (2) coagulant for thicker products such as medical, household, and industrial gloves; balloons, bladders and catheters, and (3) heat sensitive for the thickest products such as baby bottle nipples (20). NRL is the milky sap of the tree Hevea brasiliensis. The protein contained in NRL products is the cause of

17

Health and Safety in the Rubber Industry

Table 3 Epidemiological studies of cancer in the rubber industry Epidemiological studies

Type of cancer

Fox and Collier (1976) (473) Monson and Nakano (1976) (a.16) Bovet and Lob (1980) (a.17) Checkoway and co-workers (1981) (470) Negri and co-workers (1989) (365) Strauss and co-workers (1993) (a.18)

Bladder cancer (P < 0.05)

McMichael and co-workers (1975) (474) Wolf and co-workers (1981) (471) Arp and co-workers (1983) (466) Checkoway and co-workers (1984) (a.19) Santos Burgoa and co-workers (1992) (a.20)

Lymphatic and haematopoietic cancers

Fox and co-workers (1974) (475) Monson and Fine (1978) (a.21) Parkes and co-workers (1982) (468) Delzell and co-workers (1982) (a.22) Delzell and Monson (1985) (a.23) Andjelkovich and co-workers (1988) (a.24) Zhang and co-workers (1989) (366) Weiland and co-workers (1996) (a.25)

Lung and pleural cancer

McMichael and co-workers (1974) (a.26) Andjelkovich and co-workers (1976) (a.27) Blum and co-workers (1979) (a.28) Parkes and co-workers (1982) (468) Sorahan and co-workers (1986) (445) Sorahan and co-workers (1989) (367)

Stomach cancer

Delzell and Monson (1981) (469)

Colon cancer

Goldsmith and co-workers (1980) (472)

Prostate cancer

Delzell and Monson (1981) (469)

Liver and biliary cancer

Parkes and co-workers (1982) (468)

Oesophageal cancer

Straughan and Sorahan (2000) (a.29)

Testicular cancer

Table 4 Natural rubber latex products (a.31) Dipped products

Condoms, balloons, gloves, bladders, catheters, bottle nipples, other medical devices

Elastic thread

Garment industry

Foam

Moulded mattresses and cushions

Adhesives

Tape, packaging, envelopes and footwear

Carpet industry

Binder for backing compounds

Miscellaneous

Rubberised coir or hair for upholstery; cast products (toys); latex sheeting (e.g., dental dams)

18

Health and Safety in the Rubber Industry

NRL allergies experienced by glove users. Additionally, some rubber industry workers such as tappers and glove manufacturers suffer NRL allergies. The main routes of exposure to the proteins are direct skin contact and inhalation. The spectrum of clinical signs ranges from contact urticaria (nettle-like rash), generalised urticaria, allergic rhinitis (inflammation of the nasal mucosa), allergic contact dermatitis (itchy eyes and skin), angioedema (severe swelling) and asthma (wheezing) to anaphylaxis (a severe, life-threatening allergic reaction, the US Food and Drug Administration (FDA) reports that around 27 deaths annually are caused this way). Predisposing factors include: hand eczema, allergic rhinitis, allergic conjunctivitis or asthma (among individuals frequently wearing gloves), mucosal exposure and multiple surgical procedures. Latex allergy is confirmed by a positive wear or use test with NRL gloves, a correct positive skin prick test to NRL or a positive RAST (radioallergosorbent test) blood test. Severe allergic reactions have occurred from the prick and wear tests. Therefore, epinephrine (adrenaline) and resuscitation equipment free of NRL must be available during these procedures (20). NRL allergy may be associated with allergic reactions to fruit, especially bananas, chestnuts and avocados. Hyposensitisation to NRL is not yet possible so NRL avoidance and substitution is imperative for sensitive persons. Prevention and control of NRL allergy includes NRL avoidance in healthcare settings and rubber industries for affected workers. Synthetic non-NRL gloves should be made available for the affected workers and their co-workers. A proper dust mask should be donned to reduce inhalation of NRL aerosols. Local exhaust ventilation should be installed where NRL allergens are emitted. Monitoring of NRL allergens in the workplace is not readily available, however, accurate methods of measuring NRL allergens in the air exist. In NRL glove factories, rubber plantations and hospitals, respectively, the geometric means of NRL allergens in the air were 7.3, 2.36 and 0.46 µg/m3 (32).

1,000 workers in the United Kingdom, Australia and Finland, respectively. California has a rate of 7 cases per 1,000 workers but this includes plastic workers (20). In the UK, dermatologists and occupational physicians reported that 16-17% of occupational cases of contact dermatitis were caused by rubber chemicals (a.6). Skin reactions among rubber product users have become more frequent and include irritant contact dermatitis, allergic contact dermatitis, contact urticaria (hives), aggravation of pre-existing skin diseases and other less common skin disorders such as oil folliculitis, xerosis (dry skin), miliaria (heat rash) and depigmentation from certain phenol derivatives. Irritant contact dermatitis is the most frequent reaction and is caused by either acute exposure to strong chemicals or cumulative exposure to weaker irritants such as those found in wet work and in repeated use of solvents. In a Finnish study, 56% of all cases of contact dermatitis had irritant dermatitis, mostly from solvents and bulk rubber (a.32). Allergic contact dermatitis is a delayed type of allergic reaction from the accelerators, vulcanisers, antioxidants and antiozonants, which are added during rubber production. These chemicals are often present in the final product and may cause contact dermatitis in both the end users and rubber workers, especially in those working with Banbury, calender, extruder and assembling operations. Some workers acquire contact dermatitis while doing tasks that do not permit the use of protective clothing. Some workers have even developed allergies to the protective clothing itself, most commonly rubber gloves. The key medical test to the suspected allergen is a valid positive patch test. The patch test is performed using the various common allergens to distinguish allergic contact dermatitis from irritant contact dermatitis. However, allergic contact dermatitis (Table 5) may coexist with irritant contact dermatitis as well as with other skin disorders (20). Table 5 shows some of the rubber chemicals associated with allergic contact dermatitis.

8 Skin Irritation and Dermatitis Adverse skin reactions have been frequently reported among workers who have direct contact with rubber and with the hundreds of chemicals used in the rubber industry. Contact dermatitis is relatively common among rubber workers but less so among rubber users. Prevalence rates from industrial studies were 3.1, 3.7 and 5.6 cases per

9 Dust and Fume

9.1 Dust Working with, and handling raw materials used in, the rubber industry exposes workers to high levels of dust.

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Health and Safety in the Rubber Industry

Table 5 Agents causing contact dermatitis in rubber product workers (a.33) Chemical

Process

Product

2(2´-4´ Dinitrophenylthio) benzothiazole, which was contaminated with dinitrochlorbenzene

All areas

Tyres

4,4´-Dithiodimorpholine

Not specified

Tyres

n-Isopropyln´phenylparaphenylenediamine (IPPD)

Assembly, maintenance, compounding

Tyres

n-Dimethyl-1,3-butyl-n´phenylparaphenylenediamine

Assembly, maintenance compounding

Tyres

para-Phenylenediamine compounds

Not specified

Tyres, footwear

Ethylene thiourea (ETU)

Sewing

Non-tyre products

Resorcinal

Not specified

Tyres

Thiuram mix

Vulcanising

Rubber gloves

Mercapto mix

Vulcanising

Rubber gloves

Rubber process dust arises during rubber manufacture where ingredients are handled, weighed, added to (or mixed with) uncured material or synthetic elastomers. For all such mixed dust, the aggregated occupational exposure limit (OEL) in the UK is 6 mg/m3 (maximum exposure limit (MEL), a.10) except where a specific limit exists for a given chemical. In such cases, where the chemical is present in a concentrated form, the specific limit applies. The most common dust types in the rubber industry are carbon black and talc, otherwise only a small proportion of rubber chemicals have yet

been assigned official exposure limits. Silica is used in rubber as a filler and has a carcinogen rating.

9.1.1 Carbon Black Carbon black is a substance of world importance in terms of both tonnage produced and its special ability to strengthen rubber. Carbon black is a very fine powdery form of elemental carbon manufactured by controlled vapour phase pyrolysis of, mainly liquid, hydrocarbons (Table 6). Its carbonaceous nature and

Table 6 Physical and chemical properties of carbon black by the four methods of manufacture Property

Furnace

Thermal

Channel

Lamp black

Particle diameter (nm)

13-80

150-500

9-29

30-200

Surface area (m2/g)

20-250

5-15

100-1000

15-95

Volatile material (%)

0.3-5.0

0.1-0.5

3.5-16

0.5-15

3.5-9

7- 9

3-6

3-7

Inorganic impurities (%)

0.3-1.0

0.05-0.4

≤0.3

0.01-0.15

Organic impurities (%)

0.01-0.3

0.02-1.7

≤0.1

0.01-1.5

Sulfur (%)

0.1-1.5

≤0.3

≤0.2

0.01-10

97.9 0.4 0.7

99.3 0.3 0.1

98 0.2 0.8

98 0.4 0.4

pH

Composition (%) - carbon - hydrogen - oxygen

Redrawn with permission from K. Gardiner, The Health Effects of Carbon Black, in Hazards in the European Rubber Industry Conference, 1999 (53)

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Health and Safety in the Rubber Industry

respirable size causes respiratory morbidity to those involved in its manufacture and use (53). Carbon black is a respirable dust when particle diameters are