I a STUDY of CO-EXPOSURE to CHEMICALS and NOISE ON
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A STUDY OF CO-EXPOSURE TO CHEMICALS AND NOISE ON HEARING IN THE RUBBER INDUSTRY By Ivan Niranjan Master of Public Administration (UKZN) A research thesis submitted in fulfilment of the requirements for the degree of Doctor of Technology: Quality Management In the Department of Operations and Quality Management Faculty of Management Sciences Durban University of Technology 20th February 2014 i Dedicated to my wife CARESSE and daughters KIARA and ALKA ii DECLARATION OF CANDIDATE I, Ivan Niranjan, hereby declare that except where acknowledged, this thesis is entirely my own work, that all resources used or quoted have been acknowledged and that this study has not previously been submitted for any degree to any other tertiary educational institution. ________________________ Ivan Niranjan Student No. 18902511 APPROVED FOR SUBMISSION ______________________________ _______________ Professor Malcolm Wallis (Supervisor) Date (PhD) iii ACKNOWLEDGEMENTS I would like to extend my sincere appreciation to the following people who have made the research possible: • God for giving me the strength and determination to complete this study. • My wife Caresse and daughters Kiara and Alka for the total support and sacrifices during my studies. • To my parents, Mrs and the late Mr. Niranjan for their encouragement and support throughout my studies • My promoter, Professor Malcolm Wallis, whose guidance, objectivity, understanding, patience and insight have contributed to realizing this study. To Dr Poovendree Reddy, Head of Department Community Health Studies for her supervision of the epidemiological aspects of the study and the thesis in its entirety. • To Mr. Trevor Naidoo, Head of Department and Dr Shalini Singh, Senior Lecturer in the Department of Operations and Quality Management and Mr. Moeti Kgware, former Head of Department of Community Health Studies, for their support and understanding throughout my study. • My research assistants Kershnee Pather, Odwa Mtimkulu, Roxanne Devraj, Nozipho Ncalane, Thulisile Tshabalala and Pinkie Hlope who contributed to the data collection process. iv • My statistician, Mrs Tonya Esterhuizen whose direction, support, impartiality and perseverance positively developed this study. • The Post Graduate Studies Unit at the Durban University of Technology Prof A. Jordaan, Ms Sheena Perumal, Ms Nickey Muller, Ms Avasha Lutchman all the support during the duration of my study. • To all those who assisted me in completing this study, thank you. v ABSTRACT Hearing conservation in the industrial setting has mainly focussed on the harmful effects of noise exposure on the auditory system. This study investigated the co-exposure to noise and ototoxic chemicals on the auditory system of workers engaged by labour brokers. It examined the adequacy of current occupational health and safety legislation to address chemically induced hearing loss and makes recommendations at a policy level to protect workers’ hearing at the workplace. This study is an exploratory cross-sectional field case study in an industrial setting. A sample of 300 workers was drawn from a rubber factory involved in the manufacture of components for the motor, shoe and plumbing industries in the metropolitan area of Durban. Purposive sampling was undertaken amongst a cohort of day shift workers which constituted the research subjects. The research tools used in the study included the completion of the NoiseChem questionnaire, conducting pure tone audiometric testing on research subjects, monitoring noise exposure levels and performing chemical air monitoring of the ambient environment. This study confirms that a segment of the research subjects were exposed to both ototoxic chemicals and noise. Chemical exposure of research subjects was within legal permissible limits in most instances. Noise exposure exceeded the noise rating limit of 85 dBA in certain work areas. Multiple regression analysis revealed that there was a slight trend towards co-exposure to chemicals and noise being risk factors for hearing loss with an odds ratio of 1.7 (95% CI = 0.34 – 8.57) but the p value was not significant. No significant association with hearing loss was evident for workers exposed to chemical only with odds ratio of 0.41 (95% CI = 0.11 – 1.53, p = 0.19) and noise only with odds ratio of 0.87 (95% CI = 0.32 – 2.31, p = 0.78). The study indicated that workers exposed to both ototoxic chemicals and noise may be more susceptible to hearing loss in their current jobs. The study draws attention to policy gaps in the Occupational Health and Safety Act and proposes changes to address the shortcomings. vi TABLE OF CONTENTS Dedication ii Declaration by candidate iii Acknowledgement iv Abstract vi Table of contents vii Abbreviations xv Definition of terms xvii Study definition of noise induced hearing loss xix Scientific conference which emanated from this study xx CHAPTER ONE: INTRODUCTION 1.1 Study setting 1 1.2 Background to the study 1 1.3 Motivation for the study 6 1.4 Problem statement 6 1.5 Research objectives 7 1.6 The research design 7 1.7 Limitation of the study 7 1.8 Restriction of access to organizations 8 1.9 Structure of the succeeding chapters 10 CHAPTER TWO: CO-EXPOSURE TO CHEMICALS AND NOISE ON HEARING 2.1 Introduction 13 2.2 International perspectives on chemically induced hearing loss 16 2.3 The human mechanism of hearing 20 2.4 Origins of occupational hearing loss and the value of good hearing 27 2.5 Confounders to hearing impairment 28 2.6 Rubber manufacturing process 39 2.7 Human resource management 41 vii 2.8 Globalization and its effects on occupational health and safety 49 2.9 Summary of chapter 52 CHAPTER THREE: GLOBAL STANDARDS IN THE CONTEXT OF QUALITY MANAGEMENT 3.1 Introduction 53 3.2 Overview of international standards 54 3.3 The quality management system ISO 9001:2008 56 3.4 Environmental management system ISO 14001:2004 58 3.5 Safety management system OHSAS 18001:2007 60 3.6 Occupational health and safety management system OHSAS 61 18001:2007 3.7 Social accountability 8000 (SA 8000:2008) 64 3.8 International labour conventions 67 3.9 International labour organization (ILO) 155: Occupational safety 68 and health convention, 1981 3.10 Social accountability management systems (SA 8000 : 2008) 69 3.11 HIV and AIDS management systems: SANS 16001:2007 71 3.12 King III Report on governance for South Africa 2009 74 3.13 Consolidation of national and international standards 77 3.14 Summary of Chapter 79 CHAPTER FOUR: LEGISLATION UNDERPINNING OCCUPATIONAL HEALTH AND SAFETY IN SOUTH AFRICA 4.1 Introduction 80 4.2 The South African Constitution Act 1996 (108 of 1996) 81 4.3 The Occupational Health and Safety Act, 1993 (Act 85 of 1993) 82 4.4 Enforcement of the Occupational Health and Safety Act, 1993 (Act 94 85 of 1993) 4.5 Assmang manganese poisoning cases in Cato Ridge 96 4.6 Compensation for Occupational Injuries and Diseases Act, 1993 100 (Act 130 of 1993) viii 4.7 Circular Instruction No 171–Compensation for Occupational 102 Injuries and Diseases Act, 1993 (Act 130 of 1993) 4.8 The South African National Standards 10083:2004-the 103 measurement and assessment of occupational noise for hearing conservation purposes 4.9 The Draft National Occupational Health And Safety Policy And Bill, 106 2005 4.10 Magnitude of the occupational health and safety problem in South 108 Africa 4.11 Benefits of an integrated occupational health and safety system 109 4.12 Overcoming institutional and policy fragmentation of occupational 110 health and safety 4.13 Major occupational health and safety challenges 113 4.14 White paper on transformation of the health system 115 4.15 International best practice 116 4.16 Summary of chapter 116 CHAPTER FIVE: RESEARCH METHODOLOGY 5.1. Introduction 118 5.2 Research methodology and design 119 5.3 Request to conduct study at the rubber manufacturing organization 121 5.4 Informed consent 121 5.5 Study design 121 5.6 Sampling 122 5.7 Statistical analysis 124 5.8 Research instruments used in the study 125 5.9 Summary of chapter 130 CHAPTER SIX: RESULTS 6.1 Introduction 131 6.2 Statistical methodology 132 6.3 Demographic profile of research subjects 133 ix 6.4 Consolidation of demographic variables 134 6.5 Chemical exposures in the workplace 135 6.6 Noise exposure monitoring 137 6.7 Workers exposed to chemicals 139 6.8 Hearing threshold by each frequency and each ear 140 6.9 Linear models of hearing loss at each frequency and each ear 142 6.10 Noise induced hearing loss at 4khz at equivalent and above 25 dB 143 bilaterally 6.11 Hearing loss association 144 6.12 Noise induced hearing loss at 3, 4 or 6kHz at equivalent or above 145 25 dB 6.13 Noise induced hearing loss from 1kHz to 8kHz at equivalent and 146 above 25 dB bilaterally in the four exposure groups 6.14 Factors affecting hearing loss 147 6.15 Logistic regression model and the study definition of noise induced 161 hearing loss 6.16 Adequacy of current legislation on hearing loss acquired through 163 chemical exposure 6.17 Effectiveness of existing quality and safety management systems 165 6.18 Summary of chapter 171 CHAPTER SEVEN: DISCUSSION OF RESEARCH RESULTS 7.1 Introduction 172 7.2 Demographic profile of research subjects 172 7.3 Distribution of Research Subjects by Employer and Labour Broker 174 7.4 Workers ototoxic chemical exposures in the workplace 177 7.5 Workers noise exposure in the workplace 180 7.6 Confounding factors that predisposes research subjects to hearing 182 loss 7.7. Odds Ratio hearing loss (Combined exposure to chemicals and 185 noise on hearing) x 7.8 Adequacy of current legislation on hearing loss acquired 186 7.9 Safety, Quality and Environmental Management 187 7.10 Summary of chapter 188 CHAPTER EIGHT: CONCLUSION AND RECOMMENDATIONS 8.1 Introduction 189 8.2 Summation of study 190 8.3 Way forward 191 8.4 Conclusion 197 9.