Dr. Toye Gabriel Olajide
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PREVALENCE OF NOISE INDUCED HEARING LOSS AMONG SELECTED BOTTLING COMPANY WORKERS IN ILORIN, NIGERIA A DISSERTATION SUBMITTED BY DR. TOYE GABRIEL OLAJIDE TO THE NATIONAL POSTGRADUATE MEDICAL COLLEGE OF NIGERIA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE FELLOWSHIP OF THE MEDICAL COLLEGE IN OTORHINOLARYNGOLOGY (FMCORL) SUPERVISORS: (1) DR. F.E. OLOGE FWACS, FMCORL DEPT. OF OTORHINOLARYNGOLOGY, UNIVERSITY OF ILORIN TEACHING HOSPITAL, ILORIN. NIGERIA. (2) PROF. C.C. NWAWOLO FWACS, FMCORL ENT UNIT, DEPT. OF SURGERY, LAGOS UNIVERSITY TEACHING HOSPITAL, LAGOS. NIGERIA. CERTIFICATION We, the undersigned, hereby certify that this research titled “PREVALENCE OF NOISE INDUCED HEARING LOSS AMONG SELECTED BOTTLING COMPANY WORKERS IN ILORIN, NIGERIA” was duly carried out within the guidelines of the National Postgraduate Medical College of Nigeria, under our supervision. Dr. F.E. Ologe, FWACS, FMCORL Senior Lecturer and Consultant Otorhinolaryngologist, Department of Otorhinolaryngology, University of Ilorin Teaching Hospital, Ilorin. ………………………………… Prof. C.C. Nwawolo FWACS, FMCORL Assoc. Prof. and Consultant Otorhinolaryngologist, ENT Unit, Department of Surgery, Lagos University Teaching Hospital, Idi-Araba, Lagos. ………………………………. 2 THIS PAGE IS FOR ETHICAL CLEARANCE 3 DECLARATION I, Dr. Toye Gabriel Olajide hereby declare that this work is original and was done by me under the supervision of Dr. F.E Ologe and Prof. C.C. Nwawolo. The work has not been presented to any other College for a fellowship award nor has it been submitted elsewhere for publication. Dr. T.G. Olajide, Department of Otorhinolaryngology, University of Ilorin Teaching Hospital Ilorin. ……………………………………………… DEDICATION 4 This work is dedicated to the Glory of Almighty God and to my parents, wife and children for their support, love and care. 5 ACKNOWLEDGEMENT I am deeply indebted to the administration of the Nigerian Bottling Company Ilorin and particularly the participants for their co-operation. I also wish to acknowledge my supervisors Dr. F.E. Ologe and Prof. C.C. Nwawolo for their guidance and support in carrying out this study. I am very grateful to Mr. S.O Oladunmoye, a Clinical Audiologist who assisted with audiometric tests. My sincare appreciation also goes to Professor B.A. Oyejola, Mr. Mathew Onoja (Statistics Department, University of Ilorin) and Dr. Ojo, of Community Health & Epidemiology Department, University of Ilorin Teaching Hospital, for the analysis of the data. Finally I thank Prof. P .A. Okeowo, Drs. A.D. Dunmade, Segun Busari, S. B. Alabi and O.G.B. Nwaorgu for their contributions and constructive criticisms during the course of this study. 6 TABLE OF CONTENT Contents Page Title page i Certification ii Certificate of Ethical Clearance iii Declaration iv Dedication v Acknowledgment vi Table of Content vii Summary viii CHAPTER I Introduction 1 CHAPTER II Aims & Objectives 6 CHAPTER III Literature Review 7 CHAPTER IV Materials & Method 15 CHAPTER V Results 20 CHAPTER VI Discussion 40 CHAPTER VII Conclusion & Recommendation 45 References 46 Appendix 54 Questionnaires 57 7 SUMMARY BACKGROUND: Exposure to excessive noise is one of the most common causes of sensorineural hearing loss worldwide. The manufacturing sector, including bottling companies, are places where such exposure is being encountered. AIM: This study was carried out to determine the prevalence of noise induced hearing loss and the use of hearing protective devices (HPD) among workers exposed to excessive industrial noise in a bottling company. METHODS: A prospective study surveying workers of the production section (noise exposed area) of Nigerian Bottling Company, Ilorin was carried out in December, 2003 and December, 2005. Self administered questionnaire was used to extract information about worker’s demographic characteristics, drug, medical, and occupational history as well as information on use of hearing protective devices (HPD). Noise mapping of the various departments of the factory was carried out. Otological examination, tympanometry, audiometry was also carried out on selected subjects. Each worker, was interviewed, examined and assessed twice within the 2 year period. RESULTS: Eighty four workers, made up of 76 (90.5%) males and 8(9.5%) females were studied. Their mean age was 33.0 ± 7.6 in 2003 and increased to 35.0 ± 7.6 in 2005. The recorded noise levels in the production section ranged between 91.5-98.7 dBA. The prevalence of sensorineural hearing loss among workers was noted to be 64.9% and 86.9% for test one and test two respectively. The degree of hearing deterioration within the two years of this study was between 3.1-10.9% for the right ear and 4.8-10.7% for the left ear. More than half (53.6%) of the workers do 8 not have hearing protective devices (HPD). Of the 46.4% who have, only 38.5% claim to have used it regularly. CONCLUSION: The findings showed that there was high prevalence of sensorineural hearing loss and significant hearing deterioration among workers from exposure to excessive noise over a two year period. There is no change in the use of hearing protective device (HPD) over the two years. There is need to enforce existing occupational health laws in our industries to prevent noise induced hearing loss (NIHL), since it is eminently preventable. KEYWORDS: Prevalence, noise induced hearing loss, Bottling company workers CHAPTER ONE INTRODUCTION Noise can be described as a sound that lacks agreeable musical quality or as unpleasant sound 1, 2. Based on its temporal patterns, noise may be continuous, intermittent, impulsive, explosive or fluctuant. Intermittent noise is interrupted with periods of quiet, while continuous noise remains constant. Fluctuating noise rises and falls over time. Both impact and impulse noises are produced by a sudden intense sound wave but impact noise is caused by a collision while impulse noise is due to an explosion3. Noise induced hearing loss (NIHL) is a clinical condition that occurs gradually over many years of exposure to intense noise levels. Exposure to excessive noise is one of the most common causes of hearing loss in the world4. Being a major occupational hazard world wide, it constitutes an important public health priority because, as populations live longer and industrialization spreads, NIHL will add substantially to the global burden of disability5, 6. 9 Although industrialization is a global index of development, it has been a mixed blessing to mankind. On one hand, it enhanced the quality of life and on the other hand, poses serious threats to the management of natural systems and public health7. In Nigeria, industrial development is pursued with vigour but without adequate care for the environment7,8. A bottling company is a factory that manufactures, distributes, and markets alcoholic and non alcoholic beverages. Examples of such bottling companies are the Nigeria Bottling Company, 7-UP Bottling Company, Limca Bottlers, Nigeria Breweries Limited, Sona Breweries Limited, and Guinness Nigeria Limited. The Nigeria Bottling Company has operated continuously in Nigeria since 1953 and it produces Coca-cola, Diet Coke, Sprite, Fanta, Schweppes, Eva water, Gold Spot, Krest, Limca, Parle Club Soda, and Five Alive9. The Nigeria Bottling Company is the largest bottler in Nigeria, a nation with an estimated 133.2 million inhabitants10. The company along with its bottling partners directly provides job opportunity for an approximately 9,500 people in Nigeria9. In Can manufacturing as well as bottling plants, an average peak noise level of 100dBA is encountered11. Continual exposure to noise levels of this intensity damage and destroys hair cells within the inner ear thereby causing noise induced hearing loss (NIHL). The risk of injury and hearing loss to the ear increases with the intensity of noise level, duration, frequency of exposures, susceptibility of an individual and the type of noise 4,12,13 Individual susceptibility to NIHL varies greatly, but the reason for the difference in susceptibility is not well-understood14,15. Although NIHL is an irreversible impairment, it is 100% preventable4,16, 17. In the food and drink industries in India an estimated 29,000 workers (4.8% of the work force) suffered from ill health caused or made worse from exposure to 10 excessive noise at work in the year 2001/2002 18 . In Nigeria, it was observed that over 300,000 workers are exposed to noise exceeding 90dB (A) during an eight-hour working day8. In this regard, the textile industry has attracted more attention in Nigeria, than other industries. Many affected workers experience hearing loss considerably beyond 25 dB and this can have significant effects on their employment, as well as social and family interactions19. There is tinnitus, difficulty in detecting warning signals, comprehending speech, localizing and recognizing sound sources in the setting of background noise. Everyday activities such as watching television, using a phone or keeping up with a conversation in a group can become difficult. This may lead to feelings of isolation, depression and sometimes people withdraw from society rather than getting help for their hearing loss 19,20,21. Many countries spend huge amount of money on claims through workers’ compensation board for workers who develop NIHL. For example in Alberta, Canada it is estimated to cost $5.4 million -- a considerable commitment for a disease that makes up only 0.3% of all claims22. The estimated costs of noise to developed countries, range from 0.2% to 2% of their GDP (gross domestic product) 6. There is no accurate information on the cost of NIHL in developing countries. Developing countries, including Nigeria, often lack both effective legislation against noise and programme to prevent NIHL. Where these exist, they are often poorly enforced and implemented 6, 7. The Factories Act is the oldest and most comprehensive piece of legislation laying down minimum standards of occupational safety, occupational health, and welfare of workers in Nigeria workplaces. It has recently been updated but awaiting final approval by the country’s regulatory bodies8.