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Deterioration of noise-induced hearing loss among bottling factory workers

Published online by Cambridge University Press:  01 August 2007

F E Ologe*
Affiliation:
Department of Otorhinolaryngology, University of Ilorin, Ilorin, Nigeria
T G Olajide
Affiliation:
Department of Otorhinolaryngology, Federal Medical Centre, Iddo, Nigeria
C C Nwawolo
Affiliation:
Otorhinolaryngology Unit, Department of Surgery, University of Lagos, Nigeria
B A Oyejola
Affiliation:
Department of Statistics, University of Ilorin, Ilorin, Nigeria
*
Address for correspondence: Dr F E Ologe, P O Box 6641, Ilorin 240001, Nigeria. E-mail: foluologe@yahoo.com

Abstract

Background:

Repeated exposure to excessive noise will eventually lead to an irreversible increase in hearing thresholds. In theory, the damage reflects both the intensity of the noise and the duration of exposure. This is not linear with respect to duration of exposure; rather, the worker may experience a disproportionate loss in the early years of exposure.

Methods:

A prospective study surveying workers of the production section (i.e. most noise-exposed area) of a bottling factory was carried out in December 2003 and in December 2005. A self-administered questionnaire was used to extract information about worker's demographic characteristics, drug intake, and medical and occupational history, as well as information on the use of hearing protection devices. Noise mapping of the various departments of the factory was carried out. Otological examination, tympanometry and audiometry were also carried out on selected subjects.

Results:

Eighty-four workers, 76 (90.5 per cent) men and eight (9.5 per cent) women, were studied. Their mean age was 33.0 ± 7.6 years in 2003 and 35.0 ± 7.6 years in 2005. The recorded noise levels in the factory production section ranged between 91.5 and 98.7 dBA. The prevalence of sensorineural hearing loss among workers was noted to be 64.9 and 86.9 per cent for test one (2003) and test two (2005), respectively. The degree of hearing deterioration within the two years of this study was 1.0–3.2 dB for the right ear and 1.6–3.4 dB for the left ear. This deterioration was at discrete frequencies. More than half (53.6 per cent) of the workers did not have a hearing protection device. Of the 46.4 per cent who did, only 38.5 per cent claimed to have used it regularly.

Interpretation:

These findings showed that there was a high prevalence of mild sensorineural hearing loss and significant hearing deterioration among workers, due to exposure to excessive noise over a two-year period. The study demonstrates the practical importance of serial audiometry for noise-exposed workers as a means of monitoring hearing deterioration. It is necessary to enforce existing occupational health laws in our industries in order to prevent noise-induced hearing loss, since it is eminently preventable.

Information

Type
Main Article
Copyright
Copyright © JLO (1984) Limited 2008

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