Abstract

Objectives: The main purpose was to test the hypothesis of a relationship between noise exposure levels in the workplace, the degree of hearing loss, and the relative risk of accident (OR of single (SE) or multiple events (ME)).

Methods: We conducted a retrospective study of workers with long-standing exposures to occupational noise for a five-year period, using Hearing status and Noise exposure from the registry held by the Quebec National Institute of Public Health. Information on WRA was obtained from the Quebec Workers' Compensation Board. Hearing threshold level measurements and noise exposures were regressed on the numbers of accidents, after adjusting for age.

Results: 52,982 male workers aged 16 to 64 were included in this study, showing that: 1- exposure to extremely noisy environments (Leq8hrs „d90dBA) is associated with a higher relative risk of accident; 2- the severity of hearing impairment (average bilateral hearing threshold levels at 3, 4 and 6kHz), increases the relative risk of SE and ME when threshold levels exceed 15dB(HL); 3- the relative risk of ME (four or more) is about three times higher among severely hearing-impaired workers who are exposed to Leq8hrs „d90dBA.

Conclusion: SE and ME are associated with high noise exposure and hearing status. This suggests that reducing noise exposure contributes to increased safety in noisy industries as well as to prevention of hearing loss. These suggests that assignment of hearing-impaired workers to noisy workstations calls for ergonomic adaptations that include provision of assistive listening devices and implementation of efficient communication strategie.

Key words: multiple events, epidemiological study, noise exposure, NIHL, hearing status, occupational safety and health, work-related accidents.