The risk of noise-induced hearing loss in the Danish workforce

Abstract

The causal association between occupational noise exposure and permanent hearing loss is well-documented and well-founded primary preventive approaches have been developed. However, documentation of the impact on the present prevalence of noise-induced hearing loss in the working population is limited. This study reports on the prevalence of noise-induced hearing loss in a population sample of 788 workers from 11 trades with expected high noise exposure levels and a reference group examined according to the same protocol. Full-shift A-weighted equivalent sound levels were recorded and pure tone audiometric examinations were conducted at the work sites in soundproof booths. Data were analyzed with multivariate regression techniques and adjusted for age, sex, ear disease, smoking and environmental noise exposure. An overall two-fold increased risk of hearing handicap (hearing threshold above 20 dB averaged across 2, 3 and 4 kHz for either ear) was observed in the noise exposed workers [odds ratio (OR) 1.99, 95% confidence interval (CI) 0.91-4.34]. Workers exposed for more than 20 years to an exposure level above 85 dB(A) had a three-fold increased risk (OR 3.05, 95% CI 1.33-6.99). Workers starting in noisy work during the last 10-15 years or workers below 30 years of age showed no increased risk of hearing handicap. This indicates that preventive measures enforced during the past 10-15 years to reduce noise exposure may have borne fruit. Systematic surveillance of noise and hearing levels in appropriate populations should still be included in an efficient hearing conservation program.

Prevalence of Workers With Shifts in Hearing by Industry

“…While the prevalences in these industries were not low, these industries typically have a very high prevalence of workers with hearing loss 6,31,32 . However, hearing loss can be determined from a single audiogram and will be identifiable on every audiogram after the loss has occurred.…”

“…These industries have typically been reported as low risk for hearing loss 6,31,33,44 , although a recent study also found higher risks for these industries 21 . Typically ‘low risk’ industries may target audiometric testing for only their most highly exposed workers, and since these exposed workers represent a smaller subset in these industries, the overall hearing loss prevention efforts and culture in these industries may be insufficient.…”

“…Exposure to loud noise and/or ototoxic chemicals 2-4 in the workplace can lead to occupational hearing loss (OHL) 5,6 . The federal government has regulated occupational noise exposures in select industries since 1969 7 .…”

Noise exposure as a risk factor of cardiovascular diseases in workers

“…The High levels of noise can disturb, destroy the ability to hear, and harmful effects and may also put stress of other parts of the body, including the heart. [220]…”

“…[1] The most important effect of noise on human is hearing loss (noise induced hearing loss, NIHL), and its nonauditory effects are physical, mental and effects on performance. [23] Some harmful effects of noise on health have been proved and some like hypertension (HTN) and ischemic heart diseases are controversial among researchers. On the one hand, HTN is multifactorial and on the other hand, different races and societies have different levels of resistance against external factors like noise.…”