Description: Objectives Noise-induced hearing loss is one of the most serious occupational diseases worldwide. It is caused by interactions between environmental and genetic factors. The purpose of this study was to examine the association between the genetic susceptibility of the eye absent homolog 4 (EYA4) gene and the risk of developing noise-induced hearing loss in China. Methods A case–control association study was carried out with 326 hearing loss cases and 326 controls matched with age and duration of noise exposure, drawn from a cohort of steel workers. Five single nucleotide polymorphisms (SNPs) in the EYA4 were selected and genotyped. Logistic regression was performed to analyse the main effect of genotypes and interactions between genotypes and individual/environmental factors adjusted for confounding factors. Moreover, generalised multiple dimensionality reduction was applied to further detect interaction among the 5 selected SNPs. Results Analysis revealed that locus polymorphism of rs3813346 was associated with the risk of developing noise-induced hearing loss in the dominance model, the codominance model and the addictive model (p=0.004, 0.009 and 0.003, respectively). A significant interaction between rs9321402 and cumulative noise exposure was found (p=0.002). A significant main effect p value (p=0.006) was obtained in the high-level exposure group (cumulative noise exposure ≥98 dB(A)). Generalised multiple dimensionality reduction indicated that the combined interaction of the 2 loci—rs3813346 and rs9493627—significantly affected the incidence of noise-induced hearing loss. Conclusions The research suggests that EYA4 genetic variant and its interaction with noise levels may modify the susceptibility to develop noise-induced hearing loss in Chinese population.

Description: Objective Occupationally acquired noise-induced hearing loss (NIHL) is the most prevalent occupational disease in Austria and among the most common in many other countries. Because of the wide variation in hearing loss after equivalent exposures it has long been assumed that some individuals are more vulnerable to occupational NIHL than others. Earlier attempts to define predictors of NIHL before starting occupational noise exposure have largely failed. We present results of a prospective study evaluating the potential of temporary threshold shift (TTS) after a test exposure to predict NIHL. Methods Between 1982 and 1989, overall 311 apprentices were included into a prospective study during their initial health screening visit. At this occasion, a standardised noise exposure was applied (20 min, 200–500 Hz, 100 dBA) and the TTS at 4 kHz was determined during at least 10 min after exposure. Hearing loss was monitored at follow-up visits every 3–5 years. Follow-up was 13 years on average. Results Permanent threshold shift was predicted by duration of noise exposure, frequency of wearing noise protectors and especially by the initial TTS at 4 kHz. Using 14 dB TTS as a cut-off had 82% sensitivity and 53% specificity to predict 20 dB or higher levels of NIHL. Conclusions The TTS model can be successfully applied as a method to detect individuals at greater risk of occupational NIHL. It is recommended to routinely include such a procedure into initial workers’ examinations for suitability to work under occupational noise conditions and for counselling on the use of hearing protectors.

Description: Objectives The authors had a unique opportunity to study the early impacts of occupational and recreational exposures on the development of noise-induced hearing loss (NIHL) in a cohort of 392 young workers. The objectives of this study were to estimate strength of associations between occupational and recreational exposures and occurrence of early-stage NIHL and to determine the extent to which relationships between specific noise exposures and early-stage NIHL were mitigated through the use of hearing protection. Methods Participants were young adults who agreed to participate in a follow-up of a randomised controlled trial. While the follow-up study was designed to observe long-term effects (up to 16 years) of a hearing conservation intervention for high school students, it also provided opportunity to study the potential aetiology of NIHL in this worker cohort. Study data were collected via exposure history questionnaires and clinical audiometric examinations. Results Over the 16-year study period, the authors documented changes to hearing acuity that exceeded 15 dB at high frequencies in 42.8% of men and 27.7% of women. Analyses of risk factors for NIHL were limited to men, who comprised 68% of the cohort, and showed that risks increased in association with higher levels of the most common recreational and occupational noise sources, as well as chemical exposures with ototoxic potential. Use of hearing protection and other safety measures, although not universal and sometimes modest, appeared to offer some protection. Conclusions Early-stage NIHL can be detected in young workers by measuring high-frequency changes in hearing acuity. Hearing conservation programmes should focus on a broader range of exposures, whether in occupational or non-occupational settings. Priority exposures include gunshots, chainsaws, power tools, smoking and potentially some chemical exposures.