Influence of well-known risk factors for hearing loss in a longitudinal twin study

Johnson, A-C. et al. (2017) International Journal of Audiology. 56(supp 1) pp.63-73

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Objective: The aim was to investigate the influence of environmental exposures on hearing loss in a twin cohort.

Conclusions: Pre-existing hearing loss can increase the risk of hearing impairment due to occupational noise exposure. An increased risk for NIHL was also seen in the group with exposures below 85 dB(A), a result that indicates awareness of NIHL should be raised even for those working in environments where sound levels are below 85 dB(A).

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What can 35 years and over 700,000 measurements tell us about noise exposure in the mining industry?

Roberts, B. et al. (2017) International Journal of Audiology. 56(Supp.1) pp. 4-12

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Objective: To analyse over 700,000 cross-sectional measurements from the Mine Safety and Health Administration (MHSA) and develop statistical models to predict noise exposure for a worker.

Conclusion: Overall noise levels in mines have been decreasing. However, this decrease has not been uniform across all mining sectors. The exposure predictions from the model will be useful to help predict hearing loss in workers in the mining industry.

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Noise-induced hearing loss in a longitudinal study of Norwegian railway workers

Lie, A. et al. (2016) BMJ Open. 6:e011923 | Published online: 2 September 2016

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Objective: The aim of this study was to analyse longitudinal data to assess the risk of noise-induced hearing loss (NIHL) in Norwegian railway workers.

Design: Longitudinal.

Setting: A major Norwegian railway company.

Methods: We examined data from the first and last audiograms for the period 1991–2014, from 9640 railway workers with varying occupational noise exposure and with an average observation period of 10 years. The course of hearing acuity in seven groups of railway workers (train drivers, conductors, bus drivers, traffic controllers, train maintenance workers, track maintenance workers and others) were compared with each other and with ISO standards (ISO 1999).

Results: The change in hearing threshold during the observation period was 2–3 dB in the 0.5–4 kHz range and 6–7 dB in the 3–6 kHz range adjusted for age and sex, for all occupational groups, which is slightly less than expected (8 dB) according to ISO 1999.

Conclusions: The risk of NIHL in Norwegian railway workers during the period 1991–2014 has been negligible.

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Increased risk of injury in tinnitus patients

Cantley LF, et al. Does tinnitus, hearing asymmetry, or hearing loss predispose to occupational injury risk? International Journal of Audiology 2014 Dec 30:1-7;


Results of a new study provide further evidence that tinnitus combined with high-frequency hearing loss may represent an important safety hazard to workers, especially in noisy environments.

Researchers from Yale’s Occupational and Environmental Medicine Program (Yale University School of Medicine, New Haven, USA) recently published the results of their study in the International Journal of Audiology. The study included more than 8800 workers employed at six aluminum manufacturing plants between 2003 to 2008.

The aim was to carry out a retrospective analysis of the relative contributions of tinnitus, asymmetrical hearing loss, low-frequency hearing loss, and high-frequency hearing loss to acute injury risk. The study adjusted for ambient noise exposure and for other known predictors of injury risk.

Results showed that there is a 25% increased risk of acute injury and a subset of serious acute injuries among workers with a history of tinnitus in conjunction with high-frequency hearing loss. Low-frequency hearing loss was found to be potentially associated with minor, less serious injury risk. No evidence was found that asymmetry contributes to this risk. The authors mention already established links between tinnitus and sleep disturbance, fatigue, and distraction.

In their conclusion, the researchers point to the importance of carefully examining the communication needs of hearing-impaired workers and workers with tinnitus who are exposed to workplace noise. They also recommend that more studies be conducted to assess relationships between tinnitus, hearing loss, and injury risk.