Dangers to hearing in the military context: noise and chemicals

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Published on 23 December 2013

Exposure to gunfire, explosions, transport noise and machinery is a well-known cause of hearing loss in military personnel. Some estimates of the number of Iraq and Afghanistan veterans with job-related hearing loss and/or tinnitus are as high as 400,000.

Exposure to certain chemicals as a source of hearing loss remains an important area of study in occupational health. Researchers from the Department of Environmental and Occupational Health, at George Washington University (USA) set out to compare the risk of hearing loss between personnel exposed to occupational noise alone, and those exposed to noise and certain organic solvents, specifically toluene, styrene, xylene, benzene, and jet fuel. They carried out a retrospective study among more than 500 Air Force Reserve personnel.

Cases were assessed on the basis of audiometric examinations and industrial hygiene documentation, including occupational exposure assessments and purchasing records for the chemical substances under study. Industrial hygiene data was also used to determine noise exposure to identify subjects whose workplaces had sound pressure levels greater than or equal to 85 dB. Equivalent cumulative levels of noise exposure were also calculated.

Overall, the study demonstrated that hearing loss was associated with age, length of follow-up time, and noise exposure. It did, however, not find an additional risk among those exposed to noise and solvents or solvents only. The authors conclude that in their study, low and moderate solvent exposures were not associated with hearing loss.

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