Noise-induced hearing loss is permanent hearing impairment resulting from prolonged exposure to high levels of noise. While noise is a well-understood source of occupational illness, new studies are focusing on chemical-induced hearing loss (ototoxicity). This research seeks to determine if chemical substances alone, or noise and chemical co-exposure, contribute to occupational hearing loss. Given that many different types of workers are exposed to noise and chemicals at the UW, supervisors should keep this possible association in mind as part of their hazard communication to employees.
Studies have shown that certain chemical exposures can increase the risk of hearing loss. Exposure to these chemicals can have an ototoxic effect:
Metals and metal compounds such as lead, mercury, germanium and manganese.
Solvents such as toluene, styrene, xylene, ethylbenzene, trichloroethylene and some halogenated hydrocarbons.
Asphyxiants include carbon monoxide and hydrogen cyanide.
As part of the UW hearing loss prevention program, workers who are potentially exposed to high noise levels undergo annual hearing evaluations via pure-tone audiometry (PTA). Because PTA provides insufficient information regarding hearing loss from either chemicals alone or noise and chemical co-exposure, additional testing is needed.
At this time, there are no regulations from a hearing loss prevention standpoint that require controls or monitoring due to an employee’s exposure to ototoxic chemicals. However, supervisors and employees should be aware of the risk and track chemical exposure. If an employee suspects that chemicals in the workplace may be contributing to hearing loss, he or she should consult an audiologist, primary care physician or specialist.
If you have questions or feedback, please contact Brandon Kemperman at firstname.lastname@example.org or 206.543.1713.