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Chemically-Induced Hearing Loss (CIHL)


Although it doesn’t get a lot of attention, there is another very dangerous way that your employees can lose their hearing. We are all aware of the dangers of high noise, but are you aware of the potential danger of ototoxic chemicals?


Ototoxicity is damage to the ear (oto-), specifically the cochlea or auditory nerve and sometimes the vestibular system (sensory system that contributes to movement/sense of balance), by a toxin.


Many toxic chemicals that are used with regularity in the manufacturing process can cause serious hearing loss in workers exposed to those chemicals. The chemicals below can potentially cause hearing loss, with or without noise exposure.


High Priority Ototoxins: Toluene, Xylene, Styrene, (and mixtures of these three chemicals), Carbon Monoxide, Lead and derivates, Trichloroethylene.


Additional Ototoxins: Mercury and derivates, n-Hexane, Methylene Chloride, Butyl Nitrite, Carbon Disulfide, Benzene, Atoxyl, Cobalt, Manganese, Cyanide, Alcohols, Arsenic. (Not a complete list: This is representative of some of the ototoxic chemicals that are found in manufacturing processes)


Occupations which can potentially expose workers to the chemicals listed above.


**Printers, painters, artistry, aviation, boat builders, construction, farming, firemen, landscaping, machinists, oil & gas extraction, petrochemical workers, textile mill workers, wood working and/or staining


**Workers manufacturing: Glues, paints, metal products, chemicals, petroleum, leather products, furniture.


Researchers Bergstrom and Nystrom found that workers in the chemical sectors had a 23% rate of compensable hearing loss. Workers in the non-chemical sectors had only a 5-8% rate of compensable loss. And the chemical workers were exposed to less noise!

Note: The combined effect of noise plus chemicals has a much greater toxic effect on the ears.


Protect your workers who are at risk of ototoxic exposures!


  • Offer hearing tests to workers exposed to ototoxic substances even if noise exposure is at permitted levels
  • Collect information on employees’ solvent exposures
  • Reduce solvent exposures
  • Promote HPD use among workers exposed to Ototoxins, even if noise is below PEL
  • Always require respirators for workers exposed to ototoxic chemicals