When we’ve spoken in the past about hearing health and hearing conservation, we have focused on the effects of noise and excessively loud sounds. This is of course important and well recognized - that we watch our exposure to noise in order to protect our hearing.

It is less well known, though, that our hearing and other functions of the inner ear can be damaged, notably through ototoxicants – products that are toxic to the inner ear and auditory nerves. Some of these include:

Solvents: carbon disulfide, hexane, toluene, styrene, PVC
Metals: mercury, lead, arsenic
Asphyxiants: carbon monoxide, tobacco smoke

Ototoxicants in Industrial Environments
Industries that use potential ototoxicants include manufacturing, mining, utilities, construction, and agriculture. Manufacturing industry subsectors may include:

  • Fabricated metal

  • Machinery

  • Leather and Allied Product

  • Textile and Apparel

  • Petroleum

  • Paper

  • Chemical (including Paint)

    • Plastics

    • Furniture and Related Product

    • Transportation Equipment (e.g. Ship and Boat Building)

    • Electrical Equipment, Appliance and Component (e.g. Batteries)

Occupational activities that often have high noise exposure and could have synergistic effects when combined with ototoxicant exposure include:

  • Printing

  • Painting

  • Construction

  • Manufacturing occupations in the subsectors listed above

    • Fueling vehicles and aircraft

    • Firefighting

    • Weapons firing

    • Pesticide spraying


Synergistic Effects
Both OSHA and NIOSH recognize the synergistic (combined) effects of these chemicals and air pollutants on hearing loss. That is to say, we might be safe for eight hours of noise exposure at 85 dB. However if we are exposed to solvents at the same time, the sensory cells and nerves in our hearing system are more susceptible to damage at lower noise levels.

Excessive noise will often cause mechanical damage to the sensory cells of the ear. Damage from ototoxicants we mentioned is typically chemical damage. One caveat to this is recent studies that indicate constant, long-term noise, often below regulatory levels, can cause chemical toxicity in the sensory hair cells.

The Take-Home
We’ve highlighted industrial environments, but obviously many of these materials can be found and are used in home settings, especially the solvents. Be aware of the short-term and long-term risks of both noise exposure and chemicals and air-borne toxins to your hearing and balance, as well as the risk of developing tinnitus. Use a respirator if these materials are going to be used and lower your exposure time.