Noise and Occupational Hearing Loss

Chemicals and Hearing Loss

Exposure to certain chemicals can cause damage to different parts of the ear. These chemicals are called ototoxicants or “ototoxic chemicals.” Exposure to ototoxic chemicals can cause hearing loss. Sometimes, exposure to chemicals can make ears more sensitive to the harmful effects of noise.

Like with noise, hearing loss caused by ototoxic chemicals varies based on

• How often you are exposed (exposure frequency).
• How much you are exposed (chemical strength/potency).
• How long you are exposed (duration).

Exposure to other workplace hazards (such as noise) and other individual factors (such as age and smoking status) also influence the effect of chemicals that damage hearing. 

Examples of chemicals that damage hearing

• Solvents (e.g., toluene, styrene, xylene, ethylbenzene, and trichloroethylene)
• Metals and compounds (e.g., mercury compounds, lead, and organic tin compounds)
• Asphyxiants (e.g., carbon monoxide, hydrogen cyanide and its salts, and tobacco smoke)
• Nitriles (e.g., 3-butenenitrile, cis-2-pentenenitrile, and acrylonitrile)
• Pharmaceuticals (e.g., certain antineoplastic drugs
• Pesticides

Workers can be exposed to these chemicals in different ways:

• Breathing them in.
• Consuming food or drinks that have been contaminated.
• Absorbing chemicals through the skin by touching them.

Once exposed, these chemicals can travel through the blood stream and injure the inner ear and damage the nerves that transmit information to the brain.

How Employers and Health and Safety Professionals Can Prevent Ototoxic Chemical Exposure

Use the hierarchy of controls to prevent ototoxic chemical exposure:

• Avoid using ototoxic chemicals in the workplace or replace with less toxic chemicals.
• Improve ventilation.
• Train workers to safely handle chemicals.
• Supply personal protective equipment (PPE) to workers.
• Train workers to use PPE correctly.

Exposure limits for many chemicals were set without specifically considering ototoxicity, so exposures may create a hearing risk at levels below existing guidance, especially when combined with noise exposures. Review the OSHA-NIOSH Safety and Health Information Bulletin to learn more about how to prevent ototoxic chemical exposure and keep your workers safe.

How Workers Can Prevent Ototoxic Chemical Exposure

If you work with any chemicals, take the following actions to help protect yourself:

• Read and follow all requirements on each chemical’s Safety Data Sheet.
• Wear gloves resistant to the chemical(s) of concern, long sleeves, eye protection, and other protective equipment as needed.
• Wear a properly selected respirator, as appropriate.

Industries That Are More Likely to Use Ototoxic Chemicals:

• Manufacturing, which 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)
  • Solar cell
• Mining
• Oil and gas extraction
• Utilities
• Construction
• Agriculture
• Public safety

Being exposed to both loud noise and ototoxic chemicals can cause more hearing damage than either noise or chemical exposure by itself.  Job activities with exposure to both chemical and noise hazards may include

• Printing
• Painting
• Construction
• Manufacturing jobs in the industries listed above
• Fueling vehicles and aircraft
• Firefighting
• Weapons firing
• Pesticide spraying