Occupational Hearing Loss Surveillance

Facts and Definitions

Scope of the Problem

• In the United States, hearing loss is the third-most common chronic physical condition among adults after hypertension and arthritis.
• About 12% of the U.S. working population has hearing difficulty.
• About 24% of the hearing difficulty among U.S. workers is caused by occupational exposures.
• About 8% of the U.S. working population has tinnitus (‘ringing in the ears’) and 4% has both hearing difficulty and tinnitus.

What causes Occupational Hearing Loss (OHL)?

• OHL can occur when workers are exposed to loud noise or ototoxic chemicals.
• Noise is considered loud (hazardous) when it reaches 85 decibels or higher, or if a person has to raise his/her voice to speak with someone 3 feet away (arm’s length).
• Ototoxic chemicals can cause OHL, make the ear more susceptible to the damaging effects of hazardous noise, or both. For example, a person taking certain ototoxic pharmaceuticals may lose hearing, become more susceptible to noise, or both. Ototoxic chemicals (and examples) include:
  • solvents (styrene, trichloroethylene, toluene)
  • metals and compounds (mercury compounds, lead, organic tin compounds)
  • asphyxiants (carbon monoxide, hydrogen cyanide)
  • nitriles (3-Butenenitrile, cis-2-pentenenitrile, acrylonitrile)
  • pharmaceuticals (certain antineoplastic agents)

How Many Workers are Exposed?

• About 22 million workers are exposed to hazardous noise each year.
• About 10 million workers are exposed to solvents and an unknown number are exposed to other ototoxicants.

What is OHL Surveillance?

OHL surveillance includes:

• Collecting worker hearing data, exposure data and related information for analysis;
• Estimating how many workers have hearing loss or related health outcomes and how many workers are exposed;
• Examining these estimates by industry and occupation; and
• Monitoring trends over time.

The NIOSH OHL Surveillance Project commenced to establish a national repository for OHL data, and to conduct surveillance and research of this common occupational illness.