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Millions of US workers are at risk of occupational hearing loss (OHL) due to exposure to ototoxic chemicals, loud noise, or both, reports a study in the October issue of the
Journal of Occupational and Environmental Medicine.
Led by Elizabeth Masterson, PhD, CPH, COHC, of the National Institute for Occupational Safety and Health, the researchers analyzed data from a nationally representative survey including 17,726 employed or recently employed US adults. In response to study questionnaires, 11% of respondents reported difficulty hearing.
Thirteen percent of participants reported exposure to ototoxic chemicals that can damage hearing: solvents, industrial glues, heavy metals, pesticides, motor engine exhaust, or secondhand tobacco smoke. The rate of exposure to secondhand tobacco smoke—which contains ototoxic chemicals—was five percent.
Sixteen percent of respondents were exposed to loud noise at work (at least four hours per day), while 28% had a past history of noise exposure. Ototoxic chemicals can make the ear more vulnerable to the harmful effects of noise; seven percent of workers reported both exposures.
On analysis of specific industries, nearly half of workers in the mining industry were exposed to ototoxic chemicals. Other industries with high exposure rates included oil and gas extraction; construction; agriculture, forestry, fishing, and hunting; transportation, and manufacturing. Many of the same industries had high exposure to noise.
The study is the first to assemble comprehensive national data on risk factors for OHL. The data suggest that 1.4 million workers have hearing difficulties attributable to ototoxic chemical exposures and 2.1 million attributable to noise exposure.
Although not required by current US regulations, monitoring hearing in workers exposed to ototoxic chemicals is strongly recommended by leading professional societies. The researchers discuss steps to reduce exposure to ototoxic chemicals and noise in the workplace, along with controls that may prevent the development of OHL.
"This paper shows that hearing hazards are prevalent in the workplace and identifies groups that need special attention to prevent OHL," Dr. Masterson comments. The authors highlight the need for "special attention in hearing conservation programs" targeting the estimated 12 million US workers exposed to both ototoxic chemicals and noise.