As an industrial hygienist, I'm used to quizzical looks from people when they ask what I do for a living. "So," they say, "you clean factories with a giant toothbrush?" Telling them that my job involves hearing conservation research doesn't help. Most people understand what I do for a living only when I tell them that I research the effects of noise on people and develop ways to protect them from noise.

I often see the same lack of recognition of hearing conservation among healthcare professionals. Generally, they are aware that hearing acuity often declines with age, but relatively few seem aware that excessive noise exposure can result in a far worse hearing loss that can occur much earlier in life. This is unfortunate, as healthcare professionals should be the first line of defense in preventing noise-induced hearing loss (NIHL).

The widespread lack of hearing conservation knowledge is unsurprising given the scant resources dedicated to this issue. A number of federal and state agencies have occupational noise exposure regulations, and the Environmental Protection Agency (EPA) has exposure guidelines designed to protect the public. However, none of these agencies places an emphasis on preventing NIHL, enforcement of regulations is generally lax and the EPA office responsible for noise control has not received funding since 1981.

Despite the fact that hearing conservation receives little attention in the U.S., there is a growing body of research documenting a variety of adverse effects of noise and other exposures on our health:

Workplace noise as a threat to hearing: More is known about the relationship between occupational noise and NIHL than about nearly any other occupational health hazard, and hearing conservation regulations have been in place for decades. However, U.S. regulations are less protective than those used in nearly all other countries, and a surprising number of U.S. workers are not covered by these regulations or work in workplaces that do not have effective hearing conservation programs. As a result, many American workers needlessly suffer NIHL every year.

Recreational noise as a threat to hearing: The risk of NIHL associated with recreational noise is not nearly as clear as that of workplace noise. Although alarmist media reports make it sound as though recreational noise-and especially noise from MP3 players-is a substantial risk for all Americans, the truth is that recreational noise likely contributes little to NIHL risk for workers with noisy jobs. For people with little or no occupational exposure, though, recreational noise may be the primary risk of NIHL. More research is needed to evaluate the potential risk of NIHL from activities like listening to music, shooting, attending loud events, or riding motorcycles. However, noise levels associated with these activities appear to be high enough to present a risk of NIHL for people with chronic exposures.

Ototoxic agents as a threat to hearing: While many healthcare professionals know that some pharmaceutical agents (for example, certain antibiotics and chemotherapy agents) are ototoxins, fewer are aware that other, more common substances also can harm hearing. These substances include commonly used solvents such as toluene and xylene, metals such as mercury and cadmium, kerosene and jet fuel, and organophosphate pesticides. Evaluation and prevention of potential exposure to these agents is a key step to preventing hearing loss.

Noise as a non-auditory health hazard: There is increasing evidence that excessive exposure to workplace or community noise is related to a number of non-auditory health conditions, including hypertension, heart disease and sleep disturbances. Also, new research suggests that people who work in high noise may be more likely to suffer accidents and injuries on the job.

There are a number of things you can do to help prevent NIHL:

• Write Congress and ask to have funding re-established for the EPA Office of Noise Abatement and Control;

• Write the Occupational Safety and Health Administration and request that the Hearing Conservation Amendment be updated to reflect current scientific knowledge;

• Read a manuscript on noise exposure: www.pubmedcentral.nih.gov/picrender.fcgi?artid=1637786&blobtype=pdf;

• Visit the Web site of the National Hearing Conservation Association, http://hearingconservation.org;

• Review frequently asked questions about hearing conservation: www.cdc.gov/niosh/topics/noise/faq/faq.html;

• Learn about different types of hearing protection devices: www.cdc.gov/niosh/topics/noise/abouthlp/chooseprotection.html.

Rick Neitzel, PhD, CIH, is a research scientist in the University of Washington Department of Environmental and Occupational Health Sciences. He is a Certified Industrial Hygienist, and he currently serves as president of the National Hearing Conservation Association and sits on the American Industrial Hygiene Association Noise Committee.