Researchers from the University of Michigan School of Public Health have published a study in Environmental Health Perspectives that indicates that low-level exposure to cadmium and lead found in the general U.S. population may be important risk factors for hearing loss.

Although cadmium and lead are known risk factors for hearing loss in animal ­models, until now, few epidemiologic studies have been conducted on their associations with hearing ability in the general population.

U-Mich-Shool of Publich Health
University of Michigan’s School of Public Health

The researchers investigated the associations between blood cadmium and lead exposure and hearing loss in the U.S. general population, while controlling for noise and other major risk factors contributing to hearing loss.

They analyzed data from 3,698 adults, 20–69 years of age, who had been randomly assigned to the National Health and Nutrition Examination Survey (NHANES) 1999–2004 Audiometry Examination Component. Pure-tone averages (PTA) of hearing thresholds at frequencies of 0.5, 1, 2, and 4 kHz were computed, and hearing loss was defined as a PTA >25 dB in either ear.?

When the researchers looked at the weighted geometric means of blood cadmium and lead and adjusted for clinical risk factors and exposure to occupational and nonoccupational noise, the highest (vs. lowest) quintiles of cadmium and lead were associated with 13.8% and 18.6% increases in PTA, respectively.

The findings add to other efforts to reduce environmental cadmium and lead exposures.

SOURCE: Environmental Health Perspectives