Environmental Exposures to Lead, Mercury, and Cadmium and Hearing Loss in Adults and Adolescents

Abstract

Introduction: The prevalence of hearing loss rapidly increases with aging. Hearing loss is common in all age groups even in young adults and adolescents. A growing body of evidence has suggested that heavy metals have ototoxic effects, yet few epidemiological studies have investigated the association between heavy metals and hearing loss in a general population that includes adults and adolescents. We therefore examined the association between environmental exposures to lead, mercury, and cadmium and the risk of hearing loss in adults and adolescents while controlling for potential confounding factors, including noise exposures and clinical factors. Methods: We analyzed cross-sectional data from 5,187 adults and 853 adolescents in the Korean National Health and Nutrition Examination Survey 2010-2012. Pure-tone average (PTA) of hearing thresholds at high frequency (3, 4, and 6 kHz) were computed, and hearing loss was defined as a PTA>25 dB in adults and PTA>15 dB in adolescents. Results: In adults, the highest (vs. lowest) quartiles of blood lead and cadmium were associated with 1.71 (95% CI 1.25-2.32) and 1.47 (95% CI 1.05-2.05) odds ratios for high-frequency hearing loss (p-trend<0.001 and =0.007), respectively. In adolescents, the highest quartile (vs. lowest) of blood cadmium had 3.03 (95% CI 1.44-6.40) odds ratio for high-frequency hearing loss (p-trend=0.003). No significant association between blood mercury with hearing loss was suggested in either adults or adolescents. Conclusions: The present results suggest that exposure to environmental lead and cadmium in adults and cadmium in adolescents may play an important role in the risk of hearing loss.