Environmental cadmium exposure, chronic suppurative otitis media, and hearing impairment

Abstract

Introduction : Chronic suppurative otitis media (CSOM) and hearing impairment are associated with oxidative stress, which could be induced by cadmium exposure. We evaluated the role of CSOM as a mediator in the association between environmental cadmium exposure and hearing impairment among adults. Methods : This cross-sectional study evaluated 5,838 adults aged 20–69 years who were enrolled in the Korean National Health and Nutrition Examination Survey from 2009 to 2012 and had cadmium measurements. CSOM was diagnosed by otologic examination and hearing impairment was defined as a pure-tone average (PTA) of 0.5, 1, 2, and 4 kHz >25 dB in the better ear. Results : Weighted prevalence was 2.9% for CSOM and 7.7% for hearing impairment. After adjusting for age, sex, smoking status, and body mass index, the odds ratio for CSOM by environmental cadmium exposure was 3.91 (95% CI=1.72-8.86) and that for hearing impairment was 1.66 (95% CI=1.02-2.71), comparing the highest vs. lowest quartile of blood cadmium levels. The association between blood concentration of cadmium and hearing impairment measured by PTA in both ears was found to be mediated by CSOM (Sobel = 5.564, p < 0.001) at a mediation of 5%. Conclusion : We found that environmental cadmium exposure is associated with CSOM and hearing impairment in the adult population. In addition to the directly neurotoxic effect of cadmium exposure on hearing impairment, CSOM plays a mediating role partly in the association between exposure to cadmium and hearing impairment.