Serum polychlorinated biphenyls concentrations and hearing impairment in adults.

Experimental studies have suggested the potential link between exposure to polychlorinated biphenyls (PCBs) and auditory impairment, but little evidence exists to support the ototoxicity of PCBs in human. Only a few studies have implicated PCB-induced hearing loss in children. This study investigated the association between serum PCB levels and hearing impairment in US adults. We analyzed data from 1946 adults aged 20 years and older in the National Health and Nutrition Examination Survey 1999-2004: eleven PCB congeners detected in 60-90% of the samples at greater than the limit of detection (LOD) were selected, and hearing impairment was defined as a pure-tone average of the thresholds at 0.5, 1, 2 and 4 kHz of >25 dB hearing level in better ear. The adjusted odds ratio of hearing impairment was significantly increased comparing the highest quartile (Q4) of detectable PCB range with the reference (below LOD): 5.83 (95% CI: 1.20-28.24) for 2,2',3,3',4,4',5-heptachlorobiphenyl (PCB-170), 7.79(95% CI: 1.81-33.44) for 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB-180), 7.46 (95% CI: 1.62-34.47) for 2,2',3,4',5,5',6-heptachlorobiphenyl (PCB-187), 8.59 (95% CI: 1.26-58.73) for 2,2',3,3',4,4',5,5'-octachlorobiphenyl (PCB-194), 11.62 (95% CI: 2.20-61.55) for 2,2',3,3',4,4',5,6'-octachlorobiphenyl (PCB-196). Our findings suggest that specific classes of PCB levels may be associated with hearing impairment in a general sample of adults.