Auditory Effects of Developmental Exposure to Purity-Controlled Polychlorinated Biphenyls (PCB52 and PCB180) in Rats

Abstract

Polychlorinated biphenyls (PCBs) are still present in the environment, with ongoing exposure in humans, including babies nursed by their mothers. Whereas toxicity of dioxin-like PCBs is well described, less systematic knowledge is available for non-dioxin like PCBs (NDL-PCBs) that do not act via the Ah receptor. This study compared effects of developmental exposure to two ultrapure NDL-PCB congeners (PCB52 and PCB180) on auditory function in rats, using the brainstem auditory evoked potential (BAEP). Pregnant rats received repeated oral doses of PCB52 (total dose-0, 30, 100, 300, 1000, or 3000 mg/kg body weight) or of PCB180 (total dose-0, 10, 30, 100, 300, or 1000 mg/kg). BAEPs were recorded in adult male and female offspring after stimulation with clicks or pure tones in the frequency range from 0.5 to 16 kHz. Significant elevation of BAEP thresholds was detected in the low-frequency range after developmental exposure to PCB52. Calculation of benchmark doses revealed lowest values in the frequency range of 0.5-2 kHz. Effects were more pronounced in male compared with female offspring. Latencies of waves II and IV were prolonged in exposed males, whereas only wave IV was affected in females. PCB180 increased thresholds only at few conditions and only in female offspring. These results confirm that developmental exposure to ultrapure NDL-PCBs affects auditory function, but different congeners exhibit differences in potencies.