Low-frequency hearing loss following perinatal exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB 126) in rats

Previous research has demonstrated the sensitivity of the developing rat to the ototoxic effects of exposure to Aroclor 1254. In this study we assessed the effects of developmental exposure to an individual PCB congener (3,3',4,4',5-pentachlorobiphenyl; PCB 126) on auditory function. Nulliparous Long Evans rats received either 0, 0.25, or 1.0 microg/kg/day (5 days/week) for 35 days prior to breeding and throughout gestation and lactation. Auditory thresholds for 0.5-, 1-, 4-, 8-, 16-, 32-, and 40-kHz tones were assessed in offspring on postnatal days (PND) 76-90. Perinatal maternal PCB 126 exposure caused low-frequency hearing deficits. Elevated auditory thresholds occurred in the 1.0 microg/kg/day treated group for 0.5- and 1-kHz tones, whereas thresholds were not significantly affected at any higher frequencies. These results are important in that the data implicate, at least partially, the coplanar PCBs in the developmental ototoxicity induced by Aroclor 1254.