Auditory Deficits in Rats Exposed to an Environmental PCB Mixture during Development

Previous studies have indicated that developmental exposure to polychlorinated biphenyls (PCBs) may result in hearing impair-ment in rats. The cochlea is the suggested site of action, based upon one study demonstrating a loss of outer hair cells on the basilar membrane, and another demonstrating deficits in distor-tion product otoacoustic emissions (DPOAEs). The current study was conducted to assess the possible ototoxic effects of a unique PCB mixture formulated to model the congener profile of PCBs found in fish consumed by a human population in northeastern Wisconsin. Female Long-Evans rats were dosed orally with the PCB mixture beginning 28 days prior to breeding and continuing until the pups were weaned. Dams were fed one-half of a cookie onto which was pipetted 0, 1, 3, or 6 mg/kg of the PCB mixture dissolved in a corn oil vehicle. On postnatal day (PND) 21, pups were weaned, and one male and one female from each litter wer