Effects of polychlorinated biphenyls on the peripheral and central auditory systems.

Polychlorinated biphenyls (PCBs), a class of persistent endocrine-disrupting chemicals, continue to pose significant risks to human and environmental health due to their widespread distribution, lipophilicity, and ability to bioaccumulate. Of particular concern is exposure during critical periods of neurodevelopment, which has been associated with long-lasting effects on sensory systems, including auditory processing. This review elaborates findings from both human epidemiological studies and animal models to examine the effects of PCBs on auditory function across the peripheral and central auditory pathways. Evidence indicates that PCB exposure during gestation and early postnatal life can lead to permanent auditory deficits. At the level of the auditory periphery, reductions in distortion-product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABRs) suggest cochlear outer hair cell dysfunction, potentially mediated by oxidative stress. Centrally, alterations in the primary auditory cortex and inferior colliculus have been observed, including disrupted tonotopic organization, excitation-inhibition imbalance, and impaired neuroplasticity. Notably, such central neural changes can occur out of proportion to abnormalities in ABRs, pointing to central auditory vulnerabilities. Epidemiological data in humans further support these findings, with certain PCB congeners linked to a significantly elevated risk of hearing impairment in children. PCB exposure coupled with loud noise exposure, which is growing in prevalence, leads to cumulative deficits in auditory processing. Together, these findings highlight the multi-level impact of PCB exposure on the auditory system and highlight the need for further investigation into the molecular and circuit-level mechanisms underlying these effects. Understanding the actions of PCB congeners on the auditory system in various human population cohorts is important to inform risk assessment and guide future public health policies.