Cumulative human health risk from low-level PCB exposure in waste environments: a congener-specific assessment with implications for regulatory thresholds

This study investigated the cumulative human health risks from low-level polychlorinated biphenyl (PCB) exposure in diverse waste environments, challenging conventional regulatory thresholds based on high-dose toxicity. Concentrations of 14 PCB congeners were quantified across five waste types using Gas Chromatography coupled with Mass Spectrometry (GC-MS), and cumulative non-carcinogenic and carcinogenic risks were assessed via hazard quotient (HQ) and cancer risk (CR) models. This study integrates congener-pattern analysis with physicochemical covariates to isolate source-specific risk drivers, advancing beyond traditional total-PCB approaches. Results revealed significant spatial variation, with PCB-20 and PCB-137 as dominant contributors. Total HQ values ranged from 5.36 to 6.70, all exceeding the safe threshold of 1, indicating substantial non-carcinogenic risks. CR values (3.7–4.7 × 10 −5 ) fell within acceptable limits but signify notable lifetime risks. A strong positive correlation was found between electrical conductivity (EC) and PCB mobility, while alkaline pH promoted persistence. The findings demonstrate that chronic, low-level exposure in waste sites poses significant cumulative health threats, primarily through non-cancer effects. This underscores the inadequacy of current standards and necessitates a shift toward cumulative, congener-specific risk assessment frameworks for effective regulation and remediation in developing regions.