Distribution and human health risk of polychlorinated biphenyls in soil and plants in Koko Town, Delta State, Nigeria

Polychlorinated biphenyls (PCBs) remain a global concern due to their environmental persistence and toxicity. However, their distribution in industrial and residential areas in Nigeria is insufficiently documented. This study investigated PCB concentrations in soils and commonly consumed plants from five sites around industrial areas in Koko Town, Delta State. Soil and plant samples were extracted using a Soxhlet extraction method and analyzed via GC-MS following the USEPA method 3540 C. Mean PCB concentrations were significantly higher in plants (20.75 mg kg^{- 1}) than in soils (10.32 mg kg^{- 1}), with both matrices exceeding the WHO recommended limits. PCB accumulation was highest in Pueraria phaseoloides, followed by Ceiba pentandra, Chromolaena odorata, Vermonia amygdalina, and Musa sapientum. The estimated daily intake (EDI) for adults and children exceeded the USEPA reference dose (0.000007 mg kg^{- 1}) with a hazard ratio > 1, indicating a notable health risk, particularly for children. The findings underscore the need for regular monitoring and mitigative strategies for communities vulnerable to PCB pollution.