Polychlorinated biphenyl contamination in leachates from an unregulated waste dumpsite in Enugu State, Nigeria, with associated environmental and health risks

Abstract Polychlorinated biphenyls (PCBs) pose significant environmental and public health concerns worldwide, particularly in developing countries with inadequate waste management systems. This study assessed the levels of PCB contamination, associated toxicity, and potential health and environmental risks in leachates from the Ugwuaji waste dumpsite in Enugu State, Nigeria. Leachate samples were collected from five locations and analyzed for 28 PCB congeners using gas chromatography–mass spectrometry (GC–MS). Total PCB concentrations ranged from 57.39 to 82.11 ng L⁻1, indicating considerable contamination of the dumpsite leachate. PCB-28 was the most dominant congener, whereas PCB-128 was the least abundant. Lower-chlorinated PCBs predominated across the sampling locations. This pattern is consistent with their relatively higher volatility, greater aqueous solubility, and enhanced mobility in leachate transport processes. Toxicity assessment revealed that PCB-126 and PCB-169 were the primary contributors to toxic equivalency (TEQ) values. However, health risk evaluation indicated no significant carcinogenic or non-carcinogenic risks for both adults and children under the assessed exposure scenarios. Statistical analyses suggested common anthropogenic sources and strong inter-congener correlations. These findings highlight the need for improved waste management practices, continuous environmental monitoring, and the development of cost-effective remediation strategies. The study provides essential baseline data to inform policies aimed at mitigating PCB pollution and protecting environmental and human health in Nigeria.