A targeted review on pollution, sources and risks associated with PCBs in soil and sediment in Nigeria

ABSTRACT A graphical diagram showing the sources, exposure routes and health risk of PCBs in contaminated soil and sediment in Nigeria. Polychlorinated biphenyls (PCBs) pose significant environmental risks globally, particularly in underdeveloped countries with inadequate waste handling systems. This review examined the levels of PCBs in Nigerian soil and sediments, their sources and related risks. Previous work was gathered and assessed using a suitable screening procedure from research databases. The study found both low and high levels of PCBs, and these results pose a risk to public health. The PCB levels in sediment and soil ranged from not detected (ND) – 31,900 ng/g and ND – 510,000 ng/g, respectively. The PCB sources were attributed to transformer oil spillage, oil spills, wastes, and untreated effluent discharge. The hazard index values greater than 1 have a percentage proportion of 50 and 61.5% for soil and sediment, respectively, indicating potential chronic risks. Health risk assessments showed that hazard index values for children were predominantly higher than those for adult, making them highly susceptible to health risks. The cancer risk assessment for adults and children showed low and high-risk levels. It is advised that periodic monitoring, enforcement of regulatory laws, and safe disposal of wastes be implemented by NESREA (National Environmental Standards and Regulations Enforcement Agency) to reduce the pollution of PCBs in the environment.