Concentrations and Toxic Equivalency of Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyl (PCB) Congeners in Groundwater Around Waste Dumpsites in South-West Nigeria

Polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in groundwater and leachate around selected waste dumpsites from two southwestern states of Nigeria were investigated. Samples were Soxhlet-extracted using hexane/methylene chloride mixture and cleaned-up with preconditioned solid-phase extraction cartridges. The ∑PAHs (PCBs) (all in µg/L) in the boreholes, leachate, and hand-dug well across all locations ranged from below detection limit (BDL) to 0.62 (BDL to 0.067), 1.16 to 9.96 (0.003 to 0.041), and BDL to 0.01 (0.001–0.031), respectively. Low molecular weight-PAHs accounted for ≥61% of ∑PAHs detected across all locations. The highly chlorinated hexa-PCBs [2,2′,3,4,4′,5′-HeCB(#180), 2,2′,3,4′,5′,6-HeCB(#34) and 2,2′,4,4′,5,5′-HeCB(#153)] dominated the entire congener profiles. Pyrene and 2,3′,4,4′,5-PeCB(#118) constituted 56% and 58% of the ∑PAHs and ∑PCBs, respectively. Sampled water is not adequately safe for drinking and may pose cancer risk. This study should be sustained for health risk and sustenance of an enduring ecological integrity.