Soil samples randomly taken from major e-waste sites in West Africa (Nigeria, Benin and Ghana) were examined for an extensive range of organic contaminants. Cytotoxicity measurements and assessment of activation of xeno-sensing receptors from fish (Atlantic cod) were employed as a battery of in vitro biological assays to explore the quality and toxicity profile of West African e-waste soil. The concentrations of the measured contaminants of emerging concerns (CECs) and persistent organic pollutants (POPs) in the e-waste soil differs significantly from the reference soil with chemical profiles typically dominated by legacy polybrominated diphenyl ethers (PBDEs) (405.8 μgkg-1) and emerging organophosphate ester flame retardant tris (1-chloro-2-propyl) phosphate (TCPP) (404 μgkg-1), in addition to the short chain perfluorobutane sulfonate (PFBS) (275.3 μgkg-1) and perfluorobutanoate (PFBA) (16 μgkg-1). The study revealed that perfluorooctanoic acid (PFOA) occurred only in e-waste soil from Ghana and ranged from 2.6 to 5.0 μgkg-1. Overall, non-polar e-waste soil-derived extracts had a stronger effect on COS-7 cell viability than the polar extracts and elutriates. The highest receptor activation was observed with single polar and non-polar extracts from the Nigeria and Benin sites, indicating hotspots with Er-, PPARa- and Ahr-agonist activities. Thus, the results obtained with our battery of in vitro biological assays underscored these e-waste sites as remarkably polluted spots with complex toxicity profiles of great concern for human and environmental health.
Keywords: Atlantic cod; Cytotoxicity; E-waste soil; Luciferase assay; Organic pollutants; Stress-activated receptors.
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