Human Health Risk Associated with Heavy Metal Exposure from Consumption of Freshwater Fish in the Dukku River Basin, Nigeria

Consumption of freshwater fish contaminated with heavy metals is a major pathway for chronic human exposure, particularly in riverine communities where fish constitute a primary source of dietary protein source. This study assessed the concentrations of Mn, Fe, Cu, Zn, Ni, As, Cd, Pb, and Cr in muscle tissues of four trophically diverse species: Alestes nurse, Distichodus affinis, Malapterurus electricus, and Hyperopisus bebe from the Dukku River, and evaluated carcinogenic and non-carcinogenic health risks for adults and children’s consumers. Across multiple fishing hotspots, a total of 284 specimens were purposely collected and analyzed by atomic absorption spectrophotometer. Ecotoxicological contamination was evaluated using the Metal Pollution Index (MPI), and health risks were characterized through Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), Hazard Index (HI), and Cancer (Risk). Mean concentrations of Cd, Fe, Cu, As, Mn, and Cr differed significantly (p < 0.05) across species, with M. electricus recorded the highest MPI values of 2.19 × 10-6, driven by elevated arsenic. Fe and Zn dominated the EDI across species, with children consistently exhibited higher exposure than adults. The THQ for As in M. electricus is > 1 for children, while HI > 1 for children consuming M. electricus, D. affinis and H. bebe, indicating potential non-carcinogenic health risks. As and Cd were the dominant contributors to carcinogenic risk for children consuming these three species. Consumption of certain freshwater fish species from the Dukku River poses significant health risks, particularly to children. Continuous monitoring, trophic-level-based risk characterization, and species-specific consumption advisories are recommended to protect public health.