Risk Evaluation of Selected Heavy Metals in Water and Fish in Nigeria

Freshwater is a vital media by which fish for human consumption are cultured, thus preserving its quality is essential. The presence and bio-accumulation pattern of some heavy metal concentrations in wild African Catfish, Clarias gariepinus (Burchell, 1822) muscles and water samples, collected from River Kaduna and Galma was assessed, to determine their concentrations, physico-chemical parameters, and risk evaluation of selected metals and their effects on fish quality. Analysis was carried out using standard analytical procedures and methods. Risk assessment for Fe, Pb, Ni, Cd, and Hg were based on average daily dose, hazard quotient, and cancer risk was also determined. Result showed that physico-chemical parameters, were within WHO recommended threshold limits, and mean concentrations of heavy metals followed the order Fe>Pb>Hg>Ni>Cd. Carcinogenic risk via ingestion of fish muscles for Pb, Hg and Cd were higher than the acceptable limit (10-6). Anthropogenic activities, especially indiscriminate waste disposal were suggested as the main contributor to environmental pollution. Findings reveals possible health implications, thus constant surveillance is needed.