Comparative Heavy Metal Bioaccumulation and Human Health Risk Assessment of Farmed and River-caught Catfish in Rivers State, Nigeria

Abstract

Heavy metal contamination of aquatic environments poses significant ecological and public health concerns in the Niger Delta, where fish constitute a major source of animal protein. This study assessed and compared the concentrations of ten heavy metals in farmed catfish from five aquaculture ponds and river-caught catfish from five rivers in Rivers State, Nigeria, and evaluated associated non-carcinogenic health risks. Fish samples were analysed for Fe, Mn, Zn, Cu, Ni, Cr, Pb, Cd, As, and Hg using standard acid digestion followed by Atomic Absorption Spectrophotometry. Iron showed the highest concentrations in both fish groups, ranging from 41.8–47.9 mg/kg in farmed catfish and 61.4–72.3 mg/kg in river-caught catfish. Toxic metals such as lead, cadmium, and arsenic were substantially higher in river-caught fish, with mean lead (0.61 ± 0.20 mg/kg), cadmium (0.16 ± 0.06 mg/kg), and arsenic (0.24 ± 0.08 mg/kg) exceeding FAO/WHO limits at most river sites. Estimated daily intake and hazard quotient analyses indicated acceptable risk for adults consuming farmed catfish, while children consuming river-caught catfish exhibited a cumulative hazard index of 2.23, suggesting potential health risk. The results demonstrate that riverine catfish are more vulnerable to heavy metal bioaccumulation due to environmental exposure, underscoring the need for continuous monitoring, pollution control, and consumption guidance to protect public health.