Bioaccumulation and health risks of some heavy metals in Oreochromis niloticus, sediment and water of Challawa river, Kano, Northwestern Nigeria

Heavy metals of sort Pb and Cd are of utmost importance significantly in Nigerian public health. Others such as Fe and Zn are available in the environment and typically contribute to sustenance of the ecosystem. The present study determined the bioaccumulation and health risks of some heavy metals which include Zinc (Zn), Cadmium (Cd), Iron (Fe) and Lead (Pb) in Fish (Oreochromis niloticus) with their levels in sediment and water of Challawa River, Kano, Nigeria. The heavy metals were measured using the atomic absorption spectrophotometry. The water, sediment and fish samples analysed had mean concentration of Zn, Cd, Fe and Pb greater than the World Health Organization (WHO) and Standard Organization of Nigeria (SON) standard permissible limits except for Zn in sediment, fish and Cd in sediment. The amounts of the heavy metals in all samples between the dry and wet season varied significantly (p < 0.05) with a positive relationship between the metals in water, fish, and sediment. Fe accumulates higher than Zn, Cd, and Pb from the values of bioaccumulation factors in sediment and water of Challawa river. Higher values for Estimated Daily Intake and Target Hazard Quotient of all the metals were recorded. These indicate that fish, water and sediment from Challawa river were contaminated to certain levels that has the potential health risks and hazards following the consumption of the fish species. Such has serious consequences in view of the massive population that rely on the river as a source of fish and water.