Abstract:

Heavy metal pollution is a serious environmental problem in freshwaters, potentially impacting public health, water quality and ecosystem integrity worldwide. However, the potential public health risks associated with heavy metal accumulation in water, sediment and commercial fish samples remain unclear. Here we assessed the concentrations and distribution of five heavy metal of public health importance (Iron, Copper, Zinc, Lead and Copper) in water, sediment, and edible organs (muscles, liver, gills, and intestines) of the African sharptooth catfish, Clarias gariepinus obtained from aquaculture ponds. Water, sediment, and fish samples were randomly collected from commercial fishponds across different five locations in Ondo. Metal concentrations in water, sediment and fish samples were analyzed using Atomic Absorption Spectrophotometry (AAS, Model AA-680/ Shimadzu). Mean metal levels observed in water, sediment and fish samples were compared with recommended regulatory guidelines for human consumption. Our results showed mean concentrations for all metals in water exceeded recommended permissible limits in freshwater bodies and aquatic biota, presumably suggesting potential risks for human consumers. Heavy metal levels in sediment samples indicated Fe was maximally accumulated, followed by Zn, Cu, Pb, and Cd. The highest and least accumulations for all the metals were recorded in the gills, and in the liver respectively. Higher concentrations of metals observed in gills corroborate the fact that the gill is a major route for heavy metal accumulation in fish whereas the reduced concentration of metals observed in the liver may be associated with enhanced detoxification mechanism in the liver. These results suggest that fish obtained from these aquaculture ponds may be unsafe for human consumption. Hence, we recommend a periodic assessment of heavy metal levels in commercial fish samples as a major regulatory priority.