Toxicological Assessment of Captured Fish Species from a Lotic Freshwater Ecosystem in Nigeria

Consumption of safe aquatic foods is critical to the sustainable development goal of good health and wellbeing. This study assessed the content of heavy metals in Clarias gariepinus and Tilapia zillii from Owan River and evaluated the plausible human health risk associated with their consumption. The results showed that mean concentrations of iron (25.03 – 74.98 mg/Kg), zinc (8.21 - 38.97 mg/Kg) and copper (4.48 – 12.08 mg/Kg) exceeded their permissible guideline values, while concentrations of lead (0.019 – 0.065 mg/Kg) and cadmium (0.013 – 0.041 mg/Kg) were below their respective guideline value for fish food in both fish species. The order of heavy metal accumulation in the fillets, gills and liver was Fe > Zn > Cu > Pb > Cd. The human health risk assessment indicated that the THQ values for the heavy metals were < 1, calculated HI values (0.146 – 0.214) did not exceed the threshold value of 1 (HI < 1) which implies that the consumers are not predisposed to non-carcinogenic health risk. Estimated carcinogenic risk values and integrated carcinogenic risk (ICR) values associated with the consumption of the fish species classified the consumption of C. gariepinus and T. zillii as extremely low risk (Grade I). Concerted efforts in the periodic monitoring of anthropogenic activities within the watershed to prevent the deterioration of the water quality of Owan River in order to guarantee the sustainable availability of safe aquatic foods for human consumption is recommended.