HUMAN HEALTH RISK ASSESSMENT OF HEAVY METALS IN FISHES FROM EGBE RESERVOIR, EKITI STATE, NIGERIA

Abstract

Contamination of aquatic ecosystems by industrial, agricultural, and urban activities has intensified concerns about heavy metal accumulation in fish and the associated risks to human health. In this study, heavy metal concentrations and potential health risks were assessed in five fish species-Clarias gariepinus, Oreochromis niloticus, Sarotherodon galilaeus, Parachanna obscura, and Hydrocynus forskali-collected from Egbe Reservoir, Nigeria. A total of 125 fish samples were obtained over a six-month period (July to December 2024), and muscle tissues were analysed for selected metals using atomic absorption spectrophotometry. Zinc (Zn) emerged as the dominant metal across all species, with concentrations ranging from 10.15 mg kg-1 in Hydrocynus forskali to 13.52 mg kg-1 in Clarias gariepinus. In contrast, toxic metals such as cadmium (Cd) and lead (Pb) occurred at relatively low levels and remained within established permissible limits. Estimated Daily Intake (EDI) values further indicated that dietary exposure was driven largely by essential elements, particularly Zn and Fe. Health risk assessment showed no significant non-carcinogenic risk, as all Target Hazard Quotient (THQ) values were below unity and Hazard Index (HI) values ranged from 0.035 to 0.067. In addition, carcinogenic risk (CR) values for Cd, Cr, Pb, and As fell within the acceptable range (10-6 -10-4 ), suggesting negligible lifetime cancer risk. Overall, these findings suggest that fish from Egbe Reservoir are currently safe for human consumption with respect to heavy metal contamination. Nonetheless, sustained environmental monitoring and effective pollution control measures are necessary to prevent future contamination and to safeguard ecosystem health and food safety.