Heavy Metal Concentrations and Potential Human Health Risk for Consuming Gills, Muscles, Liver and Gonads of Silver Catfish (Chrysichthys nigrodigitatus) Reaped from Great Kwa River, Calabar, Cross River State, Nigeria

The objective of this paper was to assess the concentrations of Pb, Hg, Cd, As, Cr, Zn and the potential human health risk associated with consuming contaminated gills, muscles, liver and , gonads of silver catfish (Chrysichthys nigrodigitatus) reaped from Great Kwa River, Calabar, Cross River State, Nigeria using atomic absorption spectrophotometer (AAS) after mixed acid digestion. The results showed that Mean concentrations of lead in the muscles, liver, gills, gonads (sperm and ovary) of C. nigrodigitatus range between 0.050±0.022 mg/kg to 0.242±0.027 mg/kg. The difference in lead content of C. nigrodigitatus organs was significant (p ≤ 0.05) and displayed the trend: gills > liver = muscles > gonads (sperm) = gonads (ovary). Cadmium, mercury and arsenic concentrations were not detected in the organs. Arsenic was only detected in the liver and gills of C.nigrodigitatus. The Recommended Daily Intake (RDI) and the Tolerable Upper Intake Level (UL) were compared to determine the safe levels of lead, cadmium, mercury, Zinc and arsenic that can be obtained from the consumption of C. nigrodigitatus sampled from the River. With the exception of zinc, all of the metals' average EDIs were below the suggested daily consumption threshold. For every metal in the research, the average Target Hazard Quotient (THQ) was less than 1.00. Findings suggest that there is little risk of cancer from lead, arsenic, and cadmium in C. nigrodigitatus, therefore continuous monitoring of these metals in the study area is necessary to ensure the good quality of the aquatic environment.