Assessment of Heavy Metal Concentration in Water and Tissues of Clarias gariepinus and Oreochromis niloticus from Lower River Niger, Oguro -Ajaokuta, Kogi State, Nigeria: Implications for Human Health

This study evaluated the heavy metals concentration in water and tissues of Clarias gariepinus and Oreochromis niloticus in the lower river Niger, Oguro, Ajaokuta. The sampling period was three months (June to August). Three sites along the River Niger at the location were marked for the sample collection (water and fish) and were designated as sites A, B, and C. The water and fish samples (muscle, gills, and viscera) were collected, dissected, and prepared for heavy metal analysis using a Microwave Plasma-Atomic Emission Spectrometer (MP-AES). The heavy metals investigated include Iron (Fe), Lead (Pb), Nickel (Ni), Chromium (Cr), Cadmium (Cd), and Zinc (Zn). The data collected were subjected to Analysis of Variance (ANOVA) using SPSS (version 20). The result showed that heavy metal contents of the water followed this trend: Fe>Zn>Pb>Cr>Ni>Cd across the sampling months. The heavy metal in fish tissue showed a significant (P<0.05) difference among fish species. Higher concentrations were observed in the African catfish gill compared to those from Nile Tilapia. Also, the human risk/health assessment on BAF, MOE, EDI, HI, and THQ revealed that the water and the fish tissues evaluated for heavy metal level posed no threat to the health of the consumer as they were all within the acceptable limit of WHO, USEPA, and EPA). The findings of this study did not pose any danger to consumers of fish and utilization of water from this River. Keywords: Aquatic pollution, Fish, human health, Implication, Nigeria