Heavy metal concentration and DNA damage in tilapia (Oreochromis niloticus linnaeus, 1758) and catfish (Clarias gariepinus Burchell, 1822) from contaminated Ala River, Akure, Nigeria.

Abstract

This study investigated heavy metal contamination in Clarias gariepinus, Oreochromis niloticus, and water from the polluted Ala River using atomic absorption spectroscopy. Carcinogenic and non-carcinogenic risks were assessed per USEPA guidelines. DNA damage in fish was evaluated via micronucleus assay and nuclear aberration analysis, with Alanine aminotransferase (ALT), Aspartate Aminotransferase (AST), and Alkaline Phosphatase (ALP) activities examined for potential mechanisms. Cadmium (Cd), Chromium (Cr), Nickel (Ni), and Lead (Pb) levels in fish and water exceeded WHO/FAO limits, with higher concentrations in C. gariepinus. Health risk assessments showed that estimated daily intake (EDI) of these metals in children and adults exceeded safe limits, particularly from C. gariepinus consumption. Consumption of Ala river water posed health risks, as Cd and Pb EDI values exceeded safe limits for adults and children. High hazard index levels in C. gariepinus, O. niloticus, and water indicated non-carcinogenic risks, while total cancer risk values surpassed the threshold (>10^-4), signifying significant cancer risks. DNA damage analysis showed a statistically significant (p ≤ 0.05) increase in micronuclei (MN) and other nuclear aberrations, with higher MN frequency in C. gariepinus. ALT, AST, and ALP levels were elevated, indicating physiological stress. The study underscores severe metal contamination in Ala River, urging stricter pollution control measures.