Dietary Exposure and Health Risk Assessment of Heavy Metal Bioaccumulation in Edible Tissues of Common Carp (Cyprinus carpio) From Koka Reservoir, Ethiopia

Heavy metal pollution in freshwater ecosystems threatens food safety and public health, particularly in industrializing regions. This study evaluated the bioaccumulation of heavy metals in edible tissues of Cyprinus carpio from Ethiopia's Koka Reservoir, assessing potential health risks for communities dependent on this fish as a dietary staple. Water, algae, and fish samples were collected from 2 sites influenced by river inflow and tannery effluents. Heavy metal concentrations were analyzed alongside bioaccumulation factors (BAFs), estimated weekly intake (EWI), target hazard quotients (THQ), and carcinogenic risk (CR). Although water quality parameters (pH: 8.57-8.62; dissolved oxygen: 3.60-6.30 mg/L) complied with guidelines, heavy metals in fish tissues exceeded safe levels: Pb (<0.034-3.29 mg/kg), Cd (<0.001-0.36 mg/kg), Fe (1.55-74.98 mg/kg), and Zn (0.18-135.32 mg/kg). Elevated BAFs for Zn (756.00) and Cr (110.00) indicated significant bioaccumulation and potential biomagnification. While THQ values were <1 (suggesting minimal non-carcinogenic risk), CR for Cr⁶⁺ and Pb²⁺ exceeded safety thresholds, signaling long-term carcinogenic hazards. These findings demonstrate that water quality monitoring alone is insufficient to safeguard food safety, as metals accumulate disproportionately in aquatic biota. Thus, the study recommends stricter controls on industrial effluents, sustainable agricultural practices, systematic biomonitoring, and community education to mitigate dietary heavy metals exposure, contributing to SDGs on health, food security, and sustainable resource management.