Human health risk assessment of cadmium (Cd) and lead (Pb) exposure in limnothrissa miodon fish from the four strata of Lake Kariba, Zambia

Anthropogenic activities such as agriculture, fishing, mining, mineral processing, and industrial operations significantly impact aquatic ecosystems. Fish readily bioaccumulate pollutants, transferring them through the food chain. This study assessed cadmium (Cd) and lead (Pb) concentrations in Kariba Kapenta (Limnothrissa miodon), a major commercially consumed whole fish species in Zambia. Metal concentrations were measured using Microwave Plasma Atomic Emission Spectroscopy (MPAES) on whole fish samples, reflecting portions typically consumed by local communities. The median concentrations of Cd and Pb were 0.0014 mg/kg and 0.0018 mg/kg (dry weight), respectively. Spatially, Cd concentrations were highest in Stratum IV (0.0015 mg/kg), whereas Pb peaked in Stratum II (0.0031 mg/kg). Estimated Daily Intake (EDI) values ranged from 0.00000129–0.00000171 mg/kg/day for Cd and 0.00000171–0.00000357 mg/kg/day for Pb. Corresponding Target Hazard Quotients (THQ) and Hazard Index (HI) values were all below 0.002 and 0.001, respectively, indicating negligible non-carcinogenic risk. Carcinogenic risks (CR) for both metals were below 10⁻⁴, suggesting minimal lifetime cancer risk. All concentrations were well below FAO/WHO maximum permissible limits for fish (Cd ≤ 0.05 mg/kg; Pb ≤ 0.3 mg/kg). This study provides a baseline for regular monitoring of metal contamination and health risk assessment in Kapenta, supporting safe consumption practices and public health protection in Lake Kariba communities.