Levels of Heavy Metals and Associated Human Health Risk Assessment at the Upper Genale-Dawa River Basin of Ethiopia

This study investigates the concentration of heavy metals in the Upper Genale Dawa River Basin to assess water quality and potential health risks. The primary objective was to quantify the levels of heavy metals, and to evaluate the associated risks to human health, particularly concerning non-carcinogenic and carcinogenic effects. Water samples were purposely collected from 24 sites in the River Basin. Analytical techniques were utilized to measure the heavy metal concentrations, revealing the average concentrations of heavy metals followed the order of Hg (0.029 mg/L) > Mn (0.028 mg/L) > Cu (0.022 mg/L) > Pb (0.022 mg/L) > Ni (0.021 mg/L) > As (0.021 mg/L) > Co (0.019 mg/L) > Cd (0.017 mg/L) > Fe (0.017 mg/L) > Zn (0.016 mg/L) > Cr (0.016 mg/L) > Se (0.014 mg/L). Notably, areas near significant pollution sources exhibited higher concentrations, especially Mn, which peaked at 0.165 mg/L. Pollution indices (HPI, HEI, MI) indicated that water quality was compromised for both drinking and irrigation uses. Risk assessment revealed non-carcinogenic hazards (HQ and HI) primarily linked to arsenic and cadmium, presenting intolerable risks, especially for children. Carcinogenic risk evaluations indicated a high risk for developing cancer based on oral intake, while dermal exposure remained within acceptable limits. This research highlights the urgent need for monitoring and intervention strategies to mitigate heavy metal pollution in the Genale Dawa River Basin, ensuring community health and environmental safety.