What question did this study set out to answer?

To analyze heavy metal levels in the Upper Genale Dawa River Basin and assess associated health risks.

May 18, 2026Open Access

Ecotoxicological Health Risk Analysis of Toxic Heavy Metals Accumulation in Surface Water of the Upper Genale Dawa River Basin, Ethiopia

Key Points

To analyze heavy metal levels in the Upper Genale Dawa River Basin and assess associated health risks.
Assessed the levels of heavy metals in surface water samples from the river basin.
Calculated water quality and health risk indices for both ingestion and dermal exposure.
Evaluated the ecological risk indices for multiple heavy metals.
Mean heavy metal concentrations indicated significant pollution with an HPI of 1958.40 and HI values exceeding 1 for both children and adults.
Carcinogenic risk values for exposure via drinking water highlighted potential risks, with values above the safe threshold for both demographics.
Ecological risk indices quantified severe contamination, showing the urgent need for pollution mitigation measures.

Abstract

Due to their toxicity, non-biodegradability, bioaccumulation, environmental stability, and persistence in nature, heavy metals (HMs) currently become pollutants of global concern. Either acutely or chronically exposed marine lives and human beings can result in severe damage to the structure and function of vital organs such as kidney, liver, and brain. Water quality is negatively affected by HMs released into the river ecosystem. This study, therefore, investigates the levels of HMs in surface water of the Upper Genale Dawa River Basin to assess water quality and associated ecotoxicological health risks at the study site. The mean levels of HMs (mg/L) in surface water followed the pattern: Hg (0.029) > Mn (0.028) > Cu (0.022) > Pb (0.022) > Ni (0.021) > As (0.021) > Co (0.019) > Cd (0.017) > Fe (0.017) > Zn (0.016) > Cr (0.016) > Se (0.014). Primarily, areas close to significant pollution sources exhibited higher concentrations of HMs. Water quality index (WQI) values for drinking water (Heavy Metal Pollution Index, HPI =1958.40) and (Heavy Metal Evaluation Index, HEI = 35.10) indicated the quality of water was compromised. The HI values of the HMs for both children and adults via ingestion of drinking water were 7.83 and 5.76, respectively; and its values via dermal exposure in both children and adults were found to be 1.91 and 1.01, indicating intolerable noncarcinogenic health risks to the community as HI > 1 poses non-carcinogenic risks to the exposed populations. The ecotoxicological risk indices that account the synergetic impacts of multiple-metals [Ecological Risk Index, ERI = 492.59; Degree of Contamination, CD = 34.85; modified Degree of Contamination, mCD = 2.90; and Pollution Load Index, PLI = 0.34) indicated the overall contamination of the river water by HMs considered in this study. The CR values of the HMs for both children and adults via ingestion of drinking water were 6.44*10-2 and 4.74*10-2, respectively; and its values via dermal exposure in both children and adults were found to be 5.01*10-4 and 2.65*10-4, implying the potential carcinogenic health risks to the community as CR > 1*10-4 poses carcinogenic risks to HM exposed groups. This research highlights the urgent need for monitoring and intervention strategies to mitigate HM pollution at Genale Dawa River Basin to prevent community health and the safety of the riverine ecosystem.

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