Health and ecological risk assessment of potentially toxic metals in road dust at Lalibela and Sekota towns, Ethiopia

The ecological and health problems resulted from heavy metals (Mn, Fe, Ni, Co, Cu, Zn, Cd, Hg, Pb, As, and Cr) in the road dust in the towns of Sekota and Lalibela, Ethiopia were assessed. The average heavy metal concentrations were ranged from 0.088 (Cd) to 2.714 (Fe) mg/kg. Individual metal and cumulative metals pollution levels in both towns revealed that Lalibela is moderately polluted by Zn, Pb, and Ni and Sekota being moderately polluted by Zn, Pb, Ni, As, Hg, and Cu. Furthermore, the United States Environmental Protection Agency's health risk evaluation model showed that the total heavy metal health risk levels in the road dust ranged from 5.71 × 10–3 (adult) to 2.57 × 10–2 (children), with an average risk of 7.35 × 10–2. Lalibela was found to have higher chance of risk than Sekota. The total lifetime cancer risk varied from 4.51 × 10–9 (for adults, Sekota) to 7.75 × 10–9 (for children, Lalibela), with a mean risk of 6.12 × 10–9 implying a low chance of getting cancer. The hazard quotient and hazard index of all the metals were below the limit. In general, children were found to be more susceptible than adults.