Hazard, ecological, and human health risk assessment of heavy metals in street dust in Dezful, Iran

This study aimed to investigate the potentially toxic metal (Pb, Zn, Cu, Cr, Cd, Ni, V, As, and Co) hazard in street dust from Dezful, Iran. For this purpose, we collected 30 samples of street dust from the main pedestrian sidewalks of Dezful. Subsequent heavy metal concentration data for these samples was evaluated using human health risk and potential ecological risk index (RI) assessments. The average toxic metal concentrations for Pb, Zn, Cu, Cr, Cd, Ni, V, As, and Co were 54, 224, 51, 44, 0.4, 46, 38, 3, and 8 mg/kg, respectively. Except for As, V, and Co, the mean concentration value of all heavy metals was several times higher than that of baseline concentrations. Calculations for potential ecological risk (PER) suggested a low street dust ecological risk from Pb, Zn, Cu, Cr, Ni, and V, while Cd presented a moderate ecological risk level. The highest hazard quotient (HQ) in children and adults was related to Pb by ingestion, while the lowest value was for Cd via inhalation. For all heavy metals, the hazard index (HI) was higher for children than for adults, which confirmed that the risk of exposure to these potentially harmful heavy metals is higher for children. The cancer risk (CR) values for Ni, As, Cd, and Pb for children and adults were lower than the threshold, 10−6, suggesting that the cancer risk for the majority of heavy metals measured was negligible, but more significant than the threshold for Cr, indicating that the presence of Cr in street dust requires urgent attention.