Health risk assessment and spatial trend of metals in settled dust of surrounding areas of Lake Urmia, NW Iran

Due to the rising concern about heavy metals in settled dust, a risk assessment of Arsenic (As), Cadmium (Cd), Copper (Cu), Lead (Pb), Nickel (Ni) and Zinc (Zn) has been conducted using multiple exposure paths, including oral ingestion, direct skin contact, and inhalation of dust around lake Urmia in Iran for the time period of 2020. Metal concentrations were assessed and sources were identified based on the enrichment factor and Pearson correlation coefficient. The metal concentrations were in the following order: Zn > Cu > Ni > Pb > Cd > As with arithmetic means of 3.5, 4.8, 57, 33, 25 and 83 mg/kg, respectively, which are within the range of Iran-EPA soil guideline values. A very weak correlation (r < 0.7) was found between the studied elements. The average enrichment factor (EF) for As, Cd, Cu, Ni, Pb, and Zn was 0.7, 4, 1.8, 0.5, 3.2 and 0.8, respectively, suggests minor enrichment for metals and influence from anthropogenic activity. The lifetime cancer risks (LTCR) due to exposure (three routes of inhalation) to metals were in the negligible risk category. The oral route had the highest hazard index (HI) between all of exposure paths. The HI was less than 1 for all three exposure paths. Moreover, the sensitivity analysis showed that exposure duration (ED) for As and Ni and exposure frequency (EF) for Cd and Pb had the highest impacts on LTCR values. Therefore, this study suggests the continuous monitoring of heavy metals in settled dust around the Lake Urmia as it is associated with the high health risk for the neighbourhood in the Lake Urmia's basin.