Status, Source, and Risk Assessment of Heavy Metal(Loid)s and Polycyclic Aromatic Hydrocarbons (PAHs) in the Street Dust of Ilam, Iran

A total of 25 Ilam street dust specimens were sampled to investigate the possible ecological and health risks of heavy metal(loid)s and polycyclic aromatic hydrocarbons (PAHs). We found that the average concentrations of heavy metal(loid)s, namely Pb, Zn, Cu, Cr, Cd, Ni, V, and As, were 52, 213, 63, 46, 0.4, 44, 31, and 5 mg/kg, respectively. The average concentration of all heavy metal(loid)s except for Cr and V was several times higher than the baseline values. We evaluated Zn and Pb in the region using the average enrichment factor (EF) and pollution index (PI); the Nemerow integrated pollution index (NIPI) indicated that 76% of the samples had high degrees of pollution. According to principal component analysis (PCA), three principle components are involved in the heavy metal(loid) pollution of Ilam street dust. For example, the pollution sources of Cu, Cr, Cd, and Ni likely originated from anthropogenetic origins, including traffic, tire depreciation, and gasoline use. The sources of Pb and Zn were other anthropogenic activities, such as metal corroding and the combustion of garbage and gases from industries, while V and As were probably from natural sources. The range of sum over 11 PAHs was 167–11,497 μg/kg with a mean of 2242 μg/kg. The concentration of low molecular weight (LMW) PAHs averaged 1471 μg/kg, accounting for 66% of the total PAHs; their sources were mainly associated with combustion and pyrogenic emissions. The PCA also revealed that PAHs mainly originated from burning fossil fuels. The values of RQ_{∑PAHs (MPCs)} and RQ_{∑PAHs (NCs)} were respectively >1 and ≥800, indicating a high ecosystem risk for PAHs. Mean values for RQ_{∑PAHs (MPCs)} and RQ_{∑PAHs (NCs)} were 4 and 1021, respectively, implying that Ilam street dust poses a relatively high ecosystem risk of PAHs. Street dust PAHs’ toxic equivalency quotient (TEQ) varied from 26 to 199 μg/kg. The total cancer risk was 3.92 × 10⁻⁴ and 4.06 × 10⁻⁴ for adults and children, respectively, indicating that the potential for cancer risk is very high through dust dermal contact and ingestion.