Status, source, ecological and health risk assessment of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in street dust of Abadan, Iran

Abstract

The potential hazard to human health from exposure to toxic metals and polycyclic aromatic hydrocarbons (PAHs) in street dust was assessed using thirty street dust samples collected from Abadan, an industrial city in Southwest Iran. The mean concentration of Pb, Zn, Cu, Cr, Cd, Ni, V, As and Co in the street dust was: 59, 288, 113, 50, 0.5, 57, 36, 7.1 and 7.5 (mg/kg), respectively. The majority of potentially toxic metals were elevated compared to background concentrations, with the exception of Co and V. Mean enrichment factors decreased in the following order: Zn > Pb > Cu > Cd > As > Cr > Ni > Co > V, with a high enrichment value for Zn and Pb. Cadmium had a moderate potential ecological risk compared to other toxic metals. Correlation coefficients and principal component analysis (PCA) identified three principal groups as sources of toxic metals in Abadan street dust. Metals such as Cr, Ni, Co and V were identified to originate from natural parent materials, Zn, Cu and Pb from anthropogenic sources emitted from combustion/vehicular materials and Cd and As from other anthropogenic sources such as the Abadan refinery and petrochemical complex. The sum of 13 PAHs ranged from 400 to 11,766 (μg/kg), with a mean of 2436 (μg/kg). Approximately 68%–79% of ∑PAHs comprised of higher molecular weight PAHs (HMWPAHs 4–6 rings), revealing a combustion origin. Principal component analysis (PCA) for PAHs in Abadan street dust originated mainly from vehicular, petroleum emission and fossil fuel. The toxic equivalency quantities (TEQs) of PAHs in the street dust ranges from 22 to 951 (μg/kg). High coefficients of correlation (r2 = 0.98 to 0.83, p < 0.01) among Pyrene, Benzo (a) anthracene, Chrysene, Benzo (a) pyrene, Benzo (b) fluoranthene, Benzo (k) fluoranthene, and TEQ of street dust showed that these PAHs were principal contributors to TEQ. Ecosystem risk calculations for PAHs were high since the value of RQ∑PAHs(MPCs) was ≥1 and RQ∑PAHs(NCs) was ≥800. The mean values for RQ∑PAHs(MPCs) and RQ∑PAHs(NCs) were 8 and 1151, which indicated a relatively high ecosystem risk of PAHs in street dust in Abadan. The total cancer risk was 8.64 × 10−3 for adults and 8.95 × 10−4 for children, suggesting a high potential cancer risk through both dust dermal contact and ingestion pathways.