Investigating the non-carcinogenic risk and hazard quotient of heavy metals in high-traffic districts of Tehran Metropolis

Document Type : Original Article


1 Department of Environment Engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran.

2 Agriculture and Natural Resources Department, Islamic Azad University, Ahwaz Branch, Ahwaz, Iran.



Background: This study aimed to investigate the concentrations of heavy metals bound to airborne particulate matter (PM) in high-traffic districts of Tehran and to determine the carcinogenic risk and hazard quotient (HQ) of these metals through a descriptive-applied method.

Methods: Six indoor/outdoor stations were established in three high-traffic districts. Each station was sampled (n = 36) with six replicates in winter 2018. After extraction of the metals from fiberglass filters by acid digestion based on the ASTM method, the concentrations of heavy metals were determined by inductively coupled plasma (ICP-OES) device. The human health risk was evaluated according to the U.S. EPA standard method. Data were analyzed by SPSS software using Spearman correlation and multivariate analysis of variance (MANOVA).

Results: Districts 2, 3, and 15 were the most high-traffic areas of Tehran, respectively. Average heavy metal concentrations were in order of Al > Fe > Pb > Mn > Cu > Zn > Cr > As > Ni > Cd, which were significantly different in indoor and outdoor environments. The correlations between heavy metal concentrations, carcinogenic risk, and HQ were significant in all three districts (p<0.05). Mean carcinogenic risk variables, HQ levels, and heavy metal concentrations in all three regions were in the order of districts 15 > 2 > 3, and outdoors > indoors.

Conclusions: Based on the results, serious measures are recommended to control traffic congestion in Tehran for the prevention of cancer risk and other health hazards caused by heavy metal bonded TSP (Total Suspended Particulate Matter).


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