Origin and Risk Assessment, and Evaluation of Heavy Metal Pollution in the Soil of Tehran, Iran

In this research, the concentrations of several heavy metals such as chromium (Cr), arsenic (As), nickel (Ni), copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) were measured using Enrichment Factor (EF), chemical separation, pollution index (Ipoll), ecological Risk Index (RI), and health risk assessments. The results of the soil EF showed that Cr, As, Ni, Zn, and Cu are at a minimum limit of pollution while Pb is at a moderate limit of pollution, and Cd has a significant level of pollution in the soil. The results of the chemical separation of anthropogenic and lithogenous phases demonstrated that the studied elements were of low pollution, except Cd. Based on Ipoll results, all metals were in the non-pollution zone except for Cd. The ER results of the metals in the soil of all metals were low except for Cd. According to USEPA guidelines, the risk of cancer from As, Ni, and Cr metals is high; the risk of Pb is medium; and the risk of Cd is low. The total risk of 9.68E-03 is unacceptable in the risk range because inhalation, ingestion, and skin contact with heavy metals increase cancer risk. During their average life expectancy of 70 years, 3,739 people develop various types of cancer. All metals’ hazard quotient (HQ) is lower than the safe level one in the non-cancer risk assessment. Even so, the total hazard index (HI) of 1.52E + 00 is more than 1, indicating that people are exposed to a variety of non-cancerous diseases due to breathing, swallowing, or skin contact with these metals. Eventually, Monte Carlo simulation uncertainty results in support of the results of cancer and non-cancer risk analysis. Overall, it is concluded that proper management strategies are required to control the concentration of these pollutants in Tehran’s soil to maintain the health of Tehran’s citizens.