Health and ecological risk assessment and simulation of heavy metal-contaminated soil of Tehran landfill

Abstract

The toxic effects of heavy metals in landfill soils have become a significant concern for human health. The present study aimed to estimate the health and ecological risk associated with soil heavy metal in Tehran landfill. A total of 48 soil samples were taken from the landfill and residential area and were analyzed using inductively coupled plasma-optical emission spectroscopy. The results showed the following order for heavy metal levels in landfill soil: Al > Fe > Mn > Zn > Cr > Cu > Pb > Ni > Co > As > Cd. The investigated ecological indices showed moderate to high heavy metal pollution. The principal component analysis revealed that the concentration of Pb, Cu, Zn, Cr, and Ni in the investigated soil was mainly affected by anthropogenic activities. Although the hazard index (HI) value in children was 6.5 times greater than that of adults, this value for both landfill workers and residents of the target area was at a safe level (HI ≤ 1). In the residential area, the Incremental Lifetime Cancer Risk (ILCR) value of adults (1.4 × 10⁻⁴) was greater than children ILCR value (1.2 × 10⁻⁴). Monte Carlo simulation and sensitivity analysis showed input variables such as exposure duration, exposure frequency, Ni concentration, soil ingestion rate, and As concentration have a positive effect on ILCR of 41.3, 24.3, 9.4, 9.0, and 2.9% in children, respectively. These results indicate that the landfill soil and the adjacent residential area are affected by heavy metal contamination and that the current solid waste management policies need to be revised.