# Innovative isotopic modeling and risk assessment of PTEs and PAHs in urban soils

## TL;DR

This study assesses health and environmental risks from toxic elements and PAHs in urban soils of Sanandaj City using a new isotopic modeling approach.

## Contribution

A novel isotopic modeling method using lead isotope ratios to trace contamination sources in urban soils.

## Key findings

- Cadmium (Cd) posed a significant ecological risk, while carcinogenic risks from Cr, Ni, Pb, Cd, and As exceeded acceptable thresholds.
- High molecular weight PAHs indicated pyrogenic sources, and lead contamination was traced to industrial emissions and vehicular exhaust.
- Children showed higher non-carcinogenic risks, particularly from ingestion, compared to adults.

## Abstract

This study investigates the health and environmental risks associated with Potentially Toxic Elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in urban soils of Sanandaj City, Iran, using an innovative isotopic modeling approach. A total of 53 surface soil samples were systematically collected, revealing elevated concentrations of Zinc (Zn), Copper (Cu), Nickel (Ni), Cadmium (Cd), Chromium (Cr), Arsenic (As), and Lead (Pb), with Cd posing a significant ecological risk. Ecological risk assessments indicated low risk for most elements, except for Cd, which showed a notable environmental threat. Non-carcinogenic risk assessments, based on ingestion, inhalation, and dermal exposure, revealed no significant risks for both children and adults, although children exhibited higher risks, particularly in ingestion. However, carcinogenic risk assessments demonstrated that metals like Cr, Ni, Pb, Cd, and As exceeded the acceptable risk thresholds for both populations, highlighting a severe health concern. PAH concentrations ranged from 126.44 to 2460.87 µg/kg, with a dominance of high molecular weight PAHs, suggesting significant pyrogenic sources. A novel isotopic modeling method, based on 206Pb/207Pb and 208Pb/207Pb ratios, effectively traced lead contamination sources, identifying industrial emissions and vehicular exhaust as the primary contributors. This study offers valuable insights into urban soil contamination and provides a robust framework for environmental management and policy-making to mitigate risks from PTEs and PAHs.

The online version contains supplementary material available at 10.1038/s41598-025-22183-z.