Abstract

This study investigated the contamination, spatial distribution, and eco-toxicological risks of metal(loid)s in street dust samples collected from residential, park, industrial, and high-density traffic zones of Najafabad, Iran. The results of geochemical analysis indicated that the mean concentrations of As, Cr, Co, V, and Mo were 68.27, 1.33, 7.51, 42.40, and 5.70 mg kg−1, respectively. According to local Moran statistics, the hot spots determined for As were in the industrial (99% confidence level) and residential (95% confidence level) zones. The industrial and the high-traffic zones were the hot spots for V and Co, respectively, both having a 90% confidence level. Cr and Mo had a homogenous distribution in the area. The ecological cumulative index values revealed high pollution levels caused by industrial activities. In terms of health risks estimated by the probabilistic and deterministic approaches, the Cr present in 40% of the samples was found to be higher than the allowable limit, indicating a carcinogenic risk from street dust for both children and adults. The results of sensitivity analysis showed that among the influencing factors, the “concentration of Chromium” factor (80.2%) in the adult group and the “body weight” factor (− 83.3%) in the children group exposed to V had the highest influence on the non-carcinogenic risk results. On the other hand, the “years exposed to Cobalt” factor in both the children (95.9%) and the adult (95.1%) groups had a strong influence on the carcinogenic risk results.

Introduction

The introduction discusses the dangers of street dust as a carrier of toxic metal(loid)s, particularly in urban areas of developing countries. It outlines sources of contamination (traffic, industry, agriculture) and highlights the health risks, especially for children. The authors note a lack of research in Najafabad, Iran, and set the objective to assess contamination levels, sources, spatial patterns, and health risks using deterministic and probabilistic methods.

Materials and Methods

This section describes how street dust samples were collected from 30 sites across different urban zones in Najafabad. The concentrations of five metal(loid)s (As, Cr, Co, Mo, and V) were analyzed using ICP-OES. The study used various statistical and geostatistical tools (e.g., Moran's I, Getis-Ord Gi*) and health risk models (EPA-based) to assess contamination, spatial clustering, and eco-toxicological risks. Both deterministic and probabilistic methods (Monte Carlo and Latin Hypercube Sampling) were applied to estimate human health risks.

Results and Discussion

The results show varying contamination levels, with Cr and As exceeding background and health-based limits in many samples. Hot spots of pollution were concentrated in industrial and residential areas. Cr, As, and Co posed the most significant health risks, especially for children. Sensitivity analysis showed that exposure time and body weight were critical risk factors. Cluster and correlation analyses linked contamination sources to traffic, industrial activities, and agriculture.

Conclusion

The study concludes that street dust in Najafabad is significantly contaminated by metal(loid)s, mainly from industrial and traffic-related sources. It emphasizes the carcinogenic and non-carcinogenic health risks, especially for children, and calls for strict environmental monitoring, urban planning, and public health interventions.