The health risk assessment of Heavy Metals (HMs) in road dust based on Monte Carlo simulation and bio-toxicity: a case study in Zhengzhou, China.

Heavy metals (HMs) in road dust pose a significant threat to human health. The analysis of human health risks of HMs is an important theoretical basis for risk screening and management. The chemical forms and characteristics of HMs in road dust were analyzed. Based on the bio-toxicity of the different fractions of the HMs and Monte Carlo, three assessment models, including the health risk assessment based on bio-toxicity, the health risk assessment based on the Monte Carlo simulation, and the health risk assessment based on the Monte Carlo simulation and bio-toxicity, were established. Under the Traditional Model, the non-carcinogenic risks were only harmful to children, while the carcinogenic risks were not harmful to adults and children. Under the M-Traditional Model, the probability of non-carcinogenic risks being harmful to children's health was 83.17%. The probability that carcinogenic risks pose a threat to children's health was 28.61%. Considering the bio-toxicity of HMs in different chemical forms, non-carcinogenic risks and carcinogenic risks under the B-Traditional Model were all less than the corresponding critical values, indicating that the HMs in the road dust did no harm to both the adults and children. Based on the MB-Traditional Model, the chance of non-carcinogenic risks being harmful to children's health is 15.43%. Among different HMs, the non-carcinogenic risks of As are highest and the carcinogenic risks of Cr were the highest, so As and Cr should be listed as priority control contamination. MB-Traditional Model established in this study simultaneously considered bio-toxicity and random simulation and obtained more accurate results, which could provide a theoretical basis for risk analysis and management.