Occurrence and health risks of tire-derived chemicals in urban road dust

Despite the widespread presence of tire-derived chemicals (TDCs) in the environment, research on their occurrence in road dust and the associated health risks remains limited. This study quantified 30 TDCs in 24 seasonal road dust samples collected from four functional areas in Guangzhou. In silico toxicology prediction tools were applied to assess toxicity, enabling systematic exposure and health risk assessments, as well as the identification of priority contaminants for control. Total TDC concentrations ranged from 325 to 9,671 ng/g. 1,2-Diphenylguanidine (DPG) and 4-N-(4-methylpentan-2-yl)-1-N-phenylbenzene-1,4-diamine (6PPD) were the dominant compounds, accounting for 85% and 8.6% of the total concentration, respectively. The highest total concentration was observed in business districts (mean: 4,388 ng/g) and was correlated with traffic density. However, the notable concentrations detected in green spaces with low traffic volumes (mean: 847 ng/g) suggest that abrasion of other rubber materials during pedestrian activities may represent an additional source. Dry-season concentrations were approximately twice those measured during the wet season, indicating that rainfall reduces TDC accumulation. Toxicity predictions identified neurotoxicity, carcinogenicity, mutagenicity, and endocrine disruption as the primary toxicological effects. Risk assessment indicated low health risks from inhalation and dermal contact, though attention is warranted. DPG, 6PPD, and 3H-1,3-benzothiazol-2-one were identified as priority pollutants requiring further monitoring. This study provides critical data to support future pollution control measures and regulatory strategies for TDCs in road dust.