Occurrence, sources, and health risk assessment of organophosphate esters in road dust and roadside soil from Tianjin, China.
Road dust and roadside soil samples were collected from industrial and residential areas of Tianjin, China, in summer and winter, and 14 representative organophosphate esters (OPEs) were quantified by high-performance liquid chromatography-tandem mass spectrometry to systematically investigate their concentrations, spatiotemporal variation, sources, and health risks. A markedly higher median concentration of Σ14OPEs was observed in road dust (189.78 ng/g) than in roadside soil (50.76 ng/g), and halogenated OPEs were predominant in both media. Industrial areas exhibited higher Σ14OPE levels compared to residential areas. Significant seasonal variation in OPE concentrations was observed only in roadside soil, with markedly higher levels in winter than in summer. OPEs in road dust mainly originated from industrial emissions (40.85%), other complex sources (23.19%), release from and abrasion of OPE-containing products (21.08%), and traffic emissions (14.88%), whereas the main source of OPEs in roadside soil was traffic emissions (35.38%), followed by indoor release from OPE-containing products (27.92%), release from these products combined with industrial activities (24.37%), and other sources (12.34%). Health risk assessment identified ingestion as the primary exposure route for humans, with children representing the most exposed population group. In all scenarios, non-carcinogenic and carcinogenic risks were acceptable overall, being below 1 and below 1×10-6, respectively. Risks associated with road dust were mainly due to industrial emissions and other sources of OPEs, whereas those linked to roadside soil were primarily attributed to indoor release of OPEs from OPE-containing products. Although the estimated health risks were within acceptable levels, the widespread occurrence and potential toxicity of OPEs warrant continued attention.