Occurrence features, source apportionment, and exposure risks of organic ultraviolet absorbers in surface dust, soil, and PM2.5 in a semi-arid industrial city of Xi'an, China.

Organic ultraviolet absorbers (OUVAs) are widely used in personal care and industrial products, which have attracted increasing concerns due to their adverse health effects. However, the occurrences, sources, and exposure risks of OUVAs in urban environments remain insufficiently understood. In this study, a total of 167 samples, encompassing surface dust, topsoil, and atmospheric PM2.5, were collected from the largest city of Xi'an in Northwest China. Twelve OUVAs were analyzed in these samples for their pollution characteristics, potential sources, and exposure risks. The results showed that OUVAs were widely detected in the three media. In the surface dust, topsoil, and PM2.5, the total concentration of 12 OUVAs (Σ12OUVAs) averaged as 369 ng/g, 86.6 ng/g, and 9.81 ng/m³ . OUVAs were dominated by 3-(4-methylbenzylidene) camphor (4-MBC), homosalate (HMS), and benzophenone (BP); ethylhexyl methoxycinnamate and 2-ethylhexyl 4-(dimethylamino) benzoate; and 4-MBC. Higher Σ12OUVAs were mainly distributed in the urban east-west axis and the northeastern and southern of Xi'an; the western, southwestern, and northwestern of Xi'an; and summer (13.7 ng/m³) rather than winter (5.77 ng/m³). OUVAs mainly originated from usages of sunscreen and personal care products, construction-related emissions, mixed sources, domestic wastewater. Human exposure levels to OUVAs followed ingestion > dermal contact > > inhalation and children > adolescents > youths > adults. The contributions of environmental media to the total exposure followed surface dust > topsoil > > PM2.5. Among OUVAs, 4-MBC was the major contributor to human exposure, followed by HMS and BP. The hazard quotient (HQ) and hazard index (HI) for individual and all OUVAs were below the threshold of 1, suggesting insignificant non-carcinogenic health risks.