Concentrations, profiles, and risk assessment of organic UV filters in atmospheric PM2.5 from Beijing, China

Human exposure to organic ultraviolet (UV) filters may pose health risks, but the distribution of UV filters in PM2.5 of four seasons is currently unknown. In this study, PM2.5 samples were collected during 2021-2022 in Beijing, and 15 organic UV filters were analyzed. The concentrations of Sigma UV filter ranged from 260 to 1859 pg/m(3). The highest Sigma UV filter concentrations were observed during summer, with temperature showing a significant positive correlation (p < 0.01) on the concentrations of homosalate (HMS), 2-ethylhexyl salicylate (EHS) and Ethylhexyl-4-methoxycinnamate (EHMC). The dominant compounds were HMS, EHS, and EHMC, which accounted for 93.5% of the median contributions. The median concentration of 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328) was 0.58 pg/m(3), which was lower than that in other studies. It was noteworthy that 2,4-Di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl) phenol (UV-327) and 2-(2H-Benzotriazol-2-yl)-6-(butan-2-yl)-4-tert-butylphenol (UV-350) were firstly detected in ambient PM2.5. In vivo predicted biological toxicity and absorption, distribution, metabolism, and excretion characteristics were assessed, EHMC was prioritized due to its high concentration and high potential to be absorbed by human body. The risks of Sigma UV filters through inhalation and dermal contact were negligible for both toddlers and adults, and inhalation exposure exceeded dermal contact by 2-3 orders of magnitude. This is the first study of the occurrence, profiles and risk assessment of 15 UV filters in PM2.5, and more attention should be paid for prioritized UV filters especially EHMC.