Contamination profiles and health impact of benzothiazole and its derivatives in PM2.5 in typical Chinese cities.

Although benzothiazole and its derivatives (BTHs) are considered emerging contaminants in diverse environments and organisms, little information is available about their contamination profiles and health impact in ambient particles. In this study, an optimized method of ultrasound-assisted extraction coupled with the selected reaction monitoring (SRM) mode of GC-EI-MS/MS was applied to characterize and analyze PM2.5-bound BTHs from three cities of China (Guangzhou, Shanghai, and Taiyuan) during the winter of 2018. The total BTH concentration (ΣBTHs) in PM2.5 samples from the three cities decreased in the order of Guangzhou > Shanghai > Taiyuan, independently of the PM2.5 concentration. Despite the large variation in concentration of ΣBTHs in PM2.5, 2-hydroxybenzothiazole (OTH) was always the predominant compound among the PM2.5-bound BTHs and accounted for 50-80% of total BTHs in the three regions. Results from human exposure assessment and toxicity screening indicated that the outdoor exposure risk of PM2.5-bound BTHs in toddlers was much higher than in adults, especially for OTH. The developmental and reproduction toxicity of OTH was further explored in vivo and in vitro. Exposure of mouse embryonic stem cells (mESCs) to OTH for 48 h significantly increased the intracellular reactive oxygen species (ROS) and induced DNA damage and apoptosis via the functionally activating p53 expression. In addition, the growth and development of zebrafish embryos were found to be severely affected after OTH treatment. An overall metabolomics study was conducted on the exposed zebrafish larvae. The results indicated that exposure to OTH inhibited the phenylalanine hydroxylation reaction, which further increased the accumulation of toxic phenylpyruvate and acetylphenylalanine in zebrafish. These findings provide important insights into the contamination profiles of PM2.5-bound BTHs and emphasize the health risk of OTH.