Contaminaiton Profiles And Health Risk Of Benzothiazole-based Compounds In PM_2.5in Typical Cities

Benzothiazole-based compounds（BTHs）are a class of high-yield fine chemicals that are widely used commercially as vulcanization accelerators in rubber production,corrosion inhibitors in antifreeze formulations,biocides for paper and leather,herbicides,fungicides,and UV stabilizers in textiles and plastics.Atmospheric fine particles(PM_2.5)can carry toxic pollutants through the lungs into the circulatory system of the human body due to their own particle size,causing many diseases.At present,although BTHs have been considered to be a type of emerging environmental pollutants existing in a variety of environmental substrates and organisms,there are still few reports on the regional or large-scale distribution of BTHs designed to monitor combined with PM_2.5.In addition,the various toxicity analysis of BTHs is still in its infancy,so it is necessary to clarify the pollution characteristics and health risks of BTHs in PM_2.5.Benzothiazole（BTH）,2-chlorobenzothiazole（CTH）,2-hydroxybenzothiazole（OTH）,2-aminobenzothiazole（NTH）,2-methylthio-benzothiazole（MSTH）and 2,5-Dimethyl-benzothiazole（XTH）was selected as the target analyte for this study.In this study,the pre-processing method of ultrasonic-assisted extraction and packed column purification,combined with the selective-reaction monitoring（SRM）mode of GC-EI-MS/MS,was used to quantitative analysis of BTHs in PM_2.5 from three Chinese cities（Guangzhou,Shanghai and Taiyuan）in winter in 2018.The results showed that the total BTHs concentration（ΣBTHs）in PM_2.5 samples was in the order of Guangzhou>Shanghai>Taiyuan,which did not follow the local PM_2.5 concentration trend.Although there were obvious regional differences in the concentration of BTHs in PM_2.5,2-hydroxybenzothiazole（OTH）was always the most important compound in PM_2.5,accounting for 50-80%of the total BTHs in these three cities.The results of human exposure assessment showed that the outdoor exposure risk of BTHs combined with PM_2.5 for toddlers was much more serious that for adults,especially the risk of OTH.Subsequently,the mouse embryonic stem cell（m ESCs）model was used to perfect the in vitro cytotoxicity of BTHs.Through the analysis of the MTT method,it was found that OTH had the lowest half-lethal concentration(IC₅₀)and used it as the research object of developmental toxicity mechanism.Exposing m ESCs to OTH for 48 h would significantly increase intracellular reactive oxygen species（ROS）levels,trigger DNA damage,and induce apoptosis by functionally activating p53 expression.Finally,the zebrafish embryo model was used to further study the developmental toxicity of OTH in vivo.After OTH exposure,the heart rate of the embryo was significantly reduced,and various abnormalities and even death appear,and its growth and development were severely affected.A non-targeted metabolomics study was performed on exposed zebrafish embryos.The results showed that OTH inhibited the hydroxylation reaction of phenylalanine,thereby further increasing the accumulation of toxic phenylpyruvate and acetylphenylalanine in the embryo,triggering oxidative stress and causing damage to multiple organs in the body.This study reported the pollution status of BTHs in domestic atmospheric PM_2.5 for the first time,and completed the acute toxicity data of BTHs.These findings provided important insights into the pollution characteristics of BTHs and laid a theoretical foundation for the comprehensive evaluation of the environmental risks of such substances.