Study On Pollution Characteristics And Risk Assessment Of Typical Flame Retardants In PM_2.5 Of Guangzhou And Taiyuan

PM_2.5 is an atmospheric particle with an aerodynamic diameter less than 2.5μm.PM_2.5 pollution has become an important issue of air pollution around the world,especially in China in recent years.It can be deposited deeply in the lung by inhalation,which leads to adverse effects such lung cancer and cardiovascular diseases.Flame retardants are one of the important industrial additives,which are added into manufactured materials（e.g.,electronic equipment,plastics and textiles）for preventing the spread of fire.During the past two decades,polybrominated dipheyl ethers（PBDEs）were the most commonly used flame retardants.Due to their environmental persistence,bioaccumulation and potential health effects,PBDEs were considered as one of the persistent organic pollutants（POPs）.The prohibition of PBDEs led to the high consumption of some alternative flame retardants,including non-bromodiphenyl ether brominated flame retardants（non-BDEs）and organophosphorus flame retardants（OPFRs）.Based on their chemical and physical properties,non-BDEs and OPFRs are shown to have high volatilities,suggesting that they can be released to the nearby air from the products.The alternative compounds were reported to have the similar environmental issues with PBDEs,hence non-BDEs and OPFRs have received increasing attention.It is necessary to comprehensively understand the occurrence and fate of these alternative flame retardants in the atmospheric environment.In this study,a sensitive method using gas chromatography-tandem triple quadrupole mass spectrometry combined with ultrasonic-assisted extraction and multi-phase column purification was developed for simultaneously determination of 29 flame retardants including halogenated flame retardants（HFRs）and OPFRs in PM_2.5 samples.Extraction time,as well as the type and volume of elution solvent were optimized.The recoveries of all target flame retardants from PM_2.5 samples were in the range of 70%-130%,with good repeatability and reproducibility（0.39%-17.4%）.The instrumental detection limits（IDLs）and method quantitation limits（MQLs）of HFRs were in the range of 0.004-5.44 pg and 0.002-2.52 pg m^-3,while those of OPFRs were 0.003-0.23 pg and 0.07-5.41 pg m^-3,respectively.The developed method has been successfully applied for the analysis of target flame retardants in atmospheric PM_2.5 collected from the cities of Guangzhou and Taiyuan,China.HFRs were found at concentrations of 45.7-1,230 pg m^-3 and 51.2-82.3 pg m^-3in Guangzhou and Taiyuan.The concentrations of HFRs were lower than those of OPFRs,which were detected at concentrations of 6,004-49,800 pg m^-3 and 16,741-34,346 pg m^-3 in Guangzhou and Taiyuan.Accordingly,the developed method is robust and useful for further elucidating the contamination profiles of flame retardants in PM_2.5.The concentrations of 11 OPFRs,including three chlorinated-OPFRs,three aryl-OPFRs,and five alkyl-OPFRs,in PM_2.5 samples were monitored for one year at Guangzhou and Taiyuan in China during 2017-2018.Eleven OPFRs were measured at total concentrations ranging from 3,104 to 543,958 pg m^-3.Chlorinated OPFRs were the dominant contaminants among all sampling sites with total concentration levels of 1,106-195,083 pg m^-3.The concentration proportions of tris（2-chloroisopropyl）phosphate（TCPP,27%）and tris（2-chloroethyl）phosphate（TCEP,32%）were the highest in Guangzhou and Taiyuan samples,respectively.Tri-i-butyl-phosphate（TiBP）,tris（2-chloroethyl）phosphate（TCEP）,tris（1,3-dichloroisopropyl）phosphate（TDCPP）,tris（2-ethylhexyl）phosphate（TEHP）and tri-3-cresyl phosphate（TCrP）showed positive correlation（p<0.01）to each other based on their concentrations in PM_2.5samples.Combined with the results from principal component analysis（PCA）,these OPFRs may have the same pollution source.The relationships between the concentrations of OPFRs and environmental variables,including the distribution of BDE209 and DBDPE,cell viability and DTT activity,were assessed by redundancy analysis（RDA）.The result revealed that PM_2.5-bound OPFRs from Taiyuan samples had higher DTT consumption than Guangzhou samples,indicating their strong redox activities for ROS production.Preliminary risk assessments showed that the estimated daily intakes for both toddlers and adults were much lower than the reference dose values,suggesting minimum health risks to human after exposure to PM_2.5-bound OPFRs in Guangzhou and Taiyuan.