Studies Of Human Exposure And Phototransformation Of Emerging Organic Pollutants

Ever since Poly Brominated Diphenyl Ethers（PBDEs）was banned,a variety of novel flame retardants,such as Organophosphate esters（OPEs）and Novel Brominated Flame Retardants（NBFRs）,have seen a dramatic increase in terms of production and application in the past decades.As these flame retardants are generally incorporated into materials through physical addition,they can be easily released into the environment via volatilization,abrasion,and leaching.Studies have revealed that OPEs and NBFRs can be found in the environment,organism and even human.Toxicology studies have proved that OPEs can cause neurotoxicity,reproductive toxicity,endocrine disruption,oxidative damage,and liver damage,while NFBRs could cause endocrine disruption,cardiovascular injury,and carcinogenicity.Thus,it is important to monitoring the existence and human exposure of OPEs and NBFRs in urban environment,as it ensures the safety of general population and provide guidance on proper management of related compounds.In this article,indoor air and window film samples was collected from different microenvironments（kitchen and living room）in common homes in Beijing.The concentrations and congener profiles of OPEs was examined for all the samples.The results shows that the concentration of OPEs in Beijing homes ranged from 0.61 to 82 ng m-3.Significant difference of OPEs concentration between samples from different microenvironment was observed.The partition behavior of OPEs between indoor air and window organic films was investigated,and the level of deviation was found to be excessively large compared to the measured value.The calculated EDI of OPEs via inhalation of indoor air is well below the reference dose values（RfDs）,indicating that current level of OPEs in indoor air does not pose a significant or serious health risk for the general population in Beijing.The concentration of NBFRs was also examined for the indoor air and window film samples of Beijing homes.The concentration of NBFRs ranged from 6.60 to 734.91 pg m-3,at a relatively low level.The partition behavior of OPEs between indoor air and window organic films was investigated,and the level of deviation was found to match the measured value,indicating that concentrations of NBFRs in window film could use to predict the concentration of NBFRs in corresponding indoor air sample.The calculated EDI of NBFRs via inhalation of indoor air also fall below RfDs,indicating that current level of NBFRs in indoor air does not pose a significant or serious health risk for the general population in Beijing.Dust samples from outdoor plastic sport courts,synthetic turf,and indoor plastic badminton courts was collected in multiple universities of Beijing.The concentration of OPEs ranged from 66 to 38700 ng g-1 for the outdoor samples,and from 12900 to 47200 ng g-1 for the indoor samples.The calculated EDI of OPEs via ingestion and skin adsorption is calculated,and the results fall below RfDs.Thus,it can be concluded that the concentration of OPEs in sport courts dust does not pose a significant or serious health risk for the general population in Beijing.Perfluorooctane sulfonamide derivatives（PFOSAs）are a class of PFASs containing an amide structure that have a large industrial output.FOSAs are typically composed of perfluorinated carbon chains and nonfluorinated functional groups.Furthermore,these compounds can be transformed into more toxic PFCAs or perfluoroalkyl sulfonic acids（PFSAs）via biological or abiotic processes,increasing their half-lives and causing new pollution problems.Soil is the main sink for FOSAs,with plant discharge,dry and wet deposition,sewage irrigation,and biosolid applications representing primary depository processes.Clay minerals are the main component of the soil and represent extremely active and important micro-interfaces.Some clay minerals are effective electron donors under light irradiation.Pollutants are then often adsorbed to the surfaces of clay minerals by hydrophobic partitioning and electrostatic interactions.However,transformation,especially phototransformation of FOSAs at clay interfaces,has rarely been reported,and the mechanisms through which this transformation may occur are still unclear.In this study,a new phototransformation pathway for perfluorooctane sulfonamide（FOSA）and underlying degradation mechanisms are described.Phototransformation of FOSA in a natural clay mineral（montmorillonite）suspension was compared to that in an aqueous solution.Results showed that the presence of montmorillonite can significantly promote the transformation of FOSA to perfluocarboxylic acids（increasing rate）.The phototransformation reaction was found to be initiated by the activation of adsorbed oxygen molecules on the surface of montmorillonite,which generate superoxide anion and hydroxyl radicals.Hydroxyl radicals can then attack FOSA adsorbed onto the surface of montmorillonite,promoting the transformation process.