The Characteristics And Human Risks Of Chlorinated Paraffins In Atmospheric Particles

As a group of complex and novel oganic pollutant,chlorinated paraffins（CPs）have attracted more attention since they are reported to have charactersitics of persistence,accumulation and long-range transportation.Among CPs,Short-chain chlorinated paraffins（SCCPs）were added into the Annex A of the Stockholm Covention for Persistence Organic Pollutants in April 2017,since its high acute tocixtiy was sufficienty documented.Recently,attention is widly attracted by the potential risks to both the environment and human health due to an increasing growth of CP production and usage.As China is the largest producer and consumer of CPs,SCCPs have been reported to be ubiquitously present in the various environments（indoor and outdoor atmosphere,dust,sediment and soil）,biota and human such as human milk and blood samples in which levels were even higher than polychlorinated biphenyls（PCBs）and polybrominated diphenyl ethers（PBDEs）.However,analysis of CPs is the most chalenging due to the interference causing from CP homologues and other organic compounds,thus the limited studies are available on the behavior and the potential human risks of CPs in indoor atmosphere,especially in China.Therefore,the investigations of the environmental levels and the associated human exposure risks of CPs in indoor or outdoor atmospheric particles are carried out on the basis of the optimized methods in the thesis.The parameters of pretreatment procedure for CPs were optimized.The chromatographic columns with florisil,neutral silica gel,aci silica gel and neutral alumina as well as their composite columns were used for removing the interferential compounds,such as PCBs and organochlorine pesticide（OCPs）.Also,the mass of absorbents in chromatographic coulums and eluted solvent were considered in the present study.In comparision,most of OCPs,PCBs and other interferential compounds can be removed when the mixture were pretreated with a composite chromatographic column with 5 g of florisil,2 g of neutral silica gel and 5 g of acid silica gel.CPs can be eluted in the second fraction with the mixture of n-hexane and dichromethane（7:3,v/v）,and other compounds eluting in the first fraction with 30 mL n-hexane.Several dust samples collected in different areas were successfully pre-treated by using the present procedure,indicating the availability and reliability of the methods in CPs analysisSeventy-two indoor and 66 outdoor TSP/PM₁₀/PM_2.5（particulate matters with aerodynamic diameter less than 100,10 and 2.5μm,respectively）samples from 24 homes in nin cities from the Pearl River Delta（PRD）,China,were analyzed for CPs.PM_2.5.5 is found to be the dominant particles both indoors and outdoors.CPs were mainly distributed in PM_2.5that accounted for 89.1%and 93.0%of the total particles indoors and outdoors,respectively.The geometric mean（GM）concentrations of medium-chain CPs（MCCPs）were higher than those of SCCPs（22.0 vs.9.18 ng/m³）in all particle samples.SCCPs and MCCPs in indoor particles（GM:13.4 and 30.9 ng/m³）were approximately two times higher than those outdoors（GM:6.11 and 15.2 ng/m³）.C₁₁1 and C₁₄ carbon chains with six or seven chlorine homologues were found to be predominated in all samples with average percentages of 43.0%and 55.4%,respectively.The estimated daily intakes（EDIs）of CPs via PM_2.5 inhalation were 8.1–24.6and 25.1–76.0 ng/kg·bw/day for all age subgroups based on the mean and 95th percentile concentrations of CPs.However,the estimated daily uptakes（EDUs）decreased to 4.4–16.4and 13.5–50.6 ng/kg·bw/day,respectively,when the deposition fractions of PM_2.5 in human lung were considered.Indoor PM_2.5 attributed 93.8%exposure of CPs based on both total EDIs and EDUs,indicating that the exposure via indoor PM_2.5 was very important.Infants and toddlers suffered higher exposure risks of CPs than other subgroups,indicating higher potential health risks,although the risks could be ignored via inhalation based on margin of exposure analysis.