Methodology And Exposure Assessment Of Perfluorinated Organic Compounds

A robust and sensitive method for quantitative analysis of trace levels of PFCs in human milk,blood and food was developed using ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) with stable isotope dilution technique.The method was used for determination of PFCs in human milk of general residents from 12 provinces,China. The data provides the information on the exposure level and the composition profile of PFCs in human milk in different geographical areas in China.16 Chinese Total Diet Study(TDS) samples included fish and seafood,meat,egg and milk collected from Liaoning,Ningxia, Shanghai,Sichuan in 2007 were analyzed for PFCs by the developed method,and the dietary intake as one possible route of human exposure was discussed.13 PFCs were detected in 138 whole blood samples collected in 2008 from seven cities(Liaoning province) for better understanding of the sources or pathways of human exposure in China.1.The physical and chemical properties,production,utilization,toxicity,pollution in biota,as well as development of analytical method were summarized.2.A robust and sensitive method for quantitative analysis of trace levels of PFCs in human milk,blood and food was developed using ultra performance liquid chromatography(UPLC) coupled with tandem mass spectrometry(MS/MS).Isotope-labled internal standards of perfluoro-1-(1,2,3,4-¹³C₄) octanesulfonate and perfluoro-n-(1,2,3,4-¹³C₄) octanoic acid were used to quantitate analytes.Background levels arising from instrument and procedure were effectively eliminated.The human milk was purified and extracted using weak anion exchange cartridges.The recovery test of the method was conducted by analyzing human milk spiked at two different concentrations(1 ng/mL and 10 ng/mL).The recovery range of 10 PFCs in two spike levels were 57%～136%and 73%～123%respectively.The RSD%(n= 5) was between 5%and 13%.The LOD was from 0.69 to 14.15 pg/mL,and the LOQ was from 2.72 to 20.64 pg/mL.The blood samples were extracted using ion pair extraction. Briefly,1 mL of whole blood,1 mL of 0.5 M TBA solution and 2 mL of 0.25 M sodium carbonate buffer were mixed in a 15 mL pre-washed polypropylene tube for extraction.Five milliliter of MTBE was added to the solution,the organic and aqueous layers were separated by centrifugation,and the organic layer was removed to another tube.The aqueous mixture was extracted thrice with MTBE.The organic extracting solvent was evaporated at ambient temperature under nitrogen gas flow,and then reconstituted in 1 mL of methanol/water(1:1). After centrifugation,the supernatant was passing through a 0.2μL nylon filter(Sartorius, Goettingen,Germany) to remove particles.Matrix spike recovery studies were carried out in two spike levels(10 ng/mL,30 ng/mL) using rat blood.The recovery range of 10 PFCs in two spike levels were 51%～103%and 61%～99%respectively.The RSD%(n=5) was between 4%and 19%.The LOD was from 6.52 to 34.26 pg/mL.Methanol extracting combined with Solid phase extraction(SPE) was developed for TDS samples.The recoveries of 11 analytes were between 54%to 133%.The LOD range of 11 PFCs in fish and seafood,meat,egg was respectively 4～36 pg/g dw,4～24 pg/g dw and 5～56 pg/g dw.3.PFCs were detected in human milk samples from 12 provinces including Heilongjiang, Liaoning,Hebei,Henan,Shanxi,Ningxia,Hubei,Jiangxi,Shanghai,Sichuan,Fujian and Guangxi.Of the ten PFCs analyzed,six PFCs were found above the detection limits,while PFOS and PFOA were the most abundant PFCs with the contamination ranges were 6 pg/ml～137 pg/ml and＜LOQ～814 pg/ml respectively.A significant correlation of the contamination level of the detectable six PFCs was found in human milk samples,which suggested the similar or same exposure sources of these PFCs in same area.The highest total PFCs was found from Shanghai where the geometric mean ofΣPFCs was 1044 pg/mL, followed by Liaoning(334 pg/mL) and Fujian(222 pg/mL).The lowest total PFCs level was found in Ningxia,which is a less developed inland area.The significantly different PFCs level in human milk from different geographical areas implied that there might be various sources or pathways of human exposure in different area of china.The average Estimated Daily Intake (EDI) of PFOS via human milk was 5.7 ng/kg bw/day for nursing infants(0-6 month old) with a range of 0.6～13.1 ng/kg bw/day,the average EDI_PFOA was 9.7 ng/kg bw/day with a range of 1.0～77.5 ng/kg bw/day,and that ofΣPFCs was 20.7 ng/kg bw/day with a range of 2.4～119.1 ng/kg bw/day.The EDI of PFOS and PFOA were far below the tolerable daily intake(TDI). 4.Four kinds of animal origin food samples collected from Liaoning,Ningxia,Shanghai and Sichuan as part of the Chinese Total Diet Study(TDS) in 2007 were analyzed for PFCs. Seven PFCs were found above the detection limits,while PFOS and PFOA have a relatively high frequency of detection with the contamination ranges were＜LOD～862 pg/g ww and＜LOD～2465 pg/g ww.The highest contamination of PFCs was found in fish and sea food from Shanghai,which implied that the water system in Shanghai might have a serious contamination of PFCs.The EDI via animal origin foods was calculated.The highest EDI_ΣPFCs was 5959 pg/kg bw/day from Shanghai,which was even higher than that from Canadian TDS(3968 pg/kg bw/day).However,the EDI_ΣPFCs from other three provinces was relatively low with a range from 21 to 501 pg/kg bw/day.The comparing results of EDI via animal origin foods and PFCs level in human milk in same area implied that,beside the dietary intake there might be other exposure routes such as air and water in China.5.PFCs have been identified widely in human.Monitoring of geographical distribution of PFCs in human blood can provide the information to better characterize the exposure source and pathway of these compounds.In this study,13 PFCs were detected in 138 whole blood samples collected in 2008 from seven cities(Liaoning province,China) including Fuxin, Jinzhou,Shenyang,Anshan,Yingkou,Huludao and Dalian.The highest geometric mean(GM) concentration of total PFCs was found in samples from Fuxin(17.27 ng/mL) followed by Shenyang(12.70 ng/ml) and Anshan(12.63 ng/ml).The composition profile of PFCs was varied in blood samples from seven cities.In Fuxin and Jinzhou,the percentage proportion of PFOA was significantly higher than that of perfluorohexanesulfonate(PFHxS) by about two times.By contrast,in Shenyang,Anshan and Yingkou,the percentage proportion of PFHxS was about three times higher than that of PFOA.In Huludao and Dalian,the profile of PFCs in blood was very similar with comparable proportions of PFOA and PFHxS.The results suggested different human exposure sources and pathways of PFCs in Liaoning province, China.