Exposure Levels And Accumulation Characteristics Of Four Classes Of Organic Flame Retardants In Hair Of E-waste Dismantling Workers

Objective:This study was aimed to verify the longitudinal accumulation of flame retardants(FRs)in hair,and to investigate the contributions of internal and external source of FRs along the hair shaft,which provided practical data for the necessity of standardized sample collection of human hair as a noninvasive matrix of human biomonitoring.Methods:Forty-two female e-waste dismantling workers were recruited through purposive sampling in Longtang Town,Qingyuan City,Guangdong Province.Paired hair and serum samples were collected,and the hair sample was sectioned into four 3-cm segments.The concentrations and congener profiles of Polybrominated diphenyl ethers(PBDEs),Hexabromocyclododecanes(HBCDs),Polychlorinated biphenyl(PCBs),and Phosphorus flame retardants(PFRs)in hair and paired serum were analyzed by the optimized method.The concentration differences of FRs among hair segments were examined by the Least-Significant Difference(LSD).EPA CMB82 model was performed to estimate the internal and external sources apportionment of FRs in all segmental hair.Results:1.Optimization of pretreatment methods: The accurate and reliability of the developed method meet well with the demand of FRs analysis in the hair.The recoveries of PBDEs,HBCDs,and PFRs in hair matrix spiked with low-level standards(4 ng)were 78-113%,103-117% and 66-128%,respectively.As for hair matrix spiked with high-level standards(4 ng),the recoveries of PBDEs,HBCDs,and PFRs were 68-115%,82-94% and 64-116%,respectively.The limits of quantification of the method were 0.13-22.4 ng·g-1,0.01-0.68 ng·g-1 and 0.03-55.8 ng·g-1 for PBDEs,HBCDs and PFRs,respectively.2.Levels of FRs in hair and serum of e-waste dismantling workers:(1)The median concentrations of Σ8PBDEs,Σ9PCBs,Σ3HBCDs,and Σ16PFRs in hair were 18.3(n.d.-222)ng·g-1,118(n.d.-501)ng·g-1,1.84(n.d.-19.5)ng·g-1,and 291(107-856)ng·g-1,respectively.PFRs were the dominated compounds detected in hair samples.(2)The median concentrations ofΣ2PBDEs,Σ9PCBs,and Σ3HBCDs in serum were 18.4(0.73-111)ng·g-1 lipid weight(lw),91.9(n.d.-628)ng·g-1 lw,and 0.45(n.d.-12.5)ng·g-1 lw,respectively.PFRs were not detected in any serum sample.(3)The congener profiles of FRs in hair and serum:BDE 209 was the dominant congener of PBDEs in both hair and serum;PCBs were mainly composed of tri-and penta-homologues in hair,whereas that in serum were hex-and hepta-homologues;α-HBCD was the primary diastereomer of HBCDs in both hair and serum,while γ-HBCD was not detected in any serum sample;TPHP and EHDPP were the predominant congeners of PFRs in hair.3.Accumulation characteristics of FRs in hair of e-waste dismantling workers:(1)The longitudinal accumulation of FRs concentrations along the hair shaft: The results revealed a significant increasing trend along the hair shaft for PCBs and PFRs(p < 0.05).The median concentrations of ∑9PCBs were 60.0(1.99-448)ng·g-1,105(3.62-531)ng·g-1,146(10.9-611)ng·g-1,and 147(20.5-652)ng·g-1 in the four hair segments,respectively,while those of ∑10PFRs were 187(68.2-632)ng·g-1,256(49.6-705)ng·g-1,271(98.7-1040)ng·g-1,and 363(93.2-1440)ng·g-1,respectively.The levels of PBDEs and HBCDs in proximal scalp segment(0-3 cm)were significanly lower than those in the distal scalp segment(p < 0.05).The median concentrations of ∑7PBDEs in the four hair segments from the proximal to the distal scalp were 12.9(0.74-99.2)ng·g-1,20.2(0.46-215)ng·g-1,19.6(0.79-232)ng·g-1,and 19.4(0.58-245)ng·g-1,respectively,while those of ∑3HBCDs were 2.43(0.19-14.9)ng·g-1,2.98(0.36-18.6)ng·g-1,3.30(0.72-20.7)ng·g-1,and 4.06(0.48-28.5)ng·g-1,respectively.(2)The source appointments along the hair shaft: the results of source identification analysis of four hair segments indicated that PCBs were primarily from external exposure(air and dust)accounting for approximately 80% of the total contribution.Specifically,in four hair segments,the external exposure proportions of PCBs were 51.4-114%(79.8± 15.9%),54.5-112%(83.7 ± 16.0%),51.4-113%(86.0 ± 16.5%),and 54.3-114%(88.1 ± 16.8%),respectively,whereas internal(serum)exposure proportions of PCBs were 0.20-47.2%(19.9 ± 12.0%),0.90-40.1%(17.8 ± 11.2%),1.40-47.5%(16.8 ±12.0%),and 1.10-44.8%(17.8 ± 13.2%),respectively.Along the hair shaft,the external source contributions of PCBs increased with the distance of the hair segment from the scalp,whereas the internal source contributions were the opposite.Conclusions:1.High exposure levels of legacy FRs such as PBDEs,PCBs,and currently used PFRs were detected in hairs of e-waste dismantling workers,which should be paid to continuous concern.2.Concentrations and the contributions of external sources of FRs in hair increased along the hair shaft from the proximal to the distal scalp,whereas the internal source was the opposite.The results suggested that to indicate the body burden of FRs in human through hair analysis,hair should be sampling as close to the scalp as possible.