Exposure Characteristics Of Toxic Pollutants In Residents In China Based On Human Hair Analysis

Human biomonitoring is an important part of environmental and health risk assessment system,which can reflect the changes of environmental factors in the whole period as well as the outcomes of synergistic and antagonistic effects of environmental factors.Compared with conventional biomonitoring matrixes such as blood/serum and urine,hair has the advantages of easy collection,transportation,storage and stability,and thus was increasingly widely used in human biomonitoring of exposure to heavy metals and organic pollutants.However,previous studies generally focused on the feasibility analysis of hair as human biomonitoring material,whereas few concerns were given for the exposure characteristics to toxic pollutants in ordinary population in large scale and different spatial regions.The lack of data further raised restrictions on the accurate assessment of human health risk due to exposure of toxic pollutants.In the present study,hair was applied as a biomonitoring matrix to investigated the exposure characteristics of typical toxic contaminants of ordinary residents as well as typical occupational exposure populations in large scale by using unified sampling strategy,pretreatment and analysis methods.The exposure levels,gender differences,and spatial distribution patterns of typical toxic pollutants,including heavy metals,polybrominated diphenyl ethers(PBDEs),hexabromocyclododecanes(HBCDs),phosphorus flame retardants(PFRs),dichlorodiphenyltrichloroethanes(DDTs),and hexachlorocyclohexanes(HCHs),in metropolitan residents from different regions in China were investigated.Additionally,the exposure levels,congener profiles and association of PCDD/Fs between paired hair and serum samples from occupational workers was examined in a municipal solid waste incinerator(MSWI)plant in South China.Fly ash and flue gas from the MSWI plant were also analyzed to for the source apportionment of PCDD/Fs in the hair using chemical mass balance(CMB)model.The results of the present study will provide data foundation for the application of hair as bioindicator for typical toxic contaminants for the future studies.It is also of significance for the development of more effective,faster and more scientific biomonitoring technology for assessment of human exposure to contaminants and for the improvement of the environmental and health risk assessment system.The major results of the present study are as follows:(1)PBDEs,HBCDs,PFRs,DDTs,HCHs and heavy metals were detected in hair of urban residents in China to some extent,with levels equivalent to or lower than those reported in previous studies.The concentrations of ∑ PBDEs,∑ HBCDs,∑ PFRs,∑ DDTs and ∑ HCHs were n.d.(not detected)- 789 ng/g,n.d.- 319 ng/g,n.d.- 2870 ng/g,n.d.- 382 ng/g,n.d.- 707 ng/g,with the median as 4.35 ng/g,0.77 ng/g,213ng/g,2.42 ng/g,and 1.39 ng/g,respectively.PFRs and Lead(Pb)were the most abundant chemicals among typical toxic organic contaminants and heavy metals,respectively.(2)Significant positive correlations were observed between contaminants from the same chemical groups,in accordance with their potentially same exposure sources.The ratio of p,p’-DDT / p,p’-DDE in83% of residents’ hair samples were <1,suggesting that DDTs in resident hair was primarily derived from historical residue.Similarly,the α-HCH /γ-HCH ratio in 99% of urban residents’ hair samples were <1,implying that Lindane instead of industrial HCHs,was the prominent source of HCHs that urban residents in China exposure to.Significant sex differences were found in the concentrations of typical toxic contaminants in hair of urban residents.The concentrations of BDE 28,BDE 209,TPHP,TEHP,TCIPP,iDPHP,β-HCH,p,p’-DDT,p,p’-DDE,∑PBDEs,∑HCHs,∑DDTs,Cd and Pb in hair of female residents were markedly higher than those of male residents(p < 0.05).Conversely,the levels of β-HBCD,As and Sb in the hair of males were significantly higher than those of females.(3)The levels of typical toxic organic contaminants in the hair of urban residents in different regions varied significantly,which was significantly correlated with the level of economic development,dietary habits and geographical location of individual regions.The concentrations of ∑PFRs,∑DDTs and ∑HCHs in the hair of urban residents were highest in Southeast China and lowest in Northwest China.And ∑HBCDs in resident hairs were found to be highest in the Northeast and lowest in the Southwest China.As for heavy metals,a decreased tend was found for the hair concentrations of Hg,Pb,and Cd from South Central China to Northwest China.Urban residents in Northeast and Southwest China are still affected by Se deficiency.Se could combine with and even eliminate a large proportion of the toxicity of Hg,As,Sb,and Cd in most urban residents in China.Nevertheless,nearly 50% of the volunteers may still suffer from potential health risks caused by combined exposure to Cr and Pb.(4)Octachlorodibenzo-p-dioxin(OCDD)was the predominant congener of PCDD/Fs,and 2,3,4,7,8-pentachlorodibenzofuran(PeCDF)was the indicator congener of TEQ in paired serum and hair samples of the workers in the MSWI plant,respectively.Though flue gas(which represents an external source)was identified as the primary source of PCDD/Fs in human hair.Blood and flue gas were accountable for,on average,37% and 61% of the PCDD/Fs in hair,respectively.Significantly positive correlations were found in the 1,2,3,6,7,8-hexachlorodibenzo-pdioxin(HxCDD)and OCDD levels between the hair and serum samples(p< 0.05).