Using Nails As Bioindicator For Assessment Of Human Exposure To PCBs And PBDEs And The Application For Occupationally Exposed Population

Objective:This study aimed to develop a method that allow to simultaneously determine two typical types of persistent organic pollutants（POPs）,i.e.polybrominated diphenyl ethers（PBDEs）and polychlorinated biphenyls（PCBs）,in human nails,and to investigate the influence of age,gender and occu oation duration of e-waste workers on human exposure to POPs.Additionally,the sources of POPs in human nails were identified by investigation of the relationship of compositions of PBDEs and PCBs between human nails and dust,combined with the chiral characteristics of PCB95 and PCB132 in human nails;and the potential of using human nails as biological indicators of human POPs exposure was further evaluated.Methods:In this study,PBDEs and PCBs were selected as targeted compounds.A pretreatment method was established and for analyzing PBDEs and PCBs by using a small amount of nail samples（0.1g）.The extraction solvent ratios,purification methods（composite silica column and SPE column）,SPE conditions（elution solvent and volume）,and fat removal method were optimized.Human nails of e-waste dismantling workers,rural and urban residents,and the corresponding house dust were collected from South China,and the concentrations and composition patterns of PBDEs and PCBs in human nails and dust were investigated.The primary aims of this study were to investigate the concentrations and composition profiles of PCBs and PBDEs in human nails,and the possible influence factors for human burdens of PCBs and PBDEs in nails.Furthermore,the possible internal and external sources for human exposures to PCBs in human nails are revealed by analyzing the chiral characteristics of PCB95 and PCB132.Results:1.Optimization of the sample preparation method:nail sample was extracted with n-hexane:dichloromethane（4:1,v/v）,cleaned-up on solid-phase extraction column,eluted with n-hexane（8 m L）,and the impurities was further removed by using concentrated sulfuric acid.The average recoveries of PBDEs and PCBs spiked matrix were 91%-110%and71%-102%,respectively,and in spiked solvent were 70%-110%and 61%-100%,respectively.The instrument detection limits（IDL）of PBDEs and PCBs were0.034-0.120μg·L^-1and 0.032-0.392μg·L^-1,respectively,indicating that present method allows high accuracy and reliability for quantifying PBDEs and PCBs in human nails.2.Pollution characteristics and composition patterns of PBDEs and PCBs in human nails and dust:（1）The concentrations of（50）₈PBDEs in nails of e-waste dismantling workers,rural and urban residents were 113.07-1800.00 ng/g,3.54-679.60 ng/g and 67.17-429.38 ng/g,respectively;and the concentrations of（50）₂₀PCBs were 22.71-398.19 ng/g,2.89-145.77 ng/g and 4.32-18.16 ng/g,respectively.The concentrations of（50）₈PBDEs in dust from e-waste dismantling area,rural and urban areas were 62.94-4388.05 ng/g,18.27-470.46 ng/g and 12.51-329.23 ng/g,respectively;and（50）₂₀PCBs were 244.17-1637.78 ng/g,187.22-386.88 ng/g and211.98-341.39 ng/g,respectively.（2）The major congener of PBDEs and PCBs were BDE209（91.2-98.1%）and PCB52（10.2-22.3%）,respectively,in all human nail samples,while in dust samples,the main congener of PBDEs and PCBs were BDE209（62.2-92.9%）and PCB28（8.0-22.3%）.3.The influencing factors of PBDEs and PCBs in human nails:（1）There was no significant difference in（50）₈PBDEs and（50）₂₀PCBs concentrations between males and females（p>0.05）.（2）No significant correlation was observed between the concentrations of PBDEs and PCBs in human nails and the age of e-waste dismantling workers（p=0.24-0.92）.（3）Results showed that there was a significant correlation between the concentrations for PBDEs in nails and occupational duration（r=0.36,p=0.0046）,while no significant correlation those for PCBs in human nails and occupational duration（r=0.13,p=0.23）.4.Chiral characteristics of PCBs in human nails:The enantiomeric fractions（EF）of PCB95 and PCB132 in nails of e-waste dismantling workers were 0.50±0.02and 0.40±0.07,respectively.Compared with the EF values of blood,hair,and dust samples from the same area in previous studies,there was a significant difference between the EF values of PCB95 and PCB132 in nail and blood samples,while no significant difference was found between dust and nail samples.Conclusion:1.This study optimized the extraction solvent ratio,purification column,solid-phase extraction conditions,and fat removal precedure to establish a nail sample preparation method,whichcan be used for the extraction and quantification of POPs in human nails.2.In human nails and dust samples,BDE209 was the major PBDE congener and low-chlorinated congeners were dominated for PCBs,and similar compositions of PCBs were found in human nails and dust.The results suggested that e-waste dismantling workers were exposed to high levels of PBDEs and PCBs because of disassembly and recycling of electronic products.3.No significant correlation was found between the concentrations of PBDEs and PCBs in human nails and the gender and age of the workers.However,the concentrations of PBDEs in the nails of e-waste dismantling workers were significantly correlated to the occupation duration,but not for PCBs.4.The chiral characteristics of PCB95 and PCB132 indicated that external sources（such as dust）were main sources of PCB95 and PCB132 exposure in nails of electronic waste dismantling workers,while internal sources（such as serum）contributed little.The results of the present study indicated that human nails can be used as biological indicator materials of human PCBs exposure.