Polychlorinated Biphenyls (PCBs) in Human Hair and Serum from E

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Polychlorinated biphenyls (PCBs) in Human Hair and Serum from E-Waste Recycling Workers in Southern China: Concentrations, Chiral Signatures, Correlations, and Source Identification Jing Zheng, Lehuan Yu, She-Jun Chen, Guocheng Hu, Kehui Chen, Xiao Yan, Xiaojun Luo, Sukun Zhang, Yunjiang Yu, Zhongyi Yang, and Bi Xian Mai Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.5b04955 • Publication Date (Web): 12 Jan 2016 Downloaded from http://pubs.acs.org on January 12, 2016

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Polychlorinated biphenyls (PCBs) in Human Hair and Serum from

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E-Waste Recycling Workers in Southern China: Concentrations, Chiral

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Signatures, Correlations, and Source Identification

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Jing Zheng, † Le-Huan Yu, †,‡ She-Jun Chen, *,‡ Guo-Cheng Hu,† Ke-Hui Chen, ‡,§ Xiao

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Yan, ǁ Xiao-Jun Luo, ‡ Sukun Zhang, † Yun-Jiang Yu, *,† Zhong-Yi Yang,ǁ Bi-Xian Mai, ‡

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7

Sciences, Ministry of Environmental Protection, Guangzhou 510655, China

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9

Environmental Protection and Resources Utilization, Guangzhou Institute of

Center for Environmental Health Research, South China Institute of Environmental

State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of

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Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

11

§

12

ǁ

13

Guangzhou 510275, China

14 15

TOC Art

University of Chinese Academy of Sciences, Beijing 100049, China

State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University,

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ABSTRACT

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Hair is increasingly used as a biomarker for human exposure to persistent organic

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pollutants (POPs). However, the internal and external sources of hair POPs remain a

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controversial issue. This study analyzed polychlorinated biphenyls (PCBs) in human hair

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and serum from electronic waste recycling workers. The median concentrations were 894

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ng/g and 2868 ng/g lipid in hair and serum, respectively. The PCB concentrations in male

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and female serum were similar, while concentrations in male hair were significantly

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lower than in female hair. Significant correlations between the hair and serum PCB levels

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and congener profiles suggest that air is the predominant PCB source in hair and that hair

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and blood PCB levels are largely dependent on recent accumulation. The PCB95, 132,

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and 183 chiral signatures in serum were significantly nonracemic, with mean enantiomer

28

fractions (EFs) of 0.440−0.693. Nevertheless, the hair EFs were essentially racemic

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(mean EFs = 0.495−0.503). Source apportionment using the Chemical Mass Balance

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model also indicated primary external PCB sources in human hair from the study area.

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Air, blood, and indoor dust are responsible for, on average, 64.2%, 27.2%, and 8.79% of

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the hair PCBs, respectively. This study evidenced that hair is a reliable matrix for

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monitoring human POP exposure.

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INTRODUCTION

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Although blood, breast milk, and adipose have been extensively used for monitoring

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human exposure to a variety of environmental contaminants, there are increasing studies

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using hair as an additional biomarker for exposure to persistent organic pollutants

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(POPs).1-5 Compared to other matrices, hair is easily and noninvasively collected,

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low-cost, and easily transported and stored for analysis. In addition, hair analysis can

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reveal both short and long-term exposure.6, 7

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Each hair follicle root is surrounded by numerous capillary blood vessels that supply

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substances to the hair.8 Some studies have suggested that hair serves as an indicator of

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POP levels of endogenous tissues.7 Poon et al. reported significant correlations (r =

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0.345−0.566) between human hair and serum polybrominated diphenyl ether (PBDE)

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concentrations.9 Hair is enriched with lipids (3.5−4%) and has a tendency to absorb

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lipophilic organic contaminants from external origins (e.g., from ambient air or dust).

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Neuber et al. (1999) used preschool children’s hair as a passive sampler to monitor indoor

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pesticide

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concentrations in indoor dust and human hair have been recently observed.11 Altshul et al.

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observed a strong p,p´-DDE correlation, moderate PCB congener correlations, and no

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correlations for other organochlorines between hair and blood samples. They suggest that

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organochlorines may originate from different sources.12 These inconsistent observations

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highlight the importance of identifying internal and external sources of contaminants and

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the correlations between hair and endogenous tissues.

contamination.10

In

addition,

positive

relationships

between

PBDE

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Polychlorinated biphenyls (PCBs) are a well-known class of man-made organic

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chemicals, which were formerly used in a variety of industrial and commercial

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applications. They have received significant interest due to their persistent,

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bioaccumulative, and toxic properties.13 In contrast to the decline of PCB levels in

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developed countries after their restrictions in the 1970s, high levels have been reported at

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electrical and electronic waste (e-waste) recycling sites in many developing countries.14

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Continuous long-term exposure monitoring efforts are necessary to protect populations

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living near e-waste sites, especially vulnerable populations, such as developing fetuses

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and young children.15

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Of the 209 PCB congeners, 19 congeners with three or four ortho-chlorine substituents

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are chiral. The chirality of a compound can only be modified by biological transformation

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processes (not by physical and chemical processes), such as enantioselective

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biodegradation, metabolism, or binding to structure-sensitive biological receptors.16

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Chiral PCBs undergo enantiomeric enrichment in mammals due to cytochrome P-450

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enzyme metabolism.17 Metabolism is unlikely to occur in hair shafts consisting of

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keratinized cells, which are cemented by the cell-membrane complex.8 Thus, PCB chiral

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signatures may be capable of distinguishing between the external and internal sources of

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these compounds in hair. We discussed this feasibility in a previous study via comparing

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the PCB chiral signatures in hair and indoor dust.18

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In the present study, concentrations and profiles PCBs were investigated in matched

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hair and serum samples of e waste recycling workers in an e-waste area of southern

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China, where high levels of PCBs in the environment have been reported.19 The

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objectives of this study are to determine the internal and external sources of PCBs in

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human hair and explore the PCB associations between hair and blood, which are

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important for understanding the feasibility of using human hair as a POP exposure

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biomarker. Certain atropisomeric PCB chiral signatures were also determined in hair and

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serum to provide support for source identification in hair. Furthermore, we aim to conduct

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source apportionment of PCBs in the hair by coupling PCB data of environmental

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matrices from the study area. To date, only a few studies have described the correlation

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between POP levels in human hair and internal tissues.9, 12, 20 To our knowledge, this is

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the first report on the enantioselectivity of PCBs in human serum.

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MATERIALS AND METHODS

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Sample Collection. A total of 34 matched hair and serum samples were obtained from

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e-waste recycling workers (19 males and 15 females) in a rural e-waste area in southern

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China. The study area has been described in detail in another study.21 This research was

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launched with authorization of the Ethics Committee in the School of Life Science, Sun

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Yat-sen University. Samples were collected at a local hospital by medical professionals.

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All participants provided full consent after being informed of the study's objectives in

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July 2011. The participants were asked to fill out a questionnaire, which asked for their

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age, gender, weight, height, and occupational history. Venous blood samples (8−10 mL)

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were collected from each subject in anticoagulant-free tubes. They were centrifuged for 5

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min at 3,000 rpm within 3 h of collection to isolate the serum. Hair was sampled by a

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barber in a way similar to routine haircuts using clean stainless-steel scissors. Distal hair

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of approximately 5 and 10 cm from the posterior vertex was cut for most male and female

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participants, respectively.

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Sample preparation and analysis. The hair and serum sample preparation procedures

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and instrumental analysis have been described in a previous study.22 In brief, serum

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samples were denatured using hydrochloric acid (6 M) and 2-propanol. They were then

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extracted using a hexane/methyl-tert-butylether (MTBE) (1:1, v/v) mixture after it was

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spiked with surrogate standards (PCB65 and 204). Lipids were removed from the extracts

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using concentrated sulfuric acid. Hair samples were rinsed with Milli-Q water in a

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shaking incubator (1 h, 40 °C, twice) to remove possible dust or dirt adhering to the hair

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surface, which was also recommended by a recent study.23 They were then freeze-dried,

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cut into small pieces (2−3 mm), and homogenized. Hair was incubated overnight (12 h)

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in hydrochloric acid (4 M) and a hexane/dichloromethane mixture (4:1, v/v). PCBs in the

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incubation

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hexane/dichloromethane mixture (4:1, v/v), which was repeated three times. The

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combined extracts were purified on a silica/alumina column and condensed, after which

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internal standards (PCB 24, 82, and 198) were added.

medium

were

extracted

via

liquid-liquid

extraction

with

a

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PCBs were analyzed by an Agilent 6890 gas chromatograph equipped with a 5975B

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mass spectrometer in electron impact ionization (EI) mode (GC-EI-MS). A DB-5ms

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capillary column (60 m × 0.25 mm i.d., 0.25 µm film thickness) was used to separate the

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PCB congeners. Enantiomer analysis was conducted using the Agilent GC-EI-MS. The

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atropisomeric PCB 132 and 183 enantiomers were separated on a BGB-172 (30 m × 0.25

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mm i.d., 0.18 µm film thickness) capillary column, while PCB 95 was separated on a

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Chirasil-Dex (25 m × 0.25 mm i.d., 0.25 µm film thickness) column. Further instrumental

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analysis information is provided in the Supporting Information (SI).

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Quality Control. The PCB 65 and 204 surrogate standard recoveries ranged from 65

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to 98% and from 72 to 118% in the serum samples, and 60−121% and 58−115% in the

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hair samples, respectively. The final results were not recovery corrected. Serum (Milli-Q

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water) and hair sample (hydrochloric acid and a hexane/dichloromethane mixture)

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procedural blanks were run with each sample batch. Only trace amounts (< 5% of the

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concentrations found in the corresponding field-sample extracts) were detected in the

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blanks, and the mean blank amounts were subtracted from the sample extracts. The mean

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PCB congener recoveries of 21 individuals ranged from 51% to 103% for spiked blanks

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and from 53% to 107% for spiked matrices, respectively.

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Enantiomer Fraction (EF) Determination. The EF is defined as the peak area of the

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first-eluted enantiomer divided by the total areas of both enantiomers, which were

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calculated for each peak pair with a signal-to-noise ratio exceeding 10:1. The chiral

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analysis was validated using a daily checking standard (an Aroclor mixture), and the

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mean EFs were 0.498 ± 0.007 (n = 10). A conservative EF precision value of 0.032 (95%

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confidence interval) was used for statistically comparing the sample and standard EFs.24

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Data Analysis. The statistical analysis, including t-test, Pearson Product-Moment

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Correlation, Spearman Rank Order Correlation, and linear regression, was performed

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using SigmaPlot 12.5 (Systat Software, Inc., CA). The Chemical Mass Balance (CMB)

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model was used for source apportionment of PCBs and PBDEs in the hair. It was

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performed using CMB software (CMB8.2), which was developed by the United States

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Environmental Protection Agency (US EPA). Additional model application details are

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provided in the SI.

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RESULTS AND DISCUSSION

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Concentrations and Compositions. The hair and serum PCB concentrations,

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including PCB28, 52, 66, 74, 95, 99, 101, 105, 118, 128, 138, 153, 164, 170/190, 177,

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180, 187, and 209, which were detected in over 60% of the samples, are summarized in

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Table 1. The individual PCB concentrations and associated information are given in SI

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Table S1. The total PCB concentrations in the hair ranged from 161 to 3514 ng/g, with a

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median of 894 ng/g. The serum PCB concentrations were between 256 and 11 200 ng/g

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lipid, with a median of 2868 ng/g lipid. The maximum hair and serum concentrations

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were both identified in a 50 year-old woman. The lipid-normalized hair concentrations

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(4015−87 859 ng/g lipid, estimated using a hair lipid content of 4%) were 8 times higher

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than the serum levels. These results are similar to those from a previous study, where

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average human hair PCB levels were 6 times higher than serum levels.12

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The male and female participants were 22−55 and 30−59 years old, with average ages

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of 41 and 44 years, respectively. The male and female serum PCB concentrations were

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quite similar (Table 1). Similar results have also been reported for human serums from

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other locations.25, 26 This result suggests similar PCB sources and exposure routes for

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residents living in this e-waste area. However, the male hair PCB concentrations (with a

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median value of 611 ng/g) were significantly lower than those of females (1781 ng/g) (p

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= 0.002). This is likely because the longer female hair encompasses a longer PCB

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accumulation time than the shorter male hair (either from the ambient environment or

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internal tissues), although information on the hair length for the individual participants

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was not available. A recent study found significant PBDE concentration increases in hair

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shafts from the proximal (root end) to distal segments.27 Hair washing frequency can also

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affect the levels of hair contaminants as suggested in a previous study,12 however related

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information was not obtained in the present study.

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The hair and serum PCB congener profiles, which are compared with ambient air and

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indoor dust (in homes or e-waste workshops) profiles from the study area,19,

28

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depicted in Figure 1. Blood, air, and dust may represent typical internal and external hair

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contaminants. The hair PCB congener profile closely resembled those in the air of this

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area, with the exception of higher contributions of PCB28 and 52 in the air because of

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their higher vapor pressures, suggesting air is the major PCB source in hair. The profile of

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highly chlorinated PCBs in serum was similar to that in indoor dust. This indicated that

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dust ingestion or inhalation plays an important role in the presence of PCBs in the

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e-waste recycling workers’ blood.

are

180

In both the hair and serum in the present study, lower chlorinated congeners had

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significant proportions compared to the PCB patterns typically found in human tissues

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(serum, milk, and adipose), in which PCB 153 was frequently the predominant

183

congener.29-31 PCB153 in serum is thought to be an indicator of dietary PCB intake.32 The

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congener patterns, as well as the high PCB levels in the air in this area (7825-76 330

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pg/m3),19 further support the importance of air and indoor dust for exposure of the

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e-waste recycling workers to PCBs. Similar congener profile was also found in human

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serum from an e-waste recycling site in North Vietnam.33

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There were no significant differences in both the hair and serum PCB profiles between

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the male and female participants (SI Figure S1), indicating common exposure sources.

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Marek et al. recently found that children are enriched in lower-molecular weight PCBs

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compared to their mothers because of their different exposure sources (indoor air versus

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diet).32 Nevertheless, there were appreciable differences between the hair and serum PCB

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profiles. These differences are likely due to metabolism, because highly chlorinated PCBs

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are generally more resistant to metabolism than lower chlorinated congeners. For instance,

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easily metabolized congeners PCB52 and 101 displayed substantially lower percentages

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in the serum than in the hair.

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Correlations. Significant correlations existed among the PCB congeners in the hair

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and serum, except for PCB209 and 95 in serum (SI Table S2). Potentially different

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PCB209 and 95 biological activities may lead to weak or moderate correlations with

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other congeners. The hair PCB levels exhibited no significant correlations with the age

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for male, female, and all participants, with the exception of PCB209 in male hair

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(positive correlation, r = 0.576, p = 0.010). Likewise, significant correlations were not

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found between the serum PCB levels and age.

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Statistically significant correlations (r = 0.403−0.605, p = 0.001−0.030) were identified

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between the hair PCB levels and occupational exposure duration (years of e-waste

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recycling experience; 1−11 years for the males and 4−11 for the females) for 14 highly

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chlorinated congeners (from penta- to deca-CBs). In addition, these correlations were

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observed for more PCB congeners in male hair than in female hair (Table 2). This result

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is unexpected, because scalp hair grows at an average rate of approximately 1 cm/month.

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Thus, hair contaminants are a result of recent (from a few months to a few years)

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accumulation.6,

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occupational exposure durations for an air exposure source. The lack of association for

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lower chlorinated PCBs supports this hypothesis.

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A weak association is expected between the hair PCBs and

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The significant correlations between highly chlorinated PCBs and the exposure

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duration suggest the existence of additional exposure sources for the hair. In addition to

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incorporation from blood, substances can be incorporated from deep skin compartments

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during hair shaft formation (although with some time delay) and via diffusion from

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sebum secretions.8 It is likely that PCBs, especially the more persistent congeners, in

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these storage compartments reflect the cumulative human body exposure, which explains

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the significant correlation with the occupational exposure duration. However, this

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potential source was only responsible for a small portion of the hair PCBs, as estimated

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by the coefficients of determination (r2, 0.16−0.37) from the linear regression between

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the highly chlorinated PCB hair levels and the occupational exposure duration, roughly

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accounting for 16−37%. The serum PCB levels also exhibited significant correlations

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with the occupational exposure duration for the more persistent congeners (PCB128, 138,

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164, 177, and 180), but the correlations were weak for male and female participants,

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separately (Table 1). Current PCB exposure and metabolism in the human body may

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influence these correlations.

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We found significant correlations between most hair and serum PCB concentrations,

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with no gender difference observed (Table 3). Interestingly, the correlations are stronger

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for lower chlorinated congeners than for highly chlorinated congeners. The hair and

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serum congener profiles indicated that air is the predominant hair PCB source, while air

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and indoor dust are the major sources of PCBs (lower and highly chlorinated PCBs,

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respectively) in the blood. Thus, the hair-serum correlations confirm these results. The

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correlations also clearly suggest that the hair and blood PCB levels are largely dependent

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on recent accumulation in the study area, as less chlorinated PCBs are readily subject to

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metabolism in humans compared to highly chlorinated congeners, with reported half-lives

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ranging from a few months to a few decades.35 However, lower chlorinated PCB95 is an

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exception and displayed no correlation between the hair and serum, which may suggest

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that it is associated with different biological activities.

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Altshul et al. examined the relationship between PCB and pesticide levels in hair and

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blood samples from 10 subjects.12 They found strong correlations for p,p´-DDE (the most

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stable metabolite of p,p´-DDT), moderate correlations for the more persistent PCB

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congeners, but weak or no correlations for other organochlorine compounds. Nakao et al.

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also found good correlations for the more persistent congeners of polychlorinated

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dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), whereas weak or no correlations for

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other PCDD/Fs between hair and blood samples from six donors.36 These observations

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for average people are inconsistent with our results for occupationally exposed people,

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with lower chlorinated PCBs (the less persistent congeners) exhibiting stronger

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correlations. This indicated that the relationships between hair and blood organochlorine

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compound concentrations may vary based on the exposure scenario.

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Chiral signatures. Three chiral PCB congeners (PCB95, 132, and 183) were

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determined in the hair and blood (Figure 2). The hair PCB chiral signatures were

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essentially racemic or near-racemic, with mean EFs of 0.495 ± 0.010, 0.503 ± 0.010, and

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0.498 ± 0.017 for PCB95, 132, and 183, respectively. In contrast, the blood chiral PCBs

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displayed significantly nonracemic residues, and the enantiomeric shifts of PCB95 (EFs =

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0.693 ± 0.172) were more pronounced than PCB132 (0.554 ± 0.058) and PCB183 (0.440

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± 0.027). This observation is consistent with the finding that PCBs become more

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susceptible to cytochrome P450 metabolism as the number of meta−para hydrogen atoms

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increases.37 We measured the air EFs of PCBs in this e-waste area in a previous study,

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finding that the chiral PCBs were racemic, with EFs of 0.499 ± 0.004, 0.484 ± 0.022, and

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0.494 ± 0.020 for PCB95, 132, and 183, respectively.19 This finding further suggests that

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external sources (e.g., air) are the primary PCB sources identified in human hair samples

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from this area, while internal sources (e.g., blood) contribute to a small percentage of the

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PCBs in human hair.

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To our knowledge, no studies exist regarding enantiomeric PCB compositions in

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human blood. Chu et al. determined PCB EFs in human tissues (muscle, kidney, brain,

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and liver) from Belgium. PCB atropisomers in liver, the main organ for xenobiotic

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metabolism, were much more nonracemic (PCB95 EFs = 0.510−0.748, PCB132 EFs =

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0.324−0.492) than those in other tissues (EFs = 0.505−0.569 and 0.487−0.522,

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respectively).38 Nonracemic signatures in breast milk have been reported in Switzerland

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(PCB95 EFs=0.64−0.76, PCB132 EFs = 0.67−0.82) and Spain (PCB95 EFs = 0.515 ±

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0.043, PCB132 EFs = 0.422 ± 0.040, and PCB183 EFs = 0.348 ± 0.045).39,

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difference in enantioselectivity for these three congeners in human tissues suggests varied

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PCB enantioselective elimination mechanisms in the human body, which are still poorly

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understood.17

40

The

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Implications for Organohalogen Compounds in Hair. Evidence from both the PCB

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congener profiles and chiral signatures showed that air was the primary source of PCBs

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in the hair. Thus, we explored the relationships between the partition of PCB

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concentration in the hair of all participants and air (KHA) and the octanol-air partition

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coefficient (KOA) of PCBs, which has been demonstrated to be a good predictor of

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organohalogen compound partitioning between plants and the air.41 Air samples were

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obtained during every month in 2007−2008 (not simultaneously collected with the hair).19

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Thus, we calculate KHA values for each month (based on average concentrations) and

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conducted a linear regression analysis for log KHA and log KOA (Table S3). A prevalent

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linear relationship exists for most cases, indicating that KOA is a key factor controlling the

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air to hair transfer of these compounds. The relationships are more pronounced for female

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participants than for males, likely because female hair possesses a longer exposure time

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to the air on average. According to the air-plant partition theory,41 a linear relationship

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implies that a partitioning equilibrium is likely approached between the hair and air.

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PBDEs were also measured in these samples and the log KHA−log KOA relationship was

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examined for lower brominated congeners that are present in the gaseous phase.22 The

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relationships are less significant for PBDEs than PCBs (data not shown). A non-linear

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relationship typically exists between log KHA and log KOA if PCB and PBDE data are

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simultaneously fit (Figure S2). This result suggests different PBDE (with increased KOA)

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and PCB sources in the hair.

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The results of this study highlight the importance of source apportionment of the

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organohalogen compounds in hair. CMB was applied to apportion the major sources of

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PCBs and PBDEs in the hair, respectively. Air, blood, and indoor dust sources were

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involved in the source apportionment for PCBs in hair. The results showed that air

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contributed 35.8−94.4% (on average 64.2 ± 17.2%) of the PCBs in the hair, while blood

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and dust accounted for 5.57−64.2% (27.2 ± 15.1%) and 0−43.5% (8.79 ± 12.4%),

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respectively (SI Table S4). It is evident that external sources (air and dust) dominate

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PCBs in human hair in this area. Both the high air PCB levels in this e-waste area and the

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human scalp hair lipid richness favor air to hair PCB accumulation. In a similar study, the

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authors implied significant endogenous origins for most PCBs in human hair samples

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from average people.12 These findings suggest that contributions of PCBs from internal or

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external sources to hair vary depending on the surroundings of a given person. In addition,

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a significant positive correlation between hair and blood likely exists for both exposure

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scenarios, indicating that hair is a reliable matrix for monitoring human exposure to PCBs.

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However, despite this significant correlation, it is still important that the primary PCB

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exposure pathways and related environmental matrix levels (especially in the air and diet)

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should be noted before using hair as a biomarker.

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Source apportionment PBDEs was conducted for lower and highly brominated BDEs,

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respectively. Because highly brominated congeners are barely present in the gaseous

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phase, only blood and indoor dust sources were included in the source apportionment.

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Results suggest that blood and dust are responsible for, on average, 47.9 ± 23.5% and

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40.0 ± 23.3% of the lower brominated BDEs (tri- through hexa-BDEs) in hair,

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respectively, which are significantly higher than air (12.2 ± 11.7%) (SI Table S4).

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External sources (52% in total) remain dominant, which is similar to the rough estimate

321

(55−64%) from our previous study.22 The blood and dust contributions for highly

322

brominated BDEs (hepta- though deca-BDEs) were 54.6 ± 26.8% and 45.4 ± 26.8%,

323

respectively. This differs from the previous estimate (15% from external exposure).

324

Note that the source apportionment of hair contaminants may encompass relatively

325

large uncertainties compared to air quality applications, especially for highly brominated

326

BDEs, because of chemical bio-transformation in the human body (i.e., change of the

327

source profile abundances). For instance, BDE209 and 183 in human serum possess

328

estimated half-lives of 15 and 94 days, while the half-lives of PCBs and some lower

329

brominated BDE are estimated from a few months to decades.35, 42, 43 As a result, it is

330

possible that the internal contributions to POPs in the hair may be underestimated.

331

In conclusion, hair can serve as a reliable biomarker for monitoring human exposure to

332

POPs in both general and occupationally exposed settings. Additional studies of

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contamination settings will help to further understand the link between hair and body

334

exposure. Although PCB chiral signatures are a useful tool for understanding external and

335

internal sources in hair, they are not necessarily suitable for other POPs, which may have

336

different sources.

337

ASSOCIATED CONTENT

338

The Supporting Information is available free of charge on the ACS Publications website

339

at DOI:

340

Further details of the instrumental analysis of atropisomeric PCBs and the CMB model.

341

Tables S1−4 giving detailed results for concentrations, correlation analysis, congener,

342

KHA−KOA linear regression analysis, and source apportionment. Figures S1−2 depicting

343

the gender-specific PCB profiles and KHA−KOA linear regression.

344

AUTHOR INFORMATION

345

Corresponding Authors

346

*Phone: +86-20-85291509; fax: +86-20-85290706; e-mail: [email protected].

347

* Phone: +86-20-29119807; fax: +86-20-29119627; e-mail: [email protected].

348

Notes

349

The authors declare no competing financial interest.

350

ACKNOWLEDGMENTS

351

This study was financially supported by the Strategic Priority Research Program of the

352

Chinese Academy of Sciences (No. XDB14020301), the National Science Foundation of

353

China (No. 21307037, 41422305, U1401233) and Guangdong Natural Science

354

Foundation (S2011010006081). The authors also acknowledge the US EPA for providing

355

the CMB8.2 model free of charge.

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(29) Covaci, A.; Voorspoels, S.; Roosens, L.; Jacobs, W.; Blust, R.; Neels, H., Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in human liver and adipose tissue samples from Belgium. Chemosphere 2008, 73, 170-175.

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(30) Hagmar, L.; Wallin, E.; Vessby, B.; Jonsson, B. A. G.; Bergman, A.; Rylander, L., Intra-individual variations and time trends 1991-2001 in human serum levels of PCB, DDE and hexachlorobenzene. Chemosphere 2006, 64, 1507-1513.

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(34) Drooger, J. C.; Jager, A.; Lam, M. H.; den Boer, M. D.; Sleijfer, S.; Mathijssen, R. H. J.; de Bruijn, P., Development and validation of an UPLC-MS/MS method for the quantification of tamoxifen and its main metabolites in human scalp hair. J Pharmaceut Biomed 2015, 114, 416-425.

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(35) Milbrath, M. O.; Wenger, Y.; Chang, C. W.; Emond, C.; Garabrant, D.; Gillespie, B. W.; Jolliet, O., Apparent half-lives of dioxins, furans, and polychlorinated biphenyls as a function of age, body fat, smoking status, and breast-feeding. Environ. Health Perspect. 2009, 117, 417-425.

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(36) Nakao, T.; Aozasa, O.; Ohta, S.; Miyata, H., Assessment of human exposure to PCDDs, PCDFs and Co-PCBs using hair as a human pollution indicator sample 1: development of analytical method for human hair and evaluation for exposure assessment. Chemosphere 2002, 48, 885-896.

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(37) Mcfarland, V. A.; Clarke, J. U., Environmental occurrence, abundance, and potential toxicity of polychlorinated biphenyl congeners: Considerations for a congener-specific analysis. Environ. Health Perspect. 1989, 81, 225-239.

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(38) Chu, S. G.; Covaci, A.; Schepens, P., Levels and chiral signatures of persistent organochlorine pollutants in human tissues from Belgium. Environ. Res. 2003, 93, 167-176.

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(39) Bucheli, T. D.; Brandli, R. C., Two-dimensional gas chromatography coupled to triple quadrupole mass spectrometry for the unambiguous determination of atropisomeric polychlorinated biphenyls in environmental samples. J. Chromatogr. A 2006, 1110, 156-164.

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(40) Bordajandi, L. R.; Abad, E.; Gonzalez, M. J., Occurrence of PCBs, PCDD/Fs, PBDEs and DDTs in Spanish breast milk: Enantiomeric fraction of chiral PCBs. Chemosphere 2008, 70, 567-575.

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(41) McLachlan, M. S., Framework for the interpretation of measurements of SOCs in plants. Environ. Sci. Technol. 1999, 33, 1799-1804.

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(42) Thuresson, K.; Hoglund, P.; Hagmar, L.; Sjodin, A.; Bergman, A.; Jakobsson, K., Apparent half-lives of hepta- to decabrominated diphenyl ethers in human serum as determined in occupationally exposed workers. Environ. Health Perspect. 2006, 114, 176-181.

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(43) Sjödin, A.; Hagmar, L.; Klasson-Wehler, E.; Kronholm-Diab, K.; Jakobsson, E.; Bergman, A., Flame retardant exposure: polybrominated diphenyl ethers in blood from Swedish workers. Environ. Health Perspect. 1999, 107, 643-648.

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Figure Captions

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Figure 1. PCB congener profiles in hair and serum from e-waste recycling workers, air,

479

and indoor dust in the e-waste area of southern China. Hair and serum PCB congener

480

profiles from e-waste recycling workers, air, and indoor dust in the e-waste area of

481

southern China. Air and indoor dust data are taken from previous studies.21,28

482 483

Figure 2. Enantiomer Fractions (EFs) of PCBs in hair and serum from e-waste recycling

484

workers and air in southern China. Air data are taken from a previous study.21

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485 Table 1. PCB Concentrations in Hair (ng/g) and Serum (ng/g lipid) from E-Waste Recycling Workers in Southern China Male hair Female hair Male serum Female serum Median Mean Range Median Mean Range Median Mean Range Median Mean Range PCB28 129 147 32.4-300 346 281 72.1-479 176 240 n.d.a-724 537 494 n.d.-1445 PCB52 49.9 65.5 8.83-168 192 162 36.4-288 n.d. n.d. PCB66 42.9 46.8 12.0-107 117 103 17.9-190 160 162 n.d.-406 273 262 n.d.-506 PCB74 27.4 29.5 7.58-64.6 70.8 61.8 11.8-114 286 330 n.d.-799 317 367 n.d.-983 PCB95 50.1 64.1 13.1-160 189 167 29.5-294 141 137 23.6-299 97.0 127 36.7-299 PCB99 31.4 31.9 7.42-111 73.8 73.7 11.5-184 223 271 n.d.-904 159 272 n.d.-943 PCB101 73.2 83.4 17.0-274 239 220 30.8-481 35.9 64.2 n.d.-261 40.1 90.4 n.d.-331 PCB105 23.0 38.2 6.14-191 85.4 100 13.4-315 125 209 n.d.-928 206 279 n.d.-1241 561 797 49.5-2850 PCB118 48.4 75.9 12.8-349 174 206 26.1-582 384 579 29.3-2353 PCB128 8.40 11.6 1.92-58.9 32.3 36.7 4.05-110 57.6 59.4 n.d.-163 58.5 71.0 n.d.-250 PCB138 20.4 27.5 5.59-125 77.7 82.5 12.0-228 301 356 n.d.-957 276 378 n.d.-1216 PCB153 28.1 33.6 8.65-146 98.7 101 14.9-255 341 404 n.d.-997 289 428 n.d.-1153 PCB164 8.48 10.2 1.91-43.2 31.0 32.2 5.06-78.5 90.2 116 n.d.-283 47.3 95.1 n.d.-345 PCB170/190 3.09 4.15 0.64-13.1 12.8 13.6 3.09-33.6 78.9 90.8 12.6-210 49.1 92.3 18.7-238 PCB177 1.88 2.30 0.47-6.68 6.42 6.01 1.25-11.3 15.7 21.6 n.d.-75.5 13.7 22.3 n.d.-66.2 PCB180 5.87 6.23 1.88-14.3 15.8 17.1 4.86-35.9 105 133 n.d.-376 71.0 122 n.d.-336 PCB187 3.18 3.67 1.02-8.54 8.99 9.14 2.65-17.1 51.8 54.4 n.d.-164 42.6 47.6 n.d.-120 PCB209 0.27 0.27 n.d.-1.46 1.55 2.02 n.d.-6.28 34.1 33.2 n.d.-81.8 38.6 35.8 n.d.-71.21 Total 611 682 161-2020 1781 1675 314-3514 2851 3263 315-8976 2888 3980 256-11200 a Not detectable. 486 487

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Table 2. Spearman Rank Order Correlations of PCB Concentration (ng/g) and Occupational Exposure Duration (yr) for Male (n = 17), Female (n = 12), and All Participants (n = 29)

PCB28

Male

Hair Female

All

Male

Serum Female

All

0.062

-0.028

0.193

0.153

0.394

0.329

a

PCB52 0.281 0.110 0.305 PCB66 0.216 0.274 0.311 0.201 0.155 0.242 PCB74 0.176 0.338 0.289 0.272 0.432 0.346 b PCB95 0.229 0.210 0.318 -0.288 0.244 -0.008 PCB99 0.354 0.295 0.403b 0.400 0.435 0.389b PCB101 0.341 0.352 0.417b -0.007 0.329 0.211 b c PCB105 0.525 0.323 0.517 0.172 0.374 0.255 PCB118 0.471b 0.338 0.475c 0.156 0.324 0.279 b c PCB128 0.400 0.579 0.505 0.412 0.361 0.397b PCB138 0.502b 0.419 0.530c 0.259 0.482b 0.375b b c PCB153 0.540 0.387 0.545 0.224 0.462 0.344 b c PCB164 0.582 0.458 0.551 0.462 0.406 0.382b PCB170+190 0.588b 0.679b 0.605c 0.213 0.445 0.357 b b PCB177 0.580 0.558 0.572c 0.367 0.582b 0.467b PCB180 0.564b 0.615b 0.562c 0.291 0.525b 0.421b b c PCB187 0.513 0.444 0.530 0.057 0.444 0.265 b c PCB209 0.526 0.483 0.482 0.286 0.011 0.114 Total 0.328 0.288 0.393b 0.238 0.471b 0.358 a Correlation analysis was not performed because PCB52 was not detectable in serum. b Correlations are significant at p < 0.05. cCorrelations are significant at p < 0.01. 489 490

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Table 3. Pearson Product-Moment Correlations of PCB concentrations between Hair and Blood Male PCB28 PCB66 PCB74 PCB95 PCB99 PCB101 PCB105 PCB118 PCB128 PCB138 PCB153 PCB164 PCB170/190 PCB177 PCB180 PCB187 PCB209

r 0.600 0.742 0.754 0.416 0.742 0.816 0.810 0.828 0.404 0.722 0.679 0.652 0.537 0.366 0.376 0.462 0.254

p 0.006