Polychlorinated biphenyls in human hair at an e-waste site in China: composition profiles and chiral signatures in comparison to dust

Melanin-mediated accumulation of polycyclic aromatic hydrocarbons in human hair: Insights from biomonitoring and cell exposure studies

While human hair is widely used to monitor micro-organic contaminants (MOCs), their incorporation mechanisms are poorly understood. Melanin, known to facilitate the accumulation of drugs in hair, hasn't been studied in the field of MOCs. Here, polycyclic aromatic hydrocarbons (PAHs), a class of priority MOCs, were investigated through hair biomonitoring as well as cell exposure experiments. PAH concentrations and melanin contents were measured in black and white hairs from the same individual. The results showed that five dominant PAHs (phenanthrene, fluoranthene, pyrene, benzo[a]anthracene and chrysene) in black hair (0.66 ng/g - 35.1 ng/g) were significantly higher than those in white hair (0.52 ng/g - 29.6 ng/g). Melanin contents in black hair (14.9 - 48.9 ng/g) were markedly higher than in white hair (0.35 - 2.15 ng/g) and were correlated to PAH concentrations, hinting melanin-mediated accumulation of PAHs in hair. The in vitro experiment using murine melanoma cells demonstrates that PAH levels in cells were affected by melanin, suggesting the affinity of melanin to PAHs. Both biomonitoring and cell exposure experiment implicate the pivotal role of melanin in PAH accumulation in hair. Therefore, to ensure the accuracy of hair biomonitoring for MOCs, attention must be paid to the melanin content uniformity.

A meta-analysis highlighting the increasing relevance of the hair matrix in exposure assessment to organic pollutants

Owing to a wide range of advantages, such as stability, non-invasiveness, and ease of sampling, hair has been used progressively for comprehensive biomonitoring of organic pollutants for the last three decades. This has led to the development of new analytical and multi-class analysis methods for the assessment of a broad range of organic pollutants in various population groups, ranging from small-scale studies to advanced studies with a large number of participants based on different exposure settings. This meta-analysis summarizes the existing literature on the assessment of organic pollutants in hair in terms of residue levels, the correlation of hair residue levels with those of other biological matrices and socio-demographic factors, the reliability of hair versus other biomatrices for exposure assessment, the use of segmental hair analysis for chronic exposure evaluation and the effect of external contamination on hair residue levels. Significantly high concentrations of organic pollutants such as pesticides, flame retardants, polychlorinated biphenyls and polycyclic aromatic hydrocarbon were reported in human hair samples from different regions and under different exposure settings. Similarly, high concentrations of pesticides (from agricultural activities), flame retardants (E-waste dismantling activities), dioxins and furans were observed in various occupational settings. Moreover, significant correlations (p < 0.05) for hair and blood concentrations were observed in majority of studies featuring pesticides and flame retardants. While among sociodemographic factors, gender and age significantly affected the hair concentrations in females and children in general exposure settings, whereas adult workers in occupational settings. Furthermore, the assessment of the hair burden of persistent organic pollutants in domestic and wild animals showed high concentrations for pesticides such as HCHs and DDTs whereas the laboratory-based studies using animals demonstrated strong correlations between exposure dose, exposure duration, and measured organic pollutant levels, mainly for chlorpyrifos, diazinon, terbuthylazine, aldrin, dieldrin and pyrethroid metabolites. Considering the critical analysis of the results obtained from literature review, hair is regarded as a reliable matrix for organic pollutant assessment; however, some limitations, as discussed in this review, need to be overcome to reinforce the status of hair as a suitable matrix for exposure assessment.

Non-invasive biomonitoring of infant exposure to environmental organic pollutants in north-western Spain based on hair analysis. Identification of potential sources

Recent years have seen growing interest in hair sample analysis to detect organic pollutants (OPs). This biological matrix can be analysed non-invasively for biomonitoring of OPs over a wide exposure window. Obtaining hair sample amounts that meet the needs of the analytical methodology required for the determination of the POs of interest can be challenging, especially in infants. As a result, studies assessing organic pollutants in infant hair have been very scarce. We quantified levels of about 60 OPs, including persistent organic pollutants (POPs), in 110 hair samples from a patient cohort (60 mothers and 50 infants) from Santiago de Compostela (north-western Spain). For each participant we examined relationship between OP levels and corresponding epidemiological parameters using correlations, principal component analysis (PCA), hierarchical cluster analysis, and Multivariate analysis of variance (MANOVA). For many OPs we observed significant correlations with place of residence, parity, and maternal age, as well as pet ownership. Evaluation of dietary habits showed significant associations between levels some OPs and the consumption of fish, molluscs, and cereal. There were significant associations between chlorpyrifos and deltamethrin levels and infant birth characteristics such as birthweight and head circumference. Relations between OP levels in the hair of mothers and their infants were also examined, revealing common sources of exposure for dioxin-like polychlorinated biphenyls (DLPCBs), non-dioxin-like polychlorinated biphenyls (NDLPCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs). Levels of fluoranthene (F), pyrene (P), endrin, and some PBDEs in maternal hair were significantly correlated with those in infant hair. Our findings identified common sources of exposure to OPs of distinct chemical classes.

Identification of Species-Specific Prey Uptake and Biotransformation of Chiral Polychlorinated Biphenyls (PCBs) in Riparian and Aquatic Food Webs

The atropisomeric enrichment of chiral polychlorinated biphenyls (PCBs) can trace the movement of PCBs through food webs, but it is a challenge to elucidate the prey uptake and stereoselective biotransformation of PCBs in different species. The present study investigated the concentrations and enantiomer fractions (EFs) of chiral PCBs in invertebrates, fishes, amphibians, and birds. Chiral PCB signature was estimated in total prey for different predators based on quantitative prey sources. The nonracemic PCBs in snakehead (Ophiocephalus argus) were mainly from prey. EFs of PCBs in amphibians and birds were mainly influenced by biotransformation, which showed enrichment of (+)-CBs 132 and 135/144 and different enantiomers of CBs 95 and 139/149. Biomagnification factors (BMFs) of chiral PCBs were higher than 1 for amphibians and passerine birds and lower than 1 for kingfisher (Alcedo atthis) and snakehead. BMFs were significantly correlated with EFs of chiral PCBs in predators and indicative of atropisomeric enrichment of PCBs across different species. Trophic magnification factors (TMFs) were higher in the riparian food web than in the aquatic food web because of the high metabolism capacity of chiral PCBs in aquatic predators. The results highlight the influences of species-specific prey sources and biotransformation on the trophic dynamics of chiral PCBs.

Maternal hair segments reveal metal(loid) levels over the course of pregnancy: a preliminary study in Southern China

Characterization of metal(loid) variation during pregnancy and identification of the affecting factors are important for assessing pregnancy exposures in epidemiological studies. In this study, maternal hair was collected in three segments (each 3 cm) from pregnant women in Guangzhou, China. Ten metal(loid)s, including six essential trace metal(loid)s and four toxic trace metal(loid)s, were analyzed to investigate the levels of various metal(loid)s during pregnancy and the factors that influence them. Strong pairwise correlations were observed between manganese (Mn), cobalt (Co), and vanadium (V), between selenium (Se), arsenic (As), and antimony (Sb), and between cadmium (Cd) and lead (Pb). All metal(loid)s except for Se, Mn, and Co showed strong correlations among the three hair segments, and most of the metal(loid)s had good reproducibility, with intraclass correlation coefficients (ICCs) ranging from 0.510 to 0.931, except for As (ICC = 0.334), Mn (ICC = 0.231), and Co (ICC = 0.235). Zn levels decreased, while Sb increased, in maternal hair during pregnancy. Maternal sociodemographic characteristics and dietary intake affected metal(loid) levels in maternal hair. These results provide foundational data for using maternal hair segmental analysis to evaluate exposure variation to metal(loid)s during pregnancy and the potential factors associated with them.

Incorporation of Fast-Elimination Chemicals in Hair Is Governed by Pharmacokinetics-Implications for Exposure Assessment

Mechanisms governing chemicals' incorporation in hair are incompletely understood, and gaps remain to link the concentration of chemicals in hair to level of exposure and internal dose present in the body. This study assesses the relevance of hair analysis for the biomonitoring of exposure to fast-elimination compounds and investigates the role of pharmacokinetics (PK) in their incorporation in hair. Rats were administered with pesticides, bisphenols, phthalates, and DINCH over 2 months. Hairs were analyzed for 28 chemicals/metabolites to investigate correlations between their concentration in hair and the dose administered to the animals. Urine collected over 24 h after gavage was used to determine chemicals' PK and to investigate their influence on incorporation into hair by means of linear mixed models (LMMs). Eighteen chemicals presented a significant correlation between concentration in hair and level of exposure. In models combining all chemicals, agreement between concentration in hair predicted by LMM and experimental values was moderate (R² = 0.19) but significantly increased when PK were included in the models (R² = 0.37), and even more when chemical families were considered separately (e.g., R² = 0.98 for pesticides). This study shows that pharmacokinetics mediate incorporation of chemicals in hair and suggests the relevance of hair for assessing exposure to fast-elimination chemicals.

Fetal exposure to organic contaminants revealed by infant hair: A preliminary study in south China

Fetal exposure to multiple organic contaminants (OCs) is a public concern because of the adverse effects of OCs on early life development. Infant hair has the potential to be used as an alternative matrix to identify susceptible fetuses, owing to its reliability, sensitivity, and advantages associated with sampling, handling, and ethics. However, the applicability of infant hair for assessing in utero exposure to OCs is still limited. In this study, 57 infant hair samples were collected in Guangzhou, South China, to evaluate the levels and compositions of typical OCs in the fetus. Most of the target OCs were detected in infant hair, with medians of 144 μg/g, 17.7 μg/g, 192 ng/g, 46.9 ng/g, and 1.36 ng/g for phthalate esters (PAEs), alternative plasticizers (APs), organophosphorus flame retardants (OPFRs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs), respectively. Meanwhile, paired maternal hair (0-9 cm from the scalp) was collected to examine the associations between maternal and infant hair for individual compounds. Low-brominated PBDEs tended to deposit in infant hair, with median concentrations approximately two times higher than those in maternal samples. Levels of PBDEs and 4,4'-dichlorodiphenyldichloroethylene (p,p'-DDE) in paired maternal and infant hair showed strong positive correlations (p < 0.05), while most plasticizers (PAEs and APs) were poorly correlated between paired hair samples. Exposure sources were responsible for the variation in correlation between OC levels in the paired infant and maternal samples. Crude relationships between fetal exposure to OCs and birth size were examined using the Bayesian kernel machine regression (BKMR) model. BDE-28 was found to be adversely associated with the birth size. This study provides referential information for evaluating in utero exposure to OCs and their health risks based on infant hair.

Chiral signatures of polychlorinated biphenyls in serum from e-waste workers and their correlation with hydroxylated metabolites

Elevated concentrations of polychlorinated biphenyls (PCBs) found in environmental media and biota from typical e-waste dismantling sites have raised concerns regarding their human body burden and potential negative health effects. In the present study, the enantiomeric compositions of three typical chiral congeners (PCB-95, PCB-132, and PCB-149) were measured in 24 serum samples from e-waste workers by using gas chromatography coupled to triple quadrupole tandem mass spectrometry. The mean enantiomer fractions (EFs) of chiral congeners in serum from the workers were 0.655 ± 0.103, 0.679 ± 0.164, and 0.548 ± 0.095 for PCB-95, PCB-132, and PCB-149, respectively. The (+) enantiomers of PCB-95, PCB-132, and PCB-149 were enantioselectively enriched in serum. Significant positive correlations were observed between the EF of the chiral congener PCB-95 and the total concentration of OH-PCBs, suggesting that EF values of chiral PCBs could be used to indicate the extent of biological metabolism. In addition, the EF of PCB-95 in serum samples increased with increasing work duration of the e-waste workers, thus demonstrating the usefulness of EF values of chiral PCBs as tracers of human exposure to PCBs. Because of the enantioselective enrichment of (+) enantiomers of PCB-95, PCB-132, and PCB-149, further studies are needed to explore the metabolism and toxicity of chiral contaminants in humans.

Changes in human hair levels of organic contaminants reflecting China's regulations on electronic waste recycling

To assess the impacts of regulations and laws enhancing the management of e-waste in China, hair samples of local residents and dismantling workers in a former e-waste area in 2016 and 2019, five and eight years after the implementation of legislation and regulations in this area since 2011, respectively. The temporal changes in levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organophosphorus flame retardants (OPFRs) in the hair samples were investigated. Besides, the levels of these organic contaminants in hair samples collected from the same area in 2009, 2011, and 2015 reported in previous studies were used as comparison. The highest median levels of Σ₉PCBs (719 ng/g), Σ₃Penta-BDEs (16.1 ng/g), and Σ₃Octa-BDEs (8.46 ng/g) in hair were found in 2011, with a significant decrease trend was observed from 2011 to 2019 (p < 0.05). As for Deca-BDE, the levels reached the maximum in 2015 (133 ng/g), following by a significant decrease to 2016 (7.46 ng/g) and 2019 (2.61 ng/g) (p < 0.05). The median levels of Σ₈OPFRs, also decreased significantly (p < 0.05) from 2015 (357 ng/g) to 2016 (264 ng/g) and 2019 (112 ng/g). Moreover, a significantly increasing trend was observed for the ratios of triphenyl phosphate (TPHP) and tris(2-chloropropyl) phosphate (TCIPP), two predominant OPFRs, to Deca-BDE from 2015 to 2019 (p < 0.01), suggesting a shift of "legacy" to "emerging" contaminants released from e-waste recycling in this area. The temporal changes in hair levels of typical organic contaminants in residents and dismantling workers indicated the effectiveness of the regulations on informal e-waste recycling activities and solid waste in China.

Environmental contamination and human exposure of polychlorinated biphenyls (PCBs) in China: A review

Polychlorinated biphenyls (PCBs), together with 11 other organic compounds, were initially listed as persistent organic pollutants (POPs) by the Stockholm Convention because of their potential threat to ecosystems and humans. In China, many monitoring studies have been undertaken to reveal the level of PCBs in environment since 2005 due to the introduced stricter environmental regulations. However, there are still significant gaps in understanding the overall spatial and temporal distributions of PCBs in China. This review systematically discusses the occurrence and distribution of PCBs in environmental matrices, organisms, and humans in China. Results showed that PCB contamination in northern and southern China was not significantly different, but the PCB levels in East China were commonly higher than those in West China, which might have been due to the widespread consumption of PCBs and intensive human activities in East China. Serious PCB contamination was found in e-waste disassembling areas (e.g., Taizhou of Zhejiang Province and Qingyuan and Guiyu of Guangdong Province). Higher PCB concentrations were also chronicled in megalopolises and industrial clusters. The unintentionally produced PCBs (UP-PCBs) formed during industrial thermal processes may play an increasingly significant role in PCB pollution in China. Low PCB levels were recorded in rural and underdeveloped districts, particularly in remote and high-altitude localities such as the Tibetan Plateau and the South China Sea. However, these data are limited. Human exposure to PCBs is closely related to the characteristics of environmental pollution. This review also discusses existing issues and future research prospects on PCBs in China. For instance, the accumulation characteristics and migration regularities of PCBs in food webs should be further studied. More investigations should be undertaken to assess the quantitative relationship between external and internal exposure to PCBs. For example, bioaccessibility and bioavailability studies should be supplemented to evaluate human health risks more accurately.

Concentration-dependent enantioselective accumulation of chiral polychlorinated biphenyls in Nelumbo nucifera Gaertn. root from contaminative sediment

Nelumbo nucifera Gaertn. (lotus) roots were collected from contaminated sediments which were artificially adding different concentrations of chiral polychlorinated biphenyls (PCBs) to investigate the effect of concentration on the accumulation characteristics and chiral signatures of PCBs in lotus root during its growth period of 150 days. Under high PCB exposure concentration, the biota-sediment accumulation factors (BSAFs) of PCBs 91, 95, and 136 in the lotus root were up to 0.25-0.46 and 8.10-10.5 times higher than those under low-exposure concentration (0.024-0.052). The BSAFs of PCBs 149, 176, and 183 under high-exposure concentration were up to 0.24-0.44, while they were undetected at low concentration. The significant difference observed in the BSAFs based on different concentrations indicates that the lotus root accumulation efficiency toward chiral PCBs increases with the contaminate concentration. Although the (-)-enantiomers of PCBs 91, 95, and 136 were all preferentially accumulated in lotus root under two exposure concentrations, the extent of the preferential accumulation of (-)-PCB 95 decreased with increasing exposure concentration throughout the whole growth period (30-150 days). In addition, the (-)-enantiomers of PCBs 91 and 136 also showed the same tendency during most of the growth period. Conclusively, the exposure concentrations are an important influence factor on the enantioselective accumulation of chiral PCBs in lotus root.

Analysis of polybrominated diphenyl ethers, hexabromocyclododecanes, and legacy and emerging phosphorus flame retardants in human hair

Human hair has been identified as a non-invasive alternative matrix for assessing the human exposure to specific organic contaminants. In the present study, a solvent-saving analytical method for the simultaneous determination of 8 polybrominated diphenyl ethers (PBDEs), 3 hexabromocyclododecanes (HBCDDs), 12 phosphorus flame retardants (PFRs), and 4 emerging PFRs (ePFRs) has been developed and validated for the first time. Hair sample preparation protocols include precleaning with Milli-Q water, digestion with HNO₃/H₂O₂ (1:1, v/v), liquid-liquid extraction with hexane:dichloromethane (4:1, v/v), and fractionation and cleanup on a Florisil cartridge. The method was validated by using two levels of spiked hair samples of 3 replicates for each spiking group. Limits of quantification (LOQs) were 0.12-22.4 ng/g for all analytes, average values of accuracies were ranging between 88 and 115%, 82-117%, 81-128%, and 81-95% for PBDEs, HBCDDs, PFRs, and ePFRs, respectively; and precision was also acceptable (RSD < 20%) for all analytes. Eventually, this method was applied to measure the levels of the targeted analytes in hair samples of e-waste dismantling workers (n = 14) from Qingyuan, South China. Median values ranged between 3.00 and 18.1 ng/g for PBDEs, 0.84-4.04 ng/g for HBCDDs, 2.13-131 ng/g PFRs, and 1.49-29.4 ng/g for ePFRs, respectively. PFRs/ePFRs constitute the major compounds in human hair samples, implying the wide use of PFRs/ePFRs as replacements of PBDEs and HBCDDs, as well the potential high human exposure risks of PFRs/ePFRs. Overall, this work will allow to a comprehensive assessment of human exposure to multiple groups of FRs using hair as a non-invasive bioindicator.

PCDD/Fs in paired hair and serum of workers from a municipal solid waste incinerator plant in South China: Concentrations, correlations, and source identification

Human hair has been widely used to evaluate the exposure to drugs and organic pollutants. However, reports on the relationship between polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-p-furans (PCDFs) in hair and the body burden of PCDD/Fs are limited. In this study, the association between PCDD/Fs in paired hair and serum samples from 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 determine the source apportionment of PCDD/Fs in the hair. The median international toxic equivalents (I-TEQs) of ΣPCDD/F in serum and hair were 28.0 pg TEQ/g (lipid weight) and 0.30 pg TEQ/g (dry weight), respectively. The indicator congener of PCDD/Fs for the TEQ levels was 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) in both hair and serum, the concentrations of which both exhibited significant and strong linear dependence on the total TEQ levels (p < 0.01, R² = 0.966 and R² = 0.670, respectively). Significant positive correlations were found in the 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin (HxCDD) and octachlorodibenzo-p-dioxin (OCDD) levels between the hair and serum samples (p < 0.05). Flue gas (which is 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.

Polychlorinated biphenyls in settled dusts from an end-of-life vehicle processing area and normal house dusts in northern Vietnam: Occurrence, potential sources, and risk assessment

Concentrations and congener-specific profiles of total 209 polychlorinated biphenyls (PCBs) were investigated in settled dust samples collected from end-of-life vehicle (ELV) processing, urban, and rural areas in northern Vietnam. Concentrations of total 209 PCBs, seven indicator congeners, and twelve dioxin-like PCBs decreased in the order: ELV working > ELV living ≈ urban > rural dusts. Penta- and hexa-CBs dominated the homolog patterns in all the samples with higher proportions in the ELV dusts compared to the urban and rural house dusts. The abundance and pattern of PCBs in the ELV dusts suggest on-going emissions of these compounds related to processing of vehicular oils and lubricants containing PCBs, whereas the presence of PCBs in the urban and rural house dusts indicate long-time releases. However, levels of some PCBs identified as by-products of pigment manufacturing (e.g., PCB-11 and PCB-209) were higher in the urban house dusts than those from other locations, resulting from human activities utilizing paints and pigments. Daily intake doses (ID), non-carcinogenic hazard quotient (HQ), and lifetime cancer risk (CR) of PCBs through dust ingestion were estimated for ELV workers and residents in the studied areas. The workers and children in the ELV sites were estimated to be at higher risk of PCB exposure, however almost all of the HQ < 1 and CR < 10^-4 indicate no serious risk related to dust-bound PCBs.

Levels and sources of PBDEs and PCBs in human nails from e-waste, urban, and rural areas in South China

Human nails have been increasingly used as a biomarker for human exposure to persistent organic pollutants (POPs). In the present study, the fingernails of e-waste-dismantling workers from Longtang town, Qingyuan city, rural residents from Shijiao town, Qingyuan city, and urban residents from Guangzhou city, respectively, were collected from South China to monitor the human burdens of polybrominated diphenyl ether (PBDEs) and polychlorinated biphenyl (PCBs). The median concentrations of in the nails of the e-waste-dismantling workers, and urban and rural residents were 412, 129, and 82.1 ng g^-1, respectively, and the median concentrations of were 108, 8.4, and 22.1 ng g^-1, respectively. The levels of PCBs and PBDEs in the nails of e-waste-dismantling workers were significantly higher as compared to those for urban and rural residents (p < 0.05), implying the continuous and greater exposure to these chemicals in the e-waste recycling areas. BDE 209 (92-98%) was the major congener of PBDEs and CB 52 (26-51%) was the main congener of PCB in nail samples. However, no significant gender difference was observed for PBDE and PCB levels in nails from all three investigated areas, and no significant correlation was found between their levels and the age of the participants. The enantiomer fractions (EFs) of CBs 95 and 132 indicated that the external sources (e.g. dust and/or air) were the primary sources for CBs 95 and 132 in human nails from the e-waste area, while the contribution from the internal sources (e.g. serum) could be in a small percentage. The results of this study indicate that human nails can be used as a proper indicator of human exposure to PCBs and PBDEs, and further studies are needed by a comprehensive investigation of the relationships between the PCB and PBDE levels in the nails and serum and/or other internal tissues.

Simultaneous analysis of typical halogenated endocrine disrupting chemicals and metal(loid)s in human hair

Hair analysis has been an important approach in evaluating population exposure to various environmental factors. To meet the requirements of human environmental epidemiology studies, we aimed to develop an efficient method for simultaneous analysis of various metal(loid)s and some typical environmental halogenated endocrine disrupting chemicals (hEDCs) (i.e., polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine pesticides, as well as some of their hydroxyl substituted metabolites) in a single hair sample. The hair was washed successively with surfactant solutions, methanol solvent, and deionized water to remove impurities attached to the hair surface. Efficiency was comprehensively compared among various washing strategies. The hair sample was further pulverized into fine powder with a median diameter (25th-75th percentile) of 8.6 (5.9-13.5) μm. The hair organic components were extracted by acetonitrile solvent and compared with the microwave-assisted extraction method. The hEDCs in the supernatant acetonitrile phase were quantified by gas chromatography-mass spectrometry, and the metal(loid)s in the precipitate hair were further analyzed by inductively coupled plasma mass spectrometry. Our developed method was further applied to analyze the hair samples of 165 pregnant women. The results showed that particles attached to the surface of the hair could not be washed off completely. However, we proposed a protocol framework to wash hair with relatively high efficience, which includes warm water incubation, and use of surfactant and organic solvent. The recoveries of the concerned hEDCs and metal(loid)s were overall in the range of 80% to 120%. For the women population, the method can efficiently recognize the typical exposure characteristics of the concerned hEDCs and metal(loid)s. Our study significantly ameliorated the deficiencies of the traditional hair washing strategy and developed an efficient method for simultaneous analysis of various metal(loid)s and hEDCs in a single hair sample. This method will provide important support for population complex exposure analysis and facilitate environmental exposome studies.

Application of enantiomeric fractions in environmental forensics: Uncertainties and inconsistencies

The assumption that only biological processes are enantioselective introduces challenges in the reliability of enantioselective analysis as a tool for discriminating biotic and abiotic processes in the environmental fate of chiral pollutants. Enantioselectivity does not depend on the nature of the fate process a chiral contaminant undergoes but on the interaction of the chiral contaminant with homochirality inducing external agents (e.g. chiral molecules, macromolecules or surfaces such as enzymes, blood plasma, proteins, chiral co-pollutants, humic acid and soil organominerals). The environmental behavior of a chiral contaminant is difficult to anticipate because the interactions between the chiral contaminants and the homochirality inducing external agents is often complex and strongly influenced by local environment conditions such as pH, redox conditions, organic carbon, organic nitrogen, humic acid, and redox conditions. Furthermore, the use of enantioselective analysis in environmental forensics depend on the adequate separation and accurate identification and quantification of the enantiomers of the chiral contaminant. Matrix effects, instrument effects, inadequate enantioselective separation, and poor quantification techniques introduce uncertainties in the determination of enantiomeric composition. Here we present the weaknesses of this assumption and recommend using enantiomeric fractions as chemical markers of biotransformation with caution. We recommend using stable isotopes, including abiotic controls to determine if enantioselective sorption occurs, and determining stability of enantiomers in solvent or at elevated temperatures to account for confounding factors arising from matrix effects, enantioselective abiotic processes, and enantiomerization due solvent and thermal lability of the chiral analyte, respectively to maintain the integrity of the utility of enantiomeric composition changes as an environmental forensics tool.

External interference from ambient air pollution on using hair metal(loid)s for biomarker-based exposure assessment

Hair metal(loid)s are often measured as biomarkers to evaluate population internal exposure, however, hair samples could be easily contaminated by ambient particulate matter (PM) pollution. Here, we evaluated the potential external interference from ambient PM pollution on using hair metal(loid)s for population biomarker-based exposure assessment. The raw hair samples were strictly washed and placed under various indoor and outdoor scenarios for ~6 months at sites with high PM pollution. The contaminated hair was then washed using the same method. A total of 33 hair elements were quantified by inductively coupled plasma-mass spectrometry. The surface residual PM on hair after washing was observed by scanning electron microscopy. In addition, we chose a practical exposure scenario including 77 housewives in Shanxi Province, China for validation. The results for the hair exposure experiment revealed that external contamination of some elements that had relatively high concentrations in hair was generally mild in both indoor and outdoor exposure scenarios (i.e., Zn, Mg, Se, Fe, Sr, Ti, Mn, Sn, Ge, U, Co, Mo, and As). A relatively higher external contamination of other elements (e.g., Al, Cr, Pb, Cd, Li, and most rare earth elements (REEs)) was observed, especially for those elements with relatively low hair concentrations (e.g., Cd, and REEs) in the outdoor environment. This finding was due mainly to some small ambient PM not being fully removed by the current washing strategy when the hair sample was heavily contaminated. However, results from practical exposure scenario of the housewives showed that there were overall no significant differences of hair metal(loid)s between the housewives using coal and clean energy for cooking. We concluded that the external interference on hair internal metal(loid) analysis could be negligible when hair was efficiently washed, especially for population with relatively longer indoor activities. It is therefore promising to use hair analysis for their population exposure assessment.

A proposed method of enantioselectivity analysis for residual chiral PCBs in gas chromatography

Polychlorinated biphenyls (PCBs) are harmful and persistent organic pollutants. The influence of chiral PCBs acts mainly on the different enantiomer fraction, bioaccumulation and even degradation in environmental media. Solvents and temperatures existed almost everywhere during the analysis of extraction, purification, concentration and detection, which was often underestimated in previous studies. In our study, the configuration stability of the chiral PCBs was examined from solvent and temperature aspects. Transformation phenomena for the analytic stereoisomer monomers of PCB45, PCB95, and PCB149 affected by temperature were observed. We demonstrated that higher inlet temperatures could increase the sensibility for the low-concentration environmental samples, resulting in isomerization of chiral PCBs. Real rice samples were used to verify our analysis method. Combined with density functional theory, we verified the mechanism of isomer conversion with various numbers and sites of the -Cl substituent. PCBs with tetra-ortho substituents (2, 2', 6, 6') were relatively stable and showed the highest rotational barriers (E_a) at approximate 240 kJ mol^-1. Others with trio-ortho substituents (2, 2', 6/6') showed E_a from 170 to 190 kJ mol^-1, whose enantiomeric fractions would be affected by temperature during the analysis process for environmental detection. The method we developed was a promising means to understand the mechanism of isomerization and to predict stabilities of chiral PCBs.

Occupational exposure characteristics and health risk of PBDEs at different domestic e-waste recycling workshops in China

Polybrominated diphenyl ethers (PBDEs) contained in electronic waste (e-waste) can be released to indoor environments and cause occupational health hazards during the recycling process. TVs, washing machines, refrigerators and printed wiring boar (PWB) represent the main domestic e-wastes. In this study, concentrations of Σ₇PBDEs in air and dust samples from recycling workshops handling these four major types of e-wastes were measured, and the occupational exposure risk for workers at the corresponding workshops was evaluated. Concentrations of Σ₇PBDEs in air and dust were within the ranges of 55.28-369.66 ng/m³ and 158.07-669.81 μg/g, respectively. The highest concentration of Σ₇PBDEs in air was detected in the TV recycling workshop, while the refrigerator recycling workshop had the highest level of Σ₇PBDEs in dust. The workers at these two e-waste recycling workshops were the most substantially exposed to BDE-209, which accounted for more than 85% of Σ₇PBDEs in both air and dust. Compared to other e-waste recycling workshops, the workers at the PWB recycling workshop were also more exposed to BDE-47 and BDE-99. Occupational exposure levels for inhalation and dust ingestion were within the ranges of 3939 pg/kg/d to 26,271 pg/kg/d and 104,945 pg/kg/d to 444,694 pg/kg/d, respectively. The hazard quotient (HQ) values were calculated based on the RfDs provided by the EPA. Total HQ levels of inhalation exposure and dust ingestion were less than 0.222. The results of the HQ indicated that no adverse health effects were expected for workers in these workshops; however, the exposure risk of workers in the PWB recycling workshop (HQ=0.222) was higher than that in other e-waste recycling workshops (HQ=0.022-0.072). At the PWB recycling workshop, BDE-47 and BDE-99 caused the main occupational exposure risk to the workers, while s in the recycling plants handling other types of domestic e-waste BDE-209 was the major contributor to the risk faced by the workers.

Legacy and Currently Used Organic Contaminants in Human Hair and Hand Wipes of Female E-Waste Dismantling Workers and Workplace Dust in South China

Legacy organic contaminants, such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), and several currently used organic contaminants, such as novel brominated retardants (NBFRs), organophosphate flame retardants (OPFRs), and Dechlorane Plus (DPs), were measured in the segmented hair and hand wipes of e-waste dismantling workers and in the dust from their workplace in an e-waste recycling site in South China to assess the accumulation and sources of organic contaminants in the hair shaft. The median concentrations of DPs, PBDEs, NBFRs, PCBs and OPFRs in hair samples were 23.5, 154, 156, 349, and 371 ng/g, respectively. A linear increase in organic contaminant concentrations was found along the hair shaft, with significant differences among each segment, while the age-related patterns were similar among the 7 hair segments. A linear relationship was found between the accumulation rates and the log K_OW, indicating that the accumulation rates of organic contaminants along the hair shaft decreased with increasing log K_OW values. Enantiomer fraction (EF) values of PCB-132 in distal segments were close to those in dust and air, while EFs in proximal segments were close to those in serum. The contributions of PCBs from external sources to hair increased with the distance from the scalp of hair segments, from 67.8% in 0-3 cm segments to 95.9% in 18-21 cm segments.

Health Assessment of Electronic Waste Workers in Chile: Participant Characterization

Little research has been done to evaluate the occupational health of electronic waste (e-waste) recycling workers in Latin America. The objective of this study was to complete comprehensive health evaluations on e-waste recycling workers in Chile and to compare those that work in informal (i.e., independent) to those that work in formal (i.e., established company) settings. A cross-sectional study in the summer of 2017 recruited 78 informal recycling workers from two cities and 15 formal e-waste recycling workers from a single recycling facility to assess exposures and health outcomes. Participants completed a health questionnaire and underwent a full health assessment. Herein, only health questionnaire data are reported. Participants were primarily male, middle-aged, married with children, and had worked in e-waste recycling for an average of 12 years. Participants generally reported good health status, and their prevalence of chronic diseases was comparable to national rates. Workers frequently reported exposures to several occupational stressors, including noise and insufficient income, as well as other mental health stressors. Occupational injuries were commonly reported and use of safety equipment was low. Only a few significant differences, generally of a rather small magnitude, were found between informal and formal workers. In conclusion, from survey data, we did not identify major risks to health among e-waste workers, and only minor differences between workers in informal and formal settings.

Simultaneous determination of polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons and their hydroxylated metabolites in human hair: a potential methodology to distinguish external from internal exposure

A novel method is developed to simultaneously analyse multiple chemicals in human hair and to distinguish the internal from external exposure.

Exposure to polycyclic aromatic hydrocarbons in women living in the Chinese cities of BaoDing and Dalian revealed by hair analysis

Polycyclic aromatic hydrocarbons (PAH) are produced from incomplete combustion of organic matter and released as environmental contaminants from activities such as transports, wood combustion, coal-fired power plants. In numerous urban areas worldwide, the levels of PAH exposure are considered critical regarding public health issues. The possibility to detect PAH and PAH metabolites biologically incorporated in human hair was demonstrated and proposed as biomarkers of exposure. Nevertheless, the possibility to distinguish different levels of exposure between different populations is still needed to validate the relevance of hair analysis in epidemiological studies. In this work, hair samples were collected from 204 women from two cities in China based on one year Air Quality Index history from governmental data (Baoding as polluted city and Dalian less polluted city). 8 out of the 15 parent PAH and 7 out of the 56 metabolites analyzed in this study were detected in all the samples. The highest concentrations in hair were observed for phenanthrene (4.2 to 889 pg/mg) > fluoranthene (1.05 to 204 pg/mg) > pyrene (3.2 to 124 pg/mg) for parent PAH, and for 9-OH-fluorene (0.04 to 1.78 pg/mg) > 2-OH-naphthalene (0.68 to 811 pg/mg) > 1-OH-anthracene (0.24 to 10.9 pg/mg) for metabolites. 14 parent PAH and 15 metabolites presented a significantly higher concentration in the hair samples collected from Baoding, as compared to Dalian. The median concentration of parent PAH was from 1.5 to 2.8 times higher in the hair of the subjects from Baoding than in subjects from Dalian and that of PAH metabolites was from 1 to 2.3 times higher. The study of inter-chemical associations revealed similarities and differences between the two areas, suggesting common and different sources of exposure depending on PAH respectively. The results confirmed the relevance of hair analysis to identify qualitative and quantitative differences in PAH exposure between populations from different areas. This study is the first one to investigate both parent PAH and their metabolites in a biological matrix.

Enantioselectivity in biotransformation and bioaccumulation processes of typical chiral contaminants

Chirality is a critical topic in the medicinal and agrochemical fields. One quarter of all agrochemicals was chiral in 1996, and this proportion has increased remarkably with the introduction of new compounds over time. Despite scientists have made great efforts to probe the enantiomeric selectivity of chiral chemicals in the environment since early 1990s, the different behaviours of individual enantiomers in biologically mediated processes are still unclear. In the present review, we highlight state-of-the-knowledge on the stereoselective biotransformation and accumulation of chiral contaminants in organisms ranging from invertebrates to humans. Chiral insecticides, fungicides, and herbicides, polychlorinated biphenyls (PCBs), pharmaceuticals, flame retardants hexabromocyclododecane (HBCD), and perfluorooctane sulfonate (PFOS) are all included in the target compounds. Key findings included: a) Changes in the enantiomeric fractions in vitro and in vivo models revealed that enantioselectivity commonly occurs in biotransformation and bioaccumulation. b) Emerging contaminants have become more important in the field of enantioselectivity together with their metabolites in biological transformation process. c) Chiral signatures have also been regarded as powerful tools for tracking pollution sources when the contribution of precursor is unknown. Future studies are needed in order to understand not only preliminary enrichment results but also detailed molecular mechanisms in diverse models to comprehensively understand the behaviours of chiral compounds.

Hazy Weather-Induced Variation in Environmental Behavior of PCDD/Fs and PBDEs in Winter Atmosphere of A North China Megacity

Haze is a serious pollution problem during the wintertime in North China. In this study, we investigated how the periodic cycle of winter haze events affect the environmental behaviors of two typical persistent organic pollutants, namely, polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs), in the atmosphere of a typical megacity, Beijing. The average atmospheric concentrations of the total di- to octa-CDD/Fs (∑PCDD/Fs: 378.0 pg/m³) and the total mono- to nona-BDEs (∑_9hPBDEs: 166.5 pg/m³) during haze episodes increased by 3.6-fold and 1.9-fold compared with those during the nonhaze periods, respectively; and their concentrations both linearly increased with PM_2.5 levels and decreased as a power function of the atmospheric boundary layer height. The elevated concentrations could be clearly attributed to the vertically sinking motion of airflow in the midlower troposphere. When a haze event occurred, the partitioning rate of PCDD/Fs and PBDEs into particles was reduced; the largest fraction of the particle-bound ∑PCDD/Fs was shifted from ultrafine particles to accumulation mode particles; and a steady-state model (Li-Ma-Yang model) satisfactorily described the gas-particle partitioning of the PCDD/F and PBDE homologues. The inhalation exposure risk evaluation indicated that special attention should be paid to the increased cancer risk induced by the elevated inhalation intake of PCDD/Fs during haze episodes.

Urinary metabolites of phosphate flame retardants in workers occupied with e-waste recycling and incineration

Urinary metabolites of phosphate flame retardants (PFRs) were determined in workers from an electronic waste (e-waste) recycling site and an incineration plant, in order to assess the PFR exposure risks of workers occupied with e-waste recycling and incineration. Bis(2-chloroethyl) phosphate (BCEP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and diphenyl phosphate (DPHP) were the most frequently detected chemicals (82-93%). The median concentrations of BCEP, BDCIPP, and DPHP were 1.77, 0.23, and 0.70 ng/mL, and 1.44, 0.22, and 0.11 ng/mL in samples from the e-waste site and the incineration plant, respectively. Dibutyl phosphate (DBP) was detected in all samples from the incineration plant, with a median level of 0.30 ng/mL. The concentrations of BDCIPP (r = -0.31, p < 0.05) were significantly correlated with the occupational exposure time rather than age in workers from the e-waste site. Negative and significant correlations were also observed between the concentrations of BCEP (r = -0.42, p < 0.05), BDCIPP (r = -0.37, p < 0.05), and DPHP (r = -0.37, p < 0.05) and occupational exposure time rather than age in workers from the incineration plant. No gender differences were observed in levels of PFR metabolites in urine samples (p > 0.05). Concentrations of BDCIPP in female were significantly correlated with occupational exposure time (r = -0.507, p < 0.01). Concentrations of PFR metabolites in male were not significantly correlated with age or occupational exposure time (p > 0.05). Overall, the workers with occupational exposure to PFRs had different profiles of urinary PFR metabolites. The age, occupational exposure time, and gender seemed not to be main factors mediating the exposure to PFRs for workers occupied with e-waste recycling and incineration.

Enantioselectivity of 2,2',3,5',6-Pentachlorobiphenyl (PCB 95) Atropisomers toward Ryanodine Receptors (RyRs) and Their Influences on Hippocampal Neuronal Networks

Nineteen ortho-substituted PCBs are chiral and found enantioselectively enriched in ecosystems. Their differential actions on biological targets are not understood. PCB 95 (2,2',3,5',6-pentachlorobiphenyl), a chiral PCB of current environmental relevance, is among the most potent toward modifying ryanodine receptors (RyR) function and Ca²⁺ signaling. PCB 95 enantiomers are separated and assigned aR- and aS-PCB 95 using three chiral-column HPLC and circular dichroism spectroscopy. Studies of RyR1-enriched microsomes show aR-PCB 95 with >4× greater potency (EC₅₀ = 0.20 ± 0.05 μM), ∼ 1.3× higher efficacy (B_max = 3.74 ± 0.07 μM) in [³H]Ryanodine-binding and >3× greater rates (R = 7.72 ± 0.31 nmol/sec/mg) of Ca²⁺ efflux compared with aS-PCB 95, whereas racemate has intermediate activity. aR-PCB 95 has modest selectivity for RyR2, and lower potency than racemate toward the RyR isoform mixture in brain membranes. Chronic exposure of hippocampal neuronal networks to nanomolar PCB 95 during a critical developmental period shows divergent influences on synchronous Ca²⁺ oscillation (SCO): rac-PCB 95 increasing and aR-PCB 95 decreasing SCO frequency at 50 nM, although the latter's effects are nonmonotonic at higher concentration. aS-PCB95 shows the greatest influence on inhibiting responses to 20 Hz electrical pulse trains. Considering persistence of PCB 95 in the environment, stereoselectivity toward RyRs and developing neuronal networks may clarify health risks associated with enantioisomeric enrichment of PCBs.

Organic contaminants and heavy metals in indoor dust from e-waste recycling, rural, and urban areas in South China: Spatial characteristics and implications for human exposure

The concentrations of several organic contaminants (OCs) and heavy metals were measured in indoor dust from e-waste recycling, rural, and urban areas in South China to illustrate the spatial characteristics of these pollutants and to further evaluate human exposure risks. The median concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DPs) were 38.6-3560, 2360-30,100, 665-2720, and 19.5-1860ng/g, while the median concentrations of Cd, Pb, Cu, Cr, and Zn were 2.46-40.4, 206-1380, 217- 1200, 25.3-134, and 176-212μg/g in indoor dust. The levels of all pollutants, except Zn, in dust from the e-waste recycling area were significantly higher than those from the other areas. Cd, Pb, and most OCs exhibited similar pollution patterns in the three areas, indicating that e-waste recycling activities are the major pollution source. In contrast, Cu, Cr, Zn, and penta-BDE are likely derived from household products in the rural and urban areas. The highest estimated daily intakes (EDIs) of PCBs, PBDEs, DBDPE, and DPs were 0.15-163, 3.97-1470, 1.26-169, and 0.11-134ng/kg bw/day for toddlers and adults. The highest EDIs of BDE 209 and Pb in toddlers in the e-waste recycling area were 16% and 18 times higher than the reference doses, indicating the high exposure risk of these pollutants in the e-waste recycling area.

Induction of micronuclei and cell cycle arrest by some tri- and tetrachlorobiphenyls in mammalian cells deficient in xenobiotic-metabolizing enzymes

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with continued public health concerns. The lower chlorinated biphenyls are supposed to be mutagenic following metabolic activation. However, in a preliminary study, we recently observed induction of micronuclei by several PCBs in a subclone of Chinese hamster V79 cell line, V79-Mz, which is deficient in xenobiotic-metabolizing enzyme activities. In this study, metabolism-free genotoxicity of PCBs was investigated, using 10 tri- and tetrachlorobiphenyls, in V79, V79-Mz, and human hepatoma (HepG2) cell lines. Among the four tetrachlorobiphenyls, 2,4,4',5- and 2,3'4,4'-tetrachlorobiphenyl-both having a noncoplanar configuration-induced micronuclei in V79-Mz cells, while their coplanar analogs 3,4,4',5- and 3,3',4,4'-tetrachlorobiphenyl were inactive. Furthermore, 2,3,3'- (PCB 20) and 2,3,4'-trichlorobiphenyl (PCB 22) started to induce micronuclei in V79-Mz cells at 10 μM and higher concentrations, demonstrating more potent effects than observed with 2,2',3-, 2,2',4-, 2,2',5, and 2,4,4'-trichlorobiphenyl. As representative compounds, PCB 20 and 22 induced micronuclei in relatively high concentrations in HepG2 cells (p53-proficient), though they did not induce Hprt gene mutations in V79-Mz cells. PCB 20 and 22 increased mitotic index and induced cell cycle arrest at the G2/M phase, with effects more potent in V79-Mz than in V79 cells. This study suggests that 2,3,4'- and 2,3,3'-substituted PCBs are micronuclei inducers and G2/M arresters among a number of trichlorobiphenyls in mammalian cell lines, though with potency lower than that observed recently in V79-derived cells expressing human CYP2E1. Similarly, some noncoplanar tetrachlorobiphenyls possess metabolism-independent chromosome-damaging potentials. Environ. Mol. Mutagen. 58:199-208, 2017. © 2017 Wiley Periodicals, Inc.

Dichloro-diphenyl-trichloroethanes (DDTs) in human hair and serum in rural and urban areas in South China

Human hair has been employed as a biomarker for exposure to persistent organic pollutants (POPs), but information on the source of dichloro-diphenyl-trichloroethane (DDT) and its metabolites in hair is limited. The present study investigated the contamination of DDTs in human hair from a rural area and an urban area of South China and compared with those in human serum and indoor dust. The concentrations of ∑DDTs ranged from 2.30 to 489ng/g, with a median of 21.8ng/g in human hair. The ∑DDT concentrations (median=40.8ng/g) in female hair were significantly higher than those in male hair (median=20.6ng/g). There were significantly positive correlations between the concentrations of DDTs and ages in both the female and male hair, but the age-dependence for DDTs in serum was less significant. The profile of DDT analogues in female hair, differing from that in the male hair, was more similar to that in the indoor dust, suggesting a more important role of exogenous exposure in female hair. We estimated that exogenous source is responsible for approximately 11% and 20% of the burden of DDTs in the male and female hair, respectively. Adjusted multiple linear regression model showed significantly positive association between the p,p'-DDE concentrations in the paired hair and serum samples, indicating that endogenous origins are the primary sources of DDTs in the hair of the residents in the study areas. Our findings demonstrated that human hair is a reliable biomarker for body burden of DDTs and can be used in epidemiology research and retrospective assessment of DDT exposure.

Informal processing of electronic waste at Agbogbloshie, Ghana: workers’ knowledge about associated health hazards and alternative livelihoods

Aims:

This study was conducted to investigate the electronic waste workers’ knowledge about the potential health hazards associated with their work as well as the livelihood alternatives that they would prefer if they were given the opportunity.

Methods:

A qualitative cross-sectional study was conducted to gather empirical information on e-waste workers’ knowledge about the potential hazards associated with their work and the livelihood alternatives to e-waste recycling with a sample consisting of twenty all-male electronic waste workers at the Agbogbloshie scrap metal yard in Accra, Ghana.

Results:

Electronic waste workers at Agbogbloshie were found to be exposed to a variety of injuries and illnesses. The workers’ knowledge of the association between their health status and their work was generally poor. Apart from the physical injuries, they did not believe their work played any negative role in their health conditions. They preferred occupations such as farming or professional driving located in the northern region of Ghana to be closer to their families.

Conclusions:

The study concludes that the low knowledge level of the workers on the hazards that are associated with their work has implications for them accepting technologies to protect them and the natural environment from contamination. It is therefore imperative for any intervention to consider the current low level of knowledge and actively educate the workers to raise their awareness level, taking into account the provision of opportunities for workers to acquire applicable skills for future employment in other fields.

Polychlorinated Biphenyls (PCBs) in Human Hair and Serum from E-Waste Recycling Workers in Southern China: Concentrations, Chiral Signatures, Correlations, and Source Identification

Hair is increasingly used as a biomarker for human exposure to persistent organic pollutants (POPs). However, the internal and external sources of hair POPs remain a controversial issue. This study analyzed polychlorinated biphenyls (PCBs) in human hair and serum from electronic waste recycling workers. The median concentrations were 894 ng/g and 2868 ng/g lipid in hair and serum, respectively. The PCB concentrations in male and female serum were similar, while concentrations in male hair were significantly lower than in female hair. Significant correlations between the hair and serum PCB levels and congener profiles suggest that air is the predominant PCB source in hair and that hair and blood PCB levels are largely dependent on recent accumulation. The PCB95, 132, and 183 chiral signatures in serum were significantly nonracemic, with mean enantiomer fractions (EFs) of 0.440-0.693. Nevertheless, the hair EFs were essentially racemic (mean EFs = 0.495-0.503). Source apportionment using the Chemical Mass Balance model also indicated primary external PCB sources in human hair from the study area. Air, blood, and indoor dust are responsible for, on average, 64.2%, 27.2%, and 8.79% of the hair PCBs, respectively. This study evidenced that hair is a reliable matrix for monitoring human POP exposure.

Toxicokinetics of chiral polychlorinated biphenyls across different species--a review

Nineteen polychlorinated biphenyls (chiral or C-PCBs) exist as two stable rotational isomers (atropisomers) that are non-superimposable mirror images of each other. C-PCBs are released into the environment as racemic (i.e., equal) mixtures of both atropisomers and undergo atropisomeric enrichment due to biological, but not abiotic, processes. In particular, toxicokinetic studies provide important initial insights into atropselective processes involved in the disposition (i.e., absorption, distribution, biotransformation, and excretion) of C-PCBs. The toxicokinetic of C-PCBs is highly congener and species dependent. In particular, at lower trophic levels, abiotic processes play a predominant role in C-PCB toxicokinetics. Biotransformation plays an important role in the elimination of C-PCBs in mammals. The elimination of C-PCB follows the approximate order mammals > birds > amphibians > fish, mostly due to a corresponding decrease in metabolic capacity. A few studies have shown differences in the toxicokinetics of C-PCB atropisomers; however, more work is needed to understand the toxicokinetics of C-PCBs and the underlying biological processes. Such studies will not only contribute to our understanding of the fate of C-PCBs in aquatic and terrestrial food webs but also facilitate our understanding of human exposures to C-PCBs.

An assessment of polybrominated diphenyl ethers and polychlorinated biphenyls in the indoor dust of e-waste recycling facilities in South Africa: implications for occupational exposure

Workplace exposure to persistent organic pollutants is a concern for human health. This study examined the presence of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in the indoor dust from two major e-waste recycling sites and a university electronic equipment repair workshop in Durban, South Africa, in order to evaluate the implication of dust for occupational exposure. The mean ∑(n = 8)PBDEs and ∑(n = 3)PCBs were 20,094 and 235 ng g(-1), respectively. The levels of PBDEs and PCBs obtained in one of the recycling sites (123-27,530 and 161-593 ng g(-1)) were significantly higher than the levels obtained (91-7686 and <DL-42 ng g(-1), respectively) in the same site after site cleanup/maintenance. Occupational exposure was assessed for different exposure scenarios by using the 5th and 95th percentile, and the median and mean concentrations measured at the sites. By assuming a mean and a high dust intake rate, the average and 95th percentile daily exposure doses (∑DED/ng kg(-1) bw day(-1)) of PBDEs were 3.98, 8.52 and 7.58, 16.19, respectively, and of PCBs were 0.047, 0.094 and 0.089, 0.179, respectively. The ∑DEDs of PBDEs and PCBs were lower than the reference (RfD) values for BDE 47, BDE 99, BDE 153 and BDE 209, and Aroclor 1254 and 1016. Nevertheless, continual exposure to high levels of these pollutants is a concern; but as shown, the exposure can be significantly reduced if the e-waste facilities are cleaned thoroughly regularly.

Hepatic metabolism affects the atropselective disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) in mice

To understand the role of hepatic vs extrahepatic metabolism in the disposition of chiral PCBs, we studied the disposition of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) and its hydroxylated metabolites (HO-PCBs) in mice with defective hepatic metabolism due to the liver-specific deletion of cytochrome P450 oxidoreductase (KO mice). Female KO and congenic wild type (WT) mice were treated with racemic PCB 136, and levels and chiral signatures of PCB 136 and HO-PCBs were determined in tissues and excreta 3 days after PCB administration. PCB 136 tissue levels were higher in KO compared to WT mice. Feces was a major route of PCB metabolite excretion, with 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol being the major metabolite recovered from feces. (+)-PCB 136, the second eluting PCB 136 atropisomers, was enriched in all tissues and excreta. The second eluting atropisomers of the HO-PCBs metabolites were enriched in blood and liver; 2,2',3,3',6,6'-hexachlorobiphenyl-5-ol in blood was an exception and displayed an enrichment of the first eluting atropisomers. Fecal HO-PCB levels and chiral signatures changed with time and differed between KO and WT mice, with larger HO-PCB enantiomeric fractions in WT compared to KO mice. Our results demonstrate that hepatic and, possibly, extrahepatic cytochrome P450 (P450) enzymes play a role in the disposition of PCBs.

Determination of organochlorines, polychlorinated biphenyls and polybrominated diphenyl ethers in human hair: estimation of external and internal exposure

A novel method was developed for the analysis of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in human hair samples. External contaminants of hair were extracted with acetone under sonication, while washed hair was further hydrolyzed in formic acid and acetone (1:4, v/v) with microwave assisted extraction (MAE) for internal contaminant measurements. Both internal and external extracts were cleaned up with gel permeation chromatography (GPC) and then solid phase extraction (SPE), before analyzed by a large volume injection-gas chromatography-tandem mass spectrometry (LVI-GC-MS/MS) using triple quadruple mass analyzer. Good linearity (R(2)⩾ 0.996) was established within a concentration range between 0.1 and 100 ng mL(-)(1) among all target analytes. The method was validated for accuracy, precision and sensitivity. The developed method is intended to be cost effective and robust for the routine human hair analysis of PCBs, PBDEs and OCPs including acid-labile OCPs. The described method has been applied in pilot biomonitoring study and the preliminary data suggested that the contaminant profiles with the use of partial least-squares analysis discriminant analysis (PLA-DA) could be useful in differentiating external and internal exposure.

Occurrence of polychlorinated diphenyl sulfides (PCDPSs) in surface sediments and surface water from the Nanjing section of the Yangtze River

Polychlorinated diphenyl sulfides (PCDPSs) are dioxin-like compounds that could induce various adverse effects to organisms. However, little is known about the occurrence of PCDPSs in the riverine environment. In the present study, the concentrations of twenty-one types of PCDPSs in the surface sediments and in surface water from the Nanjing section of the Yangtze River were examined. A total of 19 types of PCDPSs were detected and ∑PCDPSs concentrations in surface sediment and surface water ranged from 0.10 to 6.90 ng/g and 0.18 to 2.03 ng/L, respectively. The 2,2',4,4',5-penta-CDPS was the dominant congener in sediment (19.9%) and 2,2',3,3'-tetra-CDPS was the most abundant congener in water (12.2%). The tetra-CDPSs were the dominant congeners both in sediment and in water. Compared with sediment, the percentage of lower chlorinated PCDPSs in water increased distinctly. Source analysis revealed that the PCDPSs in the sediment and in the water mainly came from chemical wastewater rather than domestic sewage. There was a significant linear correlation between ∑PCDPS concentrations and sediment TOC contents, while no linear correlation existed between ∑PCDPS concentrations and water DOC contents. This study demonstrated the prevalent contamination by PCDPSs in sediments and in water from the Nanjing section of the Yangtze River.

Polybrominated Diphenyl Ethers (PBDEs) in paired human hair and serum from e-waste recycling workers: source apportionment of hair PBDEs and relationship between hair and serum

Human hair has been widely used as a bioindicator for human persistent organic pollutants (POPs) exposure, but studies on the sources of hair POPs and the relationship between hair and body burden are limited. This study analyzed the possible source apportionment of hair PBDEs and examined the relationship between PBDE concentrations in paired hair and serum from e-waste recycling workers. Using the ratio of BDE 99/47 and BDE 209/207 as indices, we calculated that only 15% of the highly brominated congeners (nona- and deca-BDE congeners) comes from exogenous (external) exposure for both female and male hair, but an average of 64% and 55% of the lower-brominated congeners (tetra- to penta-BDE congeners) come from exogenous exposure for female and male hair, respectively. The higher contribution of exogenous exposure for less-brominated congeners could be related to their relatively lower log KOW and higher volatility than higher-brominated congeners, which make them more readily to evaporate from dust and then to be adsorbed on hair. Higher hair PBDE levels and higher exogenous exposure of less-brominated congeners in females than in males can be attributed to a longer exogenous exposure time for females than males. Significant positive relationships were found in tri- to hepta-BDE congeners (BDE 28, 47, 66, 85, 100, 153, 154, and 183) (R = 0.36-0.55, p < 0.05) between hair and serum, but this relationship was not found for octa- to deca-BDE. Difference in the half-lives between highly brominated congeners and less-brominated congeners could be a reason. This result also implied that we should treat the results of correlation analyses between hair and other organs cautiously.