Brominated flame retardants in serum from the general population in northern China

New brominated flame retardant decabromodiphenyl ethane (DBDPE) in water sediments: A review of contamination characteristics, exposure pathways, ecotoxicological effects and health risks

As an alternative to polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) has become one of the most important new brominated flame retardants (NBFRs). However, little is known about whether this emerging contaminant may has an environmental fate similar to PBDEs. Sediments are the main sink for DBDPE in the aqueous phase. Worldwide concentration data, since it was first found in sediments to date, have been collated, and the following conclusions have been drawn. (1) DBDPE concentrations in sediments have increased rapidly, often with a higher risk of contamination in source discharge areas. Compared with other countries, DBDPE contamination in China is more severe, especially in Guangdong Province, which is closely related to its being an e-waste dismantling area. (2) The amount of DBDPE in surface sediments has exceeded that of legacy brominated flame retardants (BFRs), and data recorded in sediment cores also corroborate that DBDPE is replacing decabromodiphenyl ether (BDE-209) as one of the most dominant NBFRs in the environment. (3) The exposure pathways of DBDPE include dietary intake, air or indoor dust intake, cutaneous absorption and endogenous exposure. For sediments, dietary exposure and endogenous exposure pathways need to be considered. Sediment DBDPE can enter the human body through bioenrichment such as contaminated seafood and the food chain. (4) DBDPE can exhibit neurotoxicity, thyrotoxicity, reproductive and developmental toxicity, hepatotoxicity and oxidative stress in organisms. Long-term DBDPE exposure may increase hyperthyroidism risk and inhibit normal cells activity. This review focuses on the distribution characteristics and exposure risks of DBDPE in global water sediments, providing a strong reference for environmental management and related legal policy formulation. The next steps are to focus on continuous source monitoring, process control and sediment clean-up of DBDPE. The development of sustainable water management options for waste microplastics (MPs) and e-waste spiked with DBDPE is a priority.

The effects and mechanisms of the new brominated flame retardant BTBPE on thyroid toxicity

As an alternative to octabromodiphenyl ether (octa-BDE), 1, 2-bis (2,4, 6-tribromophenoxy) ethane (BTBPE) has been widely used in a variety of combustible materials, such as plastics, textiles and furniture. Previous studies have demonstrated the thyroid toxicity of traditional brominated flame retardants for example octa-BDE clearly. Nevertheless, little is known about the thyroid toxicity of alternative novel brominated flame retardants BTBPE. In this study, it was demonstrated that BTBPE in vivo exposure induced FT4 reduction in 2.5, 25 and 250 mg/kg bw treated group and TT4 reduction in 25 mg/kg bw treated group. TG, TPO and NIS are key proteins of thyroid hormone synthesis. The results of Western blot and RT-PCR from thyroid tissue showed decreased protein levels and gene expression levels of TG, TPO and NIS as well as regulatory proteins PAX8 and TTF2. To investigate whether the effect also occurred in humans, anthropogenic Nthy-ori 3-1 cells were selected. Similar results were seen in vitro condition. 2.5 mg/L BTBPE reduced the protein levels of PAX8, TTF1 and TTF2, which in turn inhibited the protein levels of TG and NIS. The results in vitro experiment were consistent with that in vivo, suggesting possible thyrotoxic effects of BTBPE on humans. It was indicated that BTBPE had the potential interference of T4 generation and the study provided more evidence of the effects on endocrine disorders.

Physiologically based pharmacokinetic (PBPK) modeling of BDE-209 following oral exposure in Chinese population

The wide usage of decabromodiphenyl ether (BDE-209) as additive brominated flame retardant has caused its widespread occurrence in the environment and high exposure risk in humans. Estimating its internal exposure dose and reconstruction of external exposure dose using physiologically based pharmacokinetic (PBPK) modelling approach is a key step in the risk assessment of BDE-209. However, the PBPK model for BDE-209 is currently unavailable. This study has established two oral permeability-limited PBPK models of BDE-209 without enterohepatic recirculation (EHR) (model 1) and with EHR (model 2) for Chinese population. Using the in vitro experiments, the average binding of BDE-209 to human plasma protein (99.64% ± 2.97%) was obtained. Moreover, blood sample analysis and systematic literature review were performed to obtain internal and external exposure data of BDE-209 used for model calibration and validation. The predictions of both models were within 2-fold of the observed, and a longer half-life of serum BDE-209 was observed in model 2 than model 1. Based on the models, a human biomonitoring guidance value (HBM-GV) of 93.61 μg/g lw was derived for BDE-209, and there is no health risk found for Chinese population currently. This study provides new quantitative assessment tools for health risk assessment of BDE-209.

Curcumin hinders PBDE-47-induced neutrophil extracellular traps release via Nrf2-associated ROS inhibition

Polybrominated diphenyl ethers (PBDE-47), a kind of lipophilic persistent organic pollutants (POPs) brominated flame retardant, has been widely used in various consumer products. However, the toxicity of PBDE-47 on human immune system has not been well elucidated. Neutrophil extracellular traps (NETs) contribute to the innate immune responses, and the release of NETs is recognized as the most important part of the extracellular killing mechanism. The aim of this study was to investigate the effect of PBDE-47 on NETs and its possible molecular mechanism, as well as the intervention effect of curcumin (Cur). In this study, the formation of PBDE-47-induced NETs was observed by fluorescence microscopy and scanning electron microscopy, and was also quantitatively detected by DNA dye SYTOX green. In addition, we used Cur and Nrf2 inhibitor ML385 to explore the role of reactive oxygen species (ROS), extracellular signal regulated kinase (ERK) and p38 signaling pathway in PBDE-47-induced reticular formation. We demonstrated that PBDE-47 could significantly induce the formation of NETs, and its molecular mechanism might be related to ROS burst. Cur reduced ROS and inhibited PBDE-47-induced NETs formation by interfering with Nrf2. In conclusion, this study revealed that Cur hindered PBDE-47-induced NETs via Nrf2-associated ROS inhibition, which enriched the cytotoxicity mechanism of PBDE-47, and provided a new clue for the development of Cur as an antagonist of PBDE-47-related immune injury.

PAHs and their hydroxylated metabolites in the human fingernails from e-waste dismantlers: Implications for human non-invasive biomonitoring and exposure

Non-invasive human biomonitoring methods using hair and fingernails as matrices are widely used to assess the exposure of organic contaminants. In this work, a total of 72 human fingernails were collected from workers and near-by residents from a typical electronic waste (e-waste) dismantling site, and were analyzed for human exposure to polycyclic aromatic hydrocarbons (PAHs) and their mono-hydroxyl metabolites (OH-PAHs). The concentrations of PAHs and OH-PAHs were obtained as 7.97-551 and 39.5-3280 ng/g for e-waste workers (EW workers), 7.05-431 and 27.3-3320 ng/g for non-EW workers, 7.93-289 and 124-779 ng/g for adult residents, and 8.88-1280 and 181-293 ng/g for child residents, respectively. The composition profiles of PAHs in the human fingernails of the four groups were similar, with isomers of Phe, Pyr and Fluo being the predominated congeners, while 2-OH-Nap accounted for more than 70% of the total OH-PAHs. These contaminants were found most in the fingernails of EW workers, followed by non-EW workers, adult residents, and child residents, indicating e-waste dismantling activities are the major sources of PAH exposure. However, significantly higher levels of PAHs with 4-6 rings were observed only in workers as opposed to the residents, and a significant correlation between 3-OH-Flu (p < 0.05) and 2-OH-Phe (p < 0.01) in the fingernails and urine was observed, but no significant correlation was found between the concentration of OH-PAHs in matched hair and fingernail samples. In addition, the levels of PAHs in fingernails increased with the age of EW workers. This is the first study to explore the accumulation and distribution of PAHs and OH-PAHs in human fingernails, which would provide valuable insight into non-invasive biomonitoring and health risk assessment of PAHs.

Serum levels of novel brominated flame retardants (NBFRs) in residents of a major BFR-producing region: Occurrence, impact factors and the relationship to thyroid and liver function

Five currently used novel brominated flame retardants (NBFRs) were determined in 172 serum samples collected from nonoccupational residents of a major BFR-producing region. All the 5 NBFRs presented high detection frequencies (DFs, >90%), and decabromodiphenyl ethane (DBDPE), a substitute of decabrominated diphenyl ethers (deca-BDE), was the most abundant NBFR. The levels of DBDPE were from <LOD to 1590 ng/g lw, with a median level of 32.5 ng/g lw. The median levels of other NBFRs were from 0.134 to 2.87 ng/g lw, which were at least 10 times lower than that of DBDPE. Moreover, a comparison to other studies showed that our results were significantly higher than studies conducted in background population. The levels of some NBFRs adjusted by serum lipid showed negative and significant correlation with BMI, whereas the difference disappeared when NBFRs levels were calculated based on serum volume. Certain NBFRs in female showed significantly higher concentrations than those in male. No significant effect of age, smoking habit, education level and children birth (in female) on serum NBFR levels was observed. The relationship between the serum levels of NBFRs and a series of thyroid/liver injury biomarkers was further analyzed to evaluate the health effects of these NBFRs to human being. Results showed that a 10-fold increment in the serum DBDPE level was associated with decreased total triiodothyronine (TT3) level (-0.037 nmol/L) [95% CI: -0.070, -0.003]， whereas serum pentabromoethylbenzene (PBEB) level was associated with increased total triiodothyronine (TT3) level (0.031 nmol/L) [95% CI: 0.001, 0.060]. For liver indicators, a 10-fold increment in the serum level of PBT was associated with decreased Ln aspartate aminotransferase/alanine aminotransferase (AST/ALT) level (-0.068) [95% CI: -0.129, -0.007]. A 10-fold increment in the serum level of BTBPE was associated with increased TBIL level (0.869 μmol/L) [95% CI: 0.175, 1.564], direct bilirubin (DBIL) level (0.231 μmol/L) [95% CI: 0.075, 0.388] and IDBIL level (0.638 μmol/L) [95% CI: 0.091, 1.185]. Our findings indicate that BFR production is posing heavy BFR contamination to surrounding environment and human being, and which might relate to thyroid disruption and liver injury.

Changes in thyroid hormone related proteins and gene expression induced by polychlorinated biphenyls and halogen flame retardants exposure of children in a Chinese e-waste recycling area

Polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) are major pollutants in e-waste recycling area. High internal exposure levels of PCBs and HFRs are harmful to human thyroid hormone (TH) equilibrium. To examine their disrupting effects on TH, we conducted a study on children (n = 114) of an e-waste recycling and a control area in South China. Concentrations of PCBs, HFRs, and TH levels were determined in serum samples. TH related proteins and their corresponding gene were also monitored as markers of such disruption. Levels of these chemicals in the exposed group were much greater than those in the control group. Results of the linear regression and generalized additive model indicated the presence of close relationships between the internal exposure levels and the responses of TH related proteins, gene expression. More extensive exposure concentrations of these chemicals led to higher expression of iodothyronine deiodinase I and decreased the concentrations of thyroid-stimulating hormone, expression of TH receptor α, indicating the exertion of discrepant and even contrary influences on equilibrium of TH, and a compensation of these mechanisms may kept the homeostasis of TH. These results for children warrant further investigation on the health risks of PCBs and HFRs exposure in e-waste area.

Polybrominated diphenyl ethers and decabromodiphenyl ethane in paired hair/serum and nail/serum from corresponding chemical manufacturing workers and their correlations to thyroid hormones, liver and kidney injury markers

We detected the polybrominated diphenyl ethers (PBDEs) or decabromodiphenyl ethane (DBDPE) in paired hair-serum and nail-serum samples collected from the corresponding chemical manufacturing workers. The levels of decabrominated diphenyl ether (BDE-209) or DBDPE in the serum, hair and nail samples were all significantly higher than those reported in other studies, and the "work place" (pretreatment or posttreatment workshop) was the primary influencing factor that affected the levels of specific BFRs in vivo. For BDE-209 workers, the BDE-209 in both the hair and nail samples were significantly and positively related to the BDE-209 in the serum, indicating that both hair and nails can be used as noninvasive biomatrices to reflect internal exposure to BDE-209. In DBDPE workers, hair rather than nails was more suitable for use as a noninvasive biomatrix to infer the DBDPE exposure level. A series of serum biomarkers reflecting thyroid hormones and liver and kidney injuries were tested to calculate the correlations between hair or nail BFR levels and the levels of the biomatrices. The BDE-209 in the hair samples was significantly and positively correlated with the total protein (TP), and the nail BDE-209 level was significantly and positively related to the total bilirubin (TBIL), indirect bilirubin (IDBIL) and uric acid (UA). The DBDPE in hair was significantly and positively correlated with the thyroid hormones free triiodothyronine (fT3) and total triiodothyronine (tT3) and kidney injury markers, including blood urea nitrogen (BUN), creatinine (CRE) and cystatin C (Cys-C). In addition, the nail DBDPE levels were significantly and positively correlated with the albumin/globulin (A/G), BUN, CRE and Cys-C but negatively correlated with the TP and globulin (GLO). Our findings provide preliminary evidence that hair and nails can be used as noninvasive biomatrices for assessing internal BFR exposure and health damage in occupational workers.

Mother-child transfer rates of organohalogen compounds up to four years of age

BACKGROUND

Breastfed children absorb persistent and toxic chemicals such as organohalogen compounds (OHCs) during the entire lactation period. Nursing is a main contributor to the burden of these pollutants in the first years of life, hence further assessments on the OHC load processes are needed.

OBJECTIVES

To identify the determinants of OHC increase in children at four years of age, considering concentration gains, maternal venous concentrations and breastfeeding time.

METHODS

Concentrations of 19 organochlorine compounds (OCs) and 14 polybrominated diphenyl ethers (PBDEs) were analyzed in maternal venous (n = 466), cord blood (n = 326) and children venous serum at four years of age (n = 272) in the Asturias INMA cohort representing the Spanish general population. Data were evaluated considering the socio-demographic and individual information collected at recruitment and follow up surveys, as well as the OHC physical-chemical constants.

RESULTS

The four years-old children concentration gains of the most abundant OHCs showed strong correlations (R² = 0.65-0.93) with the maternal concentrations during pregnancy and lactation period. The child gain/maternal transfer rates of most correlated pollutants were similar.

DISCUSSION

Between 65 and 93% of the variance of OCs in four years-old children was explained by the maternal concentrations during pregnancy and the lactation period. The compounds with log(Kow) > 3.7 (hydrophobic) showed analogous child gain/maternal transfer rates indicating similar processes of membrane lipid dissolution and passive diffusion from the epithelial cells into the milk. Molecular weight of these pollutants did not influence on these rates. Compounds with low log(Koa) such as hexachlorobenzene are more volatile and less retained, involving lower child gain/maternal transfer rates. These results may be useful to anticipate the increase of the concentrations of OCs in children using the maternal concentration of these compounds during pregnancy and the planned lactation period and to implement prophylactic measures in mothers with high venous pollutant concentrations.

Thyroid function and decabromodiphenyl ethane (DBDPE) exposure in Chinese adults from a DBDPE manufacturing area

Polybrominated diphenyl ethers (PBDEs), which are persistent organic pollutants, affect thyroid function. Human exposure to decabromodiphenyl ethane (DBDPE), which has a similar structure to PBDEs, has recently increased, and the health effects of DBDPE have not been well studied. The objective of this study was to determine whether human exposure to DBDPE was associated with thyroid hormone levels in adults from a DBDPE manufacturing area. Three hundred-two blood samples were collected from two populations in the largest DBDPE manufacturing area located in North China: 133 DBDPE occupationally exposed workers from a DBDPE manufacturing plant and 169 non-DBDPE occupationally exposed residents from a nearby food processing plant. The levels of DBDPE, and thyroid function parameters [total thyroxine (TT4), free T4 (FT4), total triiodothyronine (TT3), free T3 (FT3), thyroid-stimulating-hormone (TSH), thyroglobulin antibody (TG-Ab), and thyroid peroxidase antibody (TPO-Ab)] were measured in serum samples. Serum concentrations of DBDPE ranged from 3.148 to 54,360 ng g^-1 lipid weight (lw), with a geometric mean of 332.6 ng g^-1 lw. A 10-fold increase in the DBDPE concentration was associated with increase of 4.73 nmol L^-1 [95% confidence interval (CI): 2.75, 6.71] TT4 and 0.046 nmol L^-1 TT3 [95% CI: 0.012, 0.081], corresponding to increases of approximately of 4.73% (95% CI: 2.75%-6.71%) and 2.38% (95% CI: 0.62%-4.20%), respectively. DBDPE in serum was also significantly and positively associated with the concentrations of TG-Ab and TPO-Ab. Our study found that exposure to DBDPE was associated with changes in thyroid activity in adults exposed to a high concentration of DBDPE, mainly increases of TT4, TT3, TPO-Ab, and TG-Ab. The association between DBDPE exposure and thyroid homeostasis requires further investigation because increasing DBDPE exposure has emerged in recent years.

Novel and legacy flame retardants in paired human fingernails and indoor dust samples

In this study, the occurrence of 8 polybrominated diphenyl ethers (PBDEs), 5 alternative flame retardants (AFRs), and 7 organophosphate flame retardants (OPFRs) was determined in 50 pairs of human fingernail and indoor dust samples. The concentrations in fingernail were 9.79-242 ng/g, 17.7-926 ng/g, and 58.0-590 ng/g for PBDEs, AFRs, and OPFRs. Male fingernail showed significantly (p < 0.05) higher Σ₈PBDE concentrations than female fingernails, while no significant gender differences were observed for AFRs and OPFRs. Lower ratios of BDE209 to Σ₈PBDE and DBDPE to Σ₅AFRs were found in fingernails than in dust. Due to their relatively rapid in vivo debromination, BDE 209 and DBDPE in fingernails were most likely from external sources rather than internal exposure (such as through blood circulation). Similar composition profiles between fingernail and dust were observed for PBDEs (excluding BDE209), AFRs (excluding DBDPE), and OPFRs, indicating that indoor dust may be a significant source for these FRs in human fingernails. Significant correlations between fingernail and dust were observed for BDE 47 (p < 0.01; r = 0.50), TBPH (p < 0.01; r = 0.37) and TBOEP (p < 0.01; r = 0.53). Results in this study provided information about contamination levels and exposure sources of FRs, which is important for long-term biomonitoring and health risk assessment of FRs.

Levels of polybrominated diphenyl ethers in the Korean metropolitan population are declining: A trend from 2001 to 2013

Polybrominated diphenyl ethers (PBDEs) have been banned or voluntarily withdrawn from commerce worldwide. Declining levels of PBDEs in humans have been reported elsewhere, but not in Korea. We monitored 7 individual PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) in 103 human serum samples collected in 2006. The arithmetic mean and median values for the sum of the 7 PBDEs (∑PBDEs) were 7.13 and 6.70 ng/g lipid, respectively. In addition, 6 pooled human serum samples collected in 2006, 2007, 2009, 2011, 2012, and 2013 were analyzed. A decrease in PBDE levels was observed, as reflected by the median value of ∑PBDEs from 5.98 in 2006 to 2.98 ng/g lipid in 2013 as well as in the pooled samples. The levels of individual congeners also decreased but at different declining rates. Based on these results and previously reported data, a definite decline in PBDE levels in the Korean metropolitan population could be observed from 2001 to 2013, providing the first evidence in Korea of the same decline observed elsewhere in the world. Environ Toxicol Chem 2018;37:2323-2330. © 2018 SETAC.

Occurrence and profiles of halogenated phenols, polybrominated diphenyl ethers and hydroxylated polybrominated diphenyl ethers in the effluents of waste water treatment plants around Huang-Bo Sea, North China

Halogenated organic pollutants (HOPs), as ubiquitous environment contaminants, have attracted increasing concerns due to the potential adverse health impacts on organisms and even humans. Waste water treatment plants (WWTPs) are one source of HOPs to the environment through their discharge of treated effluent. In this study, the presence and profiles of 6 halogenated phenols (HP), 17 polybrominated diphenyl ethers (PBDE) and 11 hydroxylated polybrominated diphenyl ethers (OH-PBDE) were investigated in 12 WWTP effluent samples collected near Huang-Bo Sea in Dalian, China. These targeted organohalogen pollutants were found in all the effluent samples with the total concentrations of ΣHPs, ΣPBDEs and ΣOH-PBDEs ranging from 77.2 to 168.5ng/L, from not-detected to 5.3ng/L and from 0.08 to 0.88ng/L, respectively. The most abundant congeners of HPs and PBDEs in the effluents were pentachlorophenol (PCP), BDE-47 and BDE-99, while for OH-PBDEs, 6-OH-BDE-47 and 5-OH-BDE-47 were the most abundant. In addition, the statistical analysis showed that a significant (p<0.05) positive correlation was observed between BDE-47 and its metabolite 6-OH-BDE-47, indicating that PBDEs may be a source of OH-PBDEs detected in the effluents.

Polybrominated diphenyl ethers (PBDEs) and hydroxylated PBDEs in human serum from Shanghai, China: a study on their presence and correlations

Polybrominated diphenyl ethers (PBDEs) are becoming a public health concern because of their potential toxicity, from endocrine disruption system to neurodevelopmental impairments. Nonetheless, information on their levels in human blood is scarce. In this study, human serum samples collected in Shanghai, China, were analyzed for the concentrations of PBDEs and their hydroxylated metabolites (OH-PBDEs). Eight PBDE congeners and six OH-PBDE congeners were quantified in serum samples by gas chromatography with mass spectrometry (GC-MS) and high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). As a result, total PBDE concentration ranged from 0.280 to 12.330 ng g^-1 on a lipid weight basis lw (median: 1.100 ng g^-1 lw) and the total OH-PBDE level ranged from 0.045 to 0.363 ng g^-1 (lw) (median: 0.187 ng g^-1 lw). Among them, BDE-47 and 6-OH-BDE-47 were the predominant PBDEs and OH-PBDEs, respectively. In addition, based on the results of the Bartelett X ² test, BDE-47 significantly (p < 0.05) correlated with BDE-28, BDE-100, BDE-85, and BDE-154, whereas 3'-OH-BDE-7 significantly (p < 0.01) correlated with 3-OH-BDE-47, 2-OH-BDE-68, and 6'-OH-BDE-99. Among all donors, no significant association between age and PBDEs (or OH-PBDEs) was found. Further research on the exposure routes in the environment and metabolic processing of PBDEs in human blood is necessary.

Brominated flame retardant (BFRs) and Dechlorane Plus (DP) in paired human serum and segmented hair

Brominated flame retardants (BFRs) and Dechlorane Plus (DP) were measured in both human hair and paired serum samples from a cohort of university students in South China. Segmental analysis was conducted to explore gender difference and the relationships between the hair and serum. The concentrations of total PBDEs in the hair and serum samples were in a range of 0.28-34.1ng/g dry weight (dw) and 0.16-156ng/g lipid weight (lw), respectively. Concentrations of ∑DPs (sum of the syn-DP and anti-DP isomers) in all hair samples ranged from nd-5.45ng/g dry weight. Concentrations of most PBDEs and decabromodiphenylethane (DBDPE) in distal segments (5-10cm from the scalp) were higher than those in the proximal segments (0-5cm from the scalp) (t-test, p < 0.05), which could be due to the longer exposure time of distal segments. The proximal segments exhibited a unique congener profile, more close to that in the serum rather than the distal segments of hair. An obvious gender difference was found in the levels of ∑PBDEs using integrated hair samples, while the difference disappeared when considering alone the proximal segments of hair (0-5cm from scalp) for both genders. This paper provides supplement to the current knowledge on sources of BFRs and DPs in hair and declares the importance of segmental analysis.

Impacts of Unregulated Novel Brominated Flame Retardants on Human Liver Thyroid Deiodination and Sulfotransferation

The inhibitory effects of five novel brominated flame retardants, 1,2-bis(2,4,5-tribromophenoxy)ethane (BTBPE), decabromodiphenylethane (DBDPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP), and β-tetrabromoethylcyclohexane (β-TBECH), on thyroid hormone deiodinase (DIO) and sulfotransferase (SULT) activity were investigated using human in vitro liver microsomal and cytosolic bioassays. Enzymatic activity was measured by incubating active human liver subcellular fractions with thyroid hormones (T4 and rT3 separately) and measuring changes in thyroid hormone (T4, T3, rT3, and 3,3'-T2) concentrations. Only DBDPE showed inhibition of both outer and inner ring deiodination (O and IRD) of T3 and 3,3'-T2 formation from T4, respectively, with an estimated IC₅₀ of 160 nM; no statistically significant inhibition of SULT activity was observed. ORD inhibition of 3,3'-T2 formation from rT3 was also observed (IC₅₀ ∼ 100 nM). The kinetics of T4 O and IRD were also investigated, although a definitive mechanism could not be identified as the Michaelis-Menten parameters and maximal rate constants were not significantly different. Concentrations tested were intentionally above expected environmental levels, and this study suggests that these NBFRs are not potent human liver DIO and SULT inhibitors. To our knowledge, DBDPE is the first example of a nonhydroxylated contaminant inhibiting DIO activity, and further study of the mechanism of action is warranted.

Disruption of thyroid hormone (TH) levels and TH-regulated gene expression by polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and hydroxylated PCBs in e-waste recycling workers

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) are the primary toxicants released by electronic waste (e-waste) recycling, but their adverse effects on people working in e-waste recycling or living near e-waste sites have not been studied well. In the present study, the serum concentrations of PBDEs, PCBs, and hydroxylated PCBs, the circulating levels of thyroid hormones (THs), and the mRNA levels of seven TH-regulated genes in peripheral blood leukocytes of e-waste recycling workers were analyzed. The associations of the hormone levels and gene expression with the exposure to these contaminants were examined using multiple linear regression models. There were nearly no associations of the TH levels with PCBs and hydroxylated PCBs, whereas elevated hormone (T₄ and T₃) levels were associated with certain lower-brominated BDEs. While not statistically significant, we did observe a negative association between highly brominated PBDE congeners and thyroid-stimulating hormone (TSH) levels in the e-waste workers. The TH-regulated gene expression was more significantly associated with the organohalogen compounds (OHCs) than the TH levels in these workers. The TH-regulated gene expression was significantly associated with certain PCB and hydroxylated PCB congeners. However, the expression of most target genes was suppressed by PBDEs (mostly highly brominated congeners). This is the first evidence of alterations in TH-regulated gene expression in humans exposed to OHCs. Our findings indicated that OHCs may interfere with TH signaling and/or exert TH-like effects, leading to alterations in related gene expression in humans. Further research is needed to investigate the mechanisms of action and associated biological consequences of the gene expression disruption by OHCs.

Concentrations of organophosphorus, polybromobenzene, and polybrominated diphenyl ether flame retardants in human serum, and relationships between concentrations and donor ages

Organophosphorus flame retardants, polybromobenzenes, and polybrominated diphenyl ethers (PBDEs) were determined in pooled human serum samples collected in an area in which these chemicals are produced in North China. Tri (2-chloroethyl) phosphate (TCEP) was found at a higher concentration than the other chemicals, and the mean TCEP concentration was 480.4 ng/g lipid. This is the first time TCEP has been detected in human serum from China. The PBDE concentration in serum was found to have decreased between 2007 and 2013. BDE-209 remained the dominant PBDE congener, and its mean concentration was 91.3 ng/g lipid in this study. The polybromobenzene concentrations were relatively low, but pentabromobenzene and pentabromotoluene were found in very many of the samples. The highest TCEP, tris(2-butoxyethyl)phosphate, pentabromobenzene, and pentabromotoluene concentrations were found in samples from young people (<30 y old). This suggests that the risks posed by these alternative flame retardants also need more concerns.

Estimation of human exposure to halogenated flame retardants through dermal adsorption by skin wipe

This study was undertaken to determine levels of halogenated flame retardants (HFRs) on skin surface to provide preliminary exposure estimates from dermal absorption. Skin wipes of palms, back-of-hands, and forearms were collected from 30 participants by using gauze pads soaked in isopropyl alcohol. Eight polybrominated diphenyl ethers (PBDEs), two novel brominated FRs, and two Dechlorane Plus (DPs) isomers were determined. BDE209, Decabromodiphenylethane (DBDPE), and 1, 2-Bis (2, 4, 6-tribromophenoxy) ethane (BTBPE) were most frequently detected. BDE209 showed the highest median level (1760 ng m^-2), followed by DBDPE (277 ng m^-2) and anti-DP (64 ng m^-2). The comparison of levels on palms and back-of-hands revealed no statistical differences, but both were significantly higher than the levels on forearms. Detections of HFRs on arms suggested that skin areas covered by clothing were exposed to these chemicals likewise. BDE209 and DPs levels from three repeated samples showed moderate to strong reliability over 3 months, while the levels of other compounds were not statistically reliable. Males had significant higher levels than females for most HFRs, while participants' age, time from last hand washing to sampling, and other behaviors contributed limitedly to the variations in levels. Daily uptakes of HFRs through dermal absorption were estimated. The estimated median total exposure from palms, back-of-hands, and forearms were 25.9, 1.6, and 7.2 ng d^-1 for ∑PBDEs, ∑DPs, and ∑NBFRs, respectively, which were in the same ranges as those from diet and dust ingestion for adults in China, suggesting that dermal absorption would be an important exposure route for HFRs.

Traditional and new POPs in environments along the Bohai and Yellow Seas: An overview of China and South Korea

Rapid economic growth during the past two decades in the region surrounding the Bohai and Yellow Seas has resulted in severe pollution. Large amounts of monitoring data on persistent organic pollutants (POPs) in various environmental media have been accumulated, which allows us to conduct a fairly comprehensive assessment of the region around the Bohai and Yellow Seas to elucidate spatial patterns of pollution on a regional scale. This review summarized distributions of traditional and new POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and perfluoroalkyl substances (PFASs), in various environmental media. In general, due to their physico-chemical properties (poor solubility in water), OCPs and PCBs were mainly detected in sediments, PBDEs and HBCDs were mainly detected in sediments and soils. PFASs, which have greater solubility, were mainly detected in the hydrosphere. For conventional POPs, such as OCPs and PCBs, Bohai Bay and Haihe River in China, Gyeonggi Bay and Lake Sihwa in South Korea were found to be most polluted areas. While for new POPs, such as PBDEs, HBCDs and PFASs, some areas were heavily polluted due to local production and applications. Estuarine and coastal areas of the Bohai Sea were more severely contaminated by POPs than coastal regions of the Yellow Sea. Overall, the present review will guide identification of key areas for strengthening risk assessment of POPs and management practices.

Levels, profiles and dietary sources of hydroxylated PCBs and hydroxylated and methoxylated PBDEs in Japanese women serum samples

Human exposure to polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) may result in retention of specific congeners of hydroxylated PCBs (OH-PCBs) and hydroxylated/methoxylated PBDEs (OH-/MeO-PBDEs) in serum. However, dietary sources and biotransformation of OH-/MeO-PBDEs in humans are poorly understood. Therefore, this study was conducted to investigate the levels, profiles, and exposure sources of OH-/MeO-PBDEs along with OH-PCBs present in human serum. Twenty serum samples pooled from women of four age groups (30s/40s/50s/60s) living in four districts of Japan were analyzed for OH-/MeO-PBDEs, and their profiles were then compared with those of seafood (seaweed and fish). The major component of OH-PCBs in the phenolic fraction of serum was 4-OH-CB187 (mean: 85pgg^-1 wet weight (ww)). Total OH-PCBs accounted for about 1/20 of the total PCBs (mean; 1800pgg^-1 ww). In contrast, the predominant component of OH-PBDEs in serum was 6-OH-BDE47 (mean: 183pgg^-1 ww), which was about 20-fold higher than BDE-47 (mean; 8.7pgg^-1 ww). In the neutral fraction, 2'-MeO-BDE68 was primarily found at a similar concentration (mean 5.6pgg^-1 ww) to BDE-47. Both 4-OH-PCB187 and 2'-MeO-BDE68 were significantly correlated with woman's age (p<0.01), but not with 6-OH-BDE47 or BDE-47. The profiles of OH-PBDEs in serum were consistent with those in edible seaweeds (Sargassum fusiforme) sold for human consumption, whereas MeO-PBDEs had a similar profile as those in edible fish (Serranidae sp.) from Japanese coastal waters. These findings indicate that the profiles of OH-PBDEs and MeO-PBDEs in Japanese serum are different from those in other countries, and their sources may be specific edible seaweeds and fish, respectively. This is the first report of profiles and dietary sources of OH/MeO-PBDEs in human serum from Japan.

WITHDRAWN: Estimation of human exposure to halogenated flame retardants through dermal adsorption by skin wipe

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.chemosphere.2016.10.015. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

Retrospective analysis of "new" flame retardants in the global atmosphere under the GAPS Network

A retrospective analysis was conducted on air samples that were collected in 2005 under the Global Atmospheric Passive Sampling (GAPS) Network around the time period when the Stockholm Convention on Persistent Organic Pollutants came into force. Results are presented for several new flame retardants, including hexabromocyclododecane (HBCD), which was recently listed under the Convention (2013). These results represent the first global-scale distributions in air for these compounds. The targeted compounds are shown to have unique global distributions in air, which highlights the challenges in understanding the sources and environmental fate of each chemical, and ultimately in their assessments as persistent organic pollutants. The study also demonstrates the feasibility of using the PUF disk passive air sampler to study these new flame retardants in air, many of which exist entirely in the particle-phase as demonstrated in this study using a KOA-based partitioning model.

Airborne polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/furans (PBDD/Fs), and dechlorane plus (DP) in concentrated vehicle parking areas

This study investigated polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/furans (PBDD/Fs), and dechlorane plus (DP) in air around three concentrated vehicle parking areas (underground, indoor, and outdoor) in a metropolitan of South China. The parking areas showed higher concentrations of PBDEs, PBDD/Fs, and DP than their adjacent urban area or distinct congener/isomer profiles, which indicate their local emission sources. The highest PBDE and DP concentrations were found in the outdoor parking lot, which might be related to the heating effect of direct sunlight exposure. Multi-linear regression analysis results suggest that deca-BDEs without noticeable transformation contributed most to airborne PBDEs in all studied areas, followed by penta-BDEs. The statistically lower anti-DP fractions in the urban area than that of commercial product signified its degradation/transformation during transportation. Neither PBDEs nor vehicle exhaust contributed much to airborne PBDD/Fs in the parking areas. There were 68.1-100 % of PBDEs, PBDD/Fs, and DP associated with particles. Logarithms of gas-particle distribution coefficients (K ps) of PBDEs were significantly linear-correlated with those of their sub-cooled vapor pressures (p Ls) and octanol-air partition coefficients (K OAs) in all studied areas. The daily inhalation doses of PBDEs, DP, and PBDD/Fs were individually estimated as 89.7-10,741, 2.05-39.4, and 0.12-4.17 pg kg(-1) day(-1) for employees in the parking areas via Monte Carlo simulation.

Organohalogenated contaminants in type 2 diabetic serum from Jeddah, Saudi Arabia

Most of the organohalogenated contaminants (OHCs) have high environmental stability and are lipophilic in nature, thus bioaccumulate through the various routes e.g., inhalation, dermal contact and food intake. Human exposure to these OHCs can induce adverse health effects. Studies on the occurrence of OHCs in human samples from Saudi Arabia are scarce. Therefore, this study aimed at providing preliminary insight on the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated biphenyl ethers (PBDEs) in diabetic and non-diabetic donors from KSA. Serum samples were collected from type 2 diabetic patients (n = 40) and control donors (n = 20) to study the impact of OHCs on their health. For the first time we studied the difference of ƩOHCs in type 2 diabetic and control participants. The order of obtained results was ƩOCPs (35-650 ng/g lw)> ƩPCBs (15-90 ng/g lw)> ƩPBDEs (1.5-68 ng/g lw). The major contributors were p,p'-DDE (median 44 ng/g lw), PCB 153 (2.3 ng/g lw), PCB 138 (2.1 ng/g lw), BDE 153 (1.2 ng/g lw) and BDE 47 (0.85 ng/g lw). Exposure to different OHCs between male and female donors was not significantly different (p > 0.05). However, ƩPCBs and ƩOHCs were significantly higher (p < 0.05) in diabetic donors than those of control group. We computed significantly positive correlations (p < 0.05) among different OHCs and between OHCs and age factor. The current study highlights the presence of different OHCs in humans from Jeddah, KSA. This is a preliminary study based on small sample size but our results suggested that detailed studies are required to understand the sources of these pollutants and their impact on human health.

Occurrence of Dechlorane compounds and polybrominated diphenyl ethers (PBDEs) in the Korean general population

Dechlorane compounds, including Dechlorane Plus (DP), mirex, and Dechlorane (Dec) 602, 603 and 604, were measured in 61 serum samples collected from a Korean urban area (Seoul) in 2013. Dechlorane Plus and Dec 602 were dominant in most samples, whereas Dec 604 was not detected in any samples. The median value of DP was 0.75 ng/g lipid, which was comparable with the levels observed in Europe and Canada, but lower than that observed in China. Statistically significant correlations among Dechlorane compounds were observed. The median anti-isomer fractional abundance (fanti) was 0.74, and a negative correlation between fanti and the DP concentration in serum samples was observed. Polybrominated diphenyl ethers (PBDEs) were also measured for comparison with Dechlorane compounds, and BDE-153 was found the most abundant congener with a median value of 1.43 ng/g lipid. A time trend of Dechlorane compounds was investigated in 7 pooled serum samples to cover the period from 2006 to 2013. A distinct trend of Dechlorane compounds was not observed, while PBDEs steadily decreased with time.

Internal exposure levels of typical POPs and their associations with childhood asthma in Shanghai, China

Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are common persistent organic pollutants (POPs) that may be associated with childhood asthma. The concentrations of PBDEs, PCBs and OCPs were analyzed in pooled serum samples from both asthmatic and non-asthmatic children. The differences in the internal exposure levels between the case and control groups were tested (p value <0.0012). The associations between the internal exposure concentrations of the POPs and childhood asthma were estimated based on the odds ratios (ORs) calculated using logistic regression models. There were significant differences in three PBDEs, 26 PCBs and seven OCPs between the two groups, with significantly higher levels in the cases. The multiple logistic regression models demonstrated that the internal exposure concentrations of a number of the POPs (23 PCBs, p,p'-DDE and α-HCH) were positively associated with childhood asthma. Some synergistic effects were observed when the children were co-exposed to the chemicals. BDE-209 was positively associated with asthma aggravation. This study indicates the potential relationships between the internal exposure concentrations of particular POPs and the development of childhood asthma.

Uptake, translocation and biotransformation kinetics of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize (Zea mays L.)

This study presents a detailed kinetic investigation on the uptake, acropetal translocation and transformation of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize (Zea mays L.) by hydroponic exposure. Root uptake followed the order: BDE-47 > 6-MeO-BDE-47 > 6-OH-BDE-47, while 6-OH-BDE-47 was the most prone to acropetal translocation. Debromination rates of BDE-47 were 1.31 and 1.46 times greater than the hydroxylation and methoxylation rates, respectively. Transformation from BDE-47 to lower brominated OH/MeO-PBDEs occurred mainly through debromination first followed by hydroxylation or methoxylation. There was no transformation from 6-OH-BDE-47 or 6-MeO-BDE-47 to PBDEs. Methylation rate of 6-OH-BDE-47 was twice as high as that of 6-MeO-BDE-47 hydroxylation, indicating methylation of 6-OH-BDE-47 was easier and more rapid than hydroxylation of 6-MeO-BDE-47. Debromination and isomerization were potential metabolic pathways for 6-OH-BDE-47 and 6-MeO-BDE-47 in maize. This study provides important information for better understanding the mechanism on plant uptake and transformation of PBDEs.

New non-PBDE brominated flame retardants in sediment and plant samples from Jiaozhou Bay wetland

Seven non-polybrominated diphenyl ethers (non-PBDE) (TBB, TBX, PBT, PBEB, HBB, DBHCTD and BB153) were analyzed in sediment and plant samples which were collected from Xiaojianxi landfill to Dagu river estuary in Jiaozhou Bay wetland. The species of non-PBDE were different in sediment and plant samples with the concentration of 0.41-9.66ngg(-1) and 0.15-1.2ngg(-1), respectively. DBHCTD was the main non-PBDE compared with other target compounds and its concentration was 1.21-9.66ngg(-1)dw. Generally, the concentration of non-PBDE in sediment showed a decreasing tendency while discrete decline in plant has been revealed. Furthermore, DBHCTD, HBB, as well as other BFRs, might have a common BFRs degradation or similar accumulation potential in sediment, as their Pearson relationship p<0.05. Generally, the content of non-PBDE in Jiaozhou Bay wetland was higher than other published research. Therefore, more attention should be paid to non-PBDE on account of their persisting impact on human health and environment.

Urinary bromophenol glucuronide and sulfate conjugates: Potential human exposure molecular markers for polybrominated diphenyl ethers

One possible source of urinary bromophenol (BP) glucuronide and sulfate conjugates in mammalian animal models and humans is polybromodiphenyl ethers (PBDEs), a group of additive flame-retardants found ubiquitously in the environment. In order to study the correlation between levels of PBDEs in human blood plasma and those of the corresponding BP-conjugates in human urine, concentrations of 17 BDE congeners, 22 OH-BDE and 13 MeO-BDE metabolites, and 3 BPs in plasma collected from 100 voluntary donors in Hong Kong were measured by gas chromatograph tandem mass spectrometry (GC-MS). Geometric mean concentration of ΣPBDEs, ΣOH-BDEs, ΣMeO-BDEs and ΣBPs in human plasma were 4.45 ng g(-1) lw, 1.88 ng g(-1) lw, 0.42 ng g(-1) lw and 1.59 ng g(-1) lw respectively. Concentrations of glucuronide and sulfate conjugates of 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP) in paired samples of urine were determined by liquid chromatography tandem triple quadrupole mass spectrometry (LC-MS/MS). BP-conjugates were found in all of the parallel urine samples, in the range of 0.08-106.49 μg g(-1)-creatinine. Correlations among plasma concentrations of ΣPBDEs/ΣOH-BDEs/ΣMeO-BDEs/ΣBPs and BP-conjugates in urine were evaluated by multivariate regression and Pearson product correlation analyses. These urinary BP-conjugates were positively correlated with ΣPBDEs in blood plasma, but were either not or negatively correlated with other organobromine compounds in blood plasma. Stronger correlations (Pearson's r as great as 0.881) were observed between concentrations of BDE congeners having the same number and pattern of bromine substitution on their phenyl rings in blood plasma and their corresponding BP-conjugates in urine.

Comparing human exposure to emerging and legacy flame retardants from the indoor environment and diet with concentrations measured in serum

This study investigates associations between serum concentrations of emerging and legacy halogenated flame retardants (HFRs) in 46 Norwegian women and measured indoor air and dust concentrations of the HFRs as well as detailed information on diet and household factors. Hexabromobenzene (median 0.03ng/g lipid) and Dechlorane 602 (median 0.18ng/g lipid) were detected in about 50% of the samples and Dechlorane Plus syn (median 0.45ng/g lipid) and anti (median 0.85ng/g lipid) in more than 78%. The most abundant polybrominated diphenyl ethers were 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153; median 0.82ng/g lipid) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47; median 0.49ng/g lipid) detected in more than 70% of the samples. In the bivariate analysis, no consistent associations were observed between the biomonitoring data and measured concentrations in indoor air and dust. On the other hand, consumption of specific food items (mainly lamb/mutton and margarine) correlated significantly with more than two HFR serum concentrations, while this was not the case for household factors (electronic appliances). Only the significant bivariate associations with diet were confirmed by multivariate linear regression analyses, which might indicate a higher contribution from food compared to the indoor environment to the variation of the body burden of these HFRs.

Ecotoxicity and biodegradability of new brominated flame retardants: a review

Brominated flame retardants (BFRs) have been routinely used as additives in a number of consumer products for several decades in order to reduce the risk of fire accidents. Concerns about the massive use of these substances have increased due to their possible toxicity, endocrine disrupting properties and occurrence in almost all the environmental compartments, including humans and wildlife organisms. Several conventional BFRs (e.g. polybrominated diphenylethers (PBDE)) have been included in the list of Persistent Organic Pollutants and their use has been restricted because of their established toxicity and environmental persistence. Over the past few years, these compounds have been replaced with "new" BFRs (NBFRs). Despite the fact that NBFRs are different chemical molecules than traditional BFRs, most of physical-chemical properties (e.g. aromatic moiety, halogen substitution, lipophilic character) are common to both groups; therefore, their fate in the environment is potentially similar to the banned BFRs. Therefore, this article has been compiled to summarize the published scientific data regarding the biodegradability of the most widely used NBFRs, a key factor in their potential persistency in the environment, and their ecotoxicological effects on humans and test organisms. The data reviewed here document that the mechanisms through NBFRs exibit their ecotoxicity and the processes leading to their biotransformation in the environment are still poorly understood. Thus emphasis is placed on the need for further research in these areas is therefore emphasized, in order to avoid the massive use of further potentially harmful and recalcitrant substances of anthropogenic origin.

PBDE, HBCD, and novel brominated flame retardant contamination in sediments from Lake Maggiore (Northern Italy)

The reduction in the use of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) has opened the way for the introduction of novel brominated flame retardants (NBFRs) in place of the banned formulations. Important representatives of this group are decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB). In this study, the contamination due to NBRFs was investigated for the first time in Italy in the sediments of Lake Maggiore. The aim of the research was to characterize in detail the possible presence of temporal trends and/or to identify potential sources of contamination. The study also considered the PBDE and HBCD lake sediment's current contamination. The analytical results showed that sediments in Lake Maggiore and its tributary rivers had weak concentrations of PBEB, HBB, and BTBPE, but they did not have a negligible/insignificant contamination of HBCD (up to 23.7 ng/g dry weight (d.w.)). The determination of PBDEs in sediments showed that BDE-209 was the predominant congener (up to 217 and 28 ng/g d.w. in river and lake sediments, respectively). DBDPE was detected in the sediments with relevant concentrations (up to 280 ng/g d.w in the River Boesio sediments). The positive correlation of DBDPE with BDE-209 confirmed the wide and important use of this compound in the Lake Maggiore basin and the hypothesis that this compound will soon become one of the most important NBFRs used in Northern Italy. The contamination of Lake Maggiore sediments due to PBDEs, HBCD, and NBFRs were comparable to other worldwide situations.

Levels and profile of several classes of organic contaminants in matched indoor dust and serum samples from occupational settings of Pakistan

Dust ingestion is an important route of human exposure to organic contaminants, especially for flame retardants (FRs) in occupational settings. Several classes of organic contaminants were analyzed in matched dust and serum samples from academics and workers in electronics and clothing stores of Faisalabad, Pakistan. The concentrations of contaminants varied in dust as follow: organophosphate FRs (∑PFRs) > novel brominated FRs (∑NBFRs) > polybrominated diphenyl ethers (∑PBDEs) > organochlorine pesticides (∑OCPs) > polychlorinated biphenyls (∑PCBs), while, in serum, concentration varied: ∑OCPs > bromophenols (∑BPs) > ∑PCBs > ∑HO-PCBs ≈ ∑PBDEs. Two NBFRs, namely 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE) and bis(2-ethylhexyl) tetrabromophthalate (TBPH), were detected in <10% of the serum samples. p,p'-DDE was the major contaminant in serum contributing to ∼75% of the total contaminant burden. Levels of Penta-BDE congeners in serum and dust were significantly correlated (r = 0.64, p < 0.01) for the academics, suggesting dust ingestion as an important determinant for their serum levels.

Halogenated flame retardants in baby food from the United States and from China and the estimated dietary intakes by infants

Three categories of baby food (formula, cereal, and puree) were bought from United States and Chinese stores in 2013 and analyzed for polybrominated diphenyl ethers (PBDEs) and related flame retardants. The primary goal of this project was to investigate whether there were differences in the levels of flame retardants between these two nations' baby foods. The median concentrations of total PBDEs (sum of BDE-17, -28, -47, -49, -99, -100, -153, -183, and -209) were 21 and 36 pg/g fresh weight for the Unites States and Chinese baby foods, respectively. Among non-PBDE flame retardants, hexabromobenzene, Dechlorane Plus (DP), and decabromodiphenylethane were frequently detected (22-57%) with median concentrations of 1.6, 8.7, and 17 pg/g fresh weight for United States samples, and 1.3, 13, and 20 pg/g fresh weight for Chinese samples. In general, the flame retardant concentrations in the United States and Chinese samples were not statistically different, but very high DP concentrations were observed in one Chinese formula sample (4000 pg/g) and in one United States cereal sample (430 pg/g), possibly suggesting contamination of the raw materials or contamination during production of these two samples. A comparison of median estimated daily dietary intake rates of BDE-47, -99, and -153 with existing reference doses for neurodevelopmental toxicity and other existing criteria suggested no concerns for the consumption of these baby foods.

Evaluation of BDE-47 hydroxylation metabolic pathways based on a strong electron-withdrawing pentafluorobenzoyl derivatization gas chromatography/electron capture negative ionization quadrupole mass spectrometry

Understanding the metabolic pathways of polybrominated diphenyl ethers (PBDEs) is a key issue in the evaluation of their cytotoxicity after they enter the biota. In order to obtain more information concerning the metabolic pathways of PBDEs, we developed a strong electron-withdrawing pentafluorobenzoyl (PFBoyl) derivatization capillary gas chromatography/electron capture negative ionization quadrupole mass spectrometry (GC/ECNI-qMS). PFBoyl esterification greatly improves separation of the metabolites of PBDEs such as hydroxylated PBDEs (OH-PBDEs) and bromophenols (BPs) metabolites in rat liver microsomes (RLMs). On the other hand, the strong electron-withdrawing property of PFBoyl derivatized on OH-PBDEs and/or BPs makes cleavage of the ester bond on ECNI easier resulting in higher abundance of the structure-informative characteristic fragment ions at a high m/z region, which facilitate the identification of OH-PBDEs metabolites. Subsequent quantification can be performed by monitoring not only 79Br- (or 81Br-) but also their characteristic fragment ions, achieving more accurate isotope dilution quantification using GC/ECNI-qMS. These merits allow us to identify totally 12 metabolites of BDE-47, a typical example of PBDEs, in the RLMs in vitro incubation systems. In addition to the already known metabolites of BDE-47, one dihydroxylated 3,6-di-OH-BDE-47 and one dihydroxylated 3,5-di-OH-tetrabrominated dioxin were found. Moreover, the second hydroxylation took place on the same bromophenyl ring, where the first hydroxyl group was located, and was further confirmed via the identification of the dihydroxylated 2',6'-di-OH-BDE-28 of an asymmetric 2'-OH-BDE-28. This methodological development and its subsequent findings of the metabolic pathways of BDE-47 provided experimental evidence for understanding its dioxin-like behavior and endocrine disrupting risk.

Polybrominated diphenyl ethers and perfluoroalkyl substances in serum of pregnant women: levels, correlations, and potential health implications

Polybrominated diphenyl ethers (PBDEs), a group of flame retardants, and perfluoroalkyl substances (PFASs) were analysed in serum samples of pregnant women from Denmark to provide information about their exposure and to study indications of common exposure pathways. The main BDE congener was the fully brominated BDE-209 with a median value of 7.5 ng/g lipid (46 pg/mL; 9.8 pmol/g lipid). Other BDE congeners decreased in the order BDE-47 > BDE-99 > BDE-153. The summed concentration of tri- to hepta-BDEs was 7.7 ng/g lipid, i.e. in the higher end of previously reported concentrations from Europe, including plasma samples of pregnant Danish women. Total lipid contents were relatively low, on average 5.9 g/L (9.0 mmol/L). The main PFAS compound was perfluorooctane sulfonate with a median concentration of 8.4 ng/mL. Other PFASs decreased in the order perfluorooctanoic acid > perfluorononanoic acid > perfluorodecanoic acid > perfluorohexane sulfonate and resulted in a ΣPFAS of 12 ng/mL. Within each group, compounds were highly intercorrelated with the exception of BDE-209, which was not correlated with any of the other compounds. No correlations were found either between PFASs and PBDEs suggesting different sources of exposure and/or pharmacokinetic and metabolisation processes. PBDE and PFAS concentrations were in the range associated with adverse effects in some epidemiological studies.

Genotoxic effects and serum abnormalities in residents of regions proximal to e-waste disposal facilities in Jinghai, China

Electronic waste (e-waste) disposal is a growing problem in China, and its effects on human health are a concern. To determine the concentrations of pollutants in peripheral blood and genetic aberrations near an e-waste disposal area in Jinghai, China, blood samples were collected from 30 (age: 41±11.01 years) and 28 (age: 33±2.14 years) individuals residing within 5 and 40km of e-waste disposal facilities in Jinghai (China), respectively, during the week of October 21-28, 2011. Levels of inorganic pollutants (calcium, copper, iron, lead, magnesium, selenium, and zinc) and malondialdehyde (MDA), identities of persistent organic pollutants (POPs), micronucleus rates, and lymphocyte subsets were analyzed in individuals. Total RNA expression profiles were analyzed by group and gender. The population group living in proximity to the e-waste site displayed significantly higher mean levels of copper, zinc, lead, MDAs, POPs (B4-6DE, B7-9DE, total polychlorinated biphenyls, and BB-153). In addition, micronucleus rates of close-proximity group were higher compared with the remote group (18.27% vs. 7.32%). RNA expression of genes involved in metal ion binding and transport, oxidation/reduction, immune defense, and tumorigenesis varied between groups, with men most detrimentally affected (p<0.05). CD4(+)/CD8(+)T cell ratios, CD4(+)CD25(nt/hi)CD127(lo)regulatory T cell percentages, and CD95 expression were greater in the e-waste group (p<0.05). Residing in close proximity to e-waste disposal facilities (≤5km) may be associated with the accumulation of potentially harmful inorganic/organic compounds and gender-preferential genetic aberrations.

Brominated flame retardant concentrations in sera from the Canadian Health Measures Survey (CHMS) from 2007 to 2009

Pooling of surplus serum from individual samples, collected between 2007 and 2009 during Cycle 1 of the Canadian Health Measures Survey (CHMS), was performed to develop a national baseline estimate of brominated flame retardants in Canadians. Serum samples were categorized by sex and distributed by five age groups ranging from 6 to 79years. Nearly 5000 (4583) serum samples were used to form 59 composite pools. Serum pools were created to ensure a high detection frequency of these analytes in serum because low volume samples had previously resulted in non-detectable concentrations. The analytes of interest in these serum pools included 23 polybrominated diphenyl ethers (PBDEs) and three hexabromocyclododecane (HBCD) isomers (α-, β- and γ-HBCD). PBDEs were observed in all samples tested and total PBDE concentrations ranged from 27ngg(-1) lipid to 130ngg(-1) lipid (geometric mean [GM] 46ngg(-1) lipid). ∑PBDE concentrations were significantly elevated in samples representing the 6-11year old age group (GM 65ngg(-1) lipid) relative to ages above 40years, although no difference in concentration was observed between the sexes. PBDE concentrations in Canadian sera from the general population were higher than reported in Europe and Asia, but a little lower than observed in the US. PBDE 47 was the greatest contributor to ∑PBDE concentrations and the GM concentration for this congener was 22ngg(-1) lipid. The other dominant contributors to ∑PBDE concentrations were in descending order: 153 [GM 9.4ngg(-1) lipid]>99 [GM 4.6ngg(-1) lipid]≅100 [GM 4.1ngg(-1) lipid]>209 [GM 1.1ngg(-1) lipid] and 183 [GM 0.42ngg(-1) lipid]. ∑HBCD was detected in all samples analysed, although most samples were observed at concentrations <1ngg(-1) lipid, similar to global concentrations. α-HBCD was the dominant contributor to ∑HBCD concentrations in Canadians although β- and γ-HBCD were detected in 23% and 35% of the samples, respectively. No differences in ∑HBCD concentration were associated with age or sex. This dataset represents the first national data describing HBCD isomers and some PBDEs (e.g., 183, 209) in Canadians.

The human body burden of polybrominated diphenyl ethers and their relationships with thyroid hormones in the general population in Northern China

This study was conducted to determine the human body burden of polybrominated diphenyl ethers (PBDEs) and then clarify the relationships between that and the disruption of thyroid hormones in the general population in Northern China. Between November 2010 and May 2011, 124 serum samples were obtained from volunteers from the provinces of Shanxi and Liaoning. Serum samples were prepared by solid-phase extraction and analyzed for BDE-17, 28, 47, 66, 99, 100, 153, 154, 183 and 209 by gas chromatography-negative chemical ionization mass spectrometry. The median concentration of the total PBDEs was 7.2 ng/g lipid weights (lw); concentrations ranged from 2.1 to 160.3 ng/glw. The PBDE profiles in this study differed from those of other general populations. BDE-209 was the most abundant congener (median, 5.0 ng/glw; range, non-detected - 157.1 ng/glw), accounting for more than 75% of the total PBDEs, followed by BDE-153. The total PBDE concentrations in men were significantly higher as compared to women. The donors' age was correlated with a few PBDE congeners, but was not correlated with the total PBDE concentrations. The overall level of PBDEs in this study was lower than that observed in general populations in Southern China, Europe, and North America. There were apparent correlations between concentrations of several PBDE congeners and thyroid hormones. Triiodothyronine (T₃) was correlated with BDE-99 and 209 and inversely correlated with BDE-17, 28, 47, 153, 183, and the summed tri- to hepta-PBDE congeners (∑₃₋₇PBDEs). Thyroid-stimulating hormone (TSH) was correlated with BDE-17, 28, 47, and 183 and inversely correlated with BDE-99. No correlation between free tetraidothyronine (FT₄) and PBDEs was observed. Logistic regression analysis results indicated that those with higher levels of BDE-17 or BDE-153 had significantly lower odds of having T₃ levels above the normal range compared to those with lower levels of BDE-17 or BDE-153. Association between FT₄ and BDE-153 disappeared after controlling for sex and age. However, there was no significant association between TSH and PBDEs. The results of the present study showed that even at a relatively low level, PBDEs might interfere with the thyroid hormone levels in the general population.

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.

Occupational exposure to synthetic musks in barbershops, compared with the common exposure in the dormitories and households

Synthetic musks (SMs) have been widely used as fragrance ingredients in personal care and sanitary commodities. Due to their high volatility and particle-binding affinity, the indoor dust is a major reservoir of SMs, and dust ingestion could be an important exposure way to special populations, such as hairdressers. In spite of the known toxicity of SMs, there is no information regarding the occurrence of SMs in barbershop dusts and the exposure of hairdressers through indoor dust ingestion. In the present study, the levels of two nitro musks and five polycyclic musks were measured from indoor dust samples collected from barbershops, and some other indoor dust samples were also collected from dormitories, bathhouses and households for comparison. The concentrations of ∑SMs in barbershop dusts were 10-100 times higher than those from the other three indoor microenvironments. Polycyclic musks accounted for 89.4% of ∑SMs on average in all samples, of which two compounds, HHCB and AHTN jointly dominated 97.9% of polycyclic musks. The levels of HHCB and AHTN varied from 12.2 to 8.39×10(5) and from 13.2 to 3.49×10(5) ng g(-1), respectively. The daily intakes (DIs) of ∑SMs through house dust ingestion were estimated using the model of high dust ingestion and worst-case exposure (P95), and the corresponding exposure rates were 2791, 135 and 727 ng d(-1) for the hairdressers, general population and toddlers. SMs were also detected in blood samples collected from the hairdressers and normal adults (n=50 and 10, respectively). There was no significant difference between these two groups. Despite the absence of higher SM concentrations in hairdresser's blood, we should not overlook the potential occupational health risks due to their high SMs ingestion rate.

Serum concentrations of polybrominated diphenyl ethers (PBDEs) and a polybrominated biphenyl (PBB) in men from Greenland, Poland and Ukraine

Many brominated flame retardants (BFRs)-including polybrominated diphenyl ethers (PBDEs)-have been shown to persist in the environment, and some have been associated with adverse health effects. The aim of the present study was to quantify serum concentrations of common brominated flame retardants in Inuit men from across Greenland, and in men from Warsaw, Poland and Kharkiv, Ukraine. Serum was sampled between 2002 and 2004 from men 19 to 50years of age. 299 samples were analyzed for BDE-28, 47, 99, 100, 153, 154 and 183 and the brominated biphenyl BB-153 using gas chromatography-high resolution mass spectrometry. BDE-47 and BDE-153 were detected in more than 95% of samples from all three populations. All other congeners, except BDE-154, were detected in more than 70% of samples from Greenland; lower detection frequencies were observed in Polish and Ukrainian samples. Concentrations of individual congeners were 2.7 to 15 fold higher in Greenlandic relative to Polish and Ukrainian men. Geometric mean concentrations of the sum of the most abundant PBDEs of the Penta-BDE commercial mixture (BDE-47, 99, 100, 153 and 154) were 6.1, 1.7 and 0.87ng/g lipids in the Greenlandic, Polish and Ukrainian men, respectively. Furthermore, significant geographical differences in BFR concentrations were observed within Greenland. Principal component analysis revealed distinct clustering of samples by country of origin. The associations between ΣPBDEs and age were inconsistent, varying from no association in Greenlandic and Polish study populations to a U-shaped relationship in Ukrainians. We report BFR levels for three populations for which sparse biomonitoring data exists.

Concentrations and congener profiles of polybrominated diphenyl ethers (PBDEs) in blood plasma from Hong Kong: implications for sources and exposure route

There was limited information about bioaccumulation of polybrominated diphenyl ethers (PBDEs) in humans of the general population of Hong Kong. Therefore, the present study was conducted to determine concentrations and congener profiles of PBDEs in blood plasma from Hong Kong, evaluate their sources and correlations with other organobrominated compounds, and investigate exposure routes from fish and dust. Concentrations of ∑PBDE22 ranged from 0.56 to 92 ng g(-1), lipid weight (lw), with a median of 5.4 ng g(-1). BDE-47 was the dominant congener, accounting for 26% of ∑PBDE22. Concentrations of PBDE congeners in market fish were significantly (r(2)=0.89, p<0.001) correlated with plasma. Positive but no significant correlations were observed, between concentrations of PBDE congeners in indoor dust from workplaces (r(2)=0.46, p=0.081) and homes (r(2)=0.49, p=0.10), with concentrations of PBDE in human blood plasma. The results indicated that dietary exposure, particularly consumption of fish, is a major pathway through which people in Hong Kong are exposed to PBDEs. Furthermore, our data revealed a spatial distribution and terrestrial source of BDE-28 for local people. Results of the present study, which was the first systematic study to investigate concentrations of PBDEs in blood of Hong Kong people, provides useful information to which future measurements can be compared.

Polybrominated diphenyl ethers (PBDEs) in a conventional wastewater treatment plant (WWTP) from Shanghai, the Yangtze River Delta: implication for input source and mass loading

The concentrations of 19 polybrominated diphenyl ethers (PBDEs) congeners in a conventional wastewater treatment plant (WWTP) were determined to investigate the occurrence and fate of PBDEs during wastewater treatment processes. The level of total PBDEs ranged from 1.68 to 4.64 ng/L in wastewater, with BDE209 accounting for the largest proportion, followed by penta- and octa-BDE congeners. PBDEs were found to mainly exist in the particulate phase of wastewater, which rendered sedimentation efficient for the removal of PBDEs, while the removal efficiencies might be varied for congeners with different Br atom numbers. Because of similar congener profiles, in-house dust was considered to be an important source for PBDEs in the WWTP. According to the mass loading estimation, over 60% of total PBDEs entering the WWTP accumulated in the dewatered sludge, resulting in the total PBDE release of 43.8 kg/year via sewage sludge in Shanghai. And the annual release via effluent was estimated to be 5.5 kg, less but shouldn't be neglected.

Polybrominated diphenyl ethers (PBDEs) in aborted human fetuses and placental transfer during the first trimester of pregnancy

Data on early human fetal exposure to polybrominated diphenyl ethers (PBDEs) is limited. However, early pregnancy, in particular the first trimester, is critical for fetal development. We investigated exposure to PBDEs and placental transfer during early pregnancy by analyzing PBDEs in paired aborted fetuses (n = 65), placentas (n = 65), and maternal blood samples (n = 31) at 10-13 weeks gestation, which were collected in a hospital near electronic wastes (e-wastes) recycling sites in Taizhou, China. Mean total PBDE (∑PBDE) concentrations were 4.46, 7.90, and 15.7 ng/g of lipid weight (lw) in the fetuses, placentas, and blood, respectively. The three matrices had roughly similar PBDE congener profiles, dominated by BDE-209, BDE-197, BDE-153, BDE-47, and BDE-28. Significant correlations were found between ∑PBDE concentrations in the paired matrices. Comparing the concentration ratios between the paired samples, we observed significantly higher fetus/blood and fetus/placenta ratios for BDE-28, BDE-99, and BDE-47 than for BDE-197, BDE-209, and BDE-153, while opposite results were found in placenta/blood ratios. Our results indicate that PBDEs can enter the fetus during the first trimester and low-brominated congeners cross the placenta more easily than high-brominated congeners, which tend to remain in the placenta. This phenomenon is consistent with findings at the end of pregnancy.