Polybrominated diphenyl ethers in the serum and breast milk of the resident population from production area, China

Has Regulatory Action Reduced Human Exposure to Flame Retardants?

Flame retardant (FR) exposure has been linked to several environmental and human health effects. Because of this, the production and use of several FRs are regulated globally. We reviewed the available records of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs) in human breast milk from literature to evaluate the efficacy of regulation to reduce the exposure of FRs to humans. Two-hundred and seven studies were used for analyses to determine the spatial and temporal trends of FR exposure. North America consistently had the highest concentrations of PBDEs, while Asia and Oceania dominated HBCDD exposure. BDE-49 and -99 indicated decreasing temporal trends in most regions. BDE-153, with a longer half-life than the aforementioned isomers, typically exhibited a plateau in breast milk levels. No conclusive trend could be established for HBCDD, and insufficient information was available to determine a temporal trend for BDE-209. Breakpoint analyses indicated a significant decrease in BDE-47 and -99 in Europe around the time that regulation has been implemented, suggesting a positive effect of regulation on FR exposure. However, very few studies have been conducted globally (specifically in North America) after 2013, during the time when the most recent regulations have been implemented. This meta-analysis provides insight into global trends in human exposure to PBDEs and HBCDD, but the remaining uncertainty highlights the need for ongoing evaluation and monitoring, even after a compound group is regulated.

Persistent immune injury induced by short-term decabromodiphenyl ether (BDE-209) exposure to female middle-aged Balb/c mice

Decabromodiphenyl ether (BDE-209), widely used in various industries for its excellent flame-retardant performance, could be enriched in humans and is closely associated with immune impairment. In addition, immune system is gradually declined and becoming more sensitive to environmental pollutants in the ageing process. Therefore, the immunotoxicity of BDE-209 (4, 40, and 400 mg/kg/day) to middle-aged mice and its recovery and susceptibility was first to be comprehensively investigated in this study. The results showed that BDE-209 exposure could lead to oxidative injury to immune organs (spleen, thymus, and liver), impair humoral (immunoglobulins), cellular (lymphopoiesis), and non-specific immunity, and disturb the expressions of the genes related to Th1/Th2 balance (T helper cells) in the middle-aged mice. In addition, Integrated Biomarker Response (IBR) indicated that BDE-209-induced immune impairment was challenging to self-regulated, and even exacerbated after 21 days of recovery and oxidative injury in immune organs could be the main reason. Furthermore, factorial analysis showed that middle-aged mice exposed to BDE-209 suffered from greater immune impairment than adult mice, and the immune impairment in aged mice is more difficult to be self-repaired than that in adult mice. It can be seen that the aged tend to suffer from BDE-209-induced persistent immune impairment and health threats.

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.

Global distribution and trends of polybrominated diphenyl ethers in human blood and breast milk: A quantitative meta-analysis of studies published in the period 2000-2019

Polybrominated diphenyl ethers (PBDEs) are a class of flame-retardants that are found throughout the human body. However, global trends and diversity of the concentrations in human body and the potential risks remain largely unresolved. Based on published data during 2000-2019, we conducted a systematic meta-analysis to understand the burden and risks of PBDEs in humans and their spatiotemporal variations. The report provides a global picture of PBDE concentrations in human blood and breast milk. We found the levels of body PBDE burden in the North American population were higher than those from Asia and Europe. However, high concentrations of blood PBDEs in occupational population from Asia were observed, largely because of poorly controlled e-waste recycling operations. Penta- and deca-BDE were the main contributors in North America and Asia, respectively, reflecting the difference in the production and use of these chemicals. On a global scale, no substantial decreases in the concentrations of PBDEs in the blood and breast milk were observed, although most of the chemicals have been phased out. The results suggested that humans will be exposed to PBDEs with relatively high concentrations in a certain period because of the legacy in products and the environmental media. And the potential health risks necessitate careful study in the future. Our results also remind that the uses of degradation-resistant chemicals should be attached great importance to their safety.

Levels and profiles of persistent organic pollutants in breast milk in China and their potential health risks to breastfed infants: A review

Although some persistent organic pollutants (POPs) were prohibited or limited in use several decades ago, they are still frequently detected in the human body. The purpose of this study was to understand the levels and profiles of POPs in breast milk in China and assess their potential health risks among breastfed infants under six months of age. A literature review focused on China was performed for studies published from 2001 to 2020. The POP levels in breast milk along with other important variables were extracted, and then the average individual POP levels in breast milk were estimated. This review summarises the distribution of traditional and new POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy brominated flame retardants (BFRs), perfluorinated compounds (PFCs), and chlorinated paraffins (CPs) and reported notably high levels of short-chain chlorinated paraffins and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) in breast milk. Although the levels of traditional POPs generally declined over time, especially p,p'-DDE and beta-hexachlorocyclohexane (β-HCH), women living in coastal areas, urban areas, and southern China still have a high body burden of certain POPs. In the present study, the estimated daily intake (EDI) of POPs through breastfeeding was used to evaluate the health risk for infants by comparing with acceptable levels. The findings suggested that infants born in coastal areas most likely suffered potential health risk from exposure to DDT, and the health risk of hexachlorobenzene (HCB) in infants in most nationwide regions remains a concern. More importantly, the EDI of PCBs for infants exceeds the safe limit on a national scale. Continuous surveillance of PCBs in breast milk is critical to evaluate the potential health effects on humans.

Legacy and novel halogenated flame retardants in seawater and atmosphere of the Bohai Sea: Spatial trends, seasonal variations, and influencing factors

Seventeen halogenated flame retardants (HFRs) were concurrently analyzed in surface seawater and low atmospheric samples from the Bohai Sea during four research cruises. HFRs mainly existed in particulate phases, and in general decabromodiphenyl ethane (DBDPE) was the predominant compound in both air and water samples. Relatively high concentrations were observed in the water of Laizhou Bay (LB), where the largest manufacturing base of brominated flame retardants (BFRs) in China is located and weak water exchange occurs. Transport from LB by coastal currents may be the main source of BFRs in some areas without emission sources. The HFRs in seawater exhibited distinct seasonal variation, with significantly higher concentrations in winter than those in summer. The controlling factors include the resuspension of sediment induced by large wind waves in winter and phytoplankton scavenging in spring and seawater stratification in summer. HFRs composition varied largely in different seasons, due to the different extents of riverine input and atmospheric deposition. Normally, for air masses passing through the nearby industrial regions, high concentrations of DBDPE (up to 1780 pg m^-3) co-existed with high total suspended particle (TSP) levels (up to 150 μg m^-3). The estimated atmospheric deposition fluxes of HFRs were 19, 51, and 80 kg season^-1 in spring, summer, and winter, respectively, indicating that the Bohai Sea is a sink of HFRs via atmospheric deposition. This study has increased our understanding of the behaviors and fates of the legacy and novel HFRs in the shallow coastal sea.

Fine particulate matter reduces the pluripotency and proliferation of human embryonic stem cells through ROS induced AKT and ERK signaling pathway

Epidemiological investigations have found that air fine particulate matter (PM) exposure not only causes respiratory and cardiovascular diseases in adults and children, but also affects embryonic development during pregnancy, leading to poor pregnancy outcomes. However, its exact molecular mechanism is still unclear. In this study, human embryonic stem cells (hESCs) were treated with PM at different concentrations then the morphology and proliferation capacity were measured. The mRNA and protein expression of NANOG and OCT4 were detected using quantitative PCR, immunofluorescence, western blotting, and flow cytometry. Reactive oxygen species (ROS) generation and AKT/ERK activation were also measured. Meanwhile, changes in ROS, the expression of NANOG, OCT4, and the AKT/ERK pathways were measured in the hESCs with or without pretreatment of ROS scavenger N-acetylcysteine (NAC) prior to PM exposure. After PM exposure, the proliferation capacity and expression of OCT4 and NANOG at the mRNA and protein levels were downregulated. The ROS level in the hESCs increased after PM exposure, but this increase in ROS was attenuated by pretreatment with NAC. Further analysis showed that the levels of phosphorylated AKT and ERK increased after PM exposure. After pretreatment with NAC, the phosphorylation levels of AKT and ERK, which are crucial for regulating the proliferation, pluripotency, and differentiation of hESC, were significantly attenuated compared with the non-NAC pretreated exposure group. These results suggest that PM exposure may reduce the proliferation and pluripotency of hESC through ROS-mediated AKT/ERK pathways, thereby affecting the long-term development of embryos.

Polybrominated diphenyl ethers in the environment and human external and internal exposure in China: A review

Polybrominated diphenyl ethers (PBDEs) are widely used as brominated flame retardants. Because of their toxicity and persistence, some PBDEs were restricted under the Stockholm Convention in 2009. Since then, many studies have been carried out on PBDEs in China and in many other countries. In the present review, the occurrences and contamination of PBDEs in air, water, sediment, soil, biota and daily food, human blood, hair, and other human tissues in China are comprehensively reviewed and described. The human exposure pathways and associated health risks of PBDEs are summarized. The data showed no obvious differences between North and South China, but concentrations from West China were generally lower than in East China, which can be mainly attributed to the production and widespread use of PBDEs in eastern regions. High levels of PBDEs were generally observed in the PBDE production facilities (e.g., Jiangsu Province and Shandong Province, East China) and e-waste recycling sites (Taizhou City, Zhejiang Province, East China, and Guiyu City and Qingyuan City, both located in Guangdong Province, South China) and large cities, whereas low levels were detected in rural and less-developed areas, especially in remote regions such as the Tibetan Plateau. Deca-BDE is generally the major congener. Existing problems for PBDE investigations in China are revealed, and further studies are also discussed and anticipated. In particular, non-invasive matrices such as hair should be more thoroughly studied; more accurate estimations of human exposure and health risks should be performed, such as adding bioaccessibility or bioavailability to human exposure assessments; and the degradation products and metabolites of PBDEs in human bodies should receive more attention. More investigations should be carried out to evaluate the quantitative relationships between internal and external exposure so as to provide a scientific basis for ensuring human health.

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.

Occupational exposure to polybrominated diphenyl ethers or decabromodiphenyl ethane during chemical manufacturing: Occurrence and health risk assessment

Field investigations were conducted on a decabrominated diphenyl ether (BDE-209) manufacturing plant and a decabromodiphenyl ethane (DBDPE) manufacturing plant, and worker exposure to polybrominated diphenyl ethers (PBDEs) or DBDPE was assessed. Workshop air was collected and tested to measure levels of external exposure to corresponding chemicals via air inhalation. Paired human serum and urine samples taken from 202 workers were tested to assess levels of internal BFR exposure. Levels of BDE-209 in air for the BDE-209 plant ranged from 10.6 to 295 μg m^-3, accounting for at least 99% of the total PBDEs in the workshop air, and those of DBDPE in air samples from the DBDPE plant ranged from 12.7 to 435 μg m^-3. Maximum estimated daily intakes (EDIs) of BDE-209 and DBDPE accumulated via air inhalation exceeded the corresponding RfD level recommended by the U.S. Environmental Protection Agency, indicating that for some workers, occupational exposure is likely to create significant health problems. The levels of BDE-209 measured in serum taken from BDE-209 workers ranged from 0.202 to 57.1 μg g^-1 lw, and those of DBDPE in serum taken from DBDPE workers ranged from 0.087 to 54.4 μg g^-1 lw. These values are several orders of magnitude higher than those detected in general areas and e-waste recycling sites. BDE-209 and DBDPE were detected in all of the urine samples with median levels of 1.12 and 8.6 ng mL^-1, respectively, and levels of BDE-209 and DBDPE in the urine were significantly and positively correlated with those observed in the serum.

Reflection of concentrations of polybrominated diphenyl ethers in health risk assessment: A case study in sediments from the metropolitan river, North China

As a developed city in North China, Tsingtao is believed to be suffering from the pollution of polybrominated diphenyl ethers (PBDEs) due to the rapid industrialization and urbanization in recent years. In this work, 8 PBDE congeners were detected in sediments from Moshui River, Tsingtao. BDE-209 and sum of 7 low brominated PBDE congeners (∑₇PBDEs, excluding BDE-209) ranged from 10.2 × 10^-3 to 237 × 10^-3 mg kg^-1 and from 1.62 × 10^-3 to 23.1 × 10^-3 mg kg^-1 d.w., respectively. PBDE concentrations decreased in the order of midstream > downstream > upstream, attributing to the discrepancies in anthropogenic activities among these areas. Principal component analysis coupled with multiple linear regression (PCA-MLR) revealed that 24.4% of PBDEs were derived from surface runoff of contaminated soils, 58.2% from direct discharge of local sources and 17.4% from atmospheric deposition. The probabilistic health risk assessment of PBDEs was performed by using Monte Carlo simulation. The carcinogenic and non-carcinogenic risks based on total PBDEs were low for children and teens, whilst severe for adults. However, based on bioaccessible PBDEs (in vitro gastrointestinal model), there was no obvious health risk for the three age groups. To the best of our knowledge, the present study was the first attempt to assess the health risk by using bioaccessible PBDEs in sediments.

Legacy and emerging brominated flame retardants in China: A review on food and human milk contamination, human dietary exposure and risk assessment

Brominated flame retardants (BFRs) are a large group of widely used chemicals, which have been produced and used since 1970s. As a consequence of substantial and long-term usage, BFRs have been found to be ubiquitous in humans, wildlife, and abiotic matrices around the world. Although several reports have reviewed BFRs contamination in general, none have focused specifically on foods and human milk, and the corresponding dietary exposure. Foods (including human milk) have long been recognized as a major pathway of BFRs intake for non-occupationally exposed persons. This review summarizes most available BFRs data in foods and human milk from China in recent years, and emphasizes several specific aspects, i.e., contamination levels of legacy and emerging BFRs, dietary exposure assessment and related health concerns, comparison between various BFRs, and temporal changes in BFRs contamination.

Polybrominated diphenyl ethers and indicator polychlorinated biphenyls in human milk from China under the Stockholm Convention

Seven congeners of polybrominated diphenyl ethers (PBDEs) (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153,BDE-154 and BDE-183) and six indicator polychlorinated biphenyls (PCBs) (PCB-28, PCB-52, PCB-101, PCB-138, PCB-153 and PCB-180) were measured in 32 regional pooled human milk samples originating from 1760 volunteering primiparous mothers to evaluate the current human body burden of general population and the temporal trend in China. Individual human milk samples were collected following a WHO-designed procedure. This work is one of parts of the evaluation of effectiveness of Stockholm Convention performance. The concentration of ∑₇PBDEs ranged from 0.3 ng g^-1 lipid to 4.0 ng g^-1 lipid with a mean of 1.5 ng g^-1 lipid. The concentration of ∑₆PCBs ranged from 2.3 ng g^-1 lipid to 19.0 ng g^-1 lipid with a mean of 6.6 ng g^-1 lipid. By comparing with background determination in 2007, there was no significance for ∑₇PBDEs. However, BDE-47, BDE-99, and BDE-100 significantly decreased with an average of 45%, 48%, and 46%, respectively, from 2007 to 2011, and an increase of BDE-183 was founded in most regions. For ∑₆PCBs, there was a significant decline with an average reduction of 41% from 2007 to 2011. These results indicate the effectiveness of reduction and elimination of POPs in China. Future national human milk biomonitoring is worthy to be done to further evaluate the time trend and effectiveness of the Convention performance.

A flexible plasma-treated silver-nanowire electrode for organic light-emitting devices

Silver nanowires (AgNWs) are a promising candidate to replace indium tin oxide (ITO) as transparent electrode material. However, the loose contact at the junction of the AgNWs and residual surfactant polyvinylpyrrolidone (PVP) increase the sheet resistance of the AgNWs. In this paper, an argon (Ar) plasma treatment method is applied to pristine AgNWs to remove the PVP layer and enhance the contact between AgNWs. By adjusting the processing time, we obtained AgNWs with a sheet resistance of 7.2Ω/□ and a transmittance of 78% at 550 nm. To reduce the surface roughness of the AgNWs, a peel-off process was used to transfer the AgNWs to a flexible NOA63 substrate. Then, an OLED was fabricated with the plasma-treated AgNWs electrode as anode. The highest brightness (27000 cd/m²) and current efficiency (11.8 cd/A) was achieved with a 30 nm thick light emitting layer of tris-(8-hydroxyquinoline) aluminum doped with 1% 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5 H,11H-(1)-benzopyropyrano(6,7-8-I,j)quinolizin-11-one. Compared to thermal annealing, the plasma-treated AgNW film has a lower sheet resistance, a shorter processing time, and a better hole-injection. Our results indicate that plasma treatment is an effective and efficient method to enhance the conductivity of AgNW films, and the plasma-treated AgNW electrode is suitable to manufacture flexible organic optoelectronic devices.

Polybrominated diphenyl ethers (PBDEs) and thyroid hormones in cord blood

Human exposure to polybrominated diphenyl ethers (PBDEs) has been increasing over the last three decades in China and around the world. Animal studies suggest that PBDEs could reduce blood levels of thyroid hormones, but it is unclear whether PBDEs disrupt thyroid function in humans. We used data from a prospective birth cohort of 123 pregnant women who were enrolled between September 2010 and March 2011 in Shandong, China. We measured the concentrations of eight PBDE congeners (n = 106) and five thyroid hormones (n = 107) in cord serum samples. We examined the relationship between prenatal exposure to PBDEs and thyroid function (n = 90). Median concentrations of BDEs 47, 99, 100, and 153 (detection frequencies > 75%) were 3.96, 8.27, 3.31, and 1.89 ng/g lipid, respectively. A 10-fold increase in BDE-99 and Σ₄ PBDEs (the sum of BDEs 47, 99, 100, and 153) concentrations was associated with a 0.41 μg/dL (95% confidence interval [CI]: 0.10 to 0.72) and 0.37 μg/dL (95% CI: 0.06 to 0.68) increase in total thyroxine levels (TT₄), respectively. No associations were found between other individual congeners and any of the five thyroid hormones. Our study suggests that prenatal exposure to PBDEs may be associated with higher TT₄ in cord blood. Given the inconsistent findings across existing studies, our results need to be confirmed in additional studies.

Influence of maternal and sociodemographic characteristics on the accumulation of organohalogen compounds in Argentinian women. The EMASAR study

The occurrence of organohalogen compounds in venous serum from post-partum mothers from two Argentinian cities, Salta and Ushuaia, has been investigated (n = 698). 4,4'-DDE was the most abundant compound in these cities, with geometric means of 33 and 67ng/g lipid weight, respectively. City of residence, age and parity were the main determinants of the accumulation of these compounds. Hexachlorobenzene (HCB) was the second most abundant pollutant in Ushuaia, 8.7ng/g lipid, and β-hexachlorocyclohexane (β-HCH) in Salta, 7.8ng/g lipid. Decabromodiphenyl ether was higher in Ushuaia than Salta, 8.2 and 4.1ng/g lipid, respectively. The predominance of β-HCH, 4,4'-DDE and 4,4'-DDT in Salta was related with higher use of pesticides for agricultural applications. The observed higher concentrations of 4,4'-DDE and 4,4'-DDT in the mothers from rural+semi-urban sites than in urban areas were consistent with this agricultural origin. In addition, the most volatile organochlorine compounds included in this study, HCB and α-HCH, were mainly found in Ushuaia. The concentrations of the studied organohalogen pollutants in Argentina were lower than those found in other similar studies which is consistent with the location of these cities in the southern hemisphere. Age, mainly for 4,4'-DDE and polychlorobiphenyl (PCB) congeners 138, 153 and 180, and parity, mainly for HCB, β-HCH, 4,4'-DDT and PCB congener 118, were the second main determinants of the concentrations of these compounds. Gestational weight gain also influenced on the maternal levels of HCB, β-HCH, 4,4'-DDT and PCB congeners 118, 138 and 153. Higher weight accumulation during pregnancy involved dilution of these persistent pollutants. Body mass index (BMI) was a statistically significant determinant for 4,4'-DDT, α-HCH and PCB congeners 153 and 180. The observed direct correspondence between higher BMI and 4,4'-DDT concentrations was in agreement with the above reported inputs related with agricultural applications. The reverse correspondence of BMI with α-HCH and the PCB congeners indicated higher dilution at higher weight increase.

Distribution of polybrominated diphenyl ethers in breast milk, cord blood and placentas: a systematic review

Polybrominated diphenyl ethers (PBDEs) have been extensively used as flame retardants in consumer products. PBDEs rapidly bioaccumulate in the environment, food, wild animals and humans. In this review, we investigated the harmful effects of PBDEs on humans, especially in early life, and summarised the levels of PBDEs in human biological samples (breast milk, cord blood and placentas). In addition, we described the spatiotemporal distribution of PBDEs in this review. PBDE levels in breast milk, cord blood and placentas were generally higher in North America than in other regions, such as Asia, Europe, Oceania and Africa. However, high levels of PBDEs in human biological samples were detected at e-waste recycling sites in South China, East China and South Korea. This finding suggests that newborns living in e-waste regions are exposed to high levels of PBDEs during prenatal and postnatal periods. The time trends of PBDE concentration differed according to the region. Few studies have investigated PBDE levels in humans from 1967 to 2000, but they increased rapidly after 2000. PBDE concentration peaked at approximately 2006 globally. Compared with other PBDE congeners, BDE-47, BDE-153 and BDE-209 were the major components, but the detection rate of BDE-209 was lower than those of others. Future studies should focus on determining the BDE-209 concentration, which requires the implementation of different analytical approaches. Additionally, the levels of PBDEs in human samples and the environment should be monitored, especially in e-waste recycling regions. Graphical abstract The figures described the spatial distribution of the lowest (Fig. a1) and highest concentration of ∑PBDE (Fig. a2) in different countries by 2006 and described the spatial distribution of the lowest (Fig. b1) and highest concentration of ∑PBDE (Fig. b2) in different countries from 2007 to 2015. All the figures indicated that the levels of PBDEs in North America were substantially higher than those in many regions of Europe, Asia, Oceania, or Africa. Comparing Fig. a1-b1 or Fig. a2-b2, increasing trends were observed in some countries, especially in some regions in China, Korea and Canada.

In vitro cytotoxicity of decabrominated diphenyl ether (PBDE-209) to human red blood cells (hRBCs)

This work presents the effect of decabrominated diphenyl ether (PBDE-209) on the anti-oxidative defense capacity, and ATPase activity (structure and function) of human red blood cells (hRBCs). The results show that the PBDE-209 influences the activity and content of typical biomolecules (SOD, CAT, GSH-Px, GSH and MDA) in hRBCs, causing a decline in the function of the antioxidant defense system. The PBDE-209 with a concentration of 10 μmol/L resulted in the cytoplasmic projections and structure deformation of the hRBCs. When its concentration exceeds 25 μmol/L, the relative ATPase activity was decreased to 20% of the initial activity. Since the discovered effects of PBDE-209 on hRBCs are in cell level, this study may offer some information to advise the related in vivo cytotoxicity works.

Pollution Status and Human Exposure of Decabromodiphenyl Ether (BDE-209) in China

Decabromodiphenyl ether (BDE-209/decaBDE) is a high-production-volume brominated flame retardant in China, where the decaBDE commercial mixture is manufactured in Laizhou Bay, Shandong Province, even after the prohibition of penta- and octaBDE mixtures. The demand for flame retardants produced in China has been increasing in recent years as China not only produces electronic devices but also has numerous electronic waste (e-waste) recycling regions, which receive e-wastes from both domestic and foreign sources. High concentrations of BDE-209 have been observed in biotic and abiotic media in each of the different areas, especially within the decaBDE manufacturers and e-waste recycling areas. BDE-209 has been viewed as toxic and bioaccumulative because it might debrominate to less brominated polybrominated diphenyl ethers (PBDEs) (lower molecular weight and hydrophobicity), which are more readily absorbed by organisms. The highest concentration of PBDEs in dust within urban areas reached 40 236 ng g^-1 in the Pearl River Delta, and BDE-209 contributed the greatest proportion to the total PBDEs (95.1%). Moreover, the maximum hazard quotient was found for toddlers (0.703) for BDE-209, which was close to 1. This suggests that exposure to BDE-209 might lead to increased potential for adverse effects and organ harm (e.g., the lungs) through inhalation, dust ingestion, and dermal absorption, especially for the group of toddlers compared to others. In daily food and human tissues, the amount of BDE-209 was also extensively detected. However, the toxicity and adverse effect of BDE-209 to humans are still not clear; thus, further studies are required to better assess the toxicological effects and exposure scenarios, a more enhanced environmental policy for ecological risks regarding BDE-209 and its debrominated byproducts in China.

Organochlorine pesticides and polychlorinated biphenyls in human adipose tissue from northern Tunisia: Current extent of contamination and contributions of socio-demographic characteristics and dietary habits

The aims of the present study were to investigate the current exposure levels of persistent organochlorine compounds (OCs) in adipose tissues intraoperatively collected from 40 patients over 20 years undergoing non-cancer-related surgery residing in Northern region of Tunisia (Bizerte), which constitutes an exemplary case, and examined association between levels of contamination and both socio-demographic characteristics and dietary habits. Concentration of hexachlorobenzene (HCB), hexachlorocyclohexane isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), dichlorodiphenyltrichloroethane isomers (p,p'-DDT and o,p'-DDT) and metabolites (p,p'-DDE, o,p'-DDE, p,p'-DDD and o,p'-DDD) and 12 polychlorinated biphenyls (PCBs) congeners were measured using capillary gas chromatography with electron capture detector. Overall, residue levels of OCs followed the decreasing order of DDTs > PCBs > HCB > HCHs. DDTs levels ranged from 74.49 to 1834.76ngg^-1 lipid and contributing to more than 90% to the sum of organochlorine pesticides (OCPs). p,p'-DDE was the most abundant in all samples and the p,p'-DDT/p,p'-DDE ratio (range between 1.85% and 58.45%) suggesting recent and ongoing exposure to banned commercial DDT products. PCB concentrations varied from 29.27 to 322.58ngg^-1 lipid and PCB-180, PCB-153 and PCB-138 were the dominant congeners accounting for 70% of total PCBs. We did not find significant correlations between OC exposure levels and sex, parity, habitat areas and smoking habits. In females, the adipose tissue concentrations of DDTs, HCB and PCB-118 were positively correlated with age. There was statistically significant relationship between body mass index (BMI) changes and the adipose tissue levels of HCB and HCHs. No association was found between OCPs levels and dietary factors. However, our study suggests that fish consumption may be an important contributor of PCBs adipose tissue content of PCBs in Tunisian people. The presented work is highly significant, being the first study pointing out the chronic exposure to OCs in Bizerte.

Current halogenated flame retardant concentrations in serum from residents of Shandong Province, China, and temporal changes in the concentrations

The residents of Shandong Province, China, are exposed to high concentrations of halogenated flame retardants because large amounts of halogenated flame retardants are produced in the province. We determined the concentrations of eight polybrominated diphenyl ether congeners (PBDEs), seven novel brominated flame retardants (NBFRs), and the two dechlorane plus isomers (DPs) in serum from residents of Shandong Province. The aim was to identify temporal trends in the concentrations of these pollutants. The mean total concentrations of PBDEs, NBFRs and DPs were 41, 2.2 and 2.1ng/g lipid in pooled serum samples collected in 2014, and were 32, 3.5 and 3.1ng/g lipid in pooled serum samples collected in 2015, respectively. Decabromodiphenyl ether was the dominant PBDE congener in all of the samples. The novel brominated flame retardant and dechlorane plus concentrations were between one and two orders of magnitude lower than the PBDE concentrations. The PBDE concentrations in serum decreased significantly between 2007 and 2015, but the pentabromobenzene, pentabromotoluene, and dechlorane plus concentrations were relatively stable.

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.

Organophosphate ester flame retardant concentrations and distributions in serum from inhabitants of Shandong, China, and changes between 2011 and 2015

The production and use of brominated flame retardants have been increasingly restricted. Organophosphate esters (OPEs) have been widely used as substitutes for brominated flame retardants. However, little is yet known about human exposure to OPEs. The potential health risks posed by OPEs were assessed by determining the concentrations of 6 OPEs in pooled serum samples from residents of Shandong, China. The mean ∑₆ OPE concentrations in 2011 and 2015 were 680 ng/g lipid and 709 ng/g lipid, respectively. The most abundant OPE was tri(2-chloroethyl) phosphate, contributing a mean of 82% of the ∑₆ OPE concentration. A significant correlation was found between the tri(2-chloroethyl) phosphate and tri-n-butylphosphate concentrations, possibly indicating that these OPEs are used in similar applications and have similar human exposure pathways in the study area. The mean tri(2-chloroethyl) phosphate concentration increased from 536 ng/g lipid in 2011 to 605 ng/g lipid in 2015, but the concentrations of tri-n-butylphosphate, triphenyl phosphate, and tris(methylphenyl) esters decreased between 2011 and 2015. This could indicate that chlorinated OPEs bioaccumulate in humans more strongly than nonchlorinated OPEs do. Environ Toxicol Chem 2017;36:414-421. © 2016 SETAC.

Umbilical cord blood PBDEs concentrations are associated with placental DNA methylation

BACKGROUND

In utero polybrominated diphenyl ethers (PBDEs) exposure has been associated with adverse fetal growth. Alterations in placental DNA methylation might mediate those adverse effects.

OBJECTIVES

To examine the associations between in utero PBDEs exposure and DNA methylation in human placenta.

METHODS

Eighty apparently healthy mother-newborn pairs delivering at the Second Affiliated Hospital of Wenzhou Medical College were enrolled in this study. Placental DNA methylation of LINE1, NR3C1 and IGF2 was measured by quantitative polymerase chain reaction-pyrosequencing. In utero PBDEs exposure was assessed by measuring umbilical cord blood PBDEs concentrations.

RESULTS

For LINE-1, higher levels of BDE-66 exposure were associated with decreased DNA methylation (β=-0.9, 95% CI, -1.8 to -0.1); For NR3C1, BDE-153 concentrations was significantly inversely associated with DNA methylation (β=-2.0, 95% CI, -3.7 to -0.2); For IGF2, elevated concentrations of both BDE-153 (β=-1.7; 95% CI, -3.0 to -0.4) and BDE-209 (β=-1.0; 95% CI, -1. 9 to -0.1) were significantly associated with decreased DNA methylation.

CONCLUSIONS

We found that placental DNA methylation is associated with in utero PBDEs exposure. Changes in placental DNA methylation might be part of the underlying biological pathway between in utero PBDEs exposure and adverse fetal growth.

Exposure to polybrominated diphenyl ethers and female reproductive function: A study in the production area of Shandong, China

Polybrominated diphenyl ethers (PBDEs) are widely used in commercial and household products. Few human studies have examined the effects of PBDE exposure on female reproductive function. We recruited 207 pregnant women when they were admitted for labor from September 2010 to February 2012 as part of a birth cohort study, the Laizhou Wan Birth Cohort study. Maternal sera were analyzed for eight PBDE congeners (BDE-28, -47, -85, -99, -100, -153, -154, and -183) and four sex hormones. BDE-153 exhibited the highest serum level (median 4.67ng/g lipid), followed by BDE-99 (median 3.45ng/g lipid) and BDE-28, -47, and -100 (medians near 2ng/g lipid). BDE-28, -47, -99, -100, and -153 were the most frequently detected (>90%) congeners. Follicle-stimulating hormone (FSH) levels were negatively associated with PBDE exposure. For each natural log unit increase in BDE-47, 100, and ∑₅PBDEs, FSH levels changed -1.19IU/L (95% confidence interval [CI]: -1.32, -1.02), -1.17IU/L (95%CI: -1.36, -1.01) and -1.26IU/L (95%CI: -1.55, -1.02) respectively. BDE-85, -153, and -183 were associated with adverse reproductive effects, including an increased risk of threatened abortion (odds ratio [OR] [95% CI]: 1.30 [1.03, 1.62], 1.04 [1.01, 1.08], and 1.03 [1.01, 1.06], respectively). BDE-153 was associated with an increased risk of premature birth (adjusted OR [95% CI]:1.05 [1.01, 1.09]), and BDE-28 was associated with longer time to pregnancy (adjusted OR [95% CI]: 1.34 [1.03, 1.76]). These findings suggest that maternal PBDE exposure may be inversely associated with female reproductive function.

Brominated flame retardants in the hair and serum samples from an e-waste recycling area in southeastern China: the possibility of using hair for biomonitoring

Hair samples and paired serum samples were collected from e-waste and urban areas in Wenling of Zhejiang Province, China. The PBDE and DBDPE concentrations in hair and serum samples from e-waste workers were significantly higher than those of non-occupational residents and urban residents. BDE209 was the dominating BFRs in hair and serum samples from the e-waste area, while DBDPE was the major BFRs from the urban area. Statistically significant correlations were observed between hair level and serum level for some substances (BDE209, DBDPE, BDE99, BDE47, BDE28, and BDE17), although the PBDE congener profiles in hair were different from those in the serum. A statistically significant positive correlation between the PBDE concentrations and the working age, as well as gender difference, was observed in e-waste workers. Different sources of PBDEs and DBDPE in three groups were identified by principal component analysis and spearman correlation coefficient. Hair is suggested to be a useful matrix for biomonitoring the PBDE exposure in humans.

Brominated flame retardants (BFRs): A review on environmental contamination in China

Brominated flame retardants (BFRs) which were detected extensively in environmental and biota samples worldwide, have raised significant concerns during past decades for their persistence, bioaccumulation and potential toxicity to ecological environment and human health. In this paper, we have compiled and reviewed existing literature on the contamination status of BFRs in abiotic and biotic environments in China, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane, tetrabromobisphenol A and new BFRs. Temporal trends were also summarized and evaluated. Based on this review, it has been concluded that (1) high concentrations of PBDEs were generally related to the e-waste disposal processing, while the spatial distribution pattern of other BFRs was not necessarily in accordance with this; (2) extremely high concentrations of BFRs in indoor dust emphasized the importance of indoor contamination to human body burdens, while more work need to be done to confirm its contribution; (3) PBDEs in electronics dismantling workers were higher compared to the general population, indicating the occupational exposure should be of particular concern; (4) more data are now becoming available for BFRs in aquatic and terrestrial organisms not previously studied, while studies that consider the occurrence of BFRs in organisms of different trophic levels are still of urgent need for evaluating the fate of BFRs in the food web; and (5) limited data showed a decreasing trend for PBDEs, while more data on time trends of BFR contamination in various matrices and locations are still needed before the impact of regulation of BFRs can be assessed.

Environmental pollution of polybrominated diphenyl ethers from industrial plants in China: a preliminary investigation

Although numerous studies have shown the presence of polybrominated diphenyl ethers (PBDEs) in various environmental media, attention to their distribution in the environmental media surrounding industrial facilities is limited. In this study, eight PBDEs congeners (BDE-28, -47, -99, -100, -153, -154, -183, -209) were investigated in surface soils and water samples collected from commercial PBDE manufacturers, flame-retardant plastic modification plants and waste electrical and electronic equipment recycling facilities in China. Analysis of target compounds was performed using the model NCI GC-MS in SIM mode. The concentrations of ∑8PBDEs varied from 193.1 to 22,004.3 ng/L in water samples and from 1209.3 to 226,906 ng/g dry wt in surface soils, respectively. More severe PBDE contamination, when compared with previously reported data, was found in industrial areas in this study. This indicates that these industrial areas are highly polluted with PBDEs. BDE-209 was the predominant congener, accounting for more than 94% in this study, except for a 68.75% portion at one site. Our results show that PBDE manufacturing and flame-retardant plastic modification plants, easily overlooked by the public, are two primary PBDE pollution sources although they affect surrounding areas. Further research is needed, aimed at managing industrial PBDE emissions and eliminating environmental PBDE pollution, to investigate the material flows and environmental fates of PBDEs in all stages of the life cycle.

Brominated flame retardants (BFRs) in breast milk and associated health risks to nursing infants in Northern Tanzania

The main aim of this study was to assess brominated flame retardants (BFRs) in breast milk in the Northern parts of Tanzania. Ninety-five colostrum samples from healthy, primiparous mothers at Mount Meru Regional Referral Hospital (MMRRH), Arusha Tanzania, were analyzed for polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), (2,3-dibromopropyl) (2,4,6-tribromophenyl) ether (DPTE), pentabromoethylbenzene (PBEB) and 2,3,4,5,6-pentabromotoluene (PBT). The Ʃ7PBDE (BDE 28, 47, 99, 100, 153, 154, 183) ranged from below level of detection (<LOD) to 785ng/g lipid weight (lw). BDE 47, 99, 100 and 153 were the dominating congeners, suggesting recent and ongoing exposure to banned, commercial PentaBDE mixture. A multiple linear regression model revealed that mothers eating clay soil/Pemba during pregnancy had significantly higher levels of BDE 47, 99, 100 and 153 in their breast milk than mothers who did not eat clay soil/Pemba. Infant birth weight and birth length were significantly correlated with the levels of BDE 47, 99, 100 and 153. The estimated daily intake (ng/kg body weight/day) of BDE 47 and 99 exceeded the US EPA Reference doses (RfD) in four and eight mothers, respectively, suggesting a potential health risk to the nursing infants.

Prenatal exposure to polybrominated diphenyl ethers and birth outcomes

This study aimed to examine the potential association between maternal PBDEs and birth outcomes, including birth weight (g), length (cm), head circumference (cm) and gestational age (week). 215 mothers were recruited from a prospective birth cohort in rural northern China between September 2010 and February 2012. Serum PBDE congeners were detected and their association with birth outcomes were examined. The median maternal serum concentrations of BDE-28, -47, -99, -100, -153 were 2.27, 2.26, 3.58, 2.13, 4.87 ng/g lipid, respectively. Maternal LgBDE-28 and LgBDE-100 were negatively associated with birth length (β = -0.92, 95% confidence interval (CI): -1.82, -0.02; β = -0.97, 95% CI: -1.83, -0.08). A negative association was found between LgBDE-28 and birth weight among male infants (β = -253.76, 95% CI: -438.16, -69.36). PBDE congeners were not associated with head circumference, or gestational age. Our results contribute to growing evidence suggesting that PBDEs have adverse effects on birth outcomes.

Association between prenatal exposure to polybrominated diphenyl ethers and young children's neurodevelopment in China

The use of polybrominated diphenyl ethers (PBDEs) has been dramatically increasing over the last two decades in China. Animal studies suggest that prenatal exposure to PBDEs may result in neurodevelopmental deficits. Two hundred thirty-two participating mothers were recruited from a prospective birth cohort in rural northern China between September 2010 and February 2012. We analyzed 232 cord blood specimens for selected PBDE congeners and examined their association with children's developmental quotients (DQs) at 12 (n=192) and 24 (n=149) months of age based on the Gesell Developmental Schedules (motor, adaptive, language, and social domains). There were no substantial differences by demographic characteristics among the three time points: baseline, 12 and 24 months of age. Median cord blood levels of PBDE congeners 47, 99, 100, and 153 were 3.71, 6.70, 2.63, and 2.19 ng/g lipid, respectively. At 12 months of age, neither the individual nor total (the sum of BDEs 47, 99, 100, and 153) congener levels were associated with any of the four domain DQs. However, at 24 months of age, a 10-fold increase in BDE-99 levels was associated with a 2.16-point decrease [95% confidence interval (CI): -4.52, -0.20] in language domain DQs and a 10-fold increase in BDE-47 levels was associated with a 1.89-point decrease (95% CI: -3.75, -0.03) in social domain DQs. Prenatal exposure to PBDEs was associated with lower DQs in young children. The results contribute to the growing evidence that PBDEs could act as developmental neurotoxicants,and the findings have implications for children's environmental health in China.

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.

BDE-209 inhibits pluripotent genes expression and induces apoptosis in human embryonic stem cells

Decabromodiphenyl ether (BDE-209) has been detected in human serum, semen, placenta, cord blood and milk worldwide. However, little is known regarding the potential effects on the early human embryonic development of BDE-209. In this study, human embryonic stem cell lines FY-hES-10 and FY-hES-26 were used to evaluate the potential effects and explore the toxification mechanisms using low-level BDE-209 exposure. Our data showed that BDE-209 exposure (1, 10 and 100 nM) reduced the expression of pluripotent genes such as OCT4, SOX2 and NANOG and induced human embryonic stem cells (hESCs) apoptosis. The downregulation of BIRC5/BCL2 and upregulation of BAX were related to apoptosis of hESCs induced by BDE-209 exposure. A mechanism study showed that OCT4 down-regulation accompanied by OCT4 promoter hypermethylation and increasing miR-145/miR-335 levels, OCT4 inhibitors. Moreover, BDE-209 could increase the generation of intracellular reactive oxygen species (ROS) and decrease SOD2 expression. The ROS increase and OCT4 downregulation after BDE-209 exposure could be reversed partly by antioxidant N-acetylcysteine supplement. These findings showed that BDE-209 exposure could decrease pluripotent genes expression via epigenetic regulation and induce apoptosis through ROS generation in human embryonic stem cells in vitro.

Time trends of polybrominated diphenylether (PBDE) congeners in serum of Swedish mothers and comparisons to breast milk data

In the present study our main focus was blood serum levels and time trends of the fully brominated diphenyl ether (PBDE) BDE-209 in Swedish first-time mothers, as relatively a few human data on this congener are currently available. Also, levels and temporal trends in serum of other more commonly reported PBDE congeners and HBCD were studied. In an ongoing study on POPs in Uppsala Primiparas (POPUP), serum samples (N=413) from first-time mothers from 1996 to 2010 were used. Pooling of individual samples (5-25 individuals/pool, approx. 3 pools/year) resulted in 36 pooled samples used for PBDE/HBCD analysis on GC-LRMS. In addition, serum/breast milk correlations for PBDE and HBCD levels in 30 paired samples from individual mothers sampled 2010 were studied. The mean serum level of BDE-209 (1.3ng/g lipid wt.) was highest of all studied PBDE congeners, followed by BDE-47 and BDE-153. There was no significant temporal trend for BDE-209 during the study period, whereas the levels of BDE-47, BDE-99, BDE-100 and of HBCD decreased significantly in pooled serum 1996-2010. After omission of one outlier, a significant increasing trend was observed for BDE-153. The serum/milk PBDE quotients in paired individual samples from 2010 ranged from 0.83 to 17, with the highest quotient for BDE-209. Differences in PBDE transfer from blood to milk are probably related to molecular weight or size. The correlations between serum and milk levels of tetra- to hexa-brominated congeners were generally strong (r=0.83-0.97), but weaker for BDE-183 (r=0.57) and BDE-209 (r=0.38). Regarding HBCD, serum levels in 2010 were mostly beneath LOQ which made serum/milk quotients impossible. The decreasing levels of some BFR compounds in serum over time show that exposures have decreased after the production and use of some of these substances have been restricted. The lack of temporal trend of BDE-209 suggests that the human exposure to this congener in Sweden has been stable for more than a decade.

High exposure of California firefighters to polybrominated diphenyl ethers

Concern about persistent organic pollutants (POPs) in Californians prompted the state's biomonitoring program to conduct a study in firefighters, who are occupationally exposed to high levels of POPs. In this work we present serum concentrations of several classes of POPs (polybrominated diphenyl ethers [PBDEs], polychlorinated biphenyls [PCBs], and organochlorine pesticides [OCPs]) in 101 Southern California firefighters. Despite recently reported declining trends of PBDEs in Californians, high levels were measured in firefighters' serum (Σ5PBDEs: median = 59.1 ng/(g of lipid); range = 18.8-714 ng/(g of lipid)) in comparison to other populations in California during the same period. In addition, nearly one-third of subjects had particularly high serum levels of decabromodiphenyl ether (BDE-209), consistent with other recent results in firefighters; this pattern may be a marker of recent firefighting activity. In contrast, serum levels of PCBs and OCPs measured in firefighters' sera were not elevated compared to U.S. levels. Multivariable analysis indicated that lower levels of serum PBDEs were associated with turnout gear cleaning and storage practices after fires. Our study supports the hypothesis that firefighting activities are likely to increase exposure to PBDEs and that good housekeeping and personal hygiene practices may reduce exposure to these compounds.

Residue profiles of organohalogen compounds in human serum from e-waste recycling sites in North Vietnam: Association with thyroid hormone levels

This study demonstrated the contamination levels of polychlorinated biphenyls (PCBs), hydroxylated PCBs (OH-PCBs), polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), hydroxylated PBDEs (OH-PBDEs), and bromophenols (BPhs), and their relationships with thyroid hormones (THs), in the serum of human donors from an e-waste recycling site and a rural site in Hung Yen province, Vietnam. Occupationally related exposure was indicated by significantly higher residue levels of PCBs, OH-PCBs, PBDEs, and BPhs in the serum of donors from the e-waste recycling site (median: 420, 160, 290, and 300pgg(-1) wet wt, respectively) than those in the serum of donors from the rural site (median: 290, 82, 230, and 200pgg(-)(1) wet wt, respectively). On the other hand, levels of OH-/MeO-PBDEs were significantly higher in serum of donors from the reference site (median: 160 and 20pgg(-1) wet wt, respectively) than in those from the e-waste recycling site (median: 43 and 0.52pgg(-1) wet wt, respectively). In addition, we implemented stepwise generalized linear models to assess the association between the levels of TH and PCBs, PBDEs, and their related compounds. In females, we found positive associations of PCBs and OH-PCB concentrations with total thyroxine, free thyroxine, total triiodothyronine, and free triiodothyronine, and a negative association with thyroid-stimulating hormone concentrations.

Atmospheric PBDEs at rural and urban sites in central China from 2010 to 2013: residual levels, potential sources and human exposure

Atmospheric polybrominated diphenyl ethers (PBDEs) were monitored monthly from 2010 to 2013 at rural and urban sites near a large shallow Chinese lake (Lake Chaohu). The urban areas had higher air PBDEs than the rural areas because of endogenic pollution. The highest and lowest concentrations of Σ13BDEs were observed in the winter and in the summer, respectively. A weak temperature dependence and significant positive correlations between certain PBDE congeners and the PM10 (p < 0.01) suggest transport with particulate matter. Using air-mass back-trajectories, we determined that the main sources of the PBDEs were the areas to the north, such as Shandong Province, and to the east, such as Zhejiang Province. PBDEs did not pose an appreciable risk to human health based on the inhalation exposure assessment. The residents in urban areas were exposed to higher levels of PBDEs, and wintertime exposures posed the greatest human health risk.

Concentrations and relationships between classes of persistent halogenated organic compounds in pooled human serum samples and air from Laizhou Bay, China

Persistent halogenated organic compounds, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), pentabromobenzene (PBBz), and pentabromotoluene (PBT), were analyzed in pooled human serum samples from different age groups and air samples from the south coast of Laizhou Bay, Shandong Province, China. The ∑25OCP and ∑8PBDE congeners were found at higher concentrations than the other compounds, with mean concentrations of 1500 and 240ng/g lipid in serum and 330 and 140,000pg/m(3) in the air, respectively. PBBz and PBT were detected in every serum and air sample, with mean concentrations of 4.9 and 1.4ng/g lipid in serum and 100 and 250pg/m(3) in air, respectively. In serum, the mean concentrations of ∑14PCBs and ∑DP were 7.1 and 3.6ng/g lipid, respectively, and in air, the mean concentrations of ∑12dioxin-like (DL-) PCBs and ∑DP were 1.7 and 1.4pg/m(3), respectively. Different relationships were observed between the concentrations of different compounds in serum and the volunteers' ages, and the concentration distributions with age were closely related to the historic production and usage volumes of each chemical in China. The ubiquity of PCBs, OCPs, PBDEs, DP, PBBz, and PBT in serum and air is potentially concerning, and effective measures should be taken to control the concentrations of these chemicals in the environment and humans. Significant correlations were found between the chemical concentrations in serum and air, suggesting that inhalation may be an important exposure route for the residents of Laizhou Bay.

Effects of BDE-209 contaminated sediments on zebrafish development and potential implications to human health

Polybrominated diphenyl ethers are compounds widely used as flame-retardants, which are of increasing environmental concern due to their persistence, and potential adverse effects. This study had two objectives. First, we assessed if BDE-209 in sediment was bioavailable and bioaccumulated into zebrafish embryos. Secondly, we assessed the potential impact on human and environmental health of bioavailable BDE-209 using human in vitro cell assays and zebrafish embryos. Zebrafish were exposed from 4h to 8days post-fertilization to sediments spiked with 12.5mg/kg of BDE-209. Zebrafish larvae accumulated ten fold more BDE-209 than controls in unspiked sediment after 8days. BDE-209 impacted expression of neurological pathways and altered behavior of larvae, although BDE-209 had no visible affect on thyroid function or motoneuron and neuromast development. Zebrafish data and in silico predictions suggested that BDE-209 would also interact with key human transcription factors and receptors. We therefore tested these predictions using mammalian in vitro assays. BDE-209 activated human aryl hydrocarbon receptor, peroxisome proliferator activating receptors, CF/b-cat, activator protein 1, Oct-MLP, and the estrogen receptor-related alpha (ERRα) receptor in cell-based assays. BDE-209 also inhibited human acetylcholinesterase activity. The observation that BDE-209 can be bioaccumulated from contaminated sediment highlights the need to consider this as a potential environmental exposure route. Once accumulated, our data also show that BDE-209 has the potential to cause impacts on both human and environmental health.

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.

Elevated serum polybrominated diphenyl ethers and alteration of thyroid hormones in children from Guiyu, China

Informal electronic waste (e-waste) recycling results in serious environmental pollution of polybrominated diphenyl ethers (PBDEs) and heavy metals. This study explored whether there is an association between PBDEs, heavy metal and key growth- and development-related hormones in children from Guiyu, an e-waste area in southern China. We quantified eight PBDE congeners using gas chromatographic mass spectrometry, lead and cadmium utilizing graphite furnace atomic absorption spectrometry, three thyroids with radioimmunoassay and two types of growth hormones by an enzyme-linked immune-sorbent assay (ELISA) in 162 children, 4 to 6 years old, from Guiyu. In blood, median total PBDE was 189.99 ng/g lipid. Lead and cadmium concentrations in blood averaged 14.53±4.85 µg dL-1 and 0.77±0.35 µg L-1, respectively. Spearman partial correlation analysis illustrated that lead was positively correlated with BDE153 and BDE183. Thyroid-stimulating hormone (TSH) was positively correlated with almost all PBDE congeners and negatively correlated with insulin-like growth factor binding protein-3 (IGFBP-3), whereas free triiodothyronine (FT3) and free thyroxine (FT4) were negatively correlated with BDE154. However, no correlation between the hormones and blood lead or cadmium levels was found in this study. Adjusted multiple linear regression analysis showed that total PBDEs was negatively associated with FT3 and positively associated with TSH. Notably, FT4 was positively correlated with FT3, house functions as a workshop, and father's work involved in e-waste recycling and negatively correlated with vitamin consumptions. TSH was negatively related with FT4, paternal residence time in Guiyu, working hours of mother, and child bean products intake. IGFBP-3 was positively correlated with IGF-1 and house close to an e-waste dump. These results suggest that elevated PBDEs and heavy metals related to e-waste in Guiyu may be important risk factors for hormone alterations in children.

Concentrations and trends of halogenated flame retardants in the pooled serum of residents of Laizhou Bay, China

The south coast of Laizhou Bay, in northeastern China, is a production area for halogenated flame retardants (HFR). In 2007, the authors measured serum concentrations of polybrominated diphenyl ethers (PBDEs) in Laizhou Bay residents. To assess the PBDE concentration trend, and determine the concentrations of the emerging flame retardants Dechlorane Plus (DP) and bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH), the authors measured the concentrations of 8 PBDE congeners, 2 DP isomers, and TBPH in 10 composite samples, which were pooled from the serum collected from 305 Laizhou Bay residents in October 2011. The average concentration of the total PBDE (∑8 PBDE) concentration in all serum pools was 240 ng/g lipid weight, and the highest serum pool concentration (in the 30- to 39-yr-old male group) was 780 ng/g lipid weight. Brominated diphenyl ether-209 was the dominant congener, accounting for 87% of ∑8 PBDE. Compared with a previous study, ∑8 PBDE serum concentrations in the present study showed no change in order of magnitude, but the relative contribution of BDE-209 to ∑8 PBDE was higher. The average concentration of ∑DP in all serum pools was 3.6 ng/g lipid weight, ranging from 1.4 ng/g lipid weight (in the 50- to 59-yr-old male group) to 11 ng/g lipid weight (in the 20- to 29-yr-old male group). The concentration of DP was lower than in other reported studies. The study also detected TBPH in the 30- to 39-yr-old female group, suggesting that TBPH, as an emerging HFR, requires further monitoring.

Levels of tetrabromobisphenol A, hexabromocyclododecanes and polybrominated diphenyl ethers in human milk from the general population in Beijing, China

Three brominated flame retardants (BFRs), tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) and polybrominated diphenyl ethers (PBDEs), were measured in 103 human milk samples collected from Beijing in 2011. The donors' personal information, such as dietary habit and socioeconomic and lifestyle factors, was obtained by questionnaires. Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) analysis indicated that the levels of TBBPA ranged from <LOD to 12.46 ng g(-1) lipid weight (lw), with a median value of 0.10 ng g(-1) lw. Three HBCD diastereoisomers (α-, β- and γ-HBCD) were also measured using UPLC-MS/MS. The levels of ΣHBCDs ranged from <LOD to 78.28 ng g(-1) lw, with a median value of 2.40 ng g(-1) lw. α-HBCD was generally the most abundant of the three isomers. Eight PBDE congeners, BDE-28, 47, 99, 100, 153, 154, 183 and 209, were measured using gas chromatography coupled with a mass spectrometry (GC/MS). The concentrations of ΣPBDEs ranged from 0.22 to 135.41 ng g(-1) lw, with a median value of 3.24 ng g(-1) lw. BDE-209 dominated the PBDE profile in the majority of the human milk samples. The mean estimated daily intakes (EDIs) of TBBPA, ΣHBCDs and ΣPBDEs by breast-fed infants were 2.34, 24.89 and 71.27 ng kg(-1) bw day(-1), respectively. No significant correlation was found between the BFR levels in milk and the mother's diet, place of residence, smoking habit, nursing duration or computer use habit. In contrast, the mother's age, body mass index (BMI), education level and number of computers in the home were related to the levels of some types of BFRs. More research is needed to further investigate the major source(s) of exposure, the effect of each potential factor and the possible toxicological impact of high daily BFR intake on infants.

Inverse age-dependent accumulation of decabromodiphenyl ether and other PBDEs in serum from a general adult population

Polybromodiphenyl ethers (PBDEs), including the decabromodiphenyl congener (BDE-209), were determined in the serum of 731 individuals from a general adult population (18-74 years) collected in 2002 in Catalonia (north-eastern Spain). The BDE-209 was the predominant congener (median 3.7 ng/g lipid) followed by BDE-47 (2.6 ng/g lipid) and BDE-99 (1.2 ng/g lipid). PBDEs in this population (median 15.4 ng/g lipid) ranked amongst the highest of previously described concentrations in populations in Europe, Asia, New Zealand and Australia, yet it was lower than those found in North American reports. Age was clearly the socio-demographic factor of highest influence on the PBDE distributions. However, unlike usual trends of higher accumulation of POPs through age, the higher concentrations were found in young individuals (<30 years) rather than in adults (≥30 years), with differences of 14%, 31% and 46% in the most abundant congeners (i.e. BDE-209, BDE-99 and BDE-47, respectively). This age-dependent distribution of PBDEs (including the case for BDE-209, which is shown for the first time in this study) is explained by the higher and widespread use of these compounds since the 1980s. In view that these compounds remain highly used, this accumulation pattern is likely to evolve, anticipating an increasing level of PBDE concentrations in future general population surveys, yet probably assuming an age-dependent increase pattern. Socio-economic level was also a determinant of BDE-47 concentrations, but only relevant for the least affluent class, suggesting that lifestyle and environmental conditions in the dwelling place may also contribute to exposure. Nonetheless, gender, body mass index, place of birth, parity and education level did not show any statistically significant influence on the observed PBDE distributions.

Polybrominated diphenyl ethers fate in China: a review with an emphasis on environmental contamination levels, human exposure and regulation

Because of their highly effective flame-retardant capability, polybrominated diphenyl ethers (PBDEs) have been extensively used as flame retardants in consumer goods. However, compelling evidence shows that many congeners of PBDEs have been accumulating in the environment, in biota and in human populations worldwide. In China, although octabrominated diphenyl ether (octaBDE) has never been produced or used, pentabrominated diphenyl ether (pentaBDE) and decabrominated diphenyl ether (decaBDE) have been produced and used in large quantities. In the face of increasing evidence about PBDE pollution and the adoption of international conventions, there is a growing push for China to develop more stringent methods of managing PBDE waste. This paper summarizes the information about PBDE production and application, describes the flame-retarding mechanism, and then reviews the toxicity and levels of PBDEs in China's environmental media and human tissues. Based on international regulations on PBDEs, the paper finally puts forward some suggestions for Chinese policy making and for self-regulation within the flame retardant industry.

Partitioning of persistent organic pollutants (POPs) between human serum and breast milk: a literature review

The literature was reviewed to assess the relationship between the lipid adjusted concentration in human serum and breast milk (expressed as the serum/milk ratio) of a broad range of POPs in paired samples. Thirteen studies were identified, including seven studies that reported serum/milk ratios for polychlorinated dibenzo-dioxins and -furans (PCDD/Fs), ten for polychlorinated biphenyls (PCBs), five for polybrominated diphenyl ethers (PBDEs), and five for organochlorine pesticides (OCPs). Mean serum/milk ratios ranged between 0.7 and 25 depending on the compound and congener. For PCDD/Fs, PCBs and PBDEs, a clear trend of increasing mean serum/milk ratio by increasing molar volume, hydrophobicity and number of halogen substitutes was observed. The mean serum/milk ratios reported by the 13 studies summarized here will aid comparison between human POPs exposure studies using either serum or milk samples. More studies are needed to allow a valid comparison between data obtained from analysis of breast milk and serum samples for a broader range of POPs. Furthermore such studies may shed light on compound specific factors as well as other determinants that may affect the partitioning and partition kinetics of POPs between serum and breast milk.

Polybrominated diphenyl ethers in maternal serum, umbilical cord serum, colostrum and mature breast milk. Insights from a pilot study and the literature

Human serum and mother's milk are frequently used to assess exposure to polybrominated diphenyl ethers (PBDEs), including transplacental transfer to the foetus. However, little is known about the kinetics of PBDEs, especially the highly brominated BDE congeners. In this pilot study, maternal serum samples were collected from 10 women at delivery and five to six weeks post partum. Umbilical serum was also obtained. Milk was donated two to five days, and five to six weeks after delivery. The amount of PBDEs in these samples was determined using liquid-liquid extraction and GC/MS. Low, moderately and highly brominated diphenyl ethers were present in umbilical cord serum, indicating placental transfer. The lipid-adjusted levels of BDE-47, BDE-207 and BDE-209 were similar in maternal and umbilical cord serum, whereas the cord serum levels for the penta- to octa-BDEs quantified were lower than in maternal serum. Marked changes were seen in the congener pattern in breast milk during the first month of lactation, whereas maternal serum levels did not change significantly. The general pattern was an enrichment of low to moderately brominated congeners (i.e. from BDE-17 to BDE-154, with the exception of BDE-28) in colostrum compared with maternal serum. In contrast, more highly brominated congeners were found at similar, or lower levels in colostrum than in maternal serum. After the transition from colostrum to mature milk, the levels of BDE-153 and BDE-209 were substantially reduced, and BDE-209 was below the limit of detection in 6 out of 9 samples. A literature review on the design and reporting of studies on the transfer of PBDEs from mother to infant revealed a lack of transparency in many cases. The use of the recently published STROBE-ME guidelines is therefore recommended.