Brominated flame retardants in the Arctic environment--trends and new candidates

Polybrominated diphenyl ethers (PBDEs) in background air around the Aegean: implications for phase partitioning and size distribution

The occurrence and atmospheric behavior of tri- to deca-polybrominated diphenyl ethers (PBDEs) were investigated during a 2-week campaign concurrently conducted in July 2012 at four background sites around the Aegean Sea. The study focused on the gas/particle (G/P) partitioning at three sites (Ag. Paraskevi/central Greece/suburban, Finokalia/southern Greece/remote coastal, and Urla/Turkey/rural coastal) and on the size distribution at two sites (Neochorouda/northern Greece/rural inland and Finokalia/southern Greece/remote coastal). The lowest mean total (G + P) concentrations of ∑₇PBDE (BDE-28, BDE-47, BDE-66, BDE-99, BDE-100, BDE-153, BDE-154) and BDE-209 (0.81 and 0.95 pg m^-3, respectively) were found at the remote site Finokalia. Partitioning coefficients, K _P, were calculated, and their linear relationships with ambient temperature and the physicochemical properties of the analyzed PBDE congeners, i.e., the subcooled liquid pressure (P _L°) and the octanol-air partition coefficient (K _OA), were investigated. The equilibrium adsorption (P _L°-based) and absorption (K _OA-based) models, as well as a steady-state absorption model including an equilibrium and a non-equilibrium term, both being functions of log K _OA, were used to predict the fraction Φ of PBDEs associated with the particle phase. The steady-state model proved to be superior to predict G/P partitioning of BDE-209. The distribution of particle-bound PBDEs across size fractions < 0.95, 0.95-1.5, 1.5-3.0, 3.0-7.2, and > 7.2 μm indicated a positive correlation between the mass median aerodynamic diameter and log P _L° for the less brominated congeners, whereas a negative correlation was observed for the high brominated congeners. The potential source regions of PBDEs were acknowledged as a combination of long-range transport with short-distance sources.

Oxidation reactivity of 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) by Compound I model of cytochrome P450s

Alternative brominated flame retardants (BFRs) have become prevalent as a consequence of restrictions on the use of polybrominated diphenyl ethers (PBDEs). For risk assessment of these alternatives, knowledge of their metabolism via cytochrome P450 enzymes is needed. We have previously proved that density functional theory (DFT) is able to predict the metabolism of PBDEs by revealing the molecular mechanisms. In the current study, the reactivity of 1,2-bis(2,4,6-tribromophenoxy)ethane and structurally similar chemicals with the Compound I model representing the active site of P450 enzymes was investigated. The DFT calculations delineated reaction pathways which lead to reasonable explanations for products that were detected by wet experiments, meanwhile intermediates which cannot be determined were also proposed. Results showed that alkyl hydrogen abstraction will lead to bis(2,4,6-tribromophenoxy)ethanol, which may undergo hydrolysis yielding 2,4,6-tribromophenol, a neurotoxic compound. In addition, a general pattern of oxidation reactivity regarding the 2,4,6-tribromophenyl moiety was observed among several model compounds. Our study has provided insights for convenient evaluation of the metabolism of other structurally similar BFRs.

The presence and partitioning behavior of flame retardants in waste, leachate, and air particles from Norwegian waste-handling facilities

Flame retardants in commercial products eventually make their way into the waste stream. Herein the presence of flame retardants in Norwegian landfills, incineration facilities and recycling sorting/defragmenting facilities is investigated. These facilities handled waste electrical and electronic equipment (WEEE), vehicles, digestate, glass, combustibles, bottom ash and fly ash. The flame retardants considered included polybrominated diphenyl ethers (∑BDE-10) as well as dechlorane plus, polybrominated biphenyls, hexabromobenzene, pentabromotoluene and pentabromoethylbenzene (collectively referred to as ∑FR-7). Plastic, WEEE and vehicles contained the largest amount of flame retardants (∑BDE-10: 45,000-210,000μg/kg; ∑FR-7: 300-13,000μg/kg). It was hypothesized leachate and air concentrations from facilities that sort/defragment WEEE and vehicles would be the highest. This was supported for total air phase concentrations (∑BDE-10: 9000-195,000pg/m³ WEEE/vehicle facilities, 80-900pg/m³ in incineration/sorting and landfill sites), but not for water leachate concentrations (e.g., ∑BDE-10: 15-3500ng/L in WEEE/Vehicle facilities and 1-250ng/L in landfill sites). Landfill leachate exhibited similar concentrations as WEEE/vehicle sorting and defragmenting facility leachate. To better account for concentrations in leachates at the different facilities, waste-water partitioning coefficients, K_waste were measured (for the first time to our knowledge for flame retardants). WEEE and plastic waste had elevated K_waste compared to other wastes, likely because flame retardants are directly added to these materials. The results of this study have implications for the development of strategies to reduce exposure and environmental emissions of flame retardants in waste and recycled products through improved waste management practices.

Parallel in vivo and in vitro transcriptomics analysis reveals calcium and zinc signalling in the brain as sensitive targets of HBCD neurotoxicity

Hexabromocyclododecane (HBCD) is a brominated flame retardant (BFR) that accumulates in humans and affects the nervous system. To elucidate the mechanisms of HBCD neurotoxicity, we used transcriptomic profiling in brains of female mice exposed through their diet to HBCD (199 mg/kg body weight per day) for 28 days and compared with those of neuronal N2A and NSC-19 cell lines exposed to 1 or 2 µM HBCD. Similar pathways and functions were affected both in vivo and in vitro, including Ca²⁺ and Zn²⁺ signalling, glutamatergic neuron activity, apoptosis, and oxidative stress. Release of cytosolic free Zn²⁺ by HBCD was confirmed in N2A cells. This Zn²⁺ release was partially quenched by the antioxidant N-acetyl cysteine indicating that, in accordance with transcriptomic analysis, free radical formation is involved in HBCD toxicity. To investigate the effects of HBCD in excitable cells, we isolated mouse hippocampal neurons and monitored Ca²⁺ signalling triggered by extracellular glutamate or zinc, which are co-released pre-synaptically to trigger postsynaptic signalling. In control cells application of zinc or glutamate triggered a rapid rise of intracellular [Ca²⁺]. Treatment of the cultures with 1 µM of HBCD was sufficient to reduce the glutamate-dependent Ca²⁺ signal by 50%. The effect of HBCD on zinc-dependent Ca²⁺ signalling was even more pronounced, resulting in the reduction of the Ca²⁺ signal with 86% inhibition at 1 µM HBCD. Our results show that low concentrations of HBCD affect neural signalling in mouse brain acting through dysregulation of Ca²⁺ and Zn²⁺ homeostasis.

Toxic responses of Perna viridis hepatopancreas exposed to DDT, benzo(a)pyrene and their mixture uncovered by iTRAQ-based proteomics and NMR-based metabolomics

Dichlorodiphenyltrichloroethane (DDT) and benzo(a)pyrene (BaP) are environmental estrogens (EEs) that are ubiquitous in the marine environment. In the present study, we integrated isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic and nuclear magnetic resonance (NMR)-based metabolomic approaches to explore the toxic responses of green mussel hepatopancreas exposed to DDT (10μg/L), BaP (10μg/L) and their mixture. The metabolic responses indicated that BaP primarily disturbed energy metabolism and osmotic regulation in the hepatopancreas of the male green mussel P. viridis. Both DDT and the mixture of DDT and BaP perturbed the energy metabolism and osmotic regulation in P. viridis. The proteomic responses revealed that BaP affected the proteins involved in energy metabolism, material transformation, cytoskeleton, stress responses, reproduction and development in green mussels. DDT exposure could change the proteins involved in primary metabolism, stress responses, cytoskeleton and signal transduction. However, the mixture of DDT and BaP altered proteins associated with material and energy metabolism, stress responses, signal transduction, reproduction and development, cytoskeleton and apoptosis. This study showed that iTRAQ-based proteomic and NMR-based metabolomic approaches could effectively elucidate the essential molecular mechanism of disturbances in hepatopancreas function of green mussels exposed to environmental estrogens.

Relationships between POPs, biometrics and circulating steroids in male polar bears (Ursus maritimus) from Svalbard

The aim of this study was to determine the effects of persistent organic pollutants (POPs) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (Ursus maritimus) from Svalbard, Norway (n = 23). Levels of pregnenolone (PRE), progesterone (PRO), androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in polar bear serum by gas chromatography tandem mass spectrometry (GC-MS/MS), while POPs were measured in plasma. Subsequently, associations between hormone concentrations (9 steroids), POPs (21 polychlorinated biphenyls (PCBs), 8 OH-PCBs, 8 organochlorine pesticides (OCPs) and OCP metabolites, and 2 polybrominated diphenyl ethers (PBDEs)) and biological variables (age, head length, body mass, girth, body condition index), capture date, location (latitude and longitude), lipid content and cholesterol levels were examined using principal component analysis (PCA) and orthogonal projections to latent structures (OPLS) modelling. Average concentrations of androgens, estrogens and progestagens were in the range of 0.57-83.7 (0.57-12.4 for subadults, 1.02-83.7 for adults), 0.09-2.69 and 0.57-2.44 nmol/L, respectively. The steroid profiles suggest that sex steroids were mainly synthesized through the Δ-4 pathway in male polar bears. The ratio between androgens and estrogens significantly depended on sexual maturity with androgen/estrogen ratios being approximately 60 times higher in adult males than in subadult males. PCA plots and OPLS models indicated that TS was positively related to biometrics, such as body condition index in male polar bears. A negative relationship was also observed between POPs and DHT. Consequently, POPs and body condition may potentially affect the endocrinological function of steroids, including development of reproductive tissues and sex organs and the general condition of male polar bears.

Legacy and alternative halogenated flame retardants in human milk in Europe: Implications for children's health

In this study, 10 polybrominated diphenyl ethers (PBDEs) and 19 alternative halogenated flame retardants (AFRs) were determined in >450 human milk samples across three European countries, representing northern, western and eastern Europe. This study provides first insights into the occurrence of selected AFRs in mother milk samples and compares them among three European countries. Sums of median concentrations of the most frequently detected PBDEs were 2.16, 0.88 and 0.45ngg^-1 lipid weight (lw) in Norway, the Netherlands and Slovakia, respectively. The sum of the concentrations of AFRs ranged from 0.14 to 0.25ngg^-1lw in all countries, which was 2 to 15 times less compared to Σ₇PBDEs. The Penta-BDE replacement, bis(2-ethylhexyl) tetrabromophthalate, BEH-TEBP, was present at the greatest concentrations of any of the AFRs and in some samples exceeded concentrations of BDE 47 and BDE 153. Four AFRs including bromobenzenes (hexabromobenzene, pentabromobenzene, pentabromotoluene) and another Penta-BDE replacement (2-ethylhexyl-2,3,4,5-tetrabromobenzoate, EH-TBB) were detected in >42% of all human milk samples. Because of the potential developmental neurotoxicity of the halogenated flame retardants, infant dietary intakes via breastfeeding were estimated; in four cases the intakes of BDE 47 exceeded the reference dose indicating that the present concentrations may pose a risk for children.

Environmental exposure to a major urban wastewater effluent: Effects on the energy metabolism of northern pike

Municipal wastewater effluents (MWWEs) consist of dynamic and complex mixtures of chemical and biological compounds that can alter the health of exposed aquatic organisms. Disturbance of energy metabolism has been reported in fish exposed to MWWEs. However, there is a scarcity of knowledge on the physiological events leading to perturbation of energy balance and thyroid regulation, and associated lipid metabolism. The objective of the present study was to use a set of biomarkers, from gene transcription to body condition, to investigate the effects of a chronic environmental exposure to a major primary MWWE on fatty acid metabolism and thyroid hormone levels in northern pike (Esox lucius) collected from the St. Lawrence River near Montreal (QC, Canada). The exposure of pike to MWWE was examined through determination of a suite of persistent and bioaccumulative halogenated flame retardants in liver as this effluent is a known regional source for these chemicals. Greater hepatic concentrations of polybrominated diphenyl ethers (PBDEs, range: 29.6-465ng/g w.w. and 88.8-823ng/g w.w. in females and males, respectively) and other halogenated flame retardants (e.g., dechlorane-related compounds) were determined in fish collected downstream of the MWWE's point of discharge relative to the upstream site. This exposure in male pike was associated with decreased acyl-coA oxidase (acox1) and fatty acid synthase (fasn) mRNA levels as well as a decreased acyl-coA oxidase (ACOX) activity in liver. In female pike, MWWE exposure was associated with lower circulating free and total triiodothyronine (T₃) levels and a tendency for greater total lipid percentages in liver. Present findings provide evidence that chronic exposure of a top predator fish to MWWE can be related to gender-specific effects on fatty acid metabolism and thyroid hormone homeostasis, and highlight the need for further investigation.

Human Exposure to Legacy and Emerging Halogenated Flame Retardants via Inhalation and Dust Ingestion in a Norwegian Cohort

In this study, we estimated human exposure to polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), and several emerging flame retardants (EFRs) via inhalation and dust ingestion. Sixty indoor stationary air samples, 13 personal air samples, and 60 settled dust samples were collected from a Norwegian cohort during winter 2013. PBDEs showed the highest median concentration in dust (1200 ng/g), followed by EFRs (730 ng/g) and HBCDDs (190 ng/g). The PBDE concentrations in dust were mainly driven by BDE-209 and those of EFRs by bis(2-ethylhexyl) tetrabromophthalate. EFRs predominated in stationary air samples, with 2-ethylhexyl 2,3,4,5-tetrabromobenzoate and 4-(1,2-dibromoethyl)-1,2-dibromocyclohexane having the highest median concentrations (150 and 25 pg/m³ (sum of α- and β-isomers), respectively). Different profiles and concentrations were observed in personal air samples compared to the corresponding stationary air samples. In relation to inhalation exposure, dust ingestion appears to be the major exposure pathway to FRs (median total exposure 230 pg/kg bw/d, accounting for more than 65% of the total exposure) for the Norwegian cohort. The calculated exposure due to air inhalation was substantially lower when the stationary air concentrations were used rather than personal air concentrations (43 pg/kg bw/d versus 130 pg/kg bw/d). This suggests that other exposure situations (such as outdoors or in offices) contributed significantly to the overall personal exposure, which cannot be included by using only a stationary air sampling technique. The median and 95th percentile exposures for all target FRs did not exceed the reference dose.

Distribution of PBDEs, HBCDs and PCBs in the Brisbane River estuary sediment

To date, very little or no data exist in literature for some brominated flame retardants (BFRs) and polychlorinated biphenyls in Queensland sediments. These pollutants were measured in the sediments along the Brisbane River estuary. The target compounds were regularly detected in measurable concentrations: PBDEs=33.3-97.8% (n=45), PCBs=94.1-100% (n=51) and HBCDs=79-98% (n=48). Consistently, >90% of the observed ∑₈PBDE concentration was attributed to BDE-209. Mean PBDE levels (ng/g dry wt.) were: 4.4±3.2 (∑₈PBDE) and 4.4±3.0 (BDE-209) across 22 sampling sites. The mean ∑₇PCB and ∑HBCD were 5.4±4.5 and 1.0±1.5ng/g dry wt. respectively. The 25% (α-HBCD), 8% (β-HBCD) and 67% (γ-HBCD) diastereoisomer contributions observed were consistent with values reported in the literature. Contaminant levels are fairly distributed along the River and were generally low compared to similar studies around the world.

Temporal trends of PBDEs and emerging flame retardants in belugas from the St. Lawrence Estuary (Canada) and comparisons with minke whales and Canadian Arctic belugas

An exponential level increase of the ubiquitous halogenated flame retardant (HFR) class polybrominated diphenyl ether (PBDE) has been documented during the 1990s in endangered belugas (Delphinapterus leucas) from the St. Lawrence Estuary (SLE), Eastern Canada. The recent worldwide bans and regulations of PBDE mixtures led to their replacement by alternative HFRs (so-called emerging HFRs) that are increasingly being reported in various environmental compartments. There are, however, limited knowledge on the spatial and temporal trends of PBDEs and emerging HFRs in cetaceans, especially after restrictions on PBDE usage. The first objective of this study was to investigate the occurrence of HFRs (35 PBDE congeners and 13 emerging compounds) in the blubber of belugas and minke whales (Balænoptera acutorostrata) found dead in the Estuary or Gulf of St. Lawrence as well as belugas from Nunavik (Canadian Arctic) collected as part of the Inuit subsistence hunt. A second objective was to investigate the trends of HFR concentrations in SLE beluga males between 1997 and 2013. PBDEs were the most abundant HFRs in all three whale populations, while hexabromobenzene (HBB), Chlordene Plus (CPlus), Dechlorane Plus (DP), and Dechlorane 604 Component B (Dec-604 CB) were quantified in the majority of blubber samples. Overall, concentrations of emerging HFRs were notably greater in SLE belugas compared to the two other whale populations, with the exception of DP and Dec-604 CB that were found in greater concentrations in Canadian Arctic belugas. No significant trend in blubber PBDE concentrations was found in SLE belugas during this 17-year period. This suggests that global PBDE regulations are too recent to observe changes in PBDE concentrations in belugas from this highly HFR-exposed environment. In contrast, concentrations of HBB and CPlus in SLE belugas decreased slightly from 1997 to 2013, while DP increased up until 2000 and decreased slightly thereafter. The occurrence and temporal variations of PBDEs and their replacement products in these cetaceans warrant continuous monitoring.

The flame retardant DE-71 (a mixture of polybrominated diphenyl ethers) inhibits human differentiated thyroid cell function in vitro

BACKGROUND

Normal thyroid function is essential for general growth and metabolism, but can be affected by endocrine disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs) have been used worldwide to reduce flammability in different materials and are suspected to be EDCs. The production of the commercial Penta- and OctaBDE mixtures is banned, but DecaBDEs and existing products may leak PBDEs into the environment. Our aim was to investigate the effect of the PentaBDE mixture DE-71 on human thyroid cells in vitro.

MATERIALS AND METHODS

Primary human thyroid cells were obtained as paraadenomatous tissue and cultured in monolayers. The influence of DE-71 on cyclic adenosine monophosphate (cAMP) and thyroglobulin (Tg) production was examined in the culture medium by competitive radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Real-time quantitative PCR analysis of thyroid-specific genes was performed on the exposed cell cultures. PBDE concentrations were determined in cellular and supernatant fractions of the cultures.

RESULTS

DE-71 inhibited Tg-release from TSH-stimulated thyrocytes. At 50 mg/L DE-71, mean Tg production was reduced by 71.9% (range: 8.5-98.7%), and cAMP by 95.1% (range: 91.5-98.8%) compared to controls). Expression of mRNA encoding Tg, TPO and TSHr were significantly inhibited (p<0.0001, p = 0.0079, and p = 0.0002, respectively). The majority of DE-71 added was found in the cell fraction. No cytotoxicity was found.

CONCLUSIONS

DE-71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of Tg and cAMP production, respectively, as well as expression of mRNA encoding Tg, TPO and TSHr. Our findings suggest an inhibiting effect of PBDEs on thyroid cells.

The Toxic Effects of Tetrachlorobisphenol A in Saccharomyces cerevisiae Cells via Metabolic Interference

Tetrachlorobisphenol A (TCBPA) is a common flame retardant detected in different environments. However, its toxic effects on animals and humans are not fully understood. Here, the differential intracellular metabolites and associated gene expression were used to clarify the metabolic interference of TCBPA in Saccharomyces cerevisiae, a simple eukaryotic model organism. The results indicated that TCBPA treatment promoted the glycolysis pathway but inhibited the tricarboxylic acid (TCA) cycle, energy metabolism and the hexose monophosphate pathway (HMP) pathway. Thus, the HMP pathway produced less reducing power, leading to the accumulation of reactive oxygen species (ROS) and aggravation of oxidative damage. Accordingly, the carbon flux was channelled into the accumulation of fatty acids, amino acids and glycerol instead of biomass production and energy metabolism. The accumulation of these metabolites might serve a protective function against TCBPA stress by maintaining the cell membrane integrity or providing a stable intracellular environment in S. cerevisiae. These results enhance our knowledge of the toxic effects of TCBPA on S. cerevisiae via metabolic interference and pave the way for clarification of the mechanisms underlying TCBPA toxicity in animals and humans.

PBDEs and Dechloranes in Raccoons in the Midwestern United States

Raccoons (Procyon lotor) are one of the most widespread and abundant mammals in North America. To evaluate the suitability of using raccoons as bioindicator species, we analyzed liver tissues (n = 32) collected from 2013 to 2015 for the presence of polybrominated diphenyl ethers (PBDEs) and Dechloranes. ∑PBDE concentrations ranged from 19.1 to 2125 ng/g lw (median = 98.0 ng/g lw) and did not differ between gender or age of raccoon. Dechloranes were detected in 38% of raccoons and ranged from 0.15 to 50.4 ng/g lw (median = 2.32 ng/g lw). The comparatively high PBDE concentrations, and presence of Dechloranes in the raccoons in our study suggest that biota in terrestrial habitats are still widely exposed to and susceptible to the bioaccumulation of current and emerging flame retardants.

Effects of Hydroxylated Polybrominated Diphenyl Ethers in Developing Zebrafish Are Indicative of Disruption of Oxidative Phosphorylation

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have been detected in humans and wildlife. Using in vitro models, we recently showed that OH-PBDEs disrupt oxidative phosphorylation (OXPHOS), an essential process in energy metabolism. The goal of the current study was to determine the in vivo effects of OH-PBDE reported in marine wildlife. To this end, we exposed zebrafish larvae to 17 OH-PBDEs from fertilisation to 6 days of age, and determined developmental toxicity as well as OXPHOS disruption potential with a newly developed assay of oxygen consumption in living embryos. We show here that all OH-PBDEs tested, both individually and as mixtures, resulted in a concentration-dependant delay in development in zebrafish embryos. The most potent substances were 6-OH-BDE47 and 6'-OH-BDE49 (No-Effect-Concentration: 0.1 and 0.05 µM). The first 24 h of development were the most sensitive, resulting in significant and irreversible developmental delay. All substances increased oxygen consumption, an effect indicative of OXPHOS disruption. Our results suggest that the induced developmental delay may be caused by disruption of OXPHOS. Though further studies are needed, our findings suggest that the environmental concentrations of some OH-PBDEs found in Baltic Sea wildlife in the Baltic Sea may be of toxicological concern.

Distribution, isomerization and enantiomer selectivity of hexabromocyclododecane (HBCD) diastereoisomers in different tissue and subcellular fractions of earthworms

In this study, earthworms Eisenia fetida (E. fetida) were exposed to a soil artificially contaminated with individual hexabromocyclododecane (HBCD) diastereoisomers (α-, β- and γ-HBCDs) to investigate the distribution, isomerization and enantiomer selectivity of HBCDs at tissue and subcellular levels. At the tissue level, the concentrations of HBCDs all followed the order of gut>bodyfluid>body wall, which suggested that earthworms accumulated HBCDs mainly via ingesting soil particles. At the subcellular level, the concentrations of HBCDs in an extracellular fraction consisting of granules, tissue fragment, cell membrane and intact cells (fraction A) were higher than those in an intracellular fractions consisting of the microsomal and cytosol (fraction B+C). This confirmed the passive diffusion during the distribution of HBCDs into the intracellular compartment. The distribution proportions of HBCDs varied among different tissue and subcellular fractions, and all changed over time within 14 days. The variable distributions of HBCDs in different fractions were a result of the comprehensive effects of dynamics and thermodynamics processes. The β- and γ-HBCDs were isomerized to α-HBCD in all tissue and subcellular fractions except for fraction C, and the isomerization ratios varied a lot, which seemed to be related to HBCDs residence time. The selective enrichment of (-) α-, (-) β and (-) γ-HBCDs was found in all fractions and this is consistent with that in the whole earthworm. Besides, the extents of enantio-selectivity did not change significantly among different tissue and subcellular fractions.

Risk of POP mixtures on the Arctic food chain

The exposure of the Arctic ecosystem to persistent organic pollutants (POPs) was assessed through a review of literature data. Concentrations of 19 chemicals or congeneric groups were estimated for the highest levels of the Arctic food chain (Arctic cod, ringed seals, and polar bears). The ecotoxicological risk for seals, bears, and bear cubs was estimated by applying the concentration addition (CA) concept. The risk of POP mixtures was very low in seals. By contrast, the risk was 2 orders of magnitude higher than the risk threshold for adult polar bears and even more (3 orders of magnitude above the threshold) for bear cubs fed with contaminated milk. Based on the temporal trends available for many of the chemicals, the temporal trend of the mixture risk for bear cubs was calculated. Relative to the 1980s, a decrease in risk from the POP mixture is evident, mainly because of international control measures. However, the composition of the mixture substantially changes, and the contribution of new POPs (particularly perfluorooctane sulfonate) increases. These results support the effectiveness of control measures, such as those promulgated in the Stockholm Convention, as well as the urgent need for their implementation for new and emerging POPs. Environ Toxicol Chem 2017;36:1181-1192. © 2017 SETAC.

Polybrominated diphenyl ethers (PBDEs) effects on Chironomus sancticaroli larvae after short-term exposure

In-vivo effects of polybrominated diphenyl ethers (PBDEs) containing 3, 4 and 5 bromine atoms were tested on fourth-instar larvae of Chironomus sancticaroli (Diptera: Chironomidae) after 48h of exposure, by measuring the activity of the acetyl cholinesterase, alpha and beta esterases and glutathione S-transferase. The PBDE congeners 2,2',4-triBDE (BDE-17), 2,2',4,4'-tetraBDE (BDE-47) and 2,2',4,4',5-pentaBDE (BDE-99) were evaluated at 0.5, 1.0, 2.0 and 3.0ngmL^-1. Acetyl cholinesterase activity decreased significantly (p≤0.05) at all evaluated concentrations of the three PBDE congeners, except for larvae exposed to BDE-17 at 1.0 and 2.0ngmL^-1. The significant inhibition of acetyl cholinesterase activity ranged from 18% (BDE-47 at 0.5ngmL^-1) to 72% (BDE-47 at 2.0ngmL^-1). The enzymes alpha and beta esterase were also affected by the three congeners, reducing their activity from 14% (BDE-99 at 1.0ngmL^-1) to 52% (BDE-47 at 2.0ngmL^-1) and from 7% (BDE-99 at 2.0ngmL^-1) to 34% (BDE-47 at 3.0ngmL^-1) respectively. Substantial increments in glutathione S-transferase activity were similarly observed, varying from 138% (BDE-99 2.0 at ng mL^-1) to 346% (BDE-17 at 1.0ngmL^-1). DNA strand breaks were detected exclusively in larvae exposed to BDE-99 at 2.0 and 3.0ngmL^-1 (H=11.7, p=0.019). These results showed that C. sancticaroli larvae were sensitive to the PBDEs treatments under the experimental conditions.

Spatial and temporal trends of alternative flame retardants and polybrominated diphenyl ethers in ringed seals (Phoca hispida) across the Canadian Arctic

Concentrations of alternative flame retardants and polybrominated diphenyl ethers (PBDEs) were analyzed in ringed seal (Phoca hispida) blubber collected across the Canadian Arctic during subsistence hunts between 1998 and 2013. More than 80% of sampled animals were females and juvenile males. The highest mean ΣPBDE concentrations (sum of 13 congeners) were found in seals from Nain (Nunatsiavut) as well as Inukjuaq and Arviat (Hudson Bay) and the lowest mean levels were found in seals from Lancaster Sound. BDE-47 and -99 were the predominant PBDE congeners quantified in ringed seals. The most frequently detected non-PBDE flame retardants were polybrominated biphenyl 101 (BB-101, 57% of samples analyzed for this chemical), hexabromocyclododecane (HBCDD; 38%), hexabromobenzene (HBB, 30%), and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB, 23%). The relative trophic position of seals, estimated using stable isotopes, did not vary over time and did not influence flame retardant blubber concentrations. The relative carbon source increased over time at Arviat and Resolute Bay and weak relationships were observed with ΣPBDEs in blubber of seals. ΣPBDEs increased significantly from 1998 to 2008 in ringed seals from East Baffin and subsequently decreased in recent years. PBDE levels at other sites fluctuated slightly over time. HBCDD concentrations increased at several sites over the past decade. The presence of flame retardants in ringed seals suggests their persistence and their continuous inputs in the Canadian Arctic environment. Monitoring and research on the effects of these contaminants in seals are warranted given the importance of this species in Arctic marine food webs and for local communities.

Gene expression changes in immune response pathways following oral administration of tetrabromobisphenol A (TBBPA) in female Wistar Han rats

Tetrabromobisphenol A (TBBPA) is a brominated flame retardant used globally at high volumes, primarily in the epoxy resin of circuit boards. It has been detected in the environment and in humans. The National Toxicology Program found that chronic oral TBBPA treatment of 250mg/kg and higher caused an increased incidence of uterine lesions in female Wistar Han rats. The present laboratory has previously reported changes in gene expression associated with estrogen homeostasis in liver and uterine tissue of adult female Wistar Han rats after five days of gavage with 250mg/kg of TBBPA. Microarray analysis of tissue from these same TBBPA-treated rats was performed to detect additional pathways perturbed by TBBPA. Microarray analysis of uterine tissue detected downregulation of genes in pathways of the immune response following TBBPA treatment. These results, along with validation of associated gene expression changes using droplet digital PCR, are reported here. Our findings suggest mechanisms that may be related to estrogen-mediated immunosuppression.

Human Excretion of Polybrominated Diphenyl Ether Flame Retardants: Blood, Urine, and Sweat Study

Commonly used as flame retardants, polybrominated diphenyl ethers (PBDEs) are routinely detected in the environment, animals, and humans. Although these persistent organic pollutants are increasingly recognized as having serious health implications, particularly for children, this is the first study, to our knowledge, to investigate an intervention for human elimination of bioaccumulated PBDEs. Objectives. To determine the efficacy of blood, urine, and perspiration as PBDE biomonitoring mediums; assess excretion of five common PBDE congeners (28, 47, 99, 100, and 153) in urine and perspiration; and explore the potential of induced sweating for decreasing bioaccumulated PBDEs. Results. PBDE congeners were not found in urine samples; findings focus on blood and perspiration. 80% of participants tested positive in one or more body fluids for PBDE 28, 100% for PBDE 47, 95% for PBDE 99, and 90% for PBDE 100 and PBDE 153. Induced perspiration facilitated excretion of the five congeners, with different rates of excretion for different congeners. Conclusion. Blood testing provides only a partial understanding of human PBDE bioaccumulation; testing of both blood and perspiration provides a better understanding. This study provides important baseline evidence for regular induced perspiration as a potential means for therapeutic PBDE elimination. Fetotoxic and reproductive effects of PBDE exposure highlight the importance of further detoxification research.

Elevated Concentrations of 4-Bromobiphenyl and 1,3,5-Tribromobenzene Found in Deep Water of Lake Geneva Based on GC×GC-ENCI-TOFMS and GC×GC-μECD

We quantified the concentrations of two little-studied brominated pollutants, 1,3,5-tribromobenzene (TBB) and 4-bromobiphenyl (4BBP), in the deep water column and sediments of Lake Geneva. We found aqueous concentrations of 625 ± 68 pg L^-1 for TBB and 668 ± 86 pg L^-1 for 4BBP over a depth range of 70-191.5 m (near-bottom depth), based on duplicate measurements taken at five depths during three separate 1 month sampling periods at our sampling site near Vidy Bay. These levels of TBB and 4BBP were 1 or 2 orders of magnitude higher than the quantified aqueous concentrations of the components of the pentabrominated biphenyl ether technical mixture, which is a flame retardant product that had a high production volume in Europe before 2001. We observed statistically significant vertical concentration trends for both TBB and 2,2',4,4',6-pentabromobiphenyl ether in the deep water column, which indicates that transport and/or degradation processes affect these compounds. These measurements were enabled by application of a comprehensive two-dimensional gas chromatograph coupled to an electron capture negative chemical ionization time-of-flight mass spectrometer (GC×GC-ENCI-TOFMS) and to a micro-electron capture detector (GC×GC-μECD). GC×GC-ENCI-TOFMS and GC×GC-μECD were found to be >10× more sensitive toward brominated pollutants than conventional GC×GC-EI-TOFMS (with an electron impact (EI) ionization source), the latter of which had insufficient sensitivity to detect these emerging brominated pollutants in the analyzed samples. GC×GC also enabled the estimation of several environmentally relevant partitioning properties of TBB and 4BBP, further confirming previous evidence that these pollutants are bioaccumulative and have long-range transport potential.

Trophic transfer of hexabromocyclododecane in the terrestrial and aquatic food webs from an e-waste dismantling region in East China

Trophic transfer of hexabromocyclododecane (HBCD) was investigated in both the terrestrial and aquatic food webs from an e-waste dismantling region in East China. The mean Σ₃HBCD concentrations in the terrestrial species varied from 0.91 (0.16-1.85) ng g^-1 lipid weight (lw) in dragonflies (Pantala flavescens) to 40.3 (22.1-51.1) ng g^-1 lw in rats (Rattus norvegicus). The isomeric profile indicated that α-HBCD presented a decreasing trend along the trophic level (TL) (from 97.2% to 16.3% of Σ₃HBCDs), while γ-HBCD showed a reverse trend (from 2.8% to 73.6% of Σ₃HBCDs). The trophic magnification factor (TMF) derived from the slope of the regression line between TLs and ln-transferred Σ₃HBCDs was 0.10, suggesting a trophic dilution of HBCD in the terrestrial food web. By contrast, in the aquatic species, Σ₃HBCD concentrations varied from 5.02 (3.5-6.55) ng g^-1 lw in apple snails (Ampullaria gigas spix) to 45.9 (14.9-67.8) ng g^-1 lw in grass carps (Ctenopharyngodon idellus). α-HBCD was the dominant isomer, followed by γ-HBCD in the majority of species. A positive linear relationship was observed in the plots of ln Σ₃HBCDs versus TLs (R² = 0.81, p = 0.06). The TMF for Σ₃HBCDs was 6.36, indicating a trophic magnification of HBCD in the aquatic food web. Although these results demonstrated the distinct trophic transfer of Σ₃HBCDs in different ecosystems, further research is needed to eliminate the uncertainty of the tendencies, due to the non-significant relationship and limited species.

Effects of industrial processing on essential elements and regulated and emerging contaminant levels in seafood

Mitigation of contaminants in industrial processing was studied for prawns (cooked and peeled), Greenland halibut (cold smoked) and Atlantic salmon (cold smoked and trimmed). Raw prawns had significantly higher cadmium, chromium, iron, selenium and zinc content in autumn than in spring, while summer levels typically were intermediate. Peeling raw prawns increased mercury concentration but reduced the concentration of all other elements including inorganic arsenic, total arsenic, chromium, zinc, selenium but especially cadmium, copper and iron (p < 0.05), however interaction between seasons and processing was observed. Non-toxic organic arsenic in raw Greenland halibut (N = 10) and salmon (N = 4) did not transform to carcinogenic inorganic arsenic during industrial cold smoking. Hence inorganic arsenic was low (<0.003 mg/kg wet weight) in both raw and smoked fillets rich in organic arsenic (up to 9.0 mg/kg for farmed salmon and 0.7 mg/kg for wild caught Greenland halibut per wet weight). Processing salmon did not significantly change any levels (calculated both per wet weight, dry weight or lipid content). Cold smoking decreased total arsenic (17%) and increased PCB congeners (10-22%) in Greenland halibut (wet weight). However PFOS, PCB and PBDE congeners were not different in processed Greenland halibut when corrected for water loss or lipid content.

Screening for halogenated flame retardants in European consumer products, building materials and wastes

To fulfill national and international fire safety standards, flame retardants (FRs) are being added to a wide range of consumer products and building materials consisting of flammable materials like plastic, wood and textiles. While the FR composition of some products and materials has been identified in recent years, the limited global coverage of the data and the large diversity in consumer products necessitates more information for an overall picture of the FR composition in common products/materials. To address this issue, 137 individual samples of various consumer products, building materials and wastes were collected. To identify and characterize potential sources of FRs in indoor environment, all samples were analyzed for content of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs) and novel flame retardants (NFRs). The most frequently detected were HBCDDs (85%), with the highest median concentration of Σ₄HBCDDs of 300 mg kg^-1 in polystyrenes. The highest median concentration of Σ₁₀PBDEs was found in recycled plastic materials, reaching 4 mg kg^-1. The lowest concentrations were observed for NFRs, where the median of Σ₁₂NFRs reached 0.4 mg kg^-1 in the group of electrical & electronic equipment wastes. This suggests that for consumer products and building materials that are currently in-use, legacy compounds still contribute to the overall burden of FRs. Additionally, contrasting patterns of FR composition in recycled and virgin plastics, revealed using principle component analysis (PCA), suggest that legacy flame retardants are reentering the market through recycled products, perpetuating the potential for emissions to indoor environments and thus for human exposure.

Halogenated flame retardants in bobcats from the midwestern United States

In response to the restrictions of polybrominated diphenyl ether (PBDE) flame retardants in various consumer products, alternative halogenated flame retardants have been subjected to increased use. Compared to aquatic ecosystems, relatively little information is available on the contamination of alternative flame retardants in terrestrial ecosystems, especially with regards to mammalian wildlife. In this study we used a top terrestrial carnivore, the bobcat (Lynx rufus), as a unique biomonitoring species for assessing flame retardant contamination in the Midwestern United States (U.S.) terrestrial ecosystems. Concentrations of ∑PBDEs (including all detectable PBDE congeners) ranged from 8.3 to 1920 ng/g lipid weight (median: 50.3 ng/g lw) in livers from 44 bobcats collected during 2013-2014 in Illinois. Among a variety of alternative flame retardants screened, Dechloranes (including anti- and syn-Dechlorane Plus and Dechlorane-602, 603, and 604), tetrabromo-o-chlorotoluene (TBCT), and hexabromocyclododecane (HBCD) were also frequently detected, with median concentrations of 28.7, 5.2, and 11.8 ng/g lw, respectively. Dechlorane analogue compositions in bobcats were different from what has been reported in other studies, suggesting species- or analogue-dependent bioaccumulation, biomagnification, or metabolism of Dechlorane chemicals in different food webs. Our findings, along with previously reported food web models, suggest Dechloranes may possess substantial bioaccumulation and biomagnification potencies in terrestrial mammalian food webs. Thus, attention should be given to these highly bioavailable flame retardants in future environmental biomonitoring and risk assessments in a post-PBDE era.

Review of contamination of sewage sludge and amended soils by polybrominated diphenyl ethers based on meta-analysis

Polybrominated diphenyl ethers (PBDEs) are still present in sewage sludge and sludge-amended soil, even though commercial PBDEs were prohibited or voluntarily phased out several years ago. In this study, levels and compositional profiles of seven major PBDE congeners in sludge are assessed in relation to their usage patterns in commercial products, and years of being banned and phased out in North America, Europe, and Asia. Annual accumulations and future long-term changes of PBDE in sludge-amended soil are estimated. BDE-209 has the highest concentration, followed by BDE-99 and BDE-47. The highest concentrations, up to 23,500 ng g^-1, of PBDEs in sludge were found in North America until 2004-2007, whereas since then sludge PBDE concentrations, up to 6600 ng g^-1 have been higher in Asia than on the other two continents. The amount of sludge applied and the soil organic matter content play important roles in determining PBDE concentrations in sludge-amended soil. The estimated concentrations of BDE-47, -99, and -209 in soils receiving sludge applications during the past 15 years are 40-300 times higher than in soils after the initial sludge application. The accumulated concentrations of BDE-47 and BDE-99 are expected to decrease by 99% between 2016 and 2100, whereas the decrease in the BDE-209 concentration is predicted to be approximately 87%.

Atmospheric chemical reaction mechanism and kinetics of 1,2-bis(2,4,6-tribromophenoxy)ethane initiated by OH radical: a computational study

The mechanism and kinetics of OH-initiated oxidation of BTBPE, an alternative of PBDEs, were investigated.

Legacy and emerging flame retardants (FRs) in the freshwater ecosystem: A review

In this review article, we have compiled and reviewed the previously published available literature on environmental distribution, behaviour, fate and regional trends of legacy and emerging flame retardants (FRs) including brominated (BFRs), organo-phosphate (OPFRs), novel brominated flame retardants (NBFRs) and dechlorane plus (DP) in the freshwater ecosystem. Transport and fate is discussed briefly with the evidences of de-bromination, sedimentation and accumulation in biota. De-bromination of BDE-209 is considered of concern because the lower brominated congeners are more toxic and mobile thus posing increased risk to the freshwater ecosystem. The available data on temporal and spatial trends as yet, is too few to show any consistent trends, enabling only general conclusions to be drawn. There is a lack of temporal studies in Asia, while, overall the trends are mixed, with both increasing and decreasing concentrations of BFRs and OPFRs. OPFRs and NBFRs have replaced classical BFRs (polybrominated diphenyl ethers (PBDEs)) in some countries but the amount of PBDEs in the environment is still considerable. Knowledge gaps and recommendations for future research are discussed emphasizing on further monitoring, advanced analytical methodologies, and risk assessment studies to completely understand the science of flame retardants in the freshwater ecosystem.

Bioaccumulation of PCBs in a Wild North American Felid

Organohalogenated compounds (OHCs) such as polychlorinated biphenyls (PCBs) are of global concern due to their environmental persistence, bioaccumulative potential, and adverse effects on humans and wildlife. We investigated the concentrations of PCBs in the liver tissues of bobcats (Lynx rufus) sampled in Illinois during 2013. Concentrations of ∑PCBs ranged from 76.4 to 3782 ng/g lw (median 562.97 ng/g lw). Male bobcats had significantly greater concentrations of PCBs than females (p = 0.04). Ours is one of the first studies to report PCBs in a wild North American felid. We suggest that bobcats can be used as a suitable bioindicator species to monitor organohalogen contamination in terrestrial ecosystems.

Degradation of Polymeric Brominated Flame Retardants: Development of an Analytical Approach Using PolyFR and UV Irradiation

Many well-established methods for studying the degradation of brominated flame retardants are not useful when working with polymeric and water insoluble species. An example for this specific class of flame retardants is PolyFR (polymeric flame retardant; CAS No 1195978-93-8), which is used as a substituent for hexabromocyclododecane. Although it has been on the market for two years now, almost no information is available about its long time behavior in the environment. Within this study, we focus on how to determine a possible degradation of both pure PolyFR as well as PolyFR in the final insulation product, expanded polystyrene foam. Therefore, we chose UV radiation followed by analyses of the total bromine content at different time points via ICP-MS and identified possible degradation products such as 2,4,6-tribromophenol through LC-MS. These results were then linked with measurements of the adsorbable organically bound bromine and total organic carbon in order to estimate their concentrations. With respect to the obtained ¹H NMR, GPC, and contact angle results, the possibility for further degradation was discussed, as UV irradiation can influence the decomposition of molecules in combination with other environmental factors like biodegradation.

Critical review of the analysis of brominated flame retardants and their environmental levels in Africa

World-wide, the prevalence of brominated flame retardants (BFRs) is well documented for routine analysis of environmental and biological matrices. There is, however, limited information on these compounds in the African environment and insufficient information on the analytical approaches used to obtain data. This paper presents a review on BFR levels in the African environment and the various analytical methodologies specifically applied in Africa for polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls and alternative-BFRs. The analyses include liquid sample preparation using liquid-liquid and solid phase extraction and solid sample preparation involving Soxhlet extraction, with ultrasound-assisted extraction increasingly being applied. Instrumental detection techniques were limited to gas chromatography coupled with electron capture detector and electron impact ionisation with single quadrupole mass spectrometers. Information on congener profile prevalence in indoor dust, soil, aquatic environment (water, sediment, and aquatic organisms), eggs, wastewater treatment plant compartments, landfills (leachate and sediment) and breast milk are presented. Although PBDEs were inconsistently detected, contamination was reported for all investigated matrices in the African environment. The manifestation in remote regions indicates the ubiquitous prevalence and long-range transport of these compounds. Levels in sediment, and breast milk from some African countries were higher than reported for Asia and Europe. Due to limited data or non-detection of alternative-BFRs, it is unclear whether banned formulations were replaced in Africa. Most of the data reported for BFR levels in Africa were obtained in non-African laboratories or in South Africa and formed the basis for our discussion of reported contamination levels and related methodologies.

Species-specific accumulation of polybrominated diphenyl ethers (PBDEs) and other emerging flame retardants in several species of birds from Korea

Few studies have been conducted on the alternatives to legacy flame retardants in avian species worldwide. In this study, polybrominated diphenyl ethers (PBDEs) and alternative flame retardants such as novel brominated flame retardants (NBFRs) and dechlorane plus (DP) were determined in livers of 10 species of birds from Korea to elucidate species-specific accumulation, biological factors that affect accumulation, and bioaccumulation potentials of these contaminants. Among the emerging alternative flame retardants, the highest occurrence was found for bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEHTBP), syn-DP, anti-DP, and decabromodiphenyl ethane (DBDPE). PBDE concentrations (median: 17.1 ng/g lipid wt) measured in our study were within the ranges reported in previous studies, while the concentrations of BEHTBP, BTBPE and DP were greater than those reported earlier. Residential predatory birds showed significantly greater concentrations of PBDEs and NBFRs than migratory predators and passerine birds. The concentrations of PBDEs, BEHTBP, and DP in residential predatory birds were significantly correlated with increasing stable nitrogen isotope ratio (δ¹⁵N), which indicated biomagnification potentials of these contaminants. Our results suggest that the concentrations and accumulation patterns of PBDEs, NBFRs, and DP depend on the feeding habits and migration patterns of avian species. This is the first report on the accumulation of emerging alternatives to PBDEs in birds from Korea.

Emission patterns and risk assessment of polybrominated diphenyl ethers and bromophenols in water and sediments from the Beijiang River, South China

To reveal the emission patterns of brominated flame retardants (BFRs) in the Beijiang River, South China, concentrations of polybrominated diphenyl ethers (PBDEs) and phenolic BFRs (2,4,6-tribromophenol (TBP), pentabromophenol (PeBP), tetrabromobisphenol A (TBBPA)), and bisphenol A (BPA) in water and sediments were simultaneously measured, and the geographic information system (GIS) were applied to analyse their emission patterns. Results showed that PBDEs, TBP, PeBP, TBBPA and BPA were ubiquitous in the water and sediment samples collected from the Beijiang River. However, most of the concentrations were very low or below the detection limits (DL). In water, Σ₂₀PBDEs (sum of all 20 PBDEs congeners) levels ranged from < DL to 232 pg L^-1, with the predominant congeners containing low bromine contents. The levels of TBP, PeBP, TBBPA and BPA in water were lower than 810 pg L^-1. In sediments, Σ₂₀PBDEs varied from 260 to 5640 pg g^-1 dry weight (d.w.), with the predominant congeners containing high bromine contents. The levels of TBP, PeBP, TBBPA and BPA were lower than 600 pg g^-1 d.w.. Risk assessments indicated that the water and sediments at the sampling locations imposed no estrogenic risk (E₂EQ < 1.0 ng E₂ L^-1), and the eco-toxicity assessment at three trophic levels also showed no risk at all sampling sites in water (RQ_Total < 1.0), but with a potential eco-toxicity at some sampling points in sediments (1.0<RQ_Total < 10.0).

Widespread polybrominated diphenyl ether (PBDE) contamination of urban soils in Melbourne, Australia

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in a variety of materials and products. PBDEs have been shown to accumulate in the environment and human populations while exhibiting a range of toxic effects. In this study, surface soil samples from 30 sites in the city of Melbourne, Australia, were analysed for PBDEs. Eight congeners of environmental concern (BDE-28, -47, -99, -100, -153, -154 -183 and -209) were assessed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS). PBDEs were detected in 29/30 samples with Σ₈PBDE soil concentrations ranging nd-13,200 ng/g dw and Σ₇PBDEs (excluding BDE-209) levels of nd-70.5 ng/g dw. Soils from waste disposal sites (n = 6) contained the highest median Σ₇PBDE and Σ₈PBDE concentrations, followed by manufacturing sites (n = 18) and then non-source sites (n = 6). Electronics recycling facilities contained the greatest levels of Σ₈PBDEs by a significant margin (p < 0.05) to indicate that these industries are a potential source of contamination. BDE-209 was the dominant congener, contributing an average of 75.5% to Σ₈PBDEs soil concentrations, followed by BDE-47, BDE-99 and BDE-183 at 7.90, 5.64 and 4.31%, respectively. Congener profiles reflected global estimates of Deca-BDE, Octa-BDE and Penta- BDE commercial production, with the most significant congener correlation existing between BDE-47 and BDE-99 (p < 0.001, r = 0.943). This first assessment of PBDEs in Melbourne soils indicates widespread contamination of the urban environment, including locations where direct sources to soil are not clear.

Brominated flame retardants in placental tissues: associations with infant sex and thyroid hormone endpoints

BACKGROUND

Brominated flame retardants (BFRs) are endocrine disruptors that bioaccumulate in the placenta, but it remains unclear if they disrupt tissue thyroid hormone (TH) metabolism. Our primary goal was to investigate associations between placental BFRs, TH levels, Type 3 deiodinase (DIO3) activity and TH sulfotransferase (SULT) activities.

METHODS

Placenta samples collected from 95 women who delivered term (>37 weeks) infants in Durham, NC, USA (enrolled 2010-2011) were analyzed for polybrominated diphenyl ethers (PBDEs), 2,4,6-tribromophenol (2,4,6-TBP), THs (T4, T3 and rT3), and DIO3 and TH SULT activities.

RESULTS

PBDEs and 2,4,6-TBP were detected in all placenta samples. PBDEs were higher in placental tissues from male infants compared to female infants, with 2,4,6-TBP and BDE-209 levels approximately twice as high. Among male infants, placental BDE-99 and BDE-209 were negatively associated with rT3 placental levels. For female infants, placental BDE-99 and 2,4,6-TBP were positively associated with T3 concentrations. DIO3 activity was also significantly higher in placental tissues from male infants compared to females, while 3,3'-T2 SULT activity was significantly higher in placental tissues from females compared to males. Among males, several PBDE congeners were positively correlated with T3 SULT, while BDE-99 was negatively associated with T3 SULT among females. Associations generally remained after adjustment for potential confounding by maternal age and gestational age at delivery.

CONCLUSIONS

These results suggest BFRs accumulate in the placenta and potentially alter TH function in a sex-specific manner, a possible mechanism to explain the sex-dependent impacts of environmental exposure on children's growth and development. More research is needed to elucidate the effects of BFRs on placenta function during pregnancy, as well as the biological consequences of exposure and thyroid disruption.

Overview on relative importance of house dust ingestion in human exposure to polybrominated diphenyl ethers (PBDEs): International comparison and Korea as a case

Human exposure studies to polybrominated diphenyl ethers (PBDEs) have reached different results about the relative importance of diet intake and house dust ingestion. In the present study, concentrations of PBDEs in Korean house dust (n=15) from geographically different cities were measured, which were in agreement with a previous result, and compared with those for 22 countries of five continents collected from the most recent scientific literature. Compared with other exposure pathways, diet intake was the most important contributor to total PBDEs exposure of Korean adults (i.e., 71% of overall intake). On global comparison, total PBDE levels in house dust differed by two to three orders of magnitude among the countries investigated, with a significant relationship with gross domestic product (GDP). Whereas, dietary daily intakes exhibited a narrow difference within one order of magnitude worldwide and no relationship with GDP. Consequently, the relative importance of major two pathways depended on the contamination extent of PBDEs in house dust, which may be associated with the amount of PBDE products in use. In most countries except for UK and USA, the contribution of house dust ingestion was less important than diet intake in the current and are expected to much more mitigate in the future. However, how fast the effect of regulation will be reflected to house dust and human exposure is necessary to be monitored steadily.

Seasonal accumulation of persistent organic pollutants on a high altitude glacier in the Eastern Alps

The seasonal accumulations of perfluorinated substances (PFAS), polybrominated diphenyl ethers (PBDE) and polycyclic aromatic hydrocarbons (PAH) were measured in a 10 m shallow firn core from a high altitude glacier at Mt. Ortles (Italy, 3830 m above sea level) in South Tyrol in the Italian Eastern Alps. The most abundant persistent organic pollutants of each group were perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) (for PFASs); BDE 47, BDE 99, BDE 209 (for PBDEs) and phenanthrene (PHE), fluoranthene (FLA) and pyrene (PYR) (for PAHs). All compounds show different extents of seasonality, with higher accumulation during summer time compared to winter. This seasonal difference mainly reflects meteorological conditions with a low and stable atmospheric boundary layer in winter and strong convective activity in summer, transformation processes during the transport of chemicals and/or post-depositional alterations. Change in the composition of the water-soluble PFCAs demonstrates the influence of meltwater percolation through the firn layers.

The Role of Ca2+ Imbalance in the Induction of Acute Oxidative Stress and Cytotoxicity in Cultured Rat Cerebellar Granule Cells Challenged with Tetrabromobisphenol A

Using primary cultures of rat cerebellar granule cells (CGC) we examined the role of calcium transients induced by tetrabromobisphenol A (TBBPA) in triggering oxidative stress and cytotoxicity. CGC were exposed for 30 min to 10 or 25 µM TBBPA. Changes in intracellular calcium concentration ([Ca²⁺]_i), in the production of reactive oxygen species (ROS), and in the potential of mitochondria (∆Ψm) were measured fluorometrically during the exposure. The intracellular glutathione (GSH) and catalase activity were determined after the incubation; cell viability was evaluated 24 h later. TBBPA concentration-dependently increased [Ca²⁺]_i and ROS production, and reduced GSH content, catalase activity, ∆Ψm and neuronal viability. The combination of NMDA and ryanodine receptor antagonists, MK-801 and bastadin 12 with ryanodine, respectively, prevented Ca²⁺ transients and partially reduced cytotoxicity induced by TBBPA at both concentrations. The antagonists also completely inhibited oxidative stress and depolarization of mitochondria evoked by 10 µM TBBPA, whereas these effects were only partially reduced in the 25 µM TBBPA treatment. Free radical scavengers prevented TBBPA-induced development of oxidative stress and improved CGC viability without having any effect on the rises in Ca²⁺ and drop in ∆Ψm. The co-administration of scavengers with NMDA and ryanodine receptor antagonists provided almost complete neuroprotection. These results indicate that Ca²⁺ imbalance and oxidative stress both mediate acute toxicity of TBBPA in CGC. At 10 µM TBBPA Ca²⁺ imbalance is a primary event, inducing oxidative stress, depolarization of mitochondria and cytotoxicity, whilst at a concentration of 25 µM TBBPA an additional Ca²⁺-independent portion of oxidative stress and cytotoxicity emerges.

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.

Concentrations of organochlorine pesticides, polybrominated diphenyl ethers and perfluorinated compounds in the atmosphere of North Greenland

Atmospheric concentrations of organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs) and neutral per- and polyfluoroalkyl substances (PFAS) have been measured at Villum Research Station, Station Nord (North Greenland) in the period 2008-2013. Atmospheric concentrations of OCPs at the same site have been previously reported for the years 2008-2010. The detection frequency and the average concentrations of OCPs have not significantly changed since the previous study. PBDE congeners (∑13PBDEs) were measured for the first time in North Greenland at concentrations similar to those observed for other remote sites, confirming that these compounds are ubiquitous in the Northern Hemisphere. The ∑13PBDEs concentration ranged from not detected (n.d.) to 6.26 pg m(-3). The BDE congeners found in more than 30% of the samples were BDE-17, BDE-28, BDE-47, BDE-71, BDE-99 and BDE-100. Also for neutral PFAS we present for the first time a multiyear series of measurements for North Greenland. The average sum of the seven measured neutral PFAS (∑7PFAS) ranged from 1.82 to 32.1 pg m(-3). The most abundant compound was 8:2 FTOH (44% of ∑7PFAS), followed by 6:2 FTOH and 10:2 FTOH. Perfluoroalkyl sulfonamides (FOSA) and perfluoroalkyl sulfonamidoethanols (FOSE) were also detected but at much lower concentrations than FTOHs. Temporal trends were investigated for all measured compounds but no significant trend in concentration was observed. Monthly average concentrations for the six years were calculated for each compound and the seasonal variation was investigated. Some OCPs and FTOHs showed seasonal variations, and in most cases a maximum was found during summer.

Trematomus bernacchii as an indicator of POP temporal trend in the Antarctic seawaters

The occurrence of POPs in remote areas, such as Antarctica, is the result of their ability to udergo Long Range Transport (LRT) in the atmosphere, precipitation and cold condensation. In this study, both recent levels of various POPs in Trematomus bernacchii and their changes in roughly three decades were determined in order to evaluate trends of POPs in Antarctic benthic seawaters. In fact, Trematomus bernacchii is considered a good sentinel bio-indicator for monitoring not only the extent of contamination by POPs in the Antarctic aquatic ecosystem, but also changes in Antarctic ecosystem quality and trends. A slight decreasing PCB trend was detected during 30-years time span (from early 1980's to 2010) in the circumantarctic seawaters. Two higher peaks of concentrations were reported in 2001 and 2005 in the Ross Sea and they may reflect the ice melting of icebergs. Because fire risk is very high in Antarctica due to the very dry air, a large use of flame retardants in buildings and furniture of stations is highly probable; moreover, many stations were built when there were no restrictions on flame retardants use. The PBDE levels in the T. bernacchii from 2001 to 2011 ranged 0.05-0.35 pg/g and were of the same order of magnitude in 2001/2011 and in 2002/2005, with a maximum value in 2005 (0.35 pg/g). Comparable concentrations of HCB, HCHs PCDDs and PCDFs are available only for few seasons: all these compounds showed a decreasing temporal trends and their concentrations were one or more order of magnitude lower in 2000s-2010s.