Distribution and fate of HBCD and TBBPA brominated flame retardants in North Sea estuaries and aquatic food webs

Neurotoxicity of the pentabrominated diphenyl ether mixture, DE-71, and hexabromocyclododecane (HBCD) in rat cerebellar granule cells in vitro

Polybrominated diphenyl ethers (PBDE) and hexabromocyclododecane (HBCD) are compounds used as additive flame retardants in plastics, electronic equipment, and textiles. The aim of the present study was to investigate the in vitro effects of the pentabrominated diphenyl ether mixture, DE-71, and HBCD on cerebellar granule cells (CGC). Both DE-71 and HBCD induced death of CGC in low micromolar concentrations. The NMDA receptor antagonist MK801 (3 microM), and the antioxidant alpha-tocopherol (50 microM) significantly reduced the cell death. Incubation of the compounds together with the rat liver post-mitochondrial (S9) fraction reduced cell death by 58 and 64% for DE-71 and HBCD, respectively. No ROS formation and no elevation in intracellular calcium were observed. We further demonstrated apoptotic morphology (Hoechst straining) after exposure to low levels of the two brominated flame retardants and signs of DNA laddering were found after DE-71 exposure. However, other hallmarks of apoptosis, like caspase activity, were absent indicating an atypical form of apoptosis induced by DE-71. After intraperitoneal injection of the two compounds both DE-71 and HBCD were found in significant amounts in brain (559 +/- 194 and 49 +/- 13 microg/kg, respectively) and liver (4,010 +/- 2,437 and 1,248 +/- 505 microg/kg, respectively) 72 h after injection. Our results indicate that the lower brominated PBDEs have a higher potency of bioaccumulation than HBCD, and that both compounds have a neurotoxic potential in vitro.

In Vitro Profiling of the Endocrine-Disrupting Potency of Brominated Flame Retardants

Over the last few years, increasing evidence has become available that some brominated flame retardants (BFRs) may have endocrine-disrupting (ED) potencies. The goal of the current study was to perform a systematic in vitro screening of the ED potencies of BFRs (1) to elucidate possible modes of action of BFRs in man and wildlife and (2) to classify BFRs with similar profiles of ED potencies. A test set of 27 individual BFRs were selected, consisting of 19 polybrominated diphenyl ether congeners, tetrabromobisphenol-A, hexabromocyclododecane, 2,4,6-tribromophenol, ortho-hydroxylated brominated diphenyl ether 47, and tetrabromobisphenol-A-bis(2,3)dibromopropyl ether. All BFRs were tested for their potency to interact with the arylhydrocarbon receptor, androgen receptor (AR), progesterone receptor (PR), and estrogen receptor. In addition, all BFRs were tested for their potency to inhibit estradiol (sulfation by estradiol sulfotransferase (E2SULT), to interfere with thyroid hormone 3,3',5-triiodothyronine (T3)-mediated cell proliferation, and to compete with T3-precursor thyroxine for binding to the plasma transport protein transthyretin (TTR). The results of the in vitro screening indicated that BFRs have ED potencies, some of which had not or only marginally been described before (AR antagonism, PR antagonism, E2SULT inhibition, and potentiation of T3-mediated effects). For some BFRs, the potency to induce AR antagonism, E2SULT inhibition, and TTR competition was higher than for natural ligands or clinical drugs used as positive controls. Based on their similarity in ED profiles, BFRs were classified into five different clusters. These findings support further investigation of the potential ED effects of these environmentally relevant BFRs in man and wildlife.

Levels of the flame retardants hexabromocyclododecane and tetrabromobisphenol A in the blubber of harbor porpoises (Phocoena phocoena) stranded or bycaught in the U.K., with evidence for an increase in HBCD concentrations in recent years

Within the U.K. Marine Mammals Stranding Program, analysis of brominated flame retardants began in 1999. Initially, the focus of attention was the brominated diphenyl ethers. Since the withdrawal of the pentamix and octamix polybrominated diphenyl ether (PBDE) formulations from the EU market prior to August 2004, two other high-volume products, hexabromocyclododecane (HBCO) and tetrabromobisphenol A (TBBP-A), have been included. We report the concentrations of these compounds in the blubber of harbor porpoises (Phocoena phocoena) stranded or dying due to physical trauma in the U.K. during the period 1994-2003. Analysis was undertaken using LC/MS method on a diastereoisomer basis. Eighty-five samples were analyzed for HBCD, and 68 of these for TBBP-A. alpha-HBCD dominated over the other isomers and was detected in all samples analyzed at concentrations ranging from 10 to 19 200 microg kg(-1) wet weight. The maximum concentration was about double that reported in earlier U.K. studies. TBBP-A was detected in only 18 samples and at much lower concentrations, from 6 to 35 microg kg(-1) wet weight. Investigation of possible time trends indicated a sharp increase in HBCD concentrations from about 2001 onward, which was not confounded by age (length), sex, nutritional status, or location. This may be a result of changing patterns of use of HBCD following limitations on the production and use of two PBDE formulations within the EU and will feed ongoing risk assessment activities.

Approaches for the Simultaneous Extraction of Tetrabromobisphenol A, Tetrachlorobisphenol A, and Related Phenolic Compounds from Sewage Sludge and Sediment Samples Based on Matrix Solid-Phase Dispersion

A procedure based on matrix solid-phase dispersion (MSPD) for sample preparation in the analysis of some bromophenols and halogenated bisphenols in sediments and sludges has been developed. For the first time ever, MSPD was applied for the extraction of organic contaminants from sediment and sewage sludge samples. The influence of experimental conditions on the yield of the extraction process and on the efficiency of the built-in cleanup step was thoroughly evaluated. Analysis of the extracts was performed by nonaqueous capillary electrophoresis coupled with photodiode array ultraviolet detection, using large-volume sample stacking injection based on the electroosmotic flow pump as an on-column preconcentration technique. The method was applied to the analysis of real sludges from urban sewage treatment plants, as well as river and marine sediment samples.

Determination of the flame retardant tetrabromobisphenol A in air samples by liquid chromatography-mass spectrometry

An original method based on LC-MS for determination of the flame retardant tetrabromobisphenol A (TBBPA) in air is presented, as an alternative to the traditionally used GC-MS. The soft ionization in LC-MS makes it possible to monitor the intact molecule and to use 13C-labelled TBBPA as an internal surrogate standard, two features that improve both accuracy and precision of the analyses. Comparison of different acquisition modes in electrospray ionization showed that the lowest detections limit, 3.1 pg TBBPA injected, was obtained in SIM monitoring the molecular ions 542.7/544.7. A fragmentation pathway of TBBPA in LC-ESI-MS is suggested. The only sample clean-up steps required are solvent reduction and filtration of the sample extract. Recoveries were 93% at a 30 ng level and 75% at 3 ng. The new method was tested by analyses of air samples collected at a recycling plant for electronic equipment. The amount of TBBPA found was 13.8 ng/m3 with an RSD of 5.9%. Furthermore, it was found that TBBPA in a standard solution could be partially debrominated, if not carefully protected from light during storage.

Effects of the antithyroid agent propylthiouracil in a partial life cycle assay with zebrafish

Some ubiquitous pollutants of the aquatic environment, such as PCBs or other polyhalogenated aromatic hydrocarbons, may disrupt the thyroid hormone system. In a partial life cycle assay with zebrafish (Danio rerio), we studied the effects of the reference compound propylthiouracil (PTU) on reproduction, growth and development, histopathology of some target tissues, and plasma thyroid hormone levels. PTU induced a concentration-dependent increase of egg production with a concomitant decrease of mature oocyte size but had no effect on fertilization rate or hatching. In F1, serious dysmorphogenesis was found in 4 dph larvae at the highest PTU level tested (100 mg/L), and there was a dose-dependent decrease in body length and weight at 42 dph (significant at 100 mg/L PTU). At this time, there was also a decreased scale thickness, suggesting inhibited metamorphosis, detectable at 1 mg/L PTU and higher. PTU also induced activation of the thyroid follicles in a concentration-dependent way, in juveniles associated with hyperemia in the thyroid area, and depletion of liver glycogen. Effects in adults were associated with decreased circulating levels of the thyroid hormones T3 and T4. These observations indicate that disruption of the thyroid hormone system may affect the fitness of these aquatic organisms. The zebrafish model may contribute to the identification of thyroid hormone disrupting activity in water samples and also in the interpretation of histological observations in free-ranging fish species.

Determination of Hexabromocyclododecane Diastereoisomers and Tetrabromobisphenol A in Water and Sediment by Liquid Chromatography/Mass Spectrometry

A method to determine alpha-, beta- and gamma-hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) in water and sediments was presented using solid phase extraction (SPE) and/or solvent extraction. Recoveries from sediments were approximately 100% for all the chemicals, while recoveries of alpha-, beta- and gamma-HBCDs from water were dependent on the extraction method. In the case of dichloromethane (CH2Cl2) extraction, recoveries of alpha-, beta- and gamma-HBCD from landfill leachates were 77%, 88% and 92%, respectively. Technical difficulties in HBCD measurement are discussed in terms of the physico-chemical properties of HBCD isomers. The method was applied to landfill samples and marine sediment.

Identification, quantification, and synthesis of a novel dimethoxylated polybrominated biphenyl in marine mammals caught off the coast of Japan

Bioaccumulation of persistent organic compounds can eventually lead to concentrations in wildlife and humans that are deleterious to health. The present paper documents the identification, quantification, and synthesis of a novel compound, 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl (2,2'-diMeO-BB80), present in the marine mammals Striped dolphin (Stenella coeruleoalba), Bottlenose dolphin (Tursiops truncatus), Minke whale (Balaenoptera acutorostrata), and Baird's beaked whale (Berardius bairdii) caught in the Pacific Ocean. Identification was based on comparison of the relative retention times of the compound on two gas chromatographic columns of different polarities to those of an authentic standard. Furthermore, this identification was also supported by comparison of the full scan mass spectrometric data collected employing electron ionization (El), positive ion chemical ionization (PICI), and electron capture negative ionization (ECNI). The concentrations of 2,2'-diMeO-BB80 in the samples ranged from 12 to 800 ng/g lipid, making this consistently one of the most abundant compounds among those analyzed, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), and methoxylated PBDEs. The known occurrence of 3,3',5,5'-tetrabromo-2,2'-biphenyldiol (2,2'-diOH-BB80) in the marine environment as a natural product suggests that its methylated derivative, 2,2'-diMeO-BB80, is also of natural origin. To obtain the necessary authentic standards, synthesis was performed of 2,2'-diMeO-BB80 and the known natural product 2',6-dimethoxy-2,3',4,5'-tetrabromodiphenyl ether (2',6-diMeO-BDE68).

Effects of the brominated flame retardant tetrabromobisphenol-A (TBBPA) on cell signaling and function of Mytilus hemocytes: involvement of MAP kinases and protein kinase C

Brominated flame retardants (BFRs) are a large group of compounds added to or applied as a treatment to polymeric materials to prevent fires. Tetrabisphenol A (TBBPA) is the most important individual BFR used in industry. Although TBBPA and its derivatives can be found in environmental samples, data are very limited on the presence of this compound in biota. Research on mammals indicates that TBBPA has low toxicity in vivo; however, in vitro TBBPA can act as a cytotoxicant, neurotoxicant, immunotoxicant, thyroid hormone agonist and has a weak estrogenic activity; in particular, the effects of TBBPA have been recently ascribed to its interactions with cellular signaling pathways, in particular with mitogen activated protein kinases (MAPKs). TBBPA has high acute toxicity to aquatic organisms, such as algae, molluscs, crustaceans and fish; however, little is known on the mechanisms of action of this compound in the cells of aquatic species. In this work, we investigated the possible effects and mechanisms of action of TBBPA on the immune cells, the hemocytes, of the marine mussel Mytilus galloprovincialis. The results demonstrate that TBBPA in the low micromolar range induces hemocyte lysosomal membrane destabilization. The effect was reduced or prevented by hemocyte pre-treatment by specific inhibitors of MAPKs and of protein kinase C (PKC). TBBPA stimulated phosphorylation of MAPK members and PKC, as evaluated by electrophoresis and Western blotting with anti-phospho-antibodies, although to a different extent and with distinct time-courses. A rapid (from 5 min) and transient increase in phosphoryation of the stress-activated JNK MAPKs and of PKC was observed, followed by a later increase (at 30-60 min) in phosphorylation of extracellularly regulated MAPKs (ERK2 MAPK) and of the stress-activated p38 MAPK. TBBPA significantly stimulated the hemocyte microbicidal activity towards E. coli, lysosomal enzyme release, phagocytic activity and extracellular superoxide (O2-) production. The results demonstrate that TBBPA in vitro activates the immune function of mussel hemocytes through kinase-mediated cell signaling and that common transduction pathways are involved in mediating the effects of this BFR in mammalian and aquatic invertebrate cells.

Brominated flame retardants in the atmosphere of the East-Central United States

Air samples were collected at five sites (urban, semiurban, agricultural, and remote) from Lake Michigan through the U. S. Midwest to the Gulf of Mexico every 12 days during 2002-2003 using high-volume samplers so that we could study the spatial trends of brominated flame retardants (polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and 1,2-bis(2,4,6-tribromophenoxy)-ethane (TBE)). The mean sigmaPBDE atmospheric concentration was 100 +/- 35 pg/m3 at the Chicago site, which was 3-6 times higher than that at the other sites. The sigmaPBDE atmospheric concentrations at the Chicago site were significantly higher than previous measurements made in 1997-1999. Unlike these former measurements, BDE-209 is now relatively abundant. Lower BDEs (tri- through hex-BDEs) were detected in both the particle and the gas phases, and the partitioning of these compounds between phases was highly dependent on atmospheric temperature. Higher BDEs (hepta- through deca-BDEs) were mostly detected in the particle phase. On the basis of the congener distributions in the samples, the concentrations were divided into three groups: penta-BDEs, octa-BDEs, and deca-BDEs. Penta-BDEs were the most concentrated at the Chicago site and the least concentrated at the Louisiana site; octa-BDE concentrations were low at all of the sites; deca-BDEs were the most concentrated at the Chicago site and notably high atthe Arkansas site. High concentrations of deca-BDEs, HBCDs, and TBE at the Arkansas site suggest that manufacturing areas in southern Arkansas could be the source regions. Backward trajectories for air masses with high concentrations of deca-BDEs coming to the Arkansas site suggestthat deca-BDEs bound to particles can move long distances from source regions to nonsource regions.

Accumulation of organochlorines and brominated flame retardants in estuarine and marine food chains: field measurements and model calculations

Food chain accumulation of organochlorines and brominated flame retardants in estuarine and marine environments is compared to model estimations and fresh water field data. The food chain consists of herbivores, detritivores and primary and secondary carnivores i.e. fish, fish-eating birds and marine mammals. Accumulation of polychlorinated biphenyls is predicted well by OMEGA for herbi-detritivores and primary and secondary carnivorous fish. Ratios are similar to those found for fresh water species. Accumulation ratios for fish-eating birds and mammals are overestimated by the model, which is attributed partly to biotransformation of meta-para unsubstituted congeners. Additionally, birds may feed in other less polluted areas. For brominated diphenylethers (BDE) accumulation patterns are highly species and congener specific. Accumulation depends on both K(ow) and metabolization capacities. BDE47 is the predominant congener in lower trophic levels. For marine birds and mammals accumulation ratios of BDE99 and 100 are similar to or higher than ratios of persistent PCBs.

Electron paramagnetic resonance evidence of hydroxyl radical generation and oxidative damage induced by tetrabromobisphenol A in Carassius auratus

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants (BFRs). To confirm its putative oxidative stress-inducing activity, freshwater fish Carassius auratus were injected intraperitoneally with TBBPA. One experiment lasted 3h to 28 days after a single injection of 100mg/kg TBBPA, and the other lasted 24h after a single injection of 0-300 mg/kg TBBPA. Reactive oxygen species (ROS) were trapped by phenyl-tert-butyl nitrone (PBN) and detected by electron paramagnetic resonance (EPR). Protein carbonyl (PCO) and lipid peroxidation product (LPO) content were also determined. A six-line EPR spectrum was detected in the sample prepared in air, and a multiple one was obtained in nitrogen. The observed spectrum in nitrogen fits the simulation one with PBN/OCH(3) and PBN/CH(3) quite well. As compared to the control group, TBBPA significantly induced ROS production marked by the intensity of the prominent spectra in liver and bile. TBBPA (100mg/kg) also significantly increased PCO content in liver starting 24h and LPO content 3 days after injection. Either PCO or LPO content showed significant relation with ROS production. Based on the hyperfine constants and shape of the spectrum, ROS induced by TBBPA was determined as OH. The results clearly indicated that TBBPA could induce OH generation and result in oxidative damage in liver of C. auratus.

Simultaneous determination of tetrabromobisphenol A, tetrachlorobisphenol A, bisphenol A and other halogenated analogues in sediment and sludge by high performance liquid chromatography-electrospray tandem mass spectrometry

A high performance liquid chromatography-electrospray (negative) ionization-tandem mass spectrometry (HPLC-ESI(-)-MS-MS) based method has been developed for simultaneous determination of bisphenol A (BPA), tetrachlorobisphenol A (TCBPA), and tetrabromobisphenol A (TBBPA), as well as lower brominated BPA analogues in sediment and sludge samples. Samples were extracted with MTBE, target compounds were partitioned by aqueous solution of sodium hydroxide. The solution was subsequently acidified, and the enrichment and desalting were performed via solid phase extraction (SPE). After cleanup the target compounds were determined by HPLC-ESI(-)-MS-MS. The method limits of quantification (MLOQs) from sediment and sludge for BPA, monobromo-bisphenol A (mono-BBPA), dibromo-bisphenol A (di-BBPA), tribromo-bisphenol A (tri-BBPA), TBBPA and TCBPA were 0.15, 0.02, 0.02, 0.04, 0.05, and 0.03 ng/g (dry weight), respectively. Mean recovery of the analytes from spiked samples ranged from 70 to 105%, and the relative standard deviation ranged from 4.9 to 13.1%. The method was successfully applied to sediment and sludge samples analysis.

Levels of hexabromocyclododecane in harbor porpoises and common dolphins from western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome p450

Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (sigma)-HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 microg (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 microg (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 microg (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 microg (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 microg (g of lipid)(-1), and, for Galicia (Spain), 0.1 microg (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 microg (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 microg (g of lipid)(-1), and, for Galicia, 0.2 microg (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as electron donor, compared to a set of reference samples which were identical except for the addition of NADPH. In contrast, the peak of alpha-HBCD did not decrease significantly in the presence of NADPH. In separate microsomal assays with beta- and gamma-HBCDs, new peaks of brominated compounds (signal at m/z = 79 or 81) with masses of [M + 0] were formed only when NADPH was added. This confirms the process of cytochrome P450 mediated biotransformation. Although rat and harbor seal belong to different families of the mammalia than the cetaceans, we propose that biotransformation by the cytochrome P450 system is also the most likely process to explain the exclusive accumulation of alpha-HBCD in harbor porpoise and common dolphin.