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

A significant downturn in levels of hexabromocyclododecane in the blubber of harbor porpoises (Phocoena phocoena) stranded or bycaught in the UK: an update to 2006

In an earlier paper, we reported data indicating a sharp increase in hexabromocyclododecane concentrations in the blubber of 85 harbor porpoises from the UK, from about 2001 onward. That time trend was evaluated using data from 1994-2003, generated on a diastereoisomer basis using LC-MS. In this paper we report additional data for 138 animals collected during 2003-2006. SigmaHBCD concentrations ranged from <10 to 11,500 microg kg(-1) wet weight (up to 12,800 microg kg(-1) lipid weight) and TBBP-A was not detected in any samples. The maximum SigmaHBCD concentration observed in this study was about half that seen in the earlier study (21,400 microg kg(-1) lipid weight) and, in both studies, the highest concentration was for an animal stranded or bycaught in 2003. Investigation of time trends confirmed a statistically significant increase between 2000 and 2001 (p < 0.01) and a statistically significant decrease between 2003 and 2004 (p < 0.05). Neither trend was confounded by age, sex, nutritional status, or location. Possible contributory factors to the observed decrease include the closure in 2003 of an HBCD manufacturing plant in NE England which had considerable emissions up to 2003, and two voluntary schemes intended to reduce emissions of HBCD to the environment from industry which, however, did not formally begin until 2006.

Effects of tetrabromobisphenol A as an emerging pollutant on wheat (Triticum aestivum) at biochemical levels

Biochemical responses of wheat (Triticum aestivum) to the stress of tetrabromobisphenol A (TBBPA) as an emerging pollutant were examined. The results indicated that reduction of the chlorophyll (CHL) content in wheat leaves could be observed. However, the changes in the CHL content with the increasing TBBPA concentration from 50 to 5000 mg kg(-1) were insignificant (p>0.05). Increased malondialdehyde levels were detected in wheat leaves after both 7-d and 12-d exposures. The changes in the activity of superoxide dismutases (SOD), peroxidases (POD) and catalases (CAT) in wheat leaves irregularly fluctuated with time as the TBBPA concentration increased. However, significant (p<0.05) decrease in the activity of POD and CAT treated with 500 and 5000 mg kg(-1) TBBPA could be observed. Our data also showed that the plant has the capacity to tolerate the oxidative stress, but the capacity would be lost with prolonged exposure and increasing TBBPA concentration. There were no dose-response effects in the changes between the activity of antioxidant enzymes (SOD, POD and CAT) and the concentration of TBBPA. The decrease in the activity of POD and CAT could be considered as good biomarkers of serious stress by TBBPA in soil environment.

Regio- and stereoselective isomerization of hexabromocyclododecanes (HBCDs): kinetics and mechanism of gamma- to alpha-HBCD isomerization

Hexabromocyclododecanes (HBCDs) are high production volume chemicals (>20000 ty(-1)) used as flame retardants for plastics and textiles. Lately, we reported on the stereoselective isomerization of beta-HBCDs. Herein we present insights into the mechanism and kinetics of (+)gamma- to (+)alpha- and of (-)gamma- to (-)alpha-HBCD isomerization. Only two of the six bromine atoms migrated, indicating that rearrangements of gamma- to alpha-HBCDs are regio- and stereoselective as well. The apparent first-order isomerization rate constants increased from 0.0013 to 0.0031 to 0.0070 min(-1) at 120, 130, and 140 degrees C, respectively, corresponding to half-lives of 540, 230, and 99 min. Thus, a thermal treatment of materials containing gamma-HBCDs at temperatures >100 degrees C may induce the formation of alpha-HBCDs and, hence, may alter the diastereomeric ratio of a HBCD mixture. The inversion of vicinal dibromides in like-configurations (RR/SS) prevailed, whereas unlike-configurations (RS/SR) were not affected. An intramolecular, stereoselective migration of neighboring bromine atoms via a four-center transition state would explain the observed stereoisomer pattern and first-order kinetics. Despite the fact that vicinal dibromides in HBCDs prefer synclinal (gauche) conformations, antiperiplanar (staggered) conformations are assumed to facilitate concerted 1.2-shifts of both bromine atoms. A conformation analysis revealed that under kinetic control, only those bromine atoms in the more flexible part of the molecules are migrating, whereas those in the conserved triple-turn motive were not affected. Thus, this structural motive, common to all alpha-, beta-, and gamma-HBCDs, is more rigid and less reactive than the flexible part, containing the reacting dibromides in like-configurations.

Brominated flame retardants and polychlorinated biphenyls in fish from the river Scheldt, Belgium

Levels of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), and polychlorinated biphenyls (PCBs) were measured in several fish species originating from the river Scheldt (Belgium). Five sampling locations were chosen in a highly industrialized area along the river, while two ponds in the vicinity of the river served as reference sites. The present study is a follow-up of a survey performed in 2000 which reported extremely high levels of PBDEs and HBCDs in eel (Anguilla anguilla) collected from the same region (Oudenaarde, Flanders). The sum of tri- to hepta-BDE congeners (2270+/-2260 ng/g lipid weight (lw), range 660-11500 ng/g lw) and total HBCDs (4500+/-3000 ng/g lw, range 390-12100 ng/g lw) were one order of magnitude higher than levels usually reported from freshwater systems, indicating the presence of point sources. In most samples, levels of total HBCDs were higher than those of PBDEs, probably due to the high density of factories using HBCD as an additive brominated flame retardant (BFR). The high values of HBCDs were confirmed by both gas- and liquid-chromatography-mass spectrometry. Although BFR levels were between the highest ever reported in freshwater ecosystems, PCBs could be detected at even higher concentrations (16000+/-14300 ng/g lw, range 3900-66600 ng/g lw), being among the highest levels recorded in Belgium. The inter-sampling site variation of PBDEs, HBCDs and PCBs was comparable. All locations presented similar PBDE congener profiles, with BDE 47 being the dominant congener, followed by BDE 100, BDE 99 and BDE 49, probably originating from the former use of the penta-BDE technical mixture. In order to estimate the impact of these point sources on human exposure, we further focussed on eels which showed a considerable decrease in the PBDE and HBCD levels between 2000 and 2006. Due to the wide span in concentrations between the different sampling locations, a variable contribution to the total human exposure through local eel consumption was estimated. The calculated daily intake ranged from 3 ng to 330 ng PBDEs/day for normal eel consumers, but was as high as 9800 ng PBDEs/day for anglers, which may be considered at risk.

Hexabromocyclododecanes and tetrabromobisphenol-A in indoor air and dust in Birmingham, U.K: implications for human exposure

Hexabromocyclododecanes (alpha-, beta-, and gamma-HBCDs) and tetrabromobisphenol-A (TBBP-A) were determined in indoor air from homes (n=33; median concentrations sigma HBCDs = 180 pg m(-3); TBBP-A = 15 pg m(-3)), offices (n=25; 170; 11), public microenvironments (n=4; 900; 27) and outdoor air (n=5; 37; 1). HBCDs and TBBP-A were also determined in dust from homes (n=45; median concentrations sigma HBCDs = 1300 ng g(-1); TBBP-A = 62 ng g(-1)), offices (n=28; 760; 36), cars (n=20; 13,000; 2), and public microenvironments (n=4; 2700; 230). While sigma HBCDs in car dust significantly exceeded (p < 0.05) those in homes and offices, TBBP-A in car dust was significantly lower (p < 0.05) than that in homes and offices. No significant differences were observed between sigma HBCDs and TBBP-A in air or dust from homes and offices. Compared to dietary and inhalation exposures, dust ingestion constitutes an important pathway of exposure to HBCDs and TBBP-A for the UK population. Specifically, using average dust ingestion rates and concentrations in dust, dust ingestion constitutes for adults 34% (TBBP-A) and 24% (HBCDs) of overall exposure, and for toddlers 90% (TBBP-A) and 63% (HBCDs). Inhalation appears a minor exposure pathway to both HBCDs and TBBP-A. On average, dust is 33% alpha-, 11% beta-, and 56% gamma-HBCD, while air is 22% alpha-, 11% beta-, and 65% gamma-HBCD.

Levels and trends of HBCD and BDEs in the European and Asian environments, with some information for other BFRs

In this paper, we review recent data for brominated flame retardants (particularly BDEs, HBCD and TBBP-A) in samples from the European and Asian environments, including recent temporal trend studies. Research is active and we cite over 100 studies published during 2005-2007. Environmental compartments studied comprise the atmosphere, indoor and outdoor air, sewage sludges, soils and sediments and a variety of biological samples and food chains. Findings include that the lack of reference materials for use in analytical quality control and method validation identified earlier has been addressed, and certified concentrations are now available for a number of BDE congeners in six pre-existing and one new reference materials. BDE209 was certified in three samples of indoor dust. The analysis of BDE209 remains problematic, but suitable methods for its determination are available and need to be applied. The contamination of indoor environments with BFRs has been recognised as representing a significant uptake pathway, particularly via dust. Additional data for TBBP-A are needed from areas, where it is produced and used, primarily Asia, as the worst-case scenario. As a reactive flame retardant it is less likely to leach from finished products. Also, issues regarding the importance of e-waste recycling as a source of BFRs to the local populations and the local environment require urgent study, certainly in China and possibly elsewhere. Generally, trends show a levelling in concentrations of BDEs and increases in concentrations of HBCD wherever determined and BDE209 in Asia.

Effects of tetrabromobisphenol A on the green alga Chlorella pyrenoidosa

Flow cytometry (FC) was used to determine effects of tetrabromobisphenol A (TBBPA) on the green alga Chlorella pyrenoidosa (C. pyrenoidosa) by evaluating esterase activity, membrane integrity, concentrations of intracellular reactive oxygen species (ROS) and chlorophyll a (Chl-a) auto-fluorescence. TBBPA can inhibit esterase activity. Esterase activity was inversely proportional with TBBPA with a 24 h EC(50) value of 3.13 mg TBBPA/L. After 48 h of exposure to TBBPA intracellular ROS was significantly greater than in the unexposed cells. TBBPA inhibited Chl-a fluorescence after 168 h. Concentrations of ROS were directly proportional to both magnitude and duration of exposure and was inversely proportional to cellular Chl-a. FC was useful as an integrated, ecologically relevant, measure of a functional response of the algae. The possible action pathway of TBBPA in C. pyrenoidosa is that TBBPA can cause toxic effects on esterase activity. As concentrations and exposure time increased, TBBPA change the ROS level in the internal. The role of anti-oxidative action is marked and significant at the duration of 48 h exposure, compared to the control. This suggested there was a redox cycle. TBBPA changes physiological status of cells, further decreased Chl-a fluorescence indicating inhibition.

Enantiomer-specific accumulation of hexabromocyclododecanes in eggs of predatory birds

The diastereomeric composition of hexabromocyclododecane (HBCD) in eggs of peregrine falcon (Falco peregrinus), white-tailed sea eagle (Haliaeetus albicilla), guillemot (Uria aalge) and common tern (Sterna hirundo) as well as the guillemots' main prey, herring (Clupea harengus) was determined by reversed-phase chromatography with triple-stage quadrupole mass spectrometric detection (LC-MS-MS). alpha-HBCD was the predominant diastereomer in all bird species, while in herring, gamma-HBCD made a substantial contribution. Two, as yet unidentified diastereomers, were detected in common tern egg. The alpha-, beta- and gamma-HBCD (+) and (-) enantiomers were separated using a chiral stationary phase. The enantiomer fractions for alpha-HBCD differed substantially between different bird species as well as between guillemot and its prey, herring. Total HBCD levels determined by LC-MS-MS were comparable to those previously obtained by GC-MS.

Diastereoisomer- and enantiomer-specific profiles of hexabromocyclododecane in the atmosphere of an urban city in South China

Hexabromocyclododecanes (HBCDs) are ubiquitous contaminants in the environment, but little is known on the occurrence and distribution of HBCDs in the background atmosphere of urban environments. In this study, air samples were collected from four sites in the city of Guangzhou, a typical fast developing metropolitan of South China, for quantifying the concentration levels, diasteroisomer profiles, gas-particle distribution and enantiomeric fractions of HBCDs. The results showed that the measured mean atmospheric HBCD concentrations ranged from 0.69 to 3.09 pg/m3, which were similar to those reported from remote or urban sites of the U.S., but were significantly lower than those of Europe. The analysis on diastereoisomer profiles indicated that alpha-HBCD (59--68%) was the dominant isomer and beta-HBCD was a minor isomer in all air samples, which appeared to be different from commercial products. A large variable percentage of HBCDs (69.1--97.3%) are existed in the particle phase, suggesting that long-range tansport of HBCDs might be occur in some environmental conditions. The results of enantiomeric fractions indicated that beta- and gamma-HBCD were racemic mixtures in the tested air samples and that (--)-alpha-HBCD was slightly enriched in the typical urban site, implying that the HBCDs in these studied sites might be a mixture of emissions from both local sources and soil-air exchange.

Time trend of hexabromocyclododecane in the breast milk of Japanese women

Hexabromocyclododecane (HBCD) is a type of brominated flame retardant. We investigated the time trend of the stereoisomer-specific concentrations of HBCD (alpha, beta, and gamma) in breast milk samples of Japanese women by using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pooled milk lipid samples collected in 1973, 1978, 1983, 1988, 1993, 1999, and from 2000 to 2006 were analysed. The concentration was below the detection limit in the samples collected between 1973 and 1983 and increased in those collected since 1988. Between 1988 and 2006, alpha-HBCD was detected in all 11 breast milk samples collected from 25 to 29-year-old Japanese women; gamma-HBCD, in 7; and beta-HBCD, in none of the samples. Time trend of summation operatorHBCD appeared to be related to that of the industrial HBCD consumption level in Japan.

Identification and trace level determination of brominated flame retardants by liquid chromatography/quadrupole linear ion trap mass spectrometry

We describe the development of instrumental methodology for the simultaneous determination of hexabromocyclododecane (HBCD) diastereoisomers and tetrabromobisphenol A (TBBPA) and its derivatives by liquid chromatography/quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS). Two different experiments were developed, optimized and compared. The first is based on a selected reaction monitoring (SRM) method in which the two most abundant transitions were selected for each analyte, as well as for the internal standards. In the second, the ion trap was used for the storage and subsequent fragmentation of precursor ions, obtaining an enhanced product ion (EPI) experiment. Both methods were validated by measuring quality parameters such as linearity, sensitivity, reproducibility and repeatability. Limits of detection (LODs) were in the range of 0.1-1.8 pg and 0.01-0.5 pg for SRM and EPI experiments, respectively, being lower than those published for the LC/QqQ-MS methods. Thus, LC-QqLIT-MS, used for quantification and confirmation, proved to be a powerful and very sensitive analytical tool.

Regio- and stereoselective isomerization of hexabromocyclododecanes (HBCDs): kinetics and mechanism of beta-HBCD racemization

Hexabromocyclododecanes (HBCDs) are high production volume chemicals currently produced in quantities exceeding 20000ty(-1). They are used as flame retardants for plastics and textiles. HBCDs are thermally labile compounds, rapidly decomposing at temperatures above 250 degrees C to form bromine radicals, which scavenge other radicals formed during pyrolysis. But certain HBCD stereoisomers must reach the environment without decomposition, because their levels in soils, sediments, and biota are increasing worldwide. The fate of individual HBCD stereoisomers during production, product use, disposal, and transformation in the environment remains unclear. Herein we report on the thermally induced, highly selective isomerization of (+) and (-)beta-HBCD. Regio- and stereoselective migration of only two of the six bromine atoms resulted in the racemization of both beta-HBCDs. First order rate constants (k(rac)) increased from 0.005, 0.011, 0.021, to 0.055min(-1) at 130, 140, 150, and 160 degrees C, corresponding to half life times tau(1/2) of 143, 63, 29, and 14min, respectively. From the deduced kinetic model, we conclude that any thermal treatment of enantiomerically enriched beta-HBCDs in the range of 100-160 degrees C will result in a loss of most optical activity within few hours. The simultaneous inversion of two asymmetric centers occurred with perfect stereocontrol. Selectively, vicinal dibromides with the RR- and the SS-configurations migrated at these temperatures. An intramolecular reaction mechanism with a four-center transition state is postulated, based on the obtained stereoisomer pattern and the observed reaction kinetics. Crystal structure analysis revealed that all vicinal dibromides in beta-HBCDs prefer synclinal (gauche) conformations. However, an antiperiplanar (staggered) conformation is assumed to facilitate the concerted 1.2-shifts of both bromine atoms, resulting in an inversion of both neighboring carbon atoms. First experiments with other HBCD stereoisomers suggest that the presented isomerization mechanism is of relevance for those stereoisomers as well.

Concentrations and specific loads of brominated flame retardants in sewage sludge

Many substances related to human activities end up in wastewater and accumulate in sewage sludge. The present study focuses on two classes of brominated flame retardants: polybrominated diphenyl ethers (BDE28, BDE47, BDE49, BDE66, BDE85, BDE99, BDE100, BDE119, BDE138, BDE153, BDE154, BDE183, BDE209) and hexabromocyclododecane (HBCD) detected in sewage sludge collected from a monitoring network in Switzerland. Mean concentrations (n=16 wastewater treatment plants) were 310, 149, 95 and 17microg per kg dry matter for decaBDE, HBCD, penta- and octaBDE, respectively. These numbers correspond well with other studies from European countries. DecaBDE, HBCD, penta- and octaBDE showed average specific loads (load per connected inhabitant per year) in sludge of 6.1, 3.3, 2.0 and 0.3mgcap(-1)yr(-1), respectively. This is in line with consumption and storage of the compounds in the environment and the anthroposphere. Discrepancies observed for octaBDE and HBCD can be explained by the release from materials where these compounds are incorporated in and/or their degradation during anaerobic sludge treatment. Loads from different types of monitoring sites showed that brominated flame retardants ending up in sewage sludge originate mainly from surface runoff, industrial and domestic wastewater.

Levels and body distribution of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in freshwater fishes from the Yangtze River, China

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) were determined in muscle, liver and eggs of freshwater fishes from the lower reach of the Yangtze River, China. The present study is the first to report HBCD concentrations in the environment of China. The concentrations of PBDEs and HBCDs in muscle of freshwater fishes from the Yangtze River ranged from 18 to 1100ng/g and 12 to 330ng/g lipid weight (wt.), respectively. When compared with other regions of the world, the contamination of PBDEs in biota could be regarded as moderate, whereas contamination of HBCDs in biota was relatively high. The PBDE congener profiles in fishes of the present study were markedly different from those observed in freshwater and marine fishes from other regions of the world. In the present study, BDE-15, BDE-28 and BDE-47 were the predominant congeners in the fishes. This particular congener profile in fishes from the Yangtze River revealed that a specific commercial PBDE formulation (probably made in China) might have been used in the Yangtze River Delta region.

Bioaccumulation and physiological effects of tetrabromobisphenol A in coontail Ceratophyllum demersum L

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants. In the present study, the accumulation of TBBPA and its consequent biological responses were examined in coontail (Ceratophyllum demersum L.) over 14 days' exposure. Most of the TBBPA was accumulated after 4d exposure and TBBPA concentration in plant increased with increasing TBBPA concentration in growth solution (R(2)=0.99). By using electron paramagnetic resonance (EPR), we found that the TBBPA exposure significantly increased total free radicals generation in the plants. A good positive relationship (R(2)=0.99) was found between the free radicals formation and accumulation level of TBBPA in plant. Lipid peroxidation was enhanced and chlorophyll content showed declined after TBBPA exposure. The activities of superoxide dismutase (SOD), peroxidase (POD), and the contents of glutathione were also detected. The results suggest that TBBPA accumulation in C. demersum induces oxidative stress and the level of tolerance depends on the antioxidative capacity of the plants.

Regional trend and tissue distribution of brominated flame retardants and persistent organochlorines in raccoon dogs (Nyctereutes procyonoides) from Japan

The present study investigated concentrations and patterns of brominated flame retardants, such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs), and persistent organochlorines (OCs) in liver and adipose tissues of raccoon dogs (RD: Nyctereutes procyonoides) collected from two metropolises and a local prefecture in Japan during 2001-2006. Relatively high concentrations of PBDEs were found in RD livers, while HBCD levels were the lowest among the measured organohalogen compounds. Among PBDE congeners, BDE 209 was predominant in RDs from all the regions, indicating that pollution derived from the technical decaBDE product is extensive across Japan. On the other hand, concentrations of tetra- to nona-BDE congeners in RDs from a metropolis were significantly higher than those from the other two regions, implying that there were regional differences in the past usage of the technical tetraBDE and octaBDE products. Such a regional difference was also observed for HBCD levels. Lipid-normalized concentration ratios of liver to adipose tissue (L/A ratio) for tri to hepta-BDE congeners were lower than 1.0 in the investigated eight RDs, suggesting lipid-dependent accumulation. However, the LA ratios of BDE 209 exceeded 1.0 in all the specimens, suggesting hepatic retention of this compound. In addition, lipid-dependent accumulation of a-HBCD was observed, but the L/A ratios of gamma-HBCD were greater than 1.0 in some specimens. These results indicate that Japanese RDs have been recently exposed to BDE 209 and gamma-HBCD and accumulated both these compounds preferentially in blood-rich organs, probably due to their binding to proteins and/or rapid biotransformation, as reported in experimental rodents.

Oxidation of flame retardant tetrabromobisphenol A by singlet oxygen

Wide use of flame retardants can pose an environmental hazard, and it is of interest to investigate how they may degrade. We report here that 3,3',5,5'-tetrabromobisphenol A (TBBPA) is subject to photosensitized oxidation involving singlet molecular oxygen ((1)O2). By using visible light and rose bengal or methylene blue as 102 photosensitizers, we have found that TBBPA is a 102 quencher. The quenching rate constant, k(q), depends on TBBPA ionization (pK = 7.4). In acetonitrile, where TBBPA is undissociated, the kq value is 6.1 x 10(5) M(-1) s(-1) for a TBBPA monomer and decreases to 2.9 x 10(4) M(-1) s(-1) for TBBPA dimers and/or aggregates. TBBPA dissociates in aqueous solutions, and its kq value is 1.44 x 10(9) M(-1) s(-1) in alkaline solution, decreasing to 3.9 x 10(8) M(-1) s(-1) at pH 7.2. The strong 102 quenching by TBBPA anion initiates an efficient oxidation of TBBPA, which results in oxygen consumption in aqueous micellar (e.g., Triton X-100) solutions containing photosensitizer. This oxygen consumption is mediated by transient radical species, which we detected by using EPR spectroscopy. We observed two major radicals and one minor radical generated from TBBPA by reaction with 102 at pH 10. One was identified as the 2,6-dibromo-p-benzosemiquinone radical (a2H = 2.36 G, g = 2.0056). A second radical (aH = 2.10 G, g = 2.0055) could not be identified butwas probably a 2,6-dibromo-p-benzosemiquinone radical containing an EPR-silent substituent at the 3-position. Spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DPMO) showed that other minor radicals (hydroxyl, carbon-centered) are also generated during the reaction of TBBPA with (1)O2. The photosensitized production of radicals and oxygen consumption were completely inhibited by the azide anion, an efficient physical (1)O2 quencher. Because TBBPA is a stable compound that at neutral pH does not absorb much of the atmosphere-filtered solar radiation, its photosensitized oxidation by (1)O2 may be the key reaction initiating or mediating TBBPA degradation in the natural environment.

Effects of dissolved organic matter from sewage sludge on sorption of tetrabromobisphenol A by soils

Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics of soils and the concentrations of DOM present. TBBPA sorption by Henan (HN) soil (sandy loam) and Liaoning (LN) soil (loamy clay) was promoted in the presence of DOM at low concentration (< or = 90 mg organic carbon (OC)/L), and the sorption was promoted by HN soil and inhibited by LN soil at DOM added concentration of 180 mg OC/L. TBBPA sorption by Guangxi (GX) soil (silt loam) was always inhibited in the presence of DOM. It was also found that the amount of TBBPA sorbed decreased with the increase in the solution pH value in the absence of DOM. The influencing mechanisms of DOM on the sorption of TBBPA by soils were also discussed.

Fish as biomonitors of polybrominated diphenyl ethers and hexabromocyclododecane in Czech aquatic ecosystems: pollution of the Elbe River basin

BACKGROUND

Brominated flame retardants (BFRs)--polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD)--belong to the group of relatively "new" environmental contaminants. The occurrence of these compounds in the Czech aquatic ecosystem was for the first time documented within the 3-year monitoring study initiated in 2001. In 2002-2003 HBCD and the major PBDE congeners (28, 47, 49, 66, 85, 99, 100, 153, 154, and 183) were found in 136 freshwater fish samples collected from several sampling sites located at three Czech rivers (Vltava, Elbe, Tichá Orlice). Chub (Leuciscus cephalus), barbel (Barbus barbus), bream (Abramis brama), perch (Perca fluviatilis), and trout (Salmo trutta), representing the most common fish species, were examined by gas chromatography coupled with negative chemical ionization mass spectrometry.

RESULTS

The presence of PBDE congeners and HBCD was detected in all analyzed samples (limits of detection for target analyts ranged from 0.015 to 0.1 ng/g lipid weight). Without exception the dominating congener was BDE-47. The most pronounced extent of fish contamination was found in the Vltava river at Klecany, downstream from the industrial agglomeration of Prague. As for fish species, the highest concentrations of PBDEs (sum of congeners) were measured in benthic species, represented by bream and barbel, up to 19.6 ng/g wet weight and 16.5 ng/g wet weight, respectively. The lowest accumulation occurred in predator fish (perch and trout). The highest levels of HBCD were detected in barbel from Srnojedy on the Elbe River (15.6 ng/g wet weight), downstream.

Brominated flame retardants in North-East Atlantic marine ecosystems

BACKGROUND

Concentrations of brominated flame retardants (BFRs) are reported to increase in marine ecosystems.

OBJECTIVES

Characterize exposure to BFRs in animals from different trophic levels in North-East Atlantic coastal marine ecosystems along a latitudinal gradient from southern Norway to Spitsbergen, Svalbard, in the Arctic. Calanoid species were collected from the Oslofjord (59 degrees N), Froan (64 degrees N), and Spitsbergen (> 78 degrees N); Atlantic cod (Gadus morhua) from the Oslofjord and Froan; polar cod (Boreogadus saida) from Bear Island (74 degrees N) and Spitsbergen; harbor seal (Phoca vitulina) from the Oslofjord, Froan, and Spitsbergen; and ringed seal (Phoca vitulina) from Spitsbergen. Eggs of common tern (Sterna hirundo) were collected from the Oslofjord, and eggs of arctic terns (Sterna paradisaea) from Froan and Spitsbergen.

RESULTS

Levels of polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD) generally decreased as a function of increasing latitude, reflecting distance from release sources. The clear latitudinal decrease in levels of BFRs was not pronounced in the two tern species, most likely because they are exposed during migration. The decabrominated compound BDE-209 was detected in animals from all three ecosystems, and the highest levels were found in arctic tern eggs from Spitsbergen. HBCD was found in animals from all trophic levels, except for in calanoids at Froan and Spitsbergen.

CONCLUSIONS

Even though the levels of PBDEs and HBCD are generally low in North-East Atlantic coastal marine ecosystems, there are concerns about the relatively high presence of BDE-209 and HBCD.

Brominated flame retardants in the environment of Asia-Pacific: an overview of spatial and temporal trends

In this paper, we summarize spatial and temporal trends of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in coastal and marine biota, and further assess human exposure to these brominated flame retardants (BFRs) in Asia-Pacific. The review is based mainly on the studies that were conducted in our laboratory and utilized samples archived in the environmental specimen bank (es-BANK) of Ehime University, Japan. The studies suggest that the target BFRs are ubiquitous in the environment of Asia-Pacific. Examination of spatial trends reveals that concentrations of these contaminants are relatively high in samples from Korea, South China and Japan. In general, the magnitude of environmental contamination by PBDEs in Asia-Pacific, as well as human exposure to these contaminants, seem to be comparable to or slightly higher than in Europe, but lower than in North America. Evaluation of temporal trends in concentrations of BFRs in marine mammals from the coastal waters of Japan and China showed drastic increase during the last 30 years. These changes in BFR levels in samples from Japan were in line with trends in production/use of the commercial formulations. Since the withdrawal of some PBDE products from the Japanese market in the 1990s, concentrations of HBCDs appear to exceed those of PBDEs, reflecting increasing usage of HBCDs over PBDEs. The increasing environmental contamination by BFRs in Chinese coastal waters indicates that contamination by BFRs has already become evident, even in developing countries. In view of the rising environmental levels and the high consumption volume of BFRs in Asia, further efforts should be made to monitor environmental contamination by these chemicals in order to identify sources and reduce emissions.

Occupational exposure to hexabromocyclododecane at an industrial plant

Occupational exposure to hexabromocyclododecane (HBCD) among workers at an industrial plant producing expandable polystyrene (PS) added HBCD as flame retardant has been assessed in the present study. Airborne dust samples were collected near the breathing zone of 10 male workers during three 8-h work shifts. The HBCD concentrations in the airborne dust varied from 0.2 to 150 microg/m3 (mean 12.2 and median 2.1 microg/m3). Two serum samples were obtained from each of the workers. The mean serum concentration was 190 ng/g lipids; the median was 101 ng/g lipids (range 6 to 856 ng/g lipids). HBCD was not detected above 1 ng/g lipids (LOD) in any samples from persons in a reference group with no occupational exposure to HBCD. The contribution of gamma-HBCD to the total HBCD serum concentration was notably high (39%) compared to what has usually been observed in biological samples. There was no clear correlation of serum levels with average HBCD concentrations in the airborne dust samples collected near the subjects' breathing zone. The elevated exposure levels reported in this study compared to urban air and serum levels in general populations suggest that further and more detailed exposure assessment studies should be initiated in industries where HBCD is applied.

Isomer specific determination of hexabromocyclododecanes (HBCDs) in small cetaceans from the South China Sea--Levels and temporal variation

A diastereoisomer (alpha, beta, and gamma) specific analytical method for measuring hexabromocyclododecanes (HBCDs) was developed using liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method developed was applied to analyze blubber of small cetaceans to divulge the distribution and temporal variation of HBCDs in the Asian marine environment. HBCDs were detected in all the blubber samples of finless porpoises (Neophocaena phocaenoides) and Indo-Pacific humpback dolphins (Sousa chinensis) collected from the South China Sea during 1990-2001. Concentrations of HBCDs were higher in humpback dolphins (31-380 ng/g lipid) than in finless porpoises (4.7-55 ng/g lipid), which can be attributed to habitat differences. Average concentrations of alpha-HBCD in finless porpoises increased from 9.5 ng/g lipid in 1990 to 35 ng/g lipid in 2000/01. alpha-HBCD was predominant among the three isomers with some exceptions in finless porpoises collected in 1990. This is the first report on HBCDs contamination in marine mammals from Southeast Asia.

Long-term exposure of European flounder (Platichthys flesus) to the flame-retardants tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD)

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD) are widely used flame retardants that have increasingly been found as contaminants in the aquatic environment. In the present study, European flounder (Platichthys flesus) were chronically exposed to TBBPA; (105 days) and HBCD (78 days), in a wide range including environmentally relevant concentrations. TBBPA was administered via the water, whereas HBCD was administered in food and sediment, or in sediment alone. Chemical analysis of muscle showed an average increase in internal concentrations of approximately two orders of magnitude for both compounds tested. Animals exposed to HBCD via sediment alone (8000 microg/g total organic carbon, TOC) showed a proportional increase of alpha-HBCD in muscle compared to animals exposed via food and sediment. In both studies, exposure to the test compounds did not affect general health and toxicity parameters (behavior, survival, growth rate, relative liver and gonad weight). Hepatic microsomal enzyme activities (TBBPA: EROD; HBCD: EROD, PROD, and BROD) were not induced by any of the tested chemicals. Aromatase activity in male gonads showed a mild increase with rising TBBPA levels. There were no morphological and immunohistochemical indications for increased production of the yolk precursor protein vitellogenin (VTG) in animals exposed to TBBPA and HBCD; immunochemical analysis of plasma VTG levels showed no dose response in animals exposed to TBBPA. In animals exposed to TBBPA, levels of the thyroid hormone thyroxin (T(4)) increased with internal concentrations of the test compound, possibly indicating competition of TBBPA for plasma protein binding. Triiodothyronin (T(3)) levels were not affected and histology showed no signs of altered thyroid gland activity. Other organs investigated (liver, gills, kidney, skin, and gonads) revealed no histological changes related to TBBPA or HBCD exposure. Overall, the present results indicate limited endocrine effects of these widely used flame retardants in a test species representative of European estuaries at environmentally relevant exposure levels and at internal levels up to 4300 ng TBBPA/g wet weight, and 446 microg HBCD/g lipid weight in flounder muscle.

Spatial distribution and vertical profile of polybrominated diphenyl ethers and hexabromocyclododecanes in sediment core from Tokyo Bay, Japan

Brominated flame retardants (BFRs), hexabromocyclododecanes (HBCDs) and polybrominated diethyl ethers (PBDEs) were detected in three sediment cores and six surface sediments of Tokyo Bay, Japan. HBCDs were detected for the first time in this region with concentrations ranging from 0.056 to 2.3 ng/g dry wt, implying their widespread contamination, even though their concentrations were lower than summation operatorPBDEs (di- to nona-BDEs) and BDE-209. Levels of these compounds were higher near to the highly populated industrial area of the bay implicating industrial and human activities as sources of these compounds. Summation operatorPBDEs increased in the sediment layer up to the mid-1990s and decreased afterwards, whereas BDE-209 showed an increasing trend until now, following the usage of different commercial BDE mixtures. HBCDs first appeared in the mid-1970s and increased until today. The annual surficial flux of HBCDs (0.62-2.4 ng/cm2/yr) is equal to summation operatorPBDEs (0.95-2.6 ng/cm2/yr) but lower than that of BDE-209 (17-58 ng/cm2/yr).

Spatial distribution and accumulation of brominated flame retardants, polychlorinated biphenyls and organochlorine pesticides in blue mussels (Mytilus edulis) from coastal waters of Korea

Blue mussels (Mytilus edulis) from 20 locations along the coastal waters of Korea were analyzed to elucidate the characteristic distribution and contamination status of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs) and organochlorine pesticides. To our knowledge, this is the first study to report on the contamination status of HBCDs from Korea. PBDEs and HBCDs were found in mussels at levels ranging from 6.6 to 440 and from 6.0 to 500 ng/g lipid wt., respectively. Concentrations of PBDEs in mussels from Korea were higher or comparable to available data in mussels from other countries. Among the organochlorine compounds (OCs) analyzed, levels of PCBs and DDTs were the highest followed by CHLs, HCHs and hexachlorobenzene. For all the compounds, higher concentrations were found in mussels from southeastern coast of Korea. The present study shows the importance of mussels as bioindicators for monitoring contaminants in coastal waters.

Recent developments in the analysis of brominated flame retardants and brominated natural compounds

This article reviews recent literature on the analysis of brominated flame retardants (BFRs) and brominated natural compounds (BNCs). The main literature sources are reviews from the last five years and research articles reporting new analytical developments published between 2003 and 2006. Sample pretreatment, extraction, clean-up and fractionation, injection techniques, chromatographic separation, detection methods, quality control and method validation are discussed. Only few new techniques, such as solid-phase microextraction (SPME) or pressurized liquid extraction (PLE), have been investigated for their ability of combining the extraction and clean-up steps. With respect to the separation of BFRs, the most important developments were the use of comprehensive two-dimensional gas chromatography for polybrominated diphenyl ethers (PBDEs) and the growing tendency for liquid-chromatographic techniques for hexabromocyclododecane (HBCD) stereoisomers and of tetrabromobisphenol-A (TBBP-A). At the detection stage, mass spectrometry (MS) has been developed as well-established and reliable technology in the identification and quantification of BFRs. A growing attention has been paid to quality assurance. Interlaboratory exercises directed towards BFRs have grown in popularity and have enabled laboratories to validate analytical methods and to guarantee the quality of their results. The analytical procedures used for the identification and characterization of several classes of BNCs, such as methoxylated polybrominated diphenyl ethers (MeO-PBDEs) (also metabolites of PBDEs), halogenated methyl or dimethyl bipyrroles (DBPs), are reviewed here for the first time. These compounds were generally identified during the routine analysis of BFRs and have received little attention until recently. For each topic, an overview is presented of its current status.

Solid-state conformations and absolute configurations of (+) and (-) alpha-, beta-, and gamma-hexabromocyclododecanes (HBCDs)

Hexabromocyclododecanes (HBCDs) are high production volume chemicals used as flame retardants for plastics and textiles. They are currently produced in quantities exceeding 20,000 t/y. Despite this fact, the correct stereochemistry of most HBCDs is still not known. Six stereocenters are formed during bromination of cyclododecatrienes, resulting in mixtures of different stereoisomers. Considering all elements of symmetry, 16 different stereoisomers including six pairs of enantiomers as well as 4 meso forms are possible theoretically. Recently, we isolated 8 of the 16 possible stereoisomers from a technical HBCD mixture and assigned their relative configurations. Herein, we report on the isolation of 6 enantiomerically pure alpha-, beta-, and gamma-HBCDs, obtained from preparative chiral-phase liquid chromatography, and we present their absolute configurations, which were determined from X-ray diffraction analysis. The absolute configuration of (-) alpha-HBCD was found to be (1R,2R,5S,6R,9R,10S), while the one of (+) beta-HBCD is assigned to (1S,2S,5S,6R,9S,10R), whereas the one of (-) gamma-HBCD corresponds to (1S,2S,5S,6R,9R,10S). The given structural information allows the unambiguous identification of the six most important HBCD stereoisomers, which typically account for more than 95% of technical HBCDs. In addition, we compared the solid-state conformations of racemic and enantiomerically pure alpha-, beta-, and gamma-HBCDs. In all cases, vicinal dibromides adopted a synclinal (sc) conformation with torsion angles of 69+/-6 degrees. A unique structural motive was common to all examined HBCD solid-state conformations. This conserved structure was described as an extended triple turn consisting of an arrangement of three pairs of synclinal and two antiperiplanar torsion angles.

Detection of hexabromocyclododecane and its metabolite pentabromocyclododecene in chicken egg and fish from the official food control

During routine gas chromatography with electron capture detection (GC/ECD) analysis of chicken eggs, we observed that the most prominent peak in some samples did not match the retention time of any of the food contaminants screened. Subsequent GC coupled with mass spectrometry (GC/MS) studies clarified that the mass spectrum of the peak was very similar to hexabromocyclododecane (HBCD), which was also identified by GC/MS in the egg. The unknown compound was positively identified as pentabromocyclododecene (PBCDE), a metabolite of HBCD detected for the first time in foodstuffs. Studies of the analytical method used for the analysis of pesticides and contaminants showed that this cleanup method was suitable for the determination of HBCD and PBCDE, but storage of sample extracts resulted in the loss of HBCD when the sample extracts were not sufficiently purified. The concentrations of HBCD and PBCDE in the high polluted sample were 2.0 and 3.6 mg/kg egg fat. HBCD and PBCDE were also detected in two additional eggs at lower levels (<0.15 mg/kg), whereas 75 eggs did not contain these compounds (<0.02 mg/kg). We also detected HBCD and PBCDE in two samples of whitefish (Coregonus sp.), while an eel sample (Anguilla anguilla) positively tested for HBCD did not contain PBCDE. Surprisingly, the potential metabolite of HBCD, PBCDE, has not been detected before in any food or environmental sample. The present results indicate that more attention should be paid to the detection of HBCD and its metabolite PBCDE in chicken eggs.

Indoor organophosphate and polybrominated flame retardants in Tokyo

In Japan, organophosphate and polybrominated flame retardants are used in building materials and electric appliances to protect them from fire hazards. In this study, to identify the emission sources of these flame retardants to indoor air, the migration rates (flux) of organophosphate and polybrominated flame retardants from building materials and electrical appliances to solid extraction disks that were placed in contact with the interior surfaces were measured. In addition to the migration test, indoor air and outdoor air concentrations of these flame retardants were investigated. With regard to building materials in a newly built house, triethylphosphate (TEP) and tributylphosphate (TBP) were detected in the wall and ceiling coverings, and tris(2-butoxyethyl)phosphate (TBEP) was detected in the wooden flooring cleaned with a floor polish agent. With regard to electrical appliances, triphenylphosphate (TPHP) was predominantly detected in computer monitors and tris(2-chloroethyl) phosphate (TCEP) in television (TV) sets, with the highest median levels. Among the polybrominated compounds, only 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) was detected from a few old TV sets manufactured before 1995. In an indoor and outdoor air survey, nine organophosphates and nine polybrominated flame retardants were detected from indoor air. In outdoor air, only four organophosphate flame retardants were detected. The maximum level of indoor organophosphate compounds was 1260 ng/m(3) with tris(2-chloro-1-methylethyl) phosphate (TCPP), and that of polybrominated compounds was 29.5 ng/m(3) with hexabromocyclododecane (HBCD). Tetrabromobisphenol A (TBBPA) was not detected in this study, although it has the largest demand among flame retardants in Japan. The results of the migration test and the indoor air survey revealed that in indoor air, organophosphate compounds were more predominant than polybrominated compounds in Tokyo.

PRACTICAL IMPLICATIONS

Polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE) are commonly used as flame retardants in plastics. The use of these two compounds in electric appliances will be banned in 2007 by the EU Directives on waste electrical and electronic equipment (WEEE) and on the restriction of the use of certain hazardous substances (RoHS) in electrical and electronic equipment. In Japan, the use of PBB was banned and that of PBDE diminished in the early 1990s by the self-imposed controls of the Japanese Flame Retardants Conference (Akutu and Hori, 2004). In Japan, the predominantly used organic flame retardants were tetrabromobisphenol A and organophosphate compounds. Tetrabromobisphenol A has been reported to disrupt endocrine systems (Kitamura et al., 2005), and some organophosphate flame retardants were recently reported to have neurochemical hazardous effects. Furthermore, organophosphate compounds were suspected to cause endocrine-disrupting effects (Fang et al., 2003; Ohyama et al., 2005) or attention deficit hyperactivity disorder (ADHD) (Winrow et al., 2003). In this study, organophosphate and polybrominated flame retardants were surveyed in indoor environments in Tokyo.

Organic pollutants in compost and digestate. : Part 2. Polychlorinated dibenzo-p-dioxins, and -furans, dioxin-like polychlorinated biphenyls, brominated flame retardants, perfluorinated alkyl substances, pesticides, and other compounds

Compost and digestate are important recycling fertilizers and have beneficial effects on soil parameters. However, they can contain significant amounts of organic pollutants. Here, the first comprehensive data set on dibenzo-p-dioxins and -furans (PCDD/F), dioxin-like polychlorinated biphenyls (DL-PCB), brominated flame retardants, perfluorinated alkyl substances (PFAS), pesticides, phthalates, nonylphenol and chlorinated paraffins (CP) in source-separated compost and digestate from Switzerland is presented (n = 3-18). The median summation 17PCDD/F and summation 12DL-PCB concentrations were at 3.2 ng I-TEQ kg(-1)dry weight (dw) and 3.0 ng WHO-TEQ kg(-1)dw, respectively. Brominated diphenyl ether 209 (BDE 209) accounted for 72% of the total polyBDE content (10 microg kg(-1)dw). Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) levels were at 100 and 0.51 microg kg(-1)dw, respectively. PFAS were identified for the first time in compost and digestate (median concentration 6.3 microg kg(-1)dw, summation 21compounds). Out of 269 pesticides analysed, 30 fungicides, 14 herbicides, eight insecticides and one acaricide were detected. Di-(2-ethylhexyl)phthalate (DEHP) median concentration accounted for 280 microg kg(-1)dw and nonylphenol was below the detection limit of 1 mg kg(-1)dw. The sum of short and medium chain CP was between 90 and 390 microg kg(-1)dw. The concentrations observed were at or above the levels found in background soils, which are the main recipient of compost and digestate. Where actually applied, compost can contribute considerably to the total input of organic pollutants to the soil. However, on a total Swiss agricultural area base, inputs seem to be limited.

Animal use replacement, reduction, and refinement: development of an integrated testing strategy for bioconcentration of chemicals in fish

When addressing the use of fish for the environmental safety of chemicals and effluents, there are many opportunities for applying the principles of the 3Rs: Reduce, Refine, and Replace. The current environmental regulatory testing strategy for bioconcentration and secondary poisoning has been reviewed, and alternative approaches that provide useful information are described. Several approaches can be used to reduce the number of fish used in the Organization for Economic Cooperation and Development (OECD) Test Guideline 305, including alternative in vivo test methods such as the dietary accumulation test and the static exposure approach. The best replacement approach would seem to use read-across, chemical grouping, and quantitative structure-activity relationships with an assessment of the key processes in bioconcentration: Adsorption, distribution, metabolism, and excretion. Biomimetic extraction has particular usefulness in addressing bioavailable chemicals and is in some circumstances capable of predicting uptake. Use of alternative organisms such as invertebrates should also be considered. A single cut-off value for molecular weight and size beyond which no absorption will take place cannot be identified. Recommendations for their use in bioaccumulative (B) categorization schemes are provided. Assessment of biotransformation with in vitro assays and in silico approaches holds significant promise. Further research is needed to identify their variability and confidence limits and the ways to use this as a basis to estimate bioconcentration factors. A tiered bioconcentration testing strategy has been developed taking account of the alternatives discussed.

Analysis of hexabromocyclododecane diastereomers and enantiomers by liquid chromatography/tandem mass spectrometry: Chromatographic selectivity and ionization matrix effects

Hexabromocyclododecane (HBCD) is a flame retardant that is undergoing environmental risk assessment. The liquid chromatographic retention and electrospray ionization matrix effects were investigated for HBCD methods of analysis for environmental matrices. Column selectivity towards HBCD diastereomers was evaluated for C30 and C18 stationary phases under different mobile phase conditions and column temperatures. The HBCD elution order was dependent on the shape selectivity of the stationary phase and the mobile phase composition. Greater resolution, on columns with reduced shape selectivity, of beta-HBCD and gamma-HBCD was achieved with the use of an acetonitrile/water (compared with a methanol/water) mobile phase composition. A liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the analysis of HBCD in biological tissues was evaluated for potential matrix effects. The influence of extracted matrix components on HBCD diastereomer and enantiomer analysis was investigated using a postextraction addition approach. Although the analysis of HBCD diastereomers was relatively unaffected by the sample matrix, the responses of the HBCD enantiomers in tissue samples were significantly influenced by matrix effects and other changes to the ionization conditions. The use of racemic 13C-labeled HBCD diastereomers as internal standards for enantiomer fraction measurements corrected for the changes in the mass spectrometer response.

A 28-Day Oral Dose Toxicity Study Enhanced to Detect Endocrine Effects of Hexabromocyclododecane in Wistar Rats

A 28-day repeated dose study in rats (OECD407) enhanced for endocrine and immune parameters was performed with hexabromocyclododecane (HBCD). Rats were exposed by daily gavage to HBCD dissolved in corn oil in 8 dose groups with doses ranging between 0 and 200 mg/kg bw per day (mkd). Evaluation consisted of dose-response analysis with calculation of a benchmark dose at the lower 95% one-sided confidence bound (BMDL) at predefined critical effect sizes (CESs) of 10-20%. The most remarkable findings were dose-related effects on the thyroid hormone axis, that is, decreased total thyroxin (TT4, BMDL 55.5 mkd at CES--10%), increased pituitary weight (29 mkd at 10%) and increased immunostaining of TSH in the pituitary, increased thyroid weight (1.6 mkd at 10%), and thyroid follicle cell activation. These effects were restricted to females. Female rats also showed increased absolute liver weights (22.9 mkd at 20%) and induction of T4-glucuronyl transferase (4.1 mkd at 10%), suggesting that aberrant metabolization of T4 triggers feedback activation of the thyroid hormone system. These effects were accompanied by possibly secondary effects, including increased cholesterol (7.4 mkd at 10%), increased tibial bone mineral density (> 49 mkd at 10%), both in females, and decreased splenocyte counts (0.3-6.3 mkd at 20%; only evaluated in males). Overall, female rats appeared to be more sensitive to HBCD than male rats, and an overall BMDL is proposed at 1.6 mkd, based on a 10% increase of the thyroid weight, which was the most sensitive parameter in the sequence of events.

Biodegradation and product identification of [14C]hexabromocyclododecane in wastewater sludge and freshwater aquatic sediment

In a previous study the biodegradation of hexabromocyclododecane (HBCD) was reported to occur under realistic environmental concentrations in soils and freshwater aquatic sediments with biotransformation half-lives ranging from approximately 2 days to 2 months. In this study we extend our knowledge as to the environmental behavior of HBCD with respect to the fate of the three major diastereomers of HBCD (alpha, beta, and gamma) as well as to the identification of major intermediate metabolites formed during degradation. Substantial biological transformation of the alpha-, beta-, and gamma-[14C]HBCD diastereomers was observed in wastewater (i.e., digester) sludge and in freshwater aquatic sediment microcosms prepared under aerobic and anaerobic conditions. Concomitant with the loss of [14C]HBCD in these matrixes there was a concurrent production of three [14C]products. Using a combination of high performance liquid chromatography atmospheric pressure photoionization mass spectrometry and gas chromatography electron impact ionization mass spectrometry these metabolites were identified as tetrabromocyclododecene, dibromocyclododecadiene, and cyclododecatriene. We propose that HBCD is sequentially debrominated via dihaloelimination where at each step there is the loss of two bromines from vicinal carbons with the subsequent formation of a double bond between the adjacent carbon atoms. These results demonstrate that microorganisms naturally occurring in aquatic sediments and anaerobic digester sludge mediate complete debromination of HBCD.

Exposure to tetrabromobisphenol-A alters TH-associated gene expression and tadpole metamorphosis in the Pacific tree frog Pseudacris regilla

Presently in the environment, there exist a number of chemical contaminants which share structural similarity with key naturally occurring regulatory hormones. These hormones play pivotal roles in the normal growth and development of wildlife species and humans. In particular, biphenolic chemical compounds may have the potential to act as agonists or antagonists of thyroid hormone (TH) action. We investigated whether there was any biological effect of exposure to low concentrations of the brominated fire retardant, tetrabromobisphenol-A (TBBPA), on the TH-mediated process of metamorphosis of the Pacific tree frog, Pseudacris regilla. Tadpoles exposed to 10nM (5.4microg/L) TBBPA showed an increase in TH-mediated expression of gelatinase B mRNA within 48h in the tadpole tail which was associated with increased tail resorption by 96h. Treatment with 100nM (54.4microg/L) TBBPA resulted in increased TH-mediated thyroid hormone receptor alpha mRNA expression in the tadpole brain and reduced levels of PCNA transcript in the tail. TBBPA alone was also found to alter the mRNA abundance of thyroid hormone receptor alpha in tail, gelatinase B in brain, and PCNA in both tissues of premetamorphic tadpoles. Interestingly, expression of thyroid hormone receptor beta mRNA was not affected by exposure to TBBPA either alone or in the presence of TH. The results suggest that exposure to low levels of TBBPA may act as an agonist of TH action and potentiate TH-mediated gene expression leading to accelerated anuran metamorphosis.

Hexabromocyclododecanes (HBCDs) in the environment and humans: a review

Hexabromocyclododecanes (HBCDs) are brominated aliphatic cyclic hydrocarbons used as flame retardants in thermal insulation building materials, upholstery textiles, and electronics. As a result of their widespread use and their physical and chemical properties, HBCDs are now ubiquitous contaminants in the environment and humans. This review summarizes HBCD concentrations in several environmental compartments and analyzes these data in terms of point sources versus diffuse sources, biomagnification potential, stereoisomer profiles, time trends, and global distribution. Generally, higher concentrations were measured in samples (air, sediment, and fish) collected near point sources (plants producing or processing HBCDs), while lower concentrations were recorded in samples from locations with no obvious sources of HBCDs. High concentrations were measured in top predators, such as marine mammals and birds of prey (up to 9600 and 19 200 ng/g lipid weight, respectively), suggesting a biomagnification potential for HBCDs. Relatively low HBCD concentrations were reported in the few human studies conducted to date (median values varied between 0.35 and 1.1 ng/g lipid weight). HBCD levels in biota are increasing slowly and seem to reflect the local market demand. One important observation is the shiftfrom the high percentage of the gamma-HBCD stereoisomer in the technical products to a dominance of the alpha-HBCD stereoisomer in biological samples. A combination of factors such as variations in solubility, partitioning behavior, uptake, and, possibly, selective metabolism of individual isomers may explain the observed changes in stereoisomer patterns. Recommendations for further work include research on how HBCDs are transferred from products into the environment upon production, use, and disposal. Time trends need to be analyzed more in detail, including HBCD stereoisomers, and more data on terrestrial organisms are needed, especially for humans. Whenever possible, HBCDs should be analyzed as individual stereoisomers in order to address their fate and effects.

Toxicity of tetrabromobisphenol A (TBBPA) in zebrafish (Danio rerio) in a partial life-cycle test

Toxicological effects of the widely used flame retardant, tetrabromobisphenol A (TBBPA) were assessed in a partial life-cycle test with zebrafish (Danio rerio). Exposure of adult fish during 30 days to water-borne TBBPA in nominal concentrations ranging from 0 (control) to 1.5 microM was followed by exposure of the offspring in early life stages up to 47 days posthatching (dph) to the same concentrations. Adults exposed to 3 and 6 microM showed severe disorientation and lethargy shortly after beginning of exposure and were euthanized. Because semistatic exposure resulted in fluctuating water concentrations, pooled fish samples were chemically analyzed for internal dose assessment. Egg production was decreased in fish exposed to TBBPA concentrations of 0.047 microM and higher, and a critical effect level of 7.2 microg/g lipid with a lower 5% confidence limit of 3.9 microg/g lipid for 50% decreased egg production was calculated. Histology of adult ovaries indicated a relative increase of premature oocytes in two surviving females exposed to 1.5 microM. Hatching of TBBPA-exposed larvae was decreased except in animals exposed to 0.375 microM. In the highest exposure concentration, early posthatching mortality was high (81%) in larvae and the surviving juveniles showed a significant predominance of the female phenotype. Exposure of eggs from control parents up to 6 microM TBBPA resulted in increasing malformation and pericardial fluid accumulation from 1.5 microM; at higher concentrations, all embryos failed to hatch. The presented results indicate decreased reproductive success in zebrafish at environmentally relevant TBBPA concentrations.

Brominated flame retardant concentrations and trends in abiotic media

BFR burdens in abiotic media have been less studied than in biota, despite their essential value as an aide to identifying sources, temporal and geographic trends and exposure routes. Many polymer products consist of several percent by weight of BFRs. Global trade in these can result in rapid and wholesale BFR movement. Loss from in-use products of nonreactive BFRs may be important, particularly in respect to indoor exposure. In the case of BDE-209, discharges from publicly owned treatment works may be substantial. BFR burdens in air, water and sewage sludge respond rapidly to changes in environmental BFR inputs. PBDEs have been the most widely studied. In many locales PBDE burdens in these media now surpass those of PCBs. Air and water near sources and urban areas are typically enriched relative to rural locales. The more volatile PBDEs dominate in the vapor phase, while BDE-209 typically predominates on particulates. Evidence exists for long-range transport of the more volatile PBDEs. A greater diversity of BFRs (mostly PBDEs, HBCD and TBBP-A) has been detected in sewage sludges. Land application of these sludges on agricultural fields is one conduit for soil contamination. In general, environmental concentrations of BDE-209 appear to be increasing, while penta-BDE burdens in Europe may have peaked. Sediments function as longer-term integrators of environmental burdens. Concentrations of common BFRs therein may be substantial near point sources. Evidence for debromination in the environment has been limited to date. However, some laboratory and field observations suggest it is possible to a limited extent.

Levels and trends of brominated flame retardants in the European environment

In this paper, we review those data which have recently become available for brominated flame retardants (particularly the brominated diphenyl ethers (BDEs) and hexabromocyclododecane (HBCD)) in samples from the European environment. Environmental compartments studied comprise the atmosphere, sediments and soils, sewage sludges, and a variety of biological samples and food chains. This is currently a very active research area, and we cite over 70 studies reported in the literature during 2003-04. Findings include that the input of BDEs (especially BDE209) to the Baltic Sea by atmospheric deposition now exceeds that of PCBs by a factor of almost 40 times. Sewage sludge samples from both industrial and background locations show concentrations of BDEs, HBCD and tetrabromobisphenol-A (TBBP-A) that are of a similar order, indicating that the major source is from diffuse leaching from products into wastewater streams from users, households and industries generally. Point-sources from industries using BFRs (e.g. the textile industry) also generate local hot-spots. Sediment core studies identified the presence of two of the three PBDE formulations. The penta-mix formulation was clearly present from the beginning of the 1970s, but the deca-mix only appeared in the late 1970s. BDE183, BDE209 and HBCD were detected in peregrine falcons from Sweden and other birds feeding on terrestrial food chains. BDEs are found widely distributed in fish, including those from high mountain lakes in Europe, as a consequence of long-range atmospheric transport and deposition. A temporal trend study in archived freeze-dried mussels from the Seine estuary, France, indicated an exponential increase in BDE concentrations during the period 1982-1993, which levelled off in 1999 and 2001 and then began to decline after 2002. HBCD was detected in liver and blubber samples from harbour seals and harbour porpoises from the Wadden and North Seas, though very few animals yielded positive values for TBBP-A. There are difficulties in comparing data on summation operatorBDE from studies in which different suites of BDE congeners have been determined, and we suggest a common suite which will allow the study of all three commercial PBDE formulations.

Determination of HBCD, PBDEs and MeO-BDEs in California sea lions (Zalophus californianus) stranded between 1993 and 2003

Blubber samples from male California sea lions (Zalphophus californianus) stranded between 1993 and 2003 were analyzed for 27 polybrominated diphenyl ether (PBDE) congeners, three isomers of hexabromocyclododecane (HBCD) and 14 methoxylated polybrominated diphenyl ether (MeO-BDE) congeners. Total PBDEs ranged from 450 ng/g to 4740 ng/g wet mass and total HBCD ranged from < 0.3 ng/g to 12 ng/g wet mass. The concentration of HBCD increased from 0.7 ng/g to12.0 ng/g wet mass in sea lion blubber between 1993 and 2003. However, no significant temporal trend was observed for any of the other brominated compounds over this 10 year period. Only one of the 14 MeO-BDE congeners was detected in the blubber samples, 6-methoxy-2,2',4,4'-tetrabromodiphenyl ether (6-MeO-BDE 47), and concentrations ranged from < 0.2 ng/g to 12 ng/g wet mass. A bromo-, chloro-heterocyclic compound, 1,1'-dimethyl-tetrabromo-dichloro-2,2'-bipyrrole (DBP-Br4Cl2), previously reported in marine species along the Pacific coast, was also identified in the sea lion blubber. DBP-Br4Cl2 ranged from 44 ng/g wet mass to 660 ng/g wet mass and was present at concentrations rivaling the dominant PBDE congener, BDE 47 (2,2',4,4'-tetrabromodiphenyl ether). Concentrations of DBP-Br4Cl2 were positively correlated with 6-MeO-BDE 47 (r = 0.7; p < 0.05). Both of these compounds have been identified in marine algae and sponges, and studies suggest they are both produced from natural sources. This study demonstrates that brominated compounds from both anthropogenic and biogenic sources can accumulate to similar levels in marine mammals. In addition, HBCD concentrations appear to be increasing in California sea lion populations, whereas PBDE concentrations, between 1993 and 2003, were highly variable.