Tribromodiphenyl Ether Research Articles

Hydrogen-Donor-Controlled Polybrominated Dibenzofuran (PBDF) Formation from Polybrominated Diphenyl Ether (PBDE) Photolysis in Solutions: Competition Mechanisms of Radical-Based Cyclization and Hydrogen Abstraction Reactions.

Polybrominated dibenzofurans (PBDFs) are characteristic dioxin-like products of polybrominated diphenyl ether (PBDE) photolysis. In this study, competition mechanisms of radical-based cyclization and hydrogen abstraction reactions are proposed in PBDF formation. Commonly, the ortho C-Br bond dissociation during photolysis generates aryl radicals, which undergo intramolecular cyclization to form PBDFs or hydrogen abstraction with hydrogen donors (such as organic solvents and water) to form lower brominated PBDEs. By using 2,4,4'-tribromodiphenyl ether (BDE-28) as the model reactant, the experimental PBDF formation ratios in various solutions are explained quantitatively by the calculated rate constants of cyclization and hydrogen abstraction reactions using the density functional theory (DFT) method. The solvent effect of pure and mixed solvents on PBDF formation is illustrated successfully. The structure-related hydrogen donation ability for hydrogen abstraction controls the bias of competition reactions and influences PBDF formation. Water resulted to be the most significant generation of PBDFs. Fulvic and humic acid display higher hydrogen donation ability than small-molecule organics due to the partitioning effect in aqueous solution. Quantitative structure-activity relationship (QSAR) models of the calculated rate constants for 512 cyclization and 319 hydrogen abstraction reactions using 189 PBDEs as the initial reactants in water are established, revealing the high risk of PBDF formation in aqueous solution.

Textile Washing Conveys SVOCs from Indoors to Outdoors: Application and Evaluation of a Residential Multimedia Model.

Indoor environments have elevated concentrations of numerous semivolatile organic compounds (SVOCs). Textiles provide a large surface area for accumulating SVOCs, which can be transported to outdoors through washing. A multimedia model was developed to estimate advective transport rates (fluxes) of 14 SVOCs from indoors to outdoors by textile washing, ventilation, and dust removal/disposal. Most predicted concentrations were within 1 order of magnitude of measurements from a study of 26 Canadian homes. Median fluxes to outdoors [μg·(year·home)-1] spanned approximately 4 orders of magnitude across compounds, according to the variability in estimated aggregate emissions to indoor air. These fluxes ranged from 2 (2,4,4'-tribromodiphenyl ether, BDE-28) to 30 200 (diethyl phthalate, DEP) for textile washing, 12 (BDE-28) to 123 200 (DEP) for ventilation, and 0.1 (BDE-28) to 4200 (bis(2-ethylhexyl) phthalate, DEHP) for dust removal. Relative contributions of these pathways to the total flux to outdoors strongly depended on physical-chemical properties. Textile washing contributed 20% tris-(2-chloroisopropyl)phosphate (TCPP) to 62% tris(2-butoxyethyl)phosphate (TBOEP) on average. These results suggest that residential textile washing can be an important transport pathway to outdoors for SVOCs emitted to indoor air, with implications for human and ecological exposure. Interventions should try to balance the complex tradeoff of textile washing by minimizing exposures for both human occupants and aquatic ecosystems.

Karrikinolide alleviates BDE-28, heat and Cd stressors in Brassica alboglabra by correlating and modulating biochemical attributes, antioxidative machinery and osmoregulators

In this study, we have evaluated the role of karrikin (KAR1) against the absorption and translocation of a persistent organic pollutant (POP), 2,4,4’-Tribromodiphenyl ether (BDE-28) in plants, in the presence of two other stressors, cadmium (Cd) and high temperature. Furthermore, it correlates the physiological damages of Brassica alboglabra with the three stresssors separately. The results revealed that the post-germination application of KAR1 successfully augmented the growth (200%) and pertinent physiochemical parameters of B. alboglabra. KAR1 hindered air absorption of BDE-28 in plant tissues, and reduced its translocation coefficient (TF). Moreover, BDE-28 was the most negatively correlated (−0.9) stressor with chlorophyll contents, while the maximum mitigation by KAR1 was also achieved agaist BDE-28. The effect of temperature was more severe on soluble sugars (0.51), antioxidative machinery (−0.43), and osmoregulators (0.24). Cd exhibited a stronger inverse interrelation with the enzymatic antioxidant cascade. Application of KAR1 mitigated the deleterious effects of Cd and temperature stress on plant physiological parameters along with reduced aero-concentration factor, TF, and metal tolerance index. The phytohormone reduced lipid peroxidation by decreasing synthesis of ROS and persuading its breakdown. The stability of cellular membranes was perhaps due to the commotion of KAR1 as a growth-promoting phytohormone. In the same way, KAR1 supplementation augmented the membrane stability index, antioxidant defense factors, and removal efficiency of the pollutants. Consequently, the exogenously applied KAR1 can efficiently alleviate Cd stress, heat stress, and POP toxicity.

A novel management strategy for removal and degradation of polybrominated diphenyl ethers (PBDEs) in waste printed circuit boards

Waste printed circuit boards (PCBs) contain a high level of brominated flame retardants (BFRs), among which polybrominated biphenyl ethers (PBDEs) are the most widely used additive BFRs. PBDEs are considered to be a type of persistent organic pollutants (POPs). The efficient removal/degradation of PBDEs in waste PCBs is an urgent problem in electronic waste treatment, but the degradation of PBDEs is a great challenge due to their extreme stability and persistence in nature. In this study, a novel management strategy was developed for removal and degradation of PBDEs in waste PCBs by using a simple subcritical methanol (SubCM) process. The results showed that reaction temperature, residence time, solid-to-liquid ratio, and additive NaOH are key factors influencing the removal of PBDEs from waste PCBs. Under optimal conditions (200 °C, 60 min, 1:20 g/mL), the removal efficiency of ∑8PBDEs from waste PCBs could reach 91.3% and 98.8% for the proposed process of SubCM and SubCM + NaOH, respectively. When the temperature is below 200 °C, highly brominated PBDEs congeners in waste PCBs were degraded into 2,'3,4′,6-Tetrabromodiphenyl ether (BDE71) and 2,4,4′-Tribromodiphenyl ether (BDE28) after SubCM treatment. 4-Bromophenyl ether (BDE4) and diphenyl ether were generated by the further debromination of BDE71 and BDE28 with the increase of treatment temperature. The debromination temperature of PBDEs congeners in SubCM could be markedly lowered by adding 4 g/L of NaOH. The complete debromination of PBDEs congeners in waste PCBs could be achieved at 300 °C and 250 °C for the developed process of SubCM and SubCM + NaOH, respectively.

Sorption, mobility, and bioavailability of PBDEs in the agricultural soils: Roles of co-existing metals, dissolved organic matter, and fertilizers

Polybrominated diphenyl ethers (PBDEs) are common pollutants released from electronic waste (e-waste) dismantling and recycling activities. Our city-wide survey of agricultural soils in Qingyuan (40 sampling sites), where e-waste recycling has been active, observed exceedance of PBDEs above background levels (average of 251.9ngg−1, 87 times the regional baseline concentration) together with elevated levels of metals/metalloids at the contamination hotspots, such as As (180.4mgkg−1), Cu (100.7mgkg−1), Zn (93.4mgkg−1), Pb (37.8mgkg−1), Cr (15.1mgkg−1), and Cd (0.3mgkg−1). Hence, a twenty-cycle batch sorption test on composite soil samples from the e-waste site was conducted to study the fate of BDE-28 (2,4,4′-tribromodiphenyl ether) and BDE-99 (2,2′,4,4′,5-pentabromodiphenyl ether) under the influence of co-existing trace elements (TEs) (Cu, Pb, Zn, and Cd, which exceeded Chinese Environmental Quality Standard for Soils), dissolved organic matter (extracted from local peat), and locally available commercial fertilizer. The results showed that the presence of TEs barely affected the sorption of BDEs, probably because the low concentration of BDEs in the environment resulted in nearly complete sorption onto the soil. In contrast, metals sorption onto soil was promoted by the presence of BDEs. The mobility of BDE-28 was higher than BDE-99 in water leaching tests, while the leaching concentration of BDE-99 was further reduced in simulated acid rain possibly due to protonation of π-accepting sites in soil organic matter. In the freshly spiked soil, BDEs of greater hydrophobicity and larger molecular size exhibited higher bioavailability (due to greater affinity to Tenax extraction), which was contrary to the field contaminated soil. Similarly, the co-occurrence of metals and fertilizer increased the bioavailability of newly sorbed BDE-99 more than BDE-28 in the soil. These results illustrate the need to holistically assess the fate and interactions of co-existing organic and inorganic pollutants in the agricultural soils.

Insights into the photochemical transformation pathways of triclosan and 2′-HO-BDE-28

Hydroxylated polyhalogenated diphenyl ethers (HO-PXDEs) have been recognized as a group of widely detected emerging contaminants in natural waters. Photolysis was proved to be an important transformation pathway for these compounds and their direct phototransformation results in highly toxic dioxins. However, the roles of excited states and reactive oxygen species in the photochemical transformation of these compounds are still unclear. In this study, 2′-HO-2,4,4′-trichlorodiphenyl ether (triclosan) and 2′-HO-2,4,4′-tribromodiphenyl ether (2′-HO-BDE-28) were selected as model compounds to investigate their phototransformation processes. Results showed that the direct photolysis reactions of both triclosan and 2′-HO-BDE-28 occurred via their respective excited singlet states, leading to the generation of dioxins. In addition, the energy and electron transfer reactions between excited states of model compounds and molecular O2 can lead to the generation of 1O2 and OH, which results in self-sensitized photolysis. We also found that both the k, Φ dioxin yield for anionic triclosan were higher than those of anionic 2′-HO-BDE-28. This study revealed the roles of the excited states in direct photolysis and the generation pathway of reactive oxygen species in self-sensitized photolysis of HO-PXDEs, which is important for understanding the phototransformation mechanisms of HO-PXDEs.

Optimization of Soxtec extraction procedure for determination of polybrominated diphenyl ethers in bivalve mollusc

A comprehensive and efficient method is presented for the determination of 9 polybrominated diphenyl ether congeners (PBDEs), 2,4,4′-tribromodiphenyl ether (PBDE-28), 2,3′,4,4′-tetrabromodiphenyl ether (PBDE-47), 2,2′,4,4′,6-pentabromodiphenyl ether (PBDE-66), 2,2′,4,4′,5-pentabromodiphenyl ether (PBDE-100), 2,2′,3,4,4′-pentabromodiphenyl ether (PBDE-99), 2,2′,4,4′,5,6′-hexabromodiphenyl ether (PBDE-85), 2,2′,4,4′,5,5′-hexabromodiphenyl ether (PBDE-154), 2,2′,4,4′,5,5′-hexabromodiphenyl ether (PBDE-153) and 2,2′,3,4,4′,5,6′-heptabromodiphenyl ether (PBDE-183), in mollusc bivalve samples. An experimental design was used to evaluate the influence of several operational parameters on the extraction performance and to obtain the best experimental conditions. Under the final working conditions, freeze-dried mollusc was placed in the Soxtec thimble in order to extract PBDEs with 100 mL of n-hexane-acetone (4: 1) after 1.5 h and 1 h of boiling and rinsing times, respectively. Soxtec extracts were additionally purified on a multilayered column and after injected in the gas chromatography combined with mass spectrometry (GC-MS) system. Quantitative recoveries of the analytes at three concentration levels ranged between 80 and 108%, and limits of quantification of the method (LOQs) between 0.5 and 20 ng/g. Analysis of mussel and clam samples showed that PBDE-47 and PBDE-99 were presented in almost all samples with concentrations between 0.6 and 2.6 ng/g dry weight. Moreover, a certified reference material (NIST 2974a) was used. The obtained concentrations were in agreement with the certified values.

Determination of eight polybrominated diphenyl ethers in marine sediments by ultrasonically assisted alkaline degradation extraction and gas chromatography-electron capture detection

For determination of the eight polybrominated diphenyl ethers (PBDEs) in marine sediments based on gas chromatography-electron capture detection (GC-ECD), a rapid and effective method for simultaneous sample extraction and purification was developed, in which ultrasonically assisted alkaline hydrolysis was combined with solvent extraction. The sediment sample was processed in an ultrasonic bath in 2. 00 mol/L NaOH-methanol solution for 30 min, and subsequently extracted by n-hexane. The organic phase was then separated and purified by silica column and concentrated to 100 µL for GC-ECD analysis. Under the optimized conditions, the recoveries and relative standard deviations (RSDs) for eight PBDE congeners ranged from 63.6% to 110.3% and from 1.7% to 10.5% (n = 5), respectively. The limits of detection (LODs, S/N = 3) ranged from 0.002 to 0.011 ng/g except for deca-brominated diphenyl ether (BDE-209), which was 0.097 ng/g. With high accuracy, good stability and adequate recovery, the established method was successfully applied to the analysis of PBDEs in the surface sediments from Bohai Sea. The concentrations of ∑8PBDEs (sum of 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2, 2', 4, 4', 5-pentabromodiphenyl ether (BDE-99), 2, 2', 4, 4', 6-pentabromodiphenyl ether (BDE100), 2, 2', 4, 4', 5, 5'- 1.566 to 6.760 ng/g and from 1.461 to 6.438 ng/g, respectively. A decreasing gradient of concentration was basically observed with increasing distance off the shore, indicating that anthropogenic activities, surface runoff and river inputs may be the sources of PBDEs in the sediments from Bohai Sea.

Transformation of 2,2′,4,4′-tetrabromodiphenyl ether under UV irradiation: Potential sources of the secondary pollutants

A commercial brominated flame retardant 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) was used as the model chemical to investigate the degradation and transformation of polybrominated diphenyl ethers (PBDEs) in gas and liquid phases, respectively, under ultraviolet (UV) irradiation. The results showed that BDE-47 can be transformed to less-brominated BDE analogs. A total of six compounds that are less-brominated BDEs and two brominated phenols were observed as transformation products in the reaction mixtures. Different degradation rates of BDE-47 in n-nonane and in isooctane in the same chamber system were observed. Degradation rate of BDE-47 in n-nonane was faster than in isooctane. Under UV irradiation, the bromine on the ortho positions of the phenyl rings was lost first to form 2,4,4′-tribromodiphenyl ether (BDE-28), which then progressively lead to 4,4′-dibromodiphenyl ether (BDE-15) or 2,4′-dibromodiphenyl ether (BDE-8). An airborne transformation pathway has been proposed according to observed transformation products. The more volatile less-brominated BDEs from transformation of BDE-47 are easily evaporated into air to be a source of secondary pollutants in the environment.

OH-Initiated Oxidation Mechanisms and Kinetics of 2,4,4′-Tribrominated Diphenyl Ether

2,4,4'-Tribromodiphenyl ether (BDE-28) was selected as a typical congener of polybrominated diphenyl ethers (PBDEs) to examine its fate both in the atmosphere and in water solution. All the calculations were obtained at the ground state. The mechanism result shows that the oxidations between BDE-28 and OH radicals are highly feasible especially at the less-brominated phenyl ring. Hydroxylated dibrominated diphenyl ethers (OH-PBDEs) are formed through direct bromine-substitution reactions (P1∼P3) or secondary reactions of OH-adducts (P4∼P8). Polybrominated dibenzo-p-dioxins (PBDDs) resulting from o-OH-PBDEs are favored products compared with polybrominated dibenzofurans (PBDFs) generated by bromophenols and their radicals. The complete degradation of OH adducts in the presence of O2/NO, which generates unsaturated ketones and aldehydes, is less feasible compared with the H-abstraction pathways by O2. Aqueous solution reduces the feasibility between BDE-28 and the OH radical. The rate constant of BDE-28 and the OH radical is determined to be 1.79 × 10(-12) cm(3) molecule(-1) s(-1) with an atmospheric lifetime of 6.7 days.

Effects of nitrogen and phosphorus concentrations on the bioaccumulation of polybrominated diphenyl ethers by Prorocentrum donghaiense

The growth, cellular total lipids, bioaccumulation amount, and bioaccumulation factors (BAFs) of 2,4,4′-tribromodiphenyl ether (BDE28), 2,2′,4,4′-tetrabromodiphenyl ether (BDE47), and 2,2′,4,4′,5-pentabromodiphenyl ether (BDE99) in a semi-continuous culture of Prorocentrum donghaiense were studied in relation to nitrate (0, 128, and 512 μmol/L) and phosphate (0, 8, and 32 μmol/L) concentrations. The BDE28, BDE47, and BDE99 content per cell under 0 μmol N/L were 3.77 × 10−6, 3.95 × 10−6, and 4.32 × 10−6 ng/cell, respectively, which were significantly higher than those under 128 and 512 μmol N/L. A nearly 5-fold increase in polybrominated diphenyl ether (PBDE) content per algal cell was found between 0 and 8 μmol P/L and between 8 and 32 μmol P/L. With increasing N and P concentrations, the PBDE content per volume of algal culture and the accumulation percentage of available PBDEs declined slightly. The BAFs for the PBDEs based on lipids showed that the logBAFlip under 0 μmol N/L was higher than those under 128 and 512 μmol N/L. The logBAFlip under 0 μmol P/L was higher than that under 8 μmol P/L but lower than that under 32 μmol P/L. Correlation analysis indicated a significant negative correlation between nutrient concentration and cellular total lipids, as well as the PBDE content per cell. The results indicate that different N and P concentrations change the total lipids content of P. donghaiense, thereby resulting in varying PBDE accumulation.

Biodegradation of triclosan by a wastewater microorganism

Triclosan, a synthetic antimicrobial agent, has been considered as an emerging environmental contaminant. Here we reported a triclosan-degrading wastewater bacterial isolate, Sphingopyxis strain KCY1, capable of dechlorinating triclosan with a stoichiometric release of chloride. The stain can degrade diphenyl ether but not 2,4,4′-tribromodiphenyl ether and 2,2′,4,4′-tetrabromodiphenyl ether, despite all these three compounds are structurally similar to triclosan. While strain KCY1 was unable to grow on triclosan and catechol, it could grow with glucose, sodium succinate, sodium acetate, and phenol. When grown with complex nutrient medium containing a trace amount of triclosan (as low as 5 μg/L), the strain could retain its degradation ability toward triclosan. The maximum-specific triclosan degradation rate (qm) and the half-velocity constant (Km) are 0.13 mg-triclosan/mg-protein/day and 2.8 mg-triclosan/L, respectively. As triclosan degradation progressed, five metabolites were identified and these metabolites continue to transform into non-chlorinated end products, which was supported by a sharp drop in androgenic potential. The activity of catechol 2,3-dioxygenase in the cell extract was detected. No triclosan degradation was observed in the presence of 3-fluorocatechol, an inhibitor of meta-cleavage enzyme, suggesting that triclosan degradation proceed via meta-cleavage pathway. Based on all the observations, a degradation pathway for triclosan by strain KCY1 was proposed.

Biodegradation kinetics of selected brominated flame retardants in aerobic and anaerobic soil

The purpose of the present study was to investigate the biodegradation kinetics in aerobic and anaerobic soil of the following brominated flame retardants: 2,4,4′-tribromodiphenyl ether (BDE 28), decabromodiphenyl ether (BDE 209), tetrabromobisphenol A (TBBPA), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 2,4,6-tribromophenol (246BrPh), and hexabromobenzene (HxBrBz). For comparison, the biodegradation of the chlorinated compounds 2,4,4′-trichlorodiphenyl ether (CDE 28), 2,4,6-trichlorophenol (246ClPh), hexachlorobenzene (HxClBz), and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) was also assessed. In aerobic soil, BDE 209 showed no significant degradation during the test period, but concentrations of the other BFRs declined, with half-lives decreasing in the following order: BDE 28 > TBBPA > TBECH > HxBrBz > 246BrPh. Declines in almost the same order were observed in anaerobic soil: BDE 28, BDE 209 > TBBPA > HxBrBz > TBECH >246BrPh.

Uptake and biotransformation of structurally diverse brominated flame retardants in zebrafish (Danio rerio) after dietary exposure

Zebrafish (Danio rerio) were fed a diet containing a mixture of 11 structurally diverse brominated flame retardants (BFRs) at nominal concentrations of either 1 or 100 nmol/g for up to 42 d, followed by an elimination period of 14 d. Uptake rates and elimination constants for five of the BFRs were calculated from measurements of their concentrations in the male fish during the exposure and elimination phases. Observed uptake efficiencies were highest for 2,4,4'-tribromodiphenyl ether (BDE 28) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) and were lowest for decabromodiphenyl ether (BDE 209). Estimated half-lives for TBECH and 2,4,6-tribromophenol were short (<2 d). Four BFR metabolites were identified in the fish: 2,2',3,4',5',6-Hexabromodiphenyl ether (BDE 149), 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE 154), 2,4,6-tribromoanisole, and 1,2,4,5-hexabromobenzene. These metabolites were still present in the zebrafish after the 14-d elimination period. No relationship between the BFR concentrations in the zebrafish and their log octanol-water partition coefficient (Kow) values was found. Generally, low tendencies to bioaccumulate were observed for perbrominated and hydroxylated compounds. The observed accumulation of BFR metabolites in fish, however, shows that low concentration of a BFR does not provide, in isolation, a sound indication that the BFR poses low risks.

Photodegradation of 2,2′,4,4′-tetrabromodiphenyl ether in nonionic surfactant solutions

Recently, polybrominated diphenyl ethers (PBDEs) contaminated soils in electronic waste (e-waste) disposal sites of China have been reported and aroused concern. Since surfactant-aided soil washing followed by photodestruction has been suggested as a promising technology for soil remediation, the photodegradation of 2,2′,4,4′-terabromodiphenyl ether (BDE-47) in nonionic surfactant solutions under UV-irradiation at 253.7 m was studied in the present work. The investigation was carried out on the effect of the type and concentration of surfactants, initial pH, and the addition of cations and acetone on BDE-47 photodecay. BDE-47 photodegradation all well followed pseudo-first-order kinetics under various conditions, and the decay rate was 0.4–1.3 times greater in the presence of surfactants than that in water alone. It was found that BDE-47 photodegradation was hardly affected through varying initial pH levels and retarded due to the presence of cations and acetone. The primary decay pathways in all surfactant micelles were shown to be reductive photodebromination, in which tri- to mono-BDEs were formed through a consecutive loss of bromine atoms. 2,4,4′-tribromodiphenyl ether (BDE-28), 4,4′-dibromodiphenyl ether (BDE-15), and 4-monobromodiphenyl ether (BDE-3) appeared sequentially as the predominant photoproducts over reaction time. Polybrominated dibenzofurans (mono- to tri-) were tentatively identified as additional intermediates for BDE-47 photodegradation in surfactant micelles.

Maternal transfer of brominated flame retardants in zebrafish ( Danio rerio)

In many species reproduction and embryonic development have been shown to be sensitive to environmental contaminants. Understanding embryonic exposure to environmental contaminants is thus highly important. In this study concentrations of brominated flame retardants (BFRs) were measured in zebrafish eggs after parental exposure for 42 days via the diet. Zebrafish were exposed to two doses of eleven structurally-diverse BFRs. Eight BFRs were detected in the female zebrafish and maternal transfer to eggs was evident for all eight compounds. The highest concentrations in eggs were observed for hexabromocyclododecane (HBCD) and 2,4,4′-tribromodiphenyl ether (BDE 28), followed by 2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (BDE 183) and tetrabromobisphenol A 2,3-dibromopropyl ether (TBBPA DBPE). Five potential BFR metabolites were tentatively identified in female fish and maternal transfer was observed also for these compounds. The lipid adjusted concentrations in eggs were significantly higher than the concentrations in female fish for several of the BFRs. Further, the results showed a generally higher transfer in the lower exposure level and also indicated a dependency on the physico-chemical properties of the compounds.

Identification of hydroxylated metabolites in 2,2′,4,4′-tetrabromodiphenyl ether exposed rats

Faeces from day 1–5 of orally administered 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in rat have been analysed for hydroxylated metabolites. Six hydroxylated tetrabrominated diphenyl ethers, as well as three hydroxylated tribrominated diphenyl ethers found, were structurally identified. They were 2′-hydroxy-2,4,4′-tribromodiphenyl ether, 3′-hydroxy-2,4,4′-tribromodiphenyl ether, 4′-hydroxy-2,2′,4-tribromodiphenyl ether, 6-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 2′-hydroxy-2,3′,4,4′-tetrabromodiphenyl ether, 3-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 5-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 4′-hydroxy-2,2′,4,5′-tetrabromodiphenyl ether and 4-hydroxy-2,2′,3,4′-tetrabromodiphenyl ether. The analysis was performed using gas chromatography–mass spectrometry (GC–MS). The identification of the hydroxylated polybrominated diphenyl ether (OH-PBDE) metabolites in the rat faeces was supported by similar relative retention times (RRTs) versus 2,2′,3,4,4′,5-hexabromodiphenyl ether (BDE-138) on two columns of different polarities compared to the authentic references. The identification of the OH-PBDE metabolites was also supported by full scan electron ionisation mass spectra. Two of the identified OH-PBDE metabolites have identical structures as natural products, which previously have been isolated from marine sponges and an ascidian.

Polybrominated dibenzo-p-dioxins, dibenzofurans, and diphenyl ethers in Japanese human adipose tissue.

Human adipose samples collected in Tokyo, Japan in 1970 and 2000 were analyzed for the presence of polybrominated dibenzo-p-dioxins (PBDDs), dibenzofurans (PBDFs), and diphenyl ethers (PBDEs), and the concentrations in the two groups were compared. As far as we know, the concentrations of the PBDD/Fs in adipose tissue from the general Japanese population are reported for the first time. Three PBDD/F congeners were found in the following adipose tissues: 2,3,7,8-TeBDD, 2,3,7,8-TeBDF, and 2,3,4,7,8-PeBDF. The median concentrations (ranges) of three PBDD/Fs in 1970 and 2000 were 5.1 (3.4-8.3) and 3.4 (1.9-5.3) pg/g lipid wt (l.w.), respectively. For PBDEs, seven PBDE congeners were determined in the following samples: 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5',6-hexabromodiphenyl ether (BDE-154), and 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE-183). Median concentrations (ranges) of PBDEs showed a significant increase from 29.2 (6.8-78.4) pg/g l.w. in 1970 to 1288 (466-2,753) pg/g l.w. in 2000. BDE-47, the major congener of PBDEs, was 56.2% and 35.6% of the total in 1970 and 2000, respectively, whereas the BDE-153 was < 1% and 29.7% of the total in 1970 and 2000, respectively. This may indicate that the source of PBDEs had changed during this period. Further analysis of archived human samples from 1970 to 2000 is needed to describe the details of the contamination trends of PBDD/Fs and PBDEs in the Japanese population. Furthermore, PBDD/F monitoring, particularly 2,3,7,8-TeBDD and 2,3,7,8-TeBDF, may give more toxicological information based on TeCDD toxic equivalents (TEQs).

Brominated flame retardants in archived serum samples from Norway: a study on temporal trends and the role of age.

The temporal trends and influence of age and gender on levels of selected brominated flame retardants (BFRs) in human serum have been assessed by analyzing archived samples from Norway. Serum from 40 to 50 year old men collected at six time periods during 1977 to 1999 and from eight groups of differing age and gender sampled in 1998 were pooled into six and eight samples, respectively. The BFRs were isolated using solid-phase extraction (SPE) and the serum lipids decomposed bytreatmentwith concentrated sulfuric acid directly on the polystyrene-divinylbenzene SPE column, prior to elution of the BFRs. Following diazomethane derivatization, the samples were analyzed by gas chromatography-electron capture mass spectrometry. Eight BFRs were quantified in the serum samples: 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154), 2,4,6-tribromophenol (TriBP), and tetrabromobisphenol A (TBBP-A). The serum concentrations of all the BFRs, increased during the entire period with the exception of TriBP, and the sum of the six polybrominated diphenyl ethers increased from 0.44 ng/g lipids in 1977 to 3.3 ng/g lipids in 1999. The BFR concentrations in the serum from the different age groups were relatively similar, except for the age group 0-4 years, which had 1.6-3.5 times higher serum concentrations. Women older than 25 years had lower serum concentrations of BFRs compared to the corresponding group of men. No trend related to age or gender, nor time during the period 1977 to 1999 was observed for TriBP. The present study indicates an ongoing increase in human exposure to BFRs, and the current body burden appears to be independent of age, except for infants (0-4 years old), who seem to experience elevated exposure.

Brominated flame retardants in plasma samples from three different occupational groups in Norway.

Brominated flame retardants (BFRs) are widely used in plastics, textile coatings, electrical appliances and printed circuit boards to prohibit the development of fires. In order to investigate how exposure to BFRs is related to specific occupations, samples were obtained from Norwegian individuals working at an electronics dismantling facility, in the production of printed circuit boards, or as laboratory personnel. Nine BFRs were quantified in the plasma samples: 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154), 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE-183), 2,4,6-tribromophenol (TriBP) and tetrabromobisphenol A (TBBP-A). The BFRs were extracted from plasma using solid-phase extraction (SPE). The plasma lipids were decomposed by treatment with concentrated sulfuric acid directly on the SPE column, prior to the elution of the BFRs. Following diazomethane derivatization, the samples were analysed by gas chromatography-electron capture mass spectrometry. The subjects working at the electronics dismantling plant had significantly higher plasma levels of TBBP-A and BDE-153 compared to the other groups, and the heptabrominated congener BDE-183 was only detected in plasma from this group. TriBP was generally the most abundant BFR present, and the plasma concentrations were in the range 0.17-81 ng g-1 lipids. BDE-47 was the dominant BDE congener in all the individual samples and the levels were in the range 0.43-14.6 ng g-1 lipids. The total amounts of the seven BDEs were 8.8, 3.9 and 3.0 ng g-1 lipids for the group of electronics dismantlers, circuit board producers and laboratory personnel, respectively. Generally, large variations in the individual concentration levels were found within the groups, especially in the group of electronics dismantlers, where the relative standard deviations for BDE concentrations were in the range 23-164%. The levels of BFRs were not correlated to age or the level of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153). The present work indicates that the population in Norway is exposed to several BFRs, probably with food as a major source. The elevated level of higher brominated BDEs and TBBP-A in the plasma from the workers at the dismantling plant suggests an additional occupational exposure for these individuals. Thus, human exposure to BFRs seems to originate from a combination of different sources; however, further studies investigating plasma samples from a larger number of individuals are necessary for a more complete assessment of human exposure pathways to these environmental contaminants.