Advances in the study of current-use non-PBDE brominated flame retardants and dechlorane plus in the environment and humans

The effect of anthropogenic activities on the behavior of novel brominated flame retardants in surface soil of Northern China urbanized zone

Novel brominated flame retardants (NBFRs) have emerged as an alternative to traditional brominated flame retardants (BFRs) and may pose risks to the environment and human health. However, the distribution pattern of NBFRs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, seven NBFRs were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The ∑7NBFRs ranged from n.d. to 101 ng/g, dry weight (dw) (mean: 12.6 ± 17.6 ng/g dw), which exhibited a relatively elevated level compared to NBFRs in soils from other regions worldwide. Decabromodiphenylethane (DBDPE) was the main contaminant, and its concentration ranged from 0.378 to 99 ng/g, dry weight (dw) (mean: 11.4 ± 17.0 ng/g dw), accounting for 81 % of the ∑7NBFRs. Notably, NBFRs exhibited peak concentrations within residential zones, significantly surpassing those recorded in the remaining four regions (green, farmland, water environment and other) (p < 0.05). Furthermore, the concentration of NBFRs in the soil of the Binhai New District within Tianjin was the highest, significantly exceeding that of other administrative areas, which was closely related to the intensive industrial activities in this region. The above results indicate that human activities are a key factor affecting the concentration of NBFRs in the soil. Moreover, a variety of statistical methods were employed to investigate the correlation between socioeconomic variables and the distribution of NBFRs. The concentration of NBFRs showed a significant correlation with population density and the gross domestic product (GDP) (p < 0.05), and the incorporation of administrative regional planning into structural equation models demonstrated an indirect influence on the spatial distribution of NBFRs concentration, mediated by its impact on population density. These results emphasize the association between NBFRs contamination and the degree of urbanization, thereby providing valuable insights for assessing the exposure risk of NBFRs among urban residents.

Habitat-dependent trophic transfer of legacy and emerging halogenated flame retardants in estuarine and coastal food webs near a source region

With the phase-out of legacy halogenated flame retardants (HFRs), such as decabromodiphenyl ether (BDE-209), emerging ones, such as decabromodiphenyl ethane (DBDPE), are being widely produced. We conducted field campaigns to assess the trophic transfer of legacy and emerging HFRs in estuarine and coastal food webs of Laizhou Bay, which are located near the largest HFR manufacturing base in China. Seawater, sediment, plankton, invertebrates, and fish were collected from both sites. BDE-209 was the predominant compound in the estuary, whereas DBDPE was the main contributor to HFRs in the bay, followed by BDE-209. Invertebrates, especially bivalves and sea cucumbers, showed higher levels of BDE-209 and DBDPE than fish. The HFR levels in the organisms of the two coastal zones were comparable to each other, although their concentrations in the estuarine water were one order of magnitude higher than those in the bay. The HFR profiles in benthic organisms were similar to those in the sediments, indicating that the bioaccumulation of HFRs in coastal food webs depended on the habitat. The ΣHFR concentrations followed the order filter-feeding > carnivorous for invertebrates, and demersal non-migratory fish showed higher HFR levels than oceanodromous fish. The trophic magnification factors estimated for BDE-209, dechlorane plus, and DBDPE were lower than 1, suggesting biodilution potential in both food webs, whereas several PBDE congeners exhibited biomagnification capacity. Feeding habits, habitats, hydrophobicity, bioavailability, and metabolism may be the main factors impacting the bioaccumulation of HFRs in organisms in estuarine-coastal ecosystems of northern China.

Temporal trends of novel brominated flame retardants in mollusks from the Chinese Bohai Sea (2011-2018)

Novel brominated flame retardants (NBFRs) have emerged as an alternative to traditional brominated flame retardants (BFRs); however, they may pose risks to the environment and human health. To investigate the occurrence, temporal trends, and human exposure of seven typical NBFRs (∑₇ NBFRs), seven species of mollusks (n = 329) were collected from coastal cities in the Chinese Bohai Sea area from 2011 to 2018. The ∑₇ NBFRs ranged from 1.52 to 154 ng/g dry weight (dw) (mean: 14.9 ± 21.21 ng/g dw), higher than in other areas worldwide. Decabromodiphenylethane (DBDPE) was the main contaminant, contributing to 33% of the NBFRs. Temporal trends indicate that the DBDPE and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) concentrations in mollusks increased significantly (P < 0.05) at rates of about 26% and 5.4%, respectively. This suggests that these NBFRs are continuously released into the environment of the Bohai Sea area. The higher NBFR concentrations in the southern sampling sites relative to the northern sampling sites were consistent with the spatial distribution of the NBFR industry in the Bohai Rim Economic Circle. Chlamys farreri possessed the highest ∑₇ NBFR concentrations compared with the other species, while the lowest concentrations were found in Neverita didyma and Rapana venosa, suggesting interspecific differences in bioaccumulation. The estimated daily intake of NBFRs was low, and as the main contaminant, DBDPE was unlikely to pose significant human health risks. Overall, this is the first study to comprehensively assess the occurrence, spatial distribution, and temporal trends of NBFRs in mollusks.

Alternative halogenated flame retardants (AHFRs) in green mussels from the south China sea

Restrictions of legacy brominated flame retardants, such as polybrominated diphenyl ether (PBDE) and polybrominated biphenyl (PBB), have resulted in increased usage of alternative halogenated flame retardants (AHFRs). Consequently, AHFRs contamination has caused a major concern in the scientific community. However, there is limited information on their presence in marine mussels. In this study, we investigated the occurrence and distribution of polybrominated biphenyls (PBBs), AHFRs and dehalogenated products in green mussels collected from 22 locations in the northern South China Sea (SCS). Our results revealed that ∑AHFRs were ubiquitous in green mussels with concentrations in the range of 1.08-7.71 ng/g lipid weight (lw). Among target AHFRs, hexabromobenzene (HBB), decabromodiphenyl (DBDPE) and dechlorane plus (DP) were predominant with their mean values of 1.19, 1.00 and 0.82 ng/g lw, respectively. There were negligible stereoisomer enrichments of DP in green mussels based on f_anti values, indicating a limited bioaccumulation and metabolism of DP in green mussels. In comparison with other locations, concentrations of the AHFRs in green mussels determined here were at moderate levels. Additionally, there were significant linear relationships between some AHFRs (e.g., HBB and PBEB), suggesting their similar commercial applications and sources in the environment. The estimated daily intakes of AHFRs through consumption of green mussels by the local population in South China were 0.05-0.14 ng/kg body weight/day and 0.17-0.44 ng/kg body weight/day based on the mean and 95th concentrations, respectively. To the best of our knowledge, the present study is the first to report AHFRs and dehalogenated products in green mussels.

Inhomogeneity of sediment samples in analysis of hexabromocyclododecane

The repeatability test of the analytical method for hexabromocyclododecane (HBCD) was conducted with sediment sample. The maximum HBCD concentration exceeded the minimum by a factor of 90 even though the identical sediment samples were used. Therefore, we examined which step of the analytical method was the factor causing variability. We examined the blank test, and confirmation test of the extraction and purified procedure. From these results, we confirmed that there was nothing wrong with the accuracy of our analytical method. These results indicate that the variability of HBCD concentration in the repeatability test was attributed not to the analytical method, but to the inhomogeneity of the sediment sample. Aluminum, silicon, and organic carbon in sediments were measured to compare the variability of these concentrations with that of HBCD concentration. These concentrations were similar values within identical samples which showed variability in HBCD concentration. HBCD concentration in several samples did not correlate with organic carbon content. These results suggests that sediment samples were homogeneous by itself, and HBCD was heterogeneously distributed in spite of homogeneity of organic carbon in sediment. The sediment sample with variability in HBCD concentration showed different HBCD diastereomer compositions in identical sediment. It implies that the sample contained HBCD derived from different histories or point sources. Even though we increased sample amounts to analyze the homogeneity of the sample, HBCD concentration varied within identical samples if the sample had a hot spot. Past monitoring data may contain overestimation or underestimation of HBCD concentration in sediment.

Human Sex Hormone Disrupting Effects of New Flame Retardants and Their Interactions with Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, a Case Study in South China

Even though sex hormone disrupting effects of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are widely understood, similar effects associated with new flame retardants (NFRs) have not been so well studied. This study aimed to explore the sex hormone disruption of NFRs and their interactions with PCBs and PBDEs through the conduct of an ecological study in an e-waste dismantling and control region in South China. Questionnaires and blood samples were collected from local adult residents. Results of generalized additive model and linear regression analyses indicate that several species of NFRs showed similar disrupting effects with PBDE congeners on female follicle-stimulating hormone (FSH) and male testosterone. Judged by the curved shape and statistical significance, ΣNFR (sum of 8 species of NFRs) showed stronger disrupting effects on male testosterone and female FSH compared to ΣPBDE (sum of 13 congeners of PBDEs). The interactions induced by NFRs complicated the original sex hormone disruption led by PCBs and PBDEs. The disrupting effects and interactions induced by NFRs decreased female FSH levels in the exposed group. Comprehensive evaluation is needed to provide the evidence base for judging the health risks arising from the increased usage of NFRs.

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

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

A Bayesian approach for estimating hexabromocyclododecane (HBCD) diastereomer compositions in water using data below limit of quantification

We developed a statistical model that quantitatively incorporated the stochastic fluctuations of values, which were estimated as Bayesian credible intervals (BCIs), to analyze environmental monitoring data. We used α-hexabromocyclododecane (α-HBCD) diastereomer compositions of water samples that included data points below limit of quantification. To avoid replacing "not detected (ND)" values with irrelevant values in data analysis, we substituted ND with observed values from the measurement system upon examination of the model. In our study, it was assumed that the magnitude of stochastic fluctuations of observed values in environmental samples was identical to that in iterative measurements of a standard solution at the lowest concentration. Using this model, α-HBCD diastereomer compositions could be estimated along with BCIs even for samples collected from sites where concentrations of α-HBCD were ND or near limit of quantification. The brackish areas in our study showed relatively wide ranges in composition for the 95% BCIs compared with samples from fresh water areas. In the brackish areas, concentrations of HBCD were frequently ND or near limit of quantification. Using this model, it was unnecessary to replace ND with zero or limit of quantification in data analysis, and an environmental assessment could be achieved using all of the data. Therefore, this model is considered to be a widely applicable approach in the analysis of environmental monitoring data including ND.

Determination of heterocyclic brominated flame retardants tris-(2, 3-dibromopropyl) isocyanurate and hexabromocyclododecane in sediment from Jiaozhou Bay wetland

The concentration and distribution of tris-(2,3-dibromopropyl) isocyanurate (TBC) and the three isomers of hexabromocyclododecane (HBCDs) were analyzed in the sediment of Jiaozhou Bay wetland in China. The concentrations of TBC and the three isomers of HBCDs (α-HBCD, β-HBCD, γ-HBCD) were in the ranges of 1.20 to 8.76, 1.03 to 5.69, 1.13 to 5.46, and 1.18 to 15.04ng·g^-1 dw (dry weight), respectively. γ-HBCD was the predominant congener with an average proportion of 52.42% of ΣHBCDs, average inventory of HBCDs was about 93.53ng∙cm^-2. Depending on the function of wetland, the concentration of HBCDs tended to decrease as the distance to the Xiaojianxi refuse landfill increased. Compared with previous research studies, the concentration of TBC and HBCDs in the Jiaozhou Bay wetland was at a relatively high level. Therefore, more attention should be paid to TBC and HBCDs on account of their persistent impact on human health and the environment.

The biological fate of decabromodiphenyl ethane following oral, dermal or intravenous administration

1. It was important to investigate the disposition of decabromodiphenyl ethane (DBDPE) based on concerns over its structural similarities to decabromodiphenyl ether (decaBDE), high potential for environmental persistence and bioaccumulation, and high production volume. 2. In the present study, female Sprague Dawley rats were administered a single dose of [¹⁴C]-DBDPE by oral, topical or IV routes. Another set of rats were administered 10 daily oral doses of [¹⁴C]-DBDPE. Male B6C3F1/Tac mice were administered a single oral dose. 3. DBDPE was poorly absorbed following oral dosing, with 95% of administered [¹⁴C]-radioactivity recovered in the feces unchanged, 1% recovered in the urine and less than 3% in the tissues at 72 h. DBDPE excretion was similar in male mice and female rats. Accumulation of [¹⁴C]-DBDPE was observed in liver and the adrenal gland after 10 daily oral doses to rats. 4. Rat and human skin were used to assess potential dermal uptake of DBDPE. The dermis was a depot for dermally applied DBDPE; conservative estimates predict ∼14 ± 8% of DBDPE may be absorbed into human skin in vivo; ∼7 ± 4% of the parent chemical is expected to reach systemic circulation following continuous exposure (24 h). 5. Following intravenous administration, ∼70% of the dose remained in tissues after 72 h, with the highest concentrations found in lung (1223 ± 723 pmol-eq/g), spleen (1096 ± 369 pmol-eq/g) and liver (366 ± 98 pmol-eq/g); 5 ± 1% of the dose was recovered in urine and 26 ± 4% in the feces.

Determination of hexabromocyclododecane enantiomers in chicken whole blood by a modified quick, easy, cheap, effective, rugged, and safe method with liquid chromatography and tandem mass spectrometry

A rapid and simple analytical method has been developed for the determination of hexabromocyclododecane enantiomers in chicken whole blood, based on a modified quick, easy, cheap, effective, rugged, and safe approach before liquid chromatography coupled with tandem mass spectrometry. The factors influencing performance of method were investigated by single factor experiment, and further optimized by the response surface methodology based on Box-Behnken design. The matrix effects were also evaluated by the isotopic dilution method. Under the optimal conditions, the proposed method showed good linearity within the range of 1-500 μg/L and good repeatability with relative standard deviation less than 9.5% (n = 5). The limits of detection (S/N = 3) were 0.03-0.19 μg/L. The developed method was successfully applied for the analysis of hexabromocyclododecane enantiomers in real chicken blood samples. The satisfactory recoveries ranging of 83.6-115.0% were obtained (at spiked levels of 5, 20, and 100 μg/L). The results demonstrated that the proposed method would be a practical value method for the determination of hexabromocyclododecane enantiomers in animal blood. It would be further developed with confidence to analyze other lipophilic organic pollutants in blood sample.

New non-PBDE brominated flame retardants in sediment and plant samples from Jiaozhou Bay wetland

Seven non-polybrominated diphenyl ethers (non-PBDE) (TBB, TBX, PBT, PBEB, HBB, DBHCTD and BB153) were analyzed in sediment and plant samples which were collected from Xiaojianxi landfill to Dagu river estuary in Jiaozhou Bay wetland. The species of non-PBDE were different in sediment and plant samples with the concentration of 0.41-9.66ngg(-1) and 0.15-1.2ngg(-1), respectively. DBHCTD was the main non-PBDE compared with other target compounds and its concentration was 1.21-9.66ngg(-1)dw. Generally, the concentration of non-PBDE in sediment showed a decreasing tendency while discrete decline in plant has been revealed. Furthermore, DBHCTD, HBB, as well as other BFRs, might have a common BFRs degradation or similar accumulation potential in sediment, as their Pearson relationship p<0.05. Generally, the content of non-PBDE in Jiaozhou Bay wetland was higher than other published research. Therefore, more attention should be paid to non-PBDE on account of their persisting impact on human health and environment.

Silver ion post-column derivatization electrospray ionization mass spectrometry for determination of tetrabromobisphenol A derivatives in water samples

Six TBBPA derivatives in water samples were sensitively electrospray ionized by Ag⁺ post-column derivatization and directly analyzed with HPLC-MS/MS.

Current levels and composition profiles of emerging halogenated flame retardants and dehalogenated products in sewage sludge from municipal wastewater treatment plants in China

Occurrence of new toxic chemicals in sludge from wastewater treatment plants (WWTPs) is of concern for the environment and human health. Alternative halogenated flame retardants (HFRs) are a group of potentially harmful organic contaminants in the environment. In this study, a nationwide survey was carried out to identify the occurrence of HFRs and their potential dehalogenated products in sewage sludge from 62 WWTPs in China. Of all 20 target chemicals analyzed, decabromodiphenyl ethane (DBDPE), hexabromocyclododecane (HBCD) and 1, 2-bis (2,4,6-tribromophenoxy)-ethane (BTBPE) were detected in all sludge samples, and the concentrations were in the range of 0.82-215, 0.09-65.8, and 0.10-2.26 ng g(-1) d.w., respectively. Dechlorane Plus (DP) was found in 60 of 62 samples, and the concentration ranged from nd-298 ng g(-1) with a mean of 18.9 ng g(-1) d.w. The anti-DP fractional abundance fanti (0.79) in the samples was much higher than the commercial DP composition (fanti=0.59), indicating a stereoselective degradation. Comparison with global sludge concentrations of HFRs indicate that China is at the medium pollution level in the world. Principal components analysis revealed that strong correlations existed between ln-transformed concentrations (natural logarithm) of the dominant BFRs and total organic carbon (TOC) as well as industrial wastewater proportion, influent volume and serving population. Significant linear relationships (R=0.360-0.893, p<0.01) were found among emerging brominated flame retardants (BFRs), suggesting their common commercial applications and release sources to the environment. Two kinds of dehalogenated products, pentabromocyclododecane (PBCD) and undecachloropentacyclooctadecadiene (Cl11-DP), derived from HBCD and DP, were also identified in sewage sludge for the first time.

Distribution and pollutant load of hexabromocyclododecane (HBCD) in sewage treatment plants and water from Japanese Rivers

Hexabromocyclododecane diastereoisomers (α-, β-, γ-, δ-, and ε-HBCD) were investigated in river water, sewage influent, and sewage effluent from the Yodo River basin, Japan. The mean annual values of HBCDs ranged from 0.19 to 14ngL(-1) in river water. We observed that the concentrations of HBCDs in the brackish water area were low compared with that in the fresh water area. It was implied that, when the flow of the river stagnated in the estuarine area, HBCDs settled with suspended matter because of their hydrophobic character. In the sewage treatment plants, HBCDs ranged from 16 to 400ngL(-1) in sewage influent, whereas they ranged from 0.39 to 12ngL(-1) in sewage effluent. Over 90% of HBCDs were removed from the wastewater in the sewage treatment plants. By using these results, we estimated the pollutant load of HBCDs that flows into Osaka Bay from the study area. It was estimated that approximately 15kg of HBCDs flow into Osaka Bay from the study area in a year. This value is five orders of magnitude lower than the 2010 market demand for HBCDs (3019 metrictons) in Japan.

Halogenated flame retardants during egg formation and chicken embryo development: maternal transfer, possible biotransformation, and tissue distribution

Hen muscle, eggs, and newborn chick tissues (muscle and liver) were collected from an electronic waste recycling site in southern China. The authors examined the maternal transfer, potential metabolism, and tissue distribution of several halogenated flame retardants (HFRs) during egg formation and chicken embryo development. The pollutant composition changes significantly from hen muscle to eggs and from eggs to tissues of newborn chicks. Higher-halogenated chemicals, such as octa- to deca-polybrominated diphenyl ether (PBDE) congeners, deca-polybrominated biphenyl (PBB209), and dechlorane plus (DP), are less readily transferred to eggs compared with lower-halogenated chemicals. During embryo development, PBDEs are the most likely to be metabolized, whereas decabromodiphenyl ethane (DBDPE) is the least. The authors also observed selective maternal transfer of anti-DP and stereoselective metabolism of syn-DP during chicken embryo development. During tissue development, liver has greater affinity than the muscle for chemcials with a high log octanol-water partition coefficient, with the exception of DBDPE. The differences in metabolism potential of different chemicals in chicken embryos cause pollutant composition alterations. Halogenated flame retardant from maternal transfer and tissue distribution also exhibited chemical specificity, especially for DBDPE. Levels of DBDPE were elevated along with the full process from hen muscle to eggs and from eggs to chick tissues. More attention should be paid to the selective accumulation and biotransformation of HFRs in the early development stage of birds.

Occurrence of halogenated flame retardants in sediment off an urbanized coastal zone: association with urbanization and industrialization

To examine the impacts of urbanization and industrialization on the coastal environment, sediment samples were collected from an urbanized coastal zone (i.e., Daya Bay and Hong Kong waters of South China) and analyzed for 20 polybrominated diphenyl ethers (PBDEs) and 10 alternative halogenated flame retardants (AHFRs). The sum concentration of PBDEs was in the range of 1.7-55 (mean: 17) ng g(-1), suggesting a moderate pollution level compared to the global range. The higher fractions of AHFRs (i.e., TBB+TBPH, BTBPE and DBDPE) than those of legacy PBDEs (i.e., penta-BDE, octa-BDE and deca-BDE) corresponded with the phasing out of PBDEs and increasing demand for AHFRs. Heavy contamination occurred at the estuary of Dan'ao River flowing through the Daya Bay Economic Zone, home to a variety of petrochemicals and electronics manufacturing facilities. The concentrations of HFRs in surface sediments of Hong Kong were the highest in Victoria Harbor, which receives around 1.4 million tons of primarily treated sewage daily, and a good relationship (r(2) = 0.80; p < 0.0001) between the HFR concentration and population density in each council district was observed, highlighting the effect of urbanization. Moreover, the AHFR concentrations were significantly correlated (r(2) > 0.73; p < 0.05) with the production volume of electronic devices, production value of electronic industries and population size, demonstrating the importance of industrializing and urbanizing processes in dictating the historical input patterns of AHFRs.

Levels of flame retardants HBCD, TBBPA and TBC in surface soils from an industrialized region of East China

Hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA) are of increasing concern because of their potential environmental persistence, bioaccumulation and toxicity. Tris-(2,3-dibromopropyl)isocyanurate (TBC) is another brominated flame retardant (BFR) which has recently been found in the environment and begun to attract attention. The objective of this study is to determine the concentration of these three BFRs in surface soil samples collected from a heavily industrialized and urbanized region in East China. Levels of ∑HBCDs ranged from below detection limits (0.020 ng g(-1)) to 102.6 ng g(-1) on a dry weight basis (dw) with a median level of 15.8 ng g(-1) dw. For TBBPA, the concentration ranged from below detection limits (0.025 ng g(-1)) to 78.6 ng g(-1) dw with a median level of 9.17 ng g(-1) dw. TBC was found at relatively lower concentrations ranging from below detection limits (0.024 ng g(-1)) to 16.4 ng g(-1) dw with a median level of 0.95 ng g(-1) dw. The concentrations of these three BFRs are significantly positively correlated, indicating a common source. Variable BFRs levels were found in different types of soils, with significantly higher concentrations observed at waste dumping sites and industrial areas. The diastereoisomer profiles of HBCDs in most of the soil samples differed from those of the commercial products. The mass inventories of HBCDs, TBBPA and TBC in this region gave preliminarily estimates of 6.68, 2.67 and 0.85 kg, respectively. Therefore, the ubiquitous contamination of soils by these BFRs may well reflect their widespread usage in the study area.

Polybrominated diphenyl ethers and multiple stressors influence the reproduction of free-ranging tree swallows (Tachycineta bicolor) nesting at wastewater treatment plants

Reproductive success of birds is influenced by maternal factors, ambient temperatures, predation, food supply, and/or exposure to environmental contaminants e.g., flame retardants (FRs). Reproduction of tree swallows (Tachycineta bicolor) was compared among waste water treatment plants (WWTPs) and a reference reservoir in Ontario, Canada (2007-2010), to determine the importance of exposure to polybrominated diphenyl ether (PBDEs) FRs within a complex contaminant cocktail, relative to natural and biological factors known to influence avian reproduction. The birds primarily consumed insects emerging from the reference reservoir and WWTP outflows, where effluent mixed with receiving waters. FR egg concentrations were dominated by 5 PBDE congeners (∑5PBDEs): 2,2'.4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2'4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), and 2,2',4,4',5,6'-hexabromodiphenyl ether (BDE-154), with much lower concentrations of decabromodiphenylether (BDE-209), hexabromocyclododecane (HBCDD), and novel FRs. Although higher than ∑5PBDEs, polychlorinated biphenyls (PCBs) egg concentrations were unlikely to affect the swallows' reproduction. Clutch size and timing, fledging, breeding success, and predation, varied significantly among sites, generally being poorer at WWTP1 and better at WWTP2. The early reproductive stages were sensitive to some FRs at measured concentrations. The ∑5PBDEs, maternal age, and minimum ambient temperatures predicted onset of egg laying in the most parsimonious statistical model, and there were positive relationships between egg size and HBCDD or BDE-209 concentrations. However, there were no significant correlations with any reproductive measures, individual BDE congeners or low concentrations of novel FRs, in this first such report for novel FRs and wild birds. Tree swallows are passerines, and passerines may differ from birds of prey in their reproductive sensitivity to PBDE exposure: lay date, minimum temperatures, and predation, but not PBDE exposure, predicted reproductive productivity. Overall, there was some influence of the PBDEs available in these WWTP outflows on early reproductive parameters, but not reproductive output, of these passerines.

Enantiomer-specific accumulation, depuration, metabolization and isomerization of hexabromocyclododecane (HBCD) diastereomers in mirror carp from water

Until now, the bioaccumulation of hexabromocyclododecanes (HBCDs) in aquatic organisms has been studied only via dietary exposure. To better understand the environmental fate of HBCDs, we conducted a bioaccumulation test by exposing mirror carp to three HBCD diastereomers in water during 30d of accumulation and 30d of depuration according to Organization for Economic Co-operation and Development (OECD) Test Guidelines 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure). We found that the BCFKL values (bioconcentration factor calculated from kinetic data and adjusted to lipid content) of α-HBCD in different tissues of the carp were in the range of (3.07-4.52)×10(4), much higher than those of β-HBCDs (1.03-1.90×10(3)) and γ-HBCD (0.95-1.73×10(3)), as was true of t1/2. The order of BCFK for α-, β- and γ-HBCD in different tissues was viscera>gill>skin>muscle. β-HBCD and γ-HBCD were transformed to α-HBCD, with 50.0-92.9% and 96.2-98.6% bioisomerization efficiencies by the end of the experiment, respectively. No isomerization product from α-HBCD was found. Selective enrichment of the (+) α- and γ-HBCD was found, whereas β-HBCD did not show significant enantioselectivity. New metabolites such as tetrabromocyclododecene (TBCDe), tribromocyclododecadiene (TriBCDi) and tribromocyclododecatriene (TriBCDie) were found in mirror carp for the first time under multiple reaction monitoring (MRM) mode.

Effects of low-level hexabromocyclododecane (HBCD) exposure on cardiac development in zebrafish embryos

Hexabromocyclododecane (HBCD) is one of the most widely used brominated flame retardants. In the present study, zebrafish embryos were exposed to HBCD at the low concentrations of 0, 2, 20 and 200 nM. The results showed HBCD exposure resulted in an increase in heart rate and cardiac arrhythmia after exposure for 72 h, though the survival rate and the whole malformation rate were not significantly affected. These results demonstrated that the heart might be a target of HBCD. Low-level HBCD exposure may not share the same mechanisms as exposure to high concentrations, since no obvious increase of apoptotic cells around the heart was observed in the HBCD-treated groups. It was observed that the expression of Tbx5 and Nkx2.5 was significantly elevated by HBCD treatment in a dose-dependent manner using real-time quantitative PCR, which may be mainly responsible for the alteration of heart rate, given that Tbx5 and Nkx2.5 are two factors regulating ventricle conduction. The mRNA expression of RyR2 and Atp2a2b (SERCA2a) was up-regulated in the exposure group, which may be one of reasons to affect the normal heart rate, since SERCA2a and RyR2 play an important role in calcium ion transport of cadiomyocytes. However, HBCD exposure did not significantly change the expression of Actc1l, Tnnt2, and Myh6, which are mainly muscle contractile genes that play key roles in the formation of cardiac structure. These results were consistent with the lack of effect seen on the other measurements of cardiac function, end diastolic volume, end-systolic volume, stroke volume, and cardiac output.

Levels and distribution of tetrabromobisphenol A and hexabromocyclododecane in Taihu Lake, China

The occurrence and distribution characteristics of tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCD) in water and sediments from Taihu Lake, China, were investigated. The analytes were quantified by reversed-phase liquid chromatography coupled to electrospray ionization mass spectrometry. The TBBPA levels in water ranged from below the limit of detection (LOD) to 1.12 ng/L, whereas levels in sediments were between 0.056 ng/g dry weight and 2.15 ng/g dry weight. Regarding HBCD, concentrations were from below the LOD to 0.37 ng/L for water samples and from 0.046 ng/g dry weight to 2.56 ng/g dry weight for sediments. No correlation was found between sediment total organic carbon content and TBBPA/HBCDs, while significant positive correlations (r2 = 0.63, p < 0.005) were observed between TBBPA concentrations and HBCD concentrations in sediments. The highest TBBPA (2.15 ng/g dry wt) and total HBCD concentration (2.56 ng/g dry wt) was found at sampling site 1 (S1), while total HBCD levels fell dramatically with increasing distance from S1, suggesting that the estuary inputs around Taihu Lake were important sources of TBBPA and HBCDs. Compared with the pollution levels in the other regions of the world, the concentrations of TBBPA and HBCDs in Taihu Lake were at a moderate or low level. Further study on the sources of TBBPA and HBCDs is required for both assessment of their potential risks and better pollution management in Taihu Lake.

Dechlorane Plus flame retardant in kingfishers (Alcedo atthis) from an electronic waste recycling site and a reference site, South China: influence of residue levels on the isomeric composition

Dechlorane Plus (DP) isomers were examined in common kingfishers (Alcedo atthis) and their prey fishes collected from an electronic waste (e-waste) recycling site and a reference site in South China, to investigate the possible influence of DP residue levels on the isomeric compositions. ∑DP (sum of syn-DP and anti-DP) concentrations in kingfishers from the e-waste recycling site ranged from 29 to 150 (median of 58) ng/g lipid weight (lw), which were one order of magnitude greater than those from the reference site (median = 3.9 ng/g lw). The isomer fractions of anti-DP (f(anti)) in kingfishers from the e-waste recycling site (mean of 0.65) were significantly smaller than those from the reference site (0.76). Additionally, the f(anti) values were negatively correlated to logarithm of ∑DP concentrations in the kingfishers (r(2) = 0.41, p < 0.0001). These results suggested that DP residue levels could influence its isomeric composition in the piscivorous bird.

Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China

The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that gamma-HBCD dominated in most of the sediment samples, followed by alpha- and beta-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.

Bioaccumulation of polybrominated diphenyl ethers, decabromodiphenyl ethane, and 1,2-bis(2,4,6-tribromophenoxy) ethane flame retardants in kingfishers (Alcedo atthis) from an electronic waste-recycling site in South China

Brominated flame retardants (BFRs) including polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), were investigated in common kingfishers (Alcedo atthis) and their prey fish from an electronic waste-recycling site in south China. Elevated BFR residues were detected in the kingfishers, with median concentrations of 8,760, 12, and 7.7 ng/g lipid weight for total PBDEs, DBDPE, and BTBPE, respectively. The calculated predator/prey biomagnification factors (BMFs) were greater than unity for most of the investigated PBDE congeners, with relatively higher values for some hexa-, hepta-, and octa-BDEs (e.g., BDEs 153, 183, 196, 197, 202, and 203). The average BMFs ranged 0.10 to 0.77 and 1.90 to 3.60 for DBDPE and BTBPE, respectively. The BMFs for BTBPE were comparable to or even greater than those for some tri- to penta-BDEs in certain predator/prey pairs, indicating potentially high environmental risks of this compound. Significantly higher concentration ratios of BDEs 202 and 207 to BDE 209 were observed in the kingfishers compared with their prey fish, and these ratios were negatively correlated with the logarithm of BDE 209 concentrations in the kingfishers. This may indicate biotransformation of BDE 209 to BDEs 202 and 207 in these birds. This is the first assessment of the biomagnification potentials of DBDPE and BTBPE in a wild piscivorous bird.

A highly sensitive and selective immunoassay for the detection of tetrabromobisphenol A in soil and sediment

Tetrabromobisphenol A is the most widely used brominated flame retardant. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) for the detection of tetrabromobisphenol A was developed. The limit of detection and the inhibition half-maximum concentration of tetrabromobisphenol A in phosphate buffered saline with 10% methanol were 0.05 and 0.87 ng mL(-1), respectively. Cross-reactivity values of the ELISA with a set of important brominated flame retardants including tetrabromobisphenol A-bis(2,3-dibromopropylether), 2,2',6,6'-tetrabromobisphenol A diallyl ether, hexabromocyclododecane, 1,2-bis(pentabromodiphenyl) ethane, 1,2-bis(2,4,6 tribromophenoxy) ethane, bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate, and polybrominated diphenyl ethers were <0.05%. Concentrations of tetrabromobisphenol A determined by ELISA in the soils from farmlands, the soils from an e-waste recycling site, and the sediments of a canal were in the range of non-detectable-5.6 ng g(-1), 26-104 ng g(-1) and 0.3-22 ng g(-1)dw, respectively, indicating the ubiquitous pollution of tetrabromobisphenol A. The results of this assay for 16 real world samples agreed well with those of the liquid chromatography-tandem mass spectrometry method, indicating this ELISA is suitable for screening of tetrabromobisphenol A in environmental matrices.

Deposition of brominated flame retardants to the Devon Ice Cap, Nunavut, Canada

Brominated flame retardants (BFRs) can be transported to Arctic regions via atmospheric long-range transport, however, relatively little is known about their deposition to terrestrial environments. Snow cores from the Devon Ice Cap in Nunavut, Canada served to determine the recent depositional trends of BFRs. Snow pits were dug in 2005, 2006, and 2008. Dating using annual snow accumulation data, ion chemistry, and density measurements established that the pits covered the period from approximately 1993 to spring 2008. Samples were extracted under clean room conditions, and analyzed using GC-negative ion MS for 26 tri- to decabromodiphenyl ethers (BDEs), as well as other BFRs, nonbrominated flame retardants, and industrial chemicals. Decabromodiphenyl ether (BDE-209) was the major congener present in all samples followed by nona-BDEs (BDE-207, BDE-206, and BDE-208), both accounting for 89% and 7% of total BDE, respectively. BDE-209 concentrations were in most cases significantly correlated (P < 0.05) to tri- to nona-BDE homologues, and the strength of the correlations increased with increasing degree of bromination. Prior to or after deposition BDE-209 may be subject to debromination to lighter congeners. Deposition fluxes of BDE-209 show no clear temporal trend and range between 90 and 2000 pg·cm(-2)·year(-1). Back trajectory origin in densely populated areas of northeastern North America is significantly correlated (P < 0.005) with the BDE-209 deposition flux. Several other high production volume and/or alternative BFRs such as hexabromocyclododecane (HBCD), 1,2-bis(2,4,6-dibromophenoxy)ethane (BTBPE), pentabromo ethyl benzene (PBEBz), and pentabromobenzene (PBBz), as well as the industrial chemical 1,3,5-tribromobenzene (135-TBBz) were found consistently in the snow pits.

Levels and sources of brominated flame retardants in human hair from urban, e-waste, and rural areas in South China

Human hair and indoor dust from urban, e-waste, and rural areas in south China were collected and analyzed for brominated flame retardants (BFRs). BFRs concentrations in hair from occupational e-waste recycling workers were higher than those from non-occupational exposed residents in other sampling areas. Polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE) are two major BFRs in hair samples. The PBDE congener profiles in hair from the e-waste area are different from those from urban and rural areas with relatively higher contribution of lower brominated congeners. DBDPE, instead of BDE209, has become the major BFR in non-e-waste recycling areas. Significant correlations were found between hair level and dust level for DBDPE and BTBPE but not for PBDEs. The different PBDE congener profiles between dust and hair may suggest that exogenous exposure to the PBDE adsorbed on dust is not a major source of hair PBDEs.

A review of the analysis of novel brominated flame retardants

This review provides a summary of various analytical methodologies applied to the determination of "novel" brominated flame retardants (NBFRs) in various environmental compartments, as reported in peer reviewed literature, either in print or online, until the end of 2010. NBFRs are defined here as those brominated flame retardants (BFRs) which are either new to the market or newly/recently observed in the environment. The preparation and extraction of sediment, water, sewage sludge, soil, air and marine biota samples, the extract clean-up/fractionation and subsequent instrumental analysis of NBFRs are described and critically examined. Generally, while the instrumental analysis step mainly relies on mass-spectrometric detection specifically developed for NBFRs, and hyphenated to liquid or gas chromatography, preceding steps tend to replicate methodologies applied to the determination of traditional BFRs such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). Shortcomings and gaps are discussed and recommendations for future development are given.

Occurrence, sources, and inventory of hexabromocyclododecanes (HBCDs) in soils from Chongming Island, the Yangtze River Delta (YRD)

Hexabromocyclododecanes (HBCDs) is a concern due to their large usage combining with physico-chemical properties and toxicity to wildlife and human. However, very limited data were reported on HBCDs in soils, especially from rural area. In this study, 22 soil samples were collected from Chongming Island at estuary of the Yangtze River Delta, to investigate the level, diasteroisomer profile, potential sources, and mass inventory of HBCDs. The total concentrations ranged from not detected to 93.8pgg(-1) dry weight (dw) with a mean of 23.3pgg(-1)dw, which was at the low end of the global levels. The wide distribution of HBCDs in soils suggested that the local emissions of HBCD-containing materials and/or the inputs via atmospheric transport from other regions were two possible sources. Variation of HBCDs levels was observed in different types of soils. Woodland, tideland and road soils contained slightly higher HBCDs than those of farmland and grassland. Overall, γ-HBCD was the dominant diasteroisomer in soils, followed by α-HBCD and β-HBCD. Significant but weak correlations were only found between α-HBCD and β-HBCD versus TOC content in soils. Currently, the mass inventory of HBCDs in soils of Chongming Island was 5.3kg. Based on these data, we gave perspective on human intake of HBCDs via soil ingestion by age. Local resident's intakes ranged from 15.5 to 97.8fgkg body weight(-1)d(-1), in which children are exposed more than adults.

Several current-use, non-PBDE brominated flame retardants are highly bioaccumulative: evidence from field determined bioaccumulation factors

With the phaseout of brominated flame retardants (BFRs) polybrominated diphenyl ethers (PBDEs), some non-PBDE BFRs have prompted to be alternatives to the discontinued PBDEs. To assess the bioaccumulation potential of these chemicals, field bioaccumulation factors (BAFs) for several non-PBDE BFRs including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB), were determined in the aquatic species from a natural pond in an electronic waste recycling site in South China. The log BAFs ranged 2.58-6.01, 3.24-5.58, 3.44-5.98, 2.85-5.98, 3.32-6.08, 2.04-4.77, 2.72-4.09 and 3.31-5.54 for α-HBCD, β-HBCD, γ-HBCD, ∑HBCDs, BTBPE, PBT, PBEB, and HBB, respectively. The log BAF values for HBCD isomers, BTBPE, and HBB were greater than 3.7 (corresponding BAF value 5000) in most of the investigated species, demonstrating their highly bioaccumulative properties. α-, β-, and γ-HBCDs, BTBPE, and HBB appeared comparable or had even greater BAFs compared to PBDE congeners with similar K(OW), suggesting that these BFRs may have a potentially high environmental risk. The BAFs for the given BFR compound were largely variable between species, due to the species-specific feeding ecology, trophic level, and metabolic capacity for these pollutants. Positive linear relationships between log BAF and log K(OW) (r² = 0.59, p = 0.04), and molecular weight (r² = 0.54, p = 0.06) of non-PBDE BFRs were observed in the species with low trophic level (Chinese mysterysnail), suggesting that the chemical's physicochemical properties also played key roles in the bioaccumulation processes.

Dechlorane Plus in human hair from an e-waste recycling area in South China: comparison with dust

Dechlorane Plus (DP) and a dechlorination product, 1,6,7,8,9,14,15,16,17,17,18-octadeca-7,15-diene (anti-Cl(11)-DP), were measured in human hair and indoor dust collected from an e-waste recycling area and two control areas (rural and urban) in South China. DP was detected in hair and dust samples at concentrations ranging from 0.02-58.32 ng/g and 2.78-4197 ng/g, respectively. anti-Cl(11)-DP, mainly detected in human hair and dust samples from the e-waste recycling area, ranged from nd (nondetected) to 0.23 ng/g in hair and from nd to 20.22 ng/g in dust. Average values of anti-DP fractional abundance (f(anti) ratio) in hair of e-waste dismantling workers (0.55 ± 0.11) and dust from e-waste recycling workshops (0.54 ± 0.15) were significantly lower than those in other groups (0.62-0.76 means for hair and 0.66-0.76 means for dust). Significantly positive correlation between DP concentrations in dust and hair and similarity in f(anti) ratios between hair and dust suggest that ingestion of dust comprise one of the major routes for DP exposure. Significantly positive relationships were also observed between anti-Cl(11)-DP and anti-DP for both hair and dust samples with similar regression line slopes. The ratios of anti-Cl(11)-DP to anti-DP between hair and dust show no significant difference. These results suggest that anti-Cl(11)-DP in the human body is likely accumulated from the environmental matrix and not formed from biotransformation of the parent DP.