Tetrabromobisphenol A and hexabromocyclododecane in sediments from the Zhujiang(Pearl) River Estuary and South China Sea

Marine sediments collected from the Zhujiang(Pearl) River Estuary(ZRE) and South China Sea(SCS) were utilized to study the occurrence and spatial distribution of tetrabromobisphenol A(TBBPA) and hexabromocyclododecane(HBCDD).The levels of TBBPA and HBCDD in sediments ranged from not detected(nd) to 6.14 ng/g dry weight(dw) and nd to 0.42 ng/g dw.TBBPA concentrations in marine sediments were substantially higher than HBCDD.The concentrations of TBBPA and HBCDD in the ZRE sediments were significantly greater than those in the SCS.α-HBCDD(48.7%) and γ-HBCDD(46.2%) were the two main diastereoisomers of HBCDD in sediments from the ZRE,with minor contribution of β-HBCDD(5.1%).HBCDD were only found in one sample from the northern SCS.The enantiomeric fraction of α-HBCDD in sediments from the ZRE was obviously greater than 0.5,indicating an accumulation of(+)-α-HBCDD.The enantiomers of HBCDD were not measured in sediments from the SCS.This work highlighted the environmental behaviors of TBBPA and HBCDD in marine sediments.

Temporal–spatial distribution and diastereoisomer pattern of hexabromocyclododecane in the vicinity of a chemical plant

Hexabromocyclododecane(HBCD) is an effective brominated flame-retardant additive, which is mainly produced in the coastal area of China. This study collected soil samples from a HBCD production plant and its surrounding area in Weifang, Shandong Province, China, and analyzed the temporal–spatial distribution of HBCD and its diastereoisomers in soil. The analysis results showed that the concentration of HBCD in soil near the plant was much higher than normal values, with an annual average concentration reaching 5405 ng/g. Soils 1,2 and 4 km away from the plant were also analyzed, showing that the concentration of HBCD in soil decreased accordingly with the distance from the pollution sources. In order to investigate the effect of the season on HBCD content, the soil samples were collected in all four seasons of the year 2017–2018. According to variations in the wind direction, the concentration of HBCD in soil was also changed. The distribution trend showed that the concentration of HBCD in soil in the downwind direction of the prevailing wind was higher than that in the upwind direction. In addition, this work analyzed the distribution of HBCD in vertical soil sections. It was found that the concentration of HBCD decreased with depth in the soil vertical profile. Finally, the various diastereoisomer patterns in the soil compartments were examined, finding that α-HBCD and γ-HBCD were the predominant diastereoisomers in the soil of the study area.

Trace determination of hexabromocyclododecane diastereomers in water samples with temperature controlled ionic liquid dispersive liquid phase microextraction

A novel temperature controlled ionic liquid dispersive liquid phase microextracfion （TCIL-DLPME） coupled with rapid resolution liquid chromatography-electrospray tandem mass spectrometry （RRLC-ESI-MS-MS） has been developed for the enrichment and determination of three hexabromocyclododecane diastereomers （HBCDs） in water samples. Green solvent ionic liquid （IL） was used as extraction solvent instead of toxic organic solvents. This technique also avoided the usage of dispersive solvent. Some important parameters that might affect the extraction efficiency were optimized. Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained. All the limits of detection for the three diastereomers were 0.1 ng/ mL. The linear range was obtained in the range of 1-100 ng/mL for the total amount of three HBCD diastereomers. It was satisfactory to analyze real environmental water samples with the recoveries ranging from 77.2% to 99.3%. The main advantage of the method is toxic organic solvent-free.

Hexabromocyclododecane and tetrabromobisphenol A in sediments and paddy soils from Liaohe River Basin, China： Levels, distribution and mass inventory

Hexabromocyclododecane （HBCD） and tetrabromobisphenol A （TBBPA） are two kinds of brominated flame retardants and widely present in the environment and biota. The levels, spatial distributions and mass inventories of HBCD and TBBPA were investigated in sediments and paddy soils from the Liaohe River Basin in northeast China. The concentrations of ∑HBCD and TBBPA were in the range of not detected （nd） to 4.02 ng/g dry weight （dw） and 0.03 to 4.06 ng/g dw, respectively, y-HBCD was dominated in sediments, while the abundance of a-HBCD was relatively high in paddy soils. The spatial distributions of HBCD and TBBPA in surface sediments and paddy soils indicated that the local point-input was their major source. The significant correlation between total organic carbon （TOC） contents and the HBCD levels suggested that TOC content also exerted an influence on the distribution of HBCD in sediments. Meanwhile, it was found that the irrigation with fiver water was not the major transportation pathway of HBCD and TBBPA in paddy soils. Based on the study, it was estimated that there were about 1.67 tons HBCD and 2.20 tons TBBPA deposited into sediments of the Liaohe River system every year. The total mass inventories of HBCD and TBBPA in sediments were far higher than that in paddy soils.

Accumulation and phytotoxicity of technical hexabromocyclododecane in maize

To investigate the accumulation and phytotoxicity of technical hexabromocyclododecane（HBCD）in maize,young seedlings were exposed to solutions of technical HBCD at different concentrations.The uptake kinetics showed that the HBCD concentration reached an apparent equilibrium within 96 hr,and the accumulation was much higher in roots than in shoots.HBCD accumulation in maize had a positive linear correlation with the exposure concentration.The accumulation of different diastereoisomers followed the orderγ-HBCD〉β-HBCD〉α-HBCD.Compared with their proportions in the technical HBCD exposure solution,the diastereoisomer contribution increased forβ-HBCD and decreased forγ-HBCD in both maize roots and shoots with exposure time,whereas the contribution ofα-HBCD increased in roots and decreased in shoots throughout the experimental period.These results suggest the diastereomer-specific accumulation and translocation of HBCD in maize.Inhibitory effects of HBCD on the early development of maize followed the order of germination rate〉root biomass≥root elongation〉shoot biomass≥shoot elongation.Hydroxyl radical（OH）and histone H2AX phosphorylation（γ-H2AX）were induced in maize by HBCD exposure,indicative of the generation of oxidative stress and DNA double-strand breaks in maize.An OH scavenger inhibited the expression ofγ-H2AX foci in both maize roots and shoots,which suggests the involvement of OH generation in the HBCD-induced DNA damage.The results of this study will offer useful information for a more comprehensive assessment of the environmental behavior and toxicity of technical HBCD.

Determination of hexabromocyclododecanes in sediments from the Haihe River in China by an optimized HPLC–MS–MS method

Hexabromocyclododecanes（HBCDs）,a new type of persistent organic pollutants widely used as brominated flame retardants,have attracted wide attention due to their increasing level and toxicity. A method based on high-performance liquid chromatography mass spectrometry（HPLC–MS–MS）in electrospray ionization mode has been developed by optimization of various parameters,which effectively improved the separation degree and responsive intensity of α-,β-and γ-HBCD isomers. The concentrations and distribution profiles of three HBCD isomers were investigated in sediments from the Haihe River in China.It was observed that the concentrations of HBCDs varied in the range of 0.4–58.82 ng/g,showing a decreasing trend along the flow direction,possibly due to attenuation and biodegradation along the flow direction of the Haihe River. The distribution profile of α-,β-,γ-HBCD was 7.91%–88.6%,0–91.47%,and 0.62%–42.83%,respectively. Interestingly,α-HBCD dominated in most sample sites. This was different from the distribution profile in commercial industrial products,which might be attributed to the inter-transformation and different degradation rates of the three HBCD isomers. The potential ecological risk of HBCDs in sediment was characterized under the two-tiered procedure of the European Medicines Evaluation Agency for environmental risk assessment. Although the HBCDs in the selected section of the Haihe River presented ＂no risk＂ in the sediment compartment,its risk in sediment cannot be neglected since sediment is one of the important sinks and reservoirs of pollutants.

Pollution and biodegradation of hexabromocyclododecanes:A review

Hexabromocyclododecanes(HBCDs)are the most common brominated flame-retardants after polybrominated diphenyl ethers.HBCDs can induce cancer by causing inappropriate antidiuretic hormone syndrome.Environmental contamination with HBCDs has been detected globally,with concentrations ranging from ng to|ig.Methods to degrade HBCDs include physicochemical methods,bioremediation,and phytoremediation.The photodegradation of HBCDs using simulated sunlight or ultraviolet lamps,or chemical catalysts are inefficient and expensive,as is physicochemical degradation.Consequently,bioremediation is considered as the most cost-effective and clean approach.To date,five bacterial strains capable of degrading HBCDs have been isolated and identified:Pseudomonas sp.HB01,Bacillus sp.HBCD-sjtu,Achromobacter sp.HBCD-1,Achromobacter sp.HBCD-2,and Pseudomonas aeruginosa HS9.The molecular mechanisms of biodegradation of HBCDs are discussed in this review.New microbial resources should be explored to increase the resource library in order to identify more HBCD-degrading microbes and functional genes.Synthetic biology methods may be exploited to accelerate the biodegradation capability of existing bacteria,including modification of the degrading strains or functional enzymes,and artificial construction of the degradation microflora.The most potentially useful method is combining microdegradation with physicochemical methods and phytoremediation.For example,exogenous microorganisms might be used to stimulate the adsorption capability of plants for HBCDs,or to utilize an interaction between exogenous microorganisms and rhizosphere microorganisms to form a new rhizosphere microbial community to enhance the biodegradation and absorption of HBCDs.

Rate of hexabromocyclododecane decomposition and production of brominated polycyclic aromatic hydrocarbons during combustion in a pilot-scale incinerator

Here, we examined the incineration of extruded polystyrene containing hexabromocyclododecane（HBCD） in a pilot-scale incinerator under various combustion temperatures（800–950℃） and flue gas residence times（2–8 sec）. Rates of HBCD decomposition ranged from 99.996%（800℃, 2 sec） to 99.9999%（950℃, 8 sec）; the decomposition of HBCD, except during the initial stage of combustion（flue gas residence time 〈 2 sec）, followed a pseudo-first-order kinetics model. An Arrhenius plot revealed that the activation energy and frequency factor of the decomposition of HBCD by combustion were 14.2 kJ/mol and 1.69 sec^（-1）,respectively. During combustion, 11 brominated polycyclic aromatic hydrocarbons（BrPAHs）were detected as unintentional by-products. Of the 11 BrPAHs detected, 2-bromoanthracene and 1-bromopyrene were detected at the highest concentrations. The mutagenic and carcinogenic BrPAHs 1,5-dibromoanthracene and 1-bromopyrene were most frequently detected in the flue gases analyzed. The total concentration of BrPAHs exponentially increased（range,87.8–2,040,000 ng/m^3） with increasing flue gas residence time. Results from a qualitative analysis using gas chromatography/high-resolution mass spectrometry suggest that bromofluorene and bromopyrene（or fluoranthene） congeners were also produced during the combustion.

Hexabromocyclododecane and tetrabromobisphenol-A in indoor dust from France, Kazakhstan and Nigeria: Implications for human exposure

Concentrations of hexabromocyclododecane isomers(α-,β-and γ-HBCDs)and tetrabromobisphenol-A(TBBP-A)were measured-for the first time-in indoor dust from homes,offices and cars from France,Kazakhstan and Nigeria.∑HBCDs in French and Kazakhstani house dust(median=1351 and 280 ng g^-1,respectively)were consistent with previous reports from the UK and Romania,respectively.Concentrations of ∑HBCDs in Nigerian domestic dust(median=394 ng g^-1)were substantially higher than those reported from Egyptian homes.In general,concentrations of ∑HBCDs in the studied microenvironments were higher than those of TBBP-A,which may be attributed to the major application of TBBP-A as a reactive flame retardant;rendering its release to dust more difficult.Statistical analysis revealed significantly lower ∑HBCDs in French houses than those found in both offices and cars,while ∑HBCDs in cars from Kazakhstan were higher(P<0.05)than those in homes and offices.Moreover,TBBP-A concentrations in car dust from Nigeria were lower than those found in homes and offices.Exposure estimates revealed higher intake of HBCDs and TBBP-A by toddlers via indoor dust ingestion compared to adults.Combined with their low body weight,this can raise concerns over the potential adverse health effects of such high exposure in toddlers.

Brominated flame retardants in surface sediment from Western Guangdong,South China:Occurrence,distribution and toxicity in Caenorhabditis elegans

Sediment is the ultimate sink of environmental pollutants.A total of 128 surface sediment sampleswere collected from8 rivers and 3 reservoirs in Maoming City,Guangdong Province.This study assessed the content and distribution of brominated flame retardants in sediments.The acute toxicity effects of tetrabromobisphenol A(TBBPA)and hexabromocyclododecane(HBCDs)in sediments were evaluated using Caenorhabditis elegans as model organisms.The concentration of TBBPA in sediments ranged from not detected(ND)to 12.59μg/kg andwas mainly distributed in the central area,whichwas affected by the emission of TBBPA from residential and factory.The concentration of HBCDs ranged from ND to 6.31μg/kg,and the diastereoisomer distribution was consistent,showing a trend close to the South China Sea.The composition pattern of HBCDs in the surface sediments from rivers were 41.73%-62.33%,7.89%-25.54%,and 18.76%-40.65%forα-,β-,andγ-HBCD,respectively,and in the sediments from reservoirs were 26.15%-45.52%,7.44%-19.23%,and 47.04%-61.89%forα-,β-,andγ-HBCD,respectively.When the sum of concentrations of TBBPA and HBCD in sediments were above high levels,reactive oxygen species in nematodes significantly increased,resulting in an oxidative stress response.Intestinal permeabilitywas also enhanced,causing intestinal damage.In addition,in terms of this study,TBBPA had a greater impact on biotoxicity compared to HBCDs,and more attention should be paid to the toxic effects of the river ecosystem organisms in Maoming City,Guangdong Province.This study can complement the pollution database in the study area and provide basic data for pollution control.

Laboratory studies on leaching of HBCDD from building insulation foams

A series of laboratory experiments were conducted to study emissions of hexabromocyclododecane(HBCDD)into aqueous leaching fluid under simulated landfill conditions.Expanded(EPS)and extruded(XPS)polystyrene building insulation foam samples containing HBCDD were contacted with deionised Milli-Q water containing 0,100 and 1000 mg L
1 dissolved humic matter(DHM)as leaching fluid.Concentrations of HBCDD were determined in the resulting fluid and single and serial batch experiments conducted.The impacts on HBCDD concentrations in the leaching fluid temperature and pH were examined.Data from these experiments show that HBCDD concentrations in leaching fluid following contact with EPS and XPS almost all exceeded the aqueous solubilities for each diastereomer and the technical HBCDD formula.This indicates that agitation and abrasion of EPS and XPS were significant mechanisms of HBCDD emission to leaching fluid.Specifically,under such conditions,HBCDD is likely associated with fine abraded particles of the foam and concentrations in the leaching fluid are therefore not limited by the aqueous solubility of HBCDD.Consistent with this,the length of contact time had a significant positive effect on concentrations of all diastereomers in the leaching fluid for XPS and for the least soluble diastereomer,g-HBCDD for EPS.Generally,the presence of DHM in the leaching fluid and elevated leaching fluid temperatures had significant positive effects on HBCDD concentrations in leaching fluid for both EPS and XPS.Overall,while leaching fluids of pH 8.5 significantly enhanced concentrations of a-HBCDD released from EPS,pH exerts a minor effect on concentrations of HBCDD in leaching fluid.

Chlorinated organophosphate and“legacy”brominated flame retardants in UK waste soft furnishings:A preliminary study

The Furniture and Furnishings(Fire Safety)Regulations 1988 is the major driver for the use of chemical flame retardants(FRs)in soft furnishings marketed in the UK.While these regulations specify the level of flame retardancy required,they do not specify how such levels should be achieved.Consequently,it remains unclear which FRs are present in UK soft furnishings.This is important not only to help assess what FRs we may be exposed to currently,but which FRs are currently entering the waste stream with concomitant potential for release into the environment.To address this data gap,concentrations of polybrominated diphenyl ethers(PBDEs),hexabromocyclododecane(HBCDD)and a range of chlorinated organophosphate flame retardants(OPFRs)were measured in samples of domestic and office waste soft furnishings products entering the UK waste stream in 2011 and 2012.This preliminary study measured the FR content of:carpets(n?4),curtains(n?7),mattress fabrics(n?2),furniture foam(n?9),and furniture upholstery textiles(n?10).Polybrominated diphenyl ethers(PBDEs)and hexabromocyclododecane(HBCDD)were not found at significant concentrations(below detection limits in most samples)in any of the twenty two analysed products.In contrast,7 of the 9 furniture foam samples were treated with tris(2-chloroisopropyl)phosphate(TCIPP)at a mean concentration of 1.9%w/w,with another single foam sample containing tris(1,3-dichloroisopropyl)phosphate(TDCIPP)and tris(2-chloroethyl)phosphate(TCEP)at 1.1 and 0.5%respectively.By comparison,PBDE concentrations are within the range reported previously for UK indoor dust[18],rather than the percent by weight levels required to impart flame retardancy.

Temporal trends in concentrations of legacy and novel brominated flame retardants in house dust from Birmingham in the United Kingdom

Concentrations of polybrominated diphenyl ethers(PBDEs),hexabromocyclododecane(HBCDD),tetrabromobisphenol-A(TBBPA)and two potential replacements decabromodiphenylethane(DBDPE)and 1,2-bis(2,4,6-tribromophenoxy)ethane(BTBPE)were measured in dust samples collected from 14 homes across Birmingham(UK).Concentrations were compared with those from the same city in previous studies to ascertain any temporal changes and to assess the effects of legislative restrictions.The average PHBCDDs concentration(46,000 ng/g;median=280 ng/g)included the highest dust concentration recorded globally(570,000 ng/g).This is despite the listing of HBCDD under the Stockholm Convention in 2013,demonstrating that decreases in indoor contamination will likely be slow as existing sources are gradually discarded.In contrast,concentrations of BDE-47(mean=5.7 ng/g;median=0.93 ng/g)and BDE-99(mean=11 ng/g;median=2.9 ng/g)were significantly lower than in all previous(p<0.01)studies in the same city since 2006,suggesting restrictions on the Penta-BDE formulation have been effective.The average BDE-209 concentration(4800 ng/g;median=1600 ng/g)is lower than the peak average concentration,which was observed in 2007(280,000 ng/g),however this is not a significant decline,probably due to the later imposition of Deca-BDE restrictions compared to those on Penta-BDE.Decreases in PBDE concentrations have coincided with a significant(p<0.01)increase in DBDPE concentrations(average=1500 ng/g;median=660 ng/g)since 2014,suggesting its use as a replacement flame retardant for Deca-BDE.While no significant change was detected for BTBPE(average 11 ng/g;median=0.84 ng/g in this study);concentrations of TBBPA(average=34 ng/g;median=35 ng/g)were significantly lower(p<0.05)than in 2007(average 62 ng/g).The decreases observed in PBDE concentrations,demonstrates that legislation has been effective in reducing the commercial use of PBDEs,however this has coincided with increases of alternative flame retardants such as DBDPE.

A novel method through solid phase extraction combined with gradient elution for concentration and separation of 66(ultra)trace persistent toxic pollutants in Antarctic waters

This study developed a method to perform the simultaneous concentration and selective separation of 66 （ultra） trace persistent toxic substances in Antarctic waters. The substances included 30 polychlorinated biphenyls, 17 organochlorine pesticides, 16 polycyclic aromatic hydrocarbons, 3 hexabromocyclododecanes. Solid phase extraction was performed using a C18 membrane and silica gel column. Gradient elution was conducted using organic solvents with different polarities; as a result, the efficiency of the C18 film is improved and the interferences from impurities and target compounds are eliminated. Extracts were subsequently analyzed through gas chromatography or liquid and gas chromatography coupled to tandem mass spectrometry. Method validation yielded the following values： recoveries of all target analytes in the Antarctic water ranged from 87.3% to 117.6% and reproducibility as percent relative standard deviation was lower than 5%. Quantification limits ranged from 0.004 μg L^-1 to 0.030 μg L^-1. The established method improved the recoveries and reduced the limits of detection. Results indicated the method exhibited good performance in the simultaneous concentration and selective separation of 66 （ultra） trace organic pollutants; Therefore, the proposed sample pretreatment can potentially eliminate the effects of various classes of impurities to some extent.