Brominated flame retardants and other polyhalogenated compounds in indoor air and dust from two houses in Japan

Tissue distribution of tetrabromobisphenol A and cadmium in mixture inhalation exposure

Tetrabromobisphenol A (TBBPA) and cadmium chloride (CdCl2) are the typical representative pollutants of brominated flame retardants and heavy metals found in the air of e-waste recycling workshops. However, their metabolic kinetics through mixture inhalation is unknown. In the present study, 8-week old Institute of Cancer Research (ICR) male mice were whole-body exposed to TBBPA and CdCl2 mixtures by inhalation. Tissue samples were collected for TBBPA and cadmium (Cd) analysis at 2, 4, 6, and 8 weeks during exposure and at 4 and 8 weeks after the completion of the 8-week exposure period. TBBPA was mainly distributed to the lungs, liver, kidney, testis, and spleen, with a high amount accumulated in the brain, liver, and spleen. Cd was mainly distributed to the lungs, liver, and kidney, with a high amount accumulated in the liver, kidney, and testis and a low amount accumulated in brain and serum. Tissue burden of TBBPA and Cd in all organs increased in a dose- and time-dependent manner during the exposure period. However, 4 weeks after the completion of an 8-week exposure, TBBPA concentrations in the liver, testis, brain, and serum and Cd concentrations in the liver, testis, and kidney were higher than the corresponding tissue concentrations during the exposure period. The rapid accumulation of both TBBPA and Cd in the lungs after inhalation exposure indicated a high risk of the respiratory system diseases for workers in e-waste recycling workshops. In addition, the migration of both TBBPA and Cd from lungs to liver and testis may result in more complex toxic effects in vivo.

Polybrominated diphenyl ethers and novel brominated flame retardants in indoor dust of different microenvironments in Beijing, China

The occurrence levels of eight polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) were determined and compared in indoor dust from different microenvironments (21 homes, 23 offices and 16 day care centers) in Beijing, China. Concentrations of ∑₈PBDEs in dust were 430-17,000 ng/g, 690-8600 ng/g, and 90-2300 ng/g for homes, offices, and day care centers, respectively, and were dominated by BDE-209. Concentrations of ∑₄NBFRs ranged from 310 to 17,000 ng/g, 300 to 4300 ng/g, and not detected to 500 ng/g for homes, offices, and day care centers, respectively, and were dominated by bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TEBP) and decabromodiphenylethane (DBDPE) across microenvironments. The results showed an increasing detection and elevated concentration of NBFRs (especially BEH-TEBP), indicating that monitoring of NBFRs in dust samples should be of concern in future studies. A notable finding was that the BFR concentrations in dust samples from day care centers were generally one order of magnitude lower than those from homes and offices in the present study. This implies that previous estimates of toddler exposure via dust ingestion on data from homes may be overestimated. Concentrations of BDE-209 and ∑₈PBDEs were found to be significantly higher in elevated surface dust than floor dust from day care centers. The estimates of daily intakes of BFRs via dust ingestion for Chinese adults and toddlers using Monte Carlo analysis were 2-5 orders of magnitude lower than the corresponding reference daily intakes.

Effects of novel brominated flame retardant TBBPA on human airway epithelial cell (A549) in vitro and proteome profiling

The cellular toxicity response of human airway epithelial cells (A549) to tetrabromobisphenol (TBBPA) was assessed in vitro. Cell viability, levels of intracellular reactive oxygen species (ROS), lipid peroxidation (MDA), and caspase-3 activity were determined after A549 treated with varying concentrations of TBBPA. A comparative proteomic analysis was performed in cells treated with different concentrations of TBBPA (0, 10, and 40 μg/mL). Two-way anova analysis showed that cell viability was significantly decreased after treatment by TBBPA with a concentration of 16 μg/mL for 48 hr, however, the caspase-3 activities, ROS generation, and MDA content increased. Ultrastructural observation revealed that the cell was morphological damaged after exposure to 64 μg/mL TBBPA, with mitochondria seriously injured and the smooth endoplasmic reticulum dilated. There was a good correlation between ROS generation and mitochondrial dysfunction. Seventeen differentially expressed proteins involved in various biological processes were identified. These findings provide a basis for understanding the mechanisms of cell dysfunction and perturbation of antioxidant status induced by additive flame retardant on airway epithelial cells.

Occurrence of tetrabromobisphenol a (TBBPA) and hexabromocyclododecane (HBCD) in soil and road dust in Chongqing, western China, with emphasis on diastereoisomer profiles, particle size distribution, and human exposure

Currently, the HBCDs were listed in Annex A by the Stockholm Convention, and the knowledge on the contamination of TBBPA and HBCDs in soil and road dust in China is still limited, and it is unclear what role is played by dust particle size distribution. In this study, a total of 81 soil and 43 road dust samples were analyzed with TBBPA and ΣHBCDs concentrations ranging from < LOQ to 33.8 ng/g dw (dry weight) and 0.43-15.2 ng/g dw in soil, and from < LOQ to 74.1 ng/g dw and 7.25-14.0 ng/g dw in road dust, respectively. TBBPA and HBCDs exhibited different spatial distribution patterns in soil, where relatively high levels of HBCDs were found in industrial area and commercial area, while high levels of TBBPA were detceted in residential area. However, no distinct variation in spatial distribution of these two compounds was observed in road dust. Different diastereoisomer profiles of HBCDs were also found with γ-HBCD predominating in soil and α-HBCD occupying a large proportion in road dust. The α-/γ-HBCD values in road dust were significantly greater (T-test, P < 0.05) than those in soil, which suggested that γ-HBCD in road dust were likely to transform into α-HBCD compared with soil. The distribution of dust particle size showed that HBCDs levels were increasing with the decreasing in particle sizes, while the TBBPA showed some "accidental" peak values in specific diameter ranges. The estimated daily intakes (EDIs) of TBBPA and HBCDs were assessed through dust ingestion, dermal absorption and inhalation via road dust, and all the exposure estimates were well below the reference dose (RfD), but the toddlers were more vulnerable to TBBPA and HBCDs intakes, which should be paid more attention.

Fluorotelomer alcohols (FTOHs), brominated flame retardants (BFRs), organophosphorus flame retardants (OPFRs) and cyclic volatile methylsiloxanes (cVMSs) in indoor air from occupational and home environments

Indoor air samples were collected from private homes and various occupational indoor environments using passive air sampler and analysed for fluorotelomer alcohols (FTOHs), brominated flame retardants (BFRs), organophosphorus flame retardants (OPFRs) and cyclic volatile methyl siloxanes (cVMSs). The aim was to investigate their occurrence in indoor air, factors that may affect their presence and human daily exposure dose (DED) via inhalation. In general, levels of cVMSs were 3-4 orders of magnitude greater than the other compound classes. OPFRs concentration was found significantly higher than BFRs in indoor air. The most abundant compounds in each chemical class were 8:2 FTOH, 2,4,6-TBP, TNBP and TCEP and decamethylcyclopentasiloxane (D5). Home samples contained higher level of FTOHs, BFRs and cVMSs than occupational environments, whereas concentration of OPFRs in office samples were higher. BFRs concentrations were significantly correlated with building age and with the number of electronic/electrical devices at the sampling sites. Moreover, significantly lower levels of FTOHs and cVMSs were observed in rooms with forced-ventilation system. Estimated DED via inhalation was significantly higher at home than in office and the total DED was on average 3-5 orders of magnitude lower than the reference value.

Solvent effects on quantitative analysis of brominated flame retardants with Soxhlet extraction

Reliable quantifications of brominated flame retardants (BFRs) not only ensure compliance with laws and regulations on the use of BFRs in commercial products, but also is key for accurate risk assessments of BFRs. Acetone is a common solvent widely used in the analytical procedure of BFRs, but our recent study found that acetone can react with some BFRs. It is highly likely that such reactions can negatively affect the quantifications of BFRs in environmental samples. In this study, the effects of acetone on the extraction yields of three representative BFRs [i.e., decabrominated diphenyl ether (decaBDE), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA)] were evaluated in the Soxhlet extraction (SE) system. The results showed that acetone-based SE procedure had no measureable effect for the recovery efficiencies of decaBDE but could substantially lower the extraction yields for both TBBPA and HBCD. After 24 h of extraction, the recovery efficiencies of TBBPA and HBCD by SE were 93 and 78% with acetone, 47 and 70% with 3:1 acetone:n-hexane, and 82 and 94% with 1:1 acetone:n-hexane, respectively. After 72 h of extraction, the extraction efficiencies of TBBPA and HBCD decreased to 68 and 55% with acetone, 0 and 5% with 3:1 acetone/n-hexane mixtures, and 0 and 13% with 1:1 acetone/n-hexane mixtures, respectively. The study suggested that the use of acetone alone or acetone-based mixtures should be restricted in the quantitative analysis of HBCD and TBBPA. We further evaluated nine alternative solvents for the extraction of the three BFRs. The result showed that diethyl ether might be reactive with HBCD and may not be considered as the alternative to acetone used solvents for the extraction of HBCD.

In vitro assessment of pyrethroid bioaccessibility via particle ingestion

Due to their intensive use in agricultural and residential pest control, human exposure to residues of multiple pyrethroids frequently occurs. Pyrethroids have exceptionally high affinity for solid particles, highlighting the need to understand human exposure through oral ingestion of contaminated soil or dust particles. In this study, we used artificial gastrointestinal fluids to measure the desorption or bioaccessibility of eight current-use pyrethroids in soil and dust samples. Tenax was further included as a sink in parallel treatments to simulate the effect of removal due to transfer of pyrethroids to lipid membranes. The use of 0.4 g of Tenax in 20 mL digestive fluids resulted in rapid and efficient trapping of pyrethroids, and further, greatly increased bioaccessibility. In the artificial digestive fluids without Tenax, 6.0-48.0% of pyrethroids were desorbed over 21 h, and the fractions increased by 1.6-4.1 folds to 21.5-79.3% with the Tenax sink. Therefore, 6.0-79.3% of soil or dust-borne pyrethroids may be considered bioavailable upon ingestion. While protein and sucrose increased the estimated bioaccessibility, co-presence of lipid (vegetable oil) decreased the bioaccessibility of pyrethroids, likely due to competitive phase partition. Pyrethroids were also found to be unstable in the artificial intestinal fluid containing pancreatin, further decreasing the potential bioaccessibility of pyrethroids on soil or dust particles. The limited bioaccessibility should be considered to refine the prediction of human exposure and risk through oral ingestion of pyrethroid residues.

Levels and gas-particle partitioning of hexabromocyclododecanes in the urban air of Dalian, China

The concentrations of α-, β-, and γ-hexabromocyclododecane diastereomers (HBCDs) in gas phase and particulate phase of Dalian urban air, China, were monitored from September 2016 to August 2017 with high-volume active sampler. The total concentration of ∑HBCDs (gas phase + particulate phase) ranged from 15.47 to 43.57 pg m^-3, with an average of 27.07 pg m^-3, and 73.39-96.76% of the total HBCDs were found in the particulate phase. No matter in gas phase or in particulate phase, α-HBCD was the predominant component in all, and there was a good negative correlation between the relative contribution of α-HBCD to ∑HBCDs and that of γ-HBCD to ∑HBCDs. The average ratios of the air concentration of α-HBCD to γ-HBCD were comparable with those found in decorative polystyrene, which indicated that HBCDs in outdoor air of Dalian probably came from indoor air and ventilation air from inside of buildings coupled with the already present contamination in background air. There were clear seasonal differences in the HBCD concentrations. Spearman's rank correlation analysis between the concentrations of HBCDs with meteorological parameters was conducted. The exposure risk of HBCDs was evaluated, which illustrated that the estimated exposure of HBCDs via the outdoor air in Dalian was well below the reference doses (200 ng kg^-1 bw day^-1) derived by the US National Research Council.

PCBs and organochlorine pesticides in indoor environments - A comparison of indoor contamination in Canada and Czech Republic

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are restricted compounds that are ubiquitously detected in the environment, including indoor matrices such as air and residential dust. We report concentrations of PCBs and selected OCPs in indoor air and dust from homes in Canada (23 homes) and Czech Republic (20 homes). Indoor air concentrations of PCBs and OCPs were ∼10 times higher than that outdoors. PCB concentrations of ∼450 ng/m³ were similar in both countries, higher in homes built before the restrictions on PCBs, and had congener profiles consistent with PCB mixtures manufactured or used in each country. All OCP air concentrations were higher in the Czech Republic than in the Canadian samples, suggesting greater indoor use of, for example, DDT and HCH. These data emphasize the persistence of these organochlorine compounds indoors and their presence in homes even decades after new usage was prohibited. Indoor levels of these legacy POPs remain at similar concentrations to compounds of current concern, such as brominated flame retardants and perfluorinated alkyl substances, emphasizing that they deserve ongoing attention in view of knowledge of PCB and OCP toxicity.

Polybrominated diphenyl ethers (PBDEs) in car and house dust from Thailand: Implication for human exposure

This study examines concentrations of tri- to hexa-bromodiphenylethers (BDEs 17, 28, 47, 49, 66, 85, 99, 100, 153 and 154; Σ₁₀PBDEs (polybrominated diphenyl ethers)) in car (n = 30) and house dust samples (n = 53) collected from different provinces in Thailand. The specific objectives of this study were: (i) to monitor levels of tri- to hexa-bromodiphenylethers (BDEs 17, 28, 47, 49, 66, 85, 99, 100, 153 and 154; Σ₁₀PBDEs) in vehicle and residential dust sampled from various provinces in Thailand; (ii) to compare PBDE concentrations with those detected for domestic and automobile dust in studies from other countries and (iii) to estimate exposure of the Thai population to the target PBDEs via dust ingestion. Levels of Σ₁₀PBDEs in vehicle and domestic dust were 0.68-38 and 0.59-260 ng g^-1, respectively. BDEs 99 and 47 were the most abundant congeners in all automobile and residential dust samples. A t-test analysis indicated that Σ₁₀PBDE concentrations in dust samples from dwellings exceeded significantly those from cars (p = 0.001). Furthermore, contents in dust of all PBDEs studied, except for BDE-28, were significantly higher in homes than in vehicles (p = 0.000-0.004). Principal Component Analysis (PCA) demonstrated no differences in PBDE congener patterns between Thai house and automobile dust, but revealed some subtle differences in the congener pattern between household dust samples in Thailand and those reported previously for the United Kingdom. Estimated environmental exposure of Thai adults and children for BDE-99 via dust ingestion were well within a chronic oral reference dose (RfD) for BDE-99 (100 ng/kg bw/day) proposed by the United States Environmental Protection Agency (US EPA).

A review of semi-volatile organic compounds (SVOCs) in the indoor environment: occurrence in consumer products, indoor air and dust

As many people spend a large part of their life indoors, the quality of the indoor environment is important. Data on contaminants such as flame retardants, pesticides and plasticizers are available for indoor air and dust but are scarce for consumer products such as computers, televisions, furniture, carpets, etc. This review presents information on semi-volatile organic compounds (SVOCs) in consumer products in an attempt to link the information available for chemicals in indoor air and dust with their indoor sources. A number of 256 papers were selected and divided among SVOCs found in consumer products (n = 57), indoor dust (n = 104) and air (n = 95). Concentrations of SVOCs in consumer products, indoor dust and air are reported (e.g. PFASs max: 13.9 μg/g in textiles, 5.8 μg/kg in building materials, 121 ng/g in house dust and 6.4 ng/m³ in indoor air). Most of the studies show common aims, such as human exposure and risk assessment. The main micro-environments investigated (houses, offices and schools) reflect the relevance of indoor air quality. Most of the studies show a lack of data on concentrations of chemicals in consumer goods and often only the presence of chemicals is reported. At the moment this is the largest obstacle linking chemicals in products to chemicals detected in indoor air and dust.

Contamination trends and factors affecting the transfer of hexabromocyclododecane diastereomers, tetrabromobisphenol A, and 2,4,6-tribromophenol to breast milk in Japan

This study investigated contamination trends and factors affecting the levels of brominated flame retardants (BFRs), including hexabromocyclododecane (HBCD) diastereomers, tetrabromobisphenol A (TBBP-A), and 2,4,6-tribromophenol (2,4,6-TBP), in breast milk in Japan. Breast milk samples (n = 64) were collected from mothers living in six prefectures in Japan. The mean concentrations were 2.2, 0.19, 0.29, 3.0, and 0.59 ng/g lipid weight for α-HBCD, β-HBCD, γ-HBCD, TBBP-A, and 2,4,6-TBP, respectively. Based on the previous studies, the levels of ΣHBCD in Japanese women's milk appear to be increasing, and the levels of TBBP-A are higher than those in other Asian countries. Although ΣHBCD were not correlated to phenolic BFRs, the concentration of β-HBCD was significantly correlated to the concentrations of TBBP-A (r = 0.440, p < 0.01) and 2,4,6-TBP (r = 0.320, p < 0.01). The concentration of γ-HBCD increased significantly with maternal age (r = 0.378, p < 0.01), but the concentrations of the other analytes were not dependent on age. The concentration of α-HBCD was higher in primiparae than in multiparae (p < 0.05), while TBBP-A was higher in multiparae. No significant correlation was found between the phenolic BFR levels in milk and mothers' age, working place, and drinking/smoking habits. These results suggest that exposure to α- and γ-HBCD diastereomers could be affected by maternal age and parity, respectively, because of their different kinetics and sources. Therefore, these factors should be considered when conducting infant risk assessments.

Phosphorus flame retardants and Bisphenol A in indoor dust and PM2.5 in kindergartens and primary schools in Hong Kong

Organophosphate flame retardants (PFRs) and bisphenol A (BPA) were measured in indoor dust and PM_2.5 samples from nine kindergartens and two primary schools in Hong Kong. The average levels of PM_2.5 ranged from 4.0E+03 ng/m³ to 1.5E+04 ng/m³. Average levels of PFRs (from 1.5 ng/m³ to 20 ng/m³ in PM_2.5; from 8.0E-02 μg/g dw to 2.4 μg/g dw in dust) and BPA (from 6.4E-01 ng/m³ to 1.0 ng/m³ in PM_2.5; from 1.0E-02 μg/g dw to 2.0E-01 μg/g dw in dust) were detected in most of the sampling sites. Tri-(2-Chloroethyl) phosphate (TCEP), tris(1,3-Dichloro-2-propyl) phosphate (TDCP), tris-(chloroisopropyl) phosphate (TCPP), and triphenyl phosphate (TPHP) were present in low levels in PM_2.5 with medians of 16, 14, 8.7, and 3.2 ng/m³, respectively. In dust, the medians were 1.5E-01, 5.5E-02, 5.9E-01, 8.6E-01, and 8.5E-02 μg/g dw for TCEP, TCPP, TDCPP, TPHP, and 2-ethylhexyl diphenyl phosphate, respectively. The medians of BPA were 6.4E-01 ng/m³ and 7.4E-02 μg/g dw for PM_2.5 and dust, respectively. A positive correlation was found between indoor PM_2.5 and dust in the levels of TCEP (r = 0.85; p = .05). In the individual classroom in this survey, the predominant PFRs were similar, that is, TDCP and TCEP in indoor PM_2.5 while TPHP and TDCP in dust. TPHP and TCEP in primary schools were obviously lower than those in kindergartens. The estimated daily intakes via PM_2.5 and dust for all selected PFRs ranged from 1.3E-4 μg/kg/d to 2.0E-02 μg/kg/d, and the value of less than the detection limit at 3.5E-4 μg/kg/d was found for BPA. The EDI values of TPHP in dust non-dietary intake fraction were higher than those in the others. Calculated hazard indices (EDI/RfD) ranged from 4.8E-06 and 5.5E-03, showing that PFRs and BPA in PM_2.5 and dust presented no health risks to children.

Concentrations of legacy and novel brominated flame retardants in indoor dust in Melbourne, Australia: An assessment of human exposure

Polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFR) have been used in a range of polymers to inhibit the spread of fires but also have a propensity to migrate out of consumer materials and contaminate indoor dust. In this study, a total of 57 dust samples were collected from 12 homes, eight offices and eight vehicles in Melbourne, Australia and analysed for eight PBDEs (-28, -47, -99, -100, -153, -154, -183 and -209) and seven NBFRs (PBT, PBEB, HBB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) to determine human exposure risks from dust ingestion. Samples were analysed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Legacy and replacement flame retardants were detected in all samples with overall ∑PBDE concentrations ranging from 120 to 1700,000 ng/g (median 2100 ng/g) and ∑NBFRs ranging from 1.1 to 10,000 ng/g (median 1800 ng/g). BDE-209 and DBDPE were the dominant compounds in dust samples, followed by congeners associated with commercial Penta-BDE formulations (-47, -99, -100, -153 and -154) and then EH-TBB of the FireMaster 550 and BZ-54 products. ∑Penta-BDE concentrations were elevated in office samples compared with homes and vehicles, while EH-TBB and BDE-209 measured higher concentrations in vehicles compared with their respective levels in homes and offices. Risk assessment estimates revealed the majority of exposure to occur in the home for both adults and toddlers in the City of Melbourne. Generally, body weight adjusted exposure to PBDEs and NBFRs was predicted to be 1 to 2 orders of magnitude higher for toddlers than adults. Estimated rates of BDE-47, -99, -153 and -209 ingestion were each 2 orders of magnitude or more below the USEPA's prescribed oral reference dose values (RfDs) for typical exposure scenarios. However, exposure rates for BDE-47 and -99 reached as high as 52 and 95% of RfDs, respectively, for adults and 4.4 and 7.4%, respectively, for toddlers in high exposure scenarios. This study provides the first wide-ranging survey of NBFRs in indoor dust from homes, offices and vehicles in Australia and offers further evidence of human exposure to legacy and novel brominated flame retardants via dust ingestion.

Alternative Flame Retardant, 2,4,6-Tris(2,4,6-tribromophenoxy)-1,3,5-triazine, in an E-waste Recycling Facility and House Dust in North America

A high molecular weight compound, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ), was detected during the analysis of brominated flame retardants in dust samples collected from an electrical and electronic waste (e-waste) recycling facility in Ontario, Canada. Gas chromatography coupled with both high-resolution and low-resolution mass spectrometry (MS) was used to determine TTBP-TAZ's chemical structure and concentrations. To date, TTBP-TAZ has only been detected in plastic casings of electrical and electronic equipment and house dust from The Netherlands. Here we report on the concentrations of TTBP-TAZ in selected samples from North America: e-waste dust ( n = 7) and air ( n = 4), residential dust ( n = 30), and selected outdoor air ( n = 146), precipitation ( n = 19), sediment ( n = 11) and water ( n = 2) samples from the Great Lakes environment. TTBP-TAZ was detected in all the e-waste dust and air samples, and in 70% of residential dust samples. The median concentrations of TTBP-TAZ in these three types of samples were 5540 ng/g, 5.75 ng/m³ and 6.76 ng/g, respectively. The flame retardants 2,4,6-tribromophenol, tris(2,3-dibromopropyl) isocyanurate, and 3,3',5,5'-tetrabromobisphenol A bis(2,3-dibromopropyl) ether, BDE-47 and BDE-209 were also measured for comparison. None of these other flame retardants concentrations was significantly correlated with those of TTBP-TAZ in any of the sample types suggesting different sources. TTBP-TAZ was not detected in any of the outdoor environmental samples, which may relate to its application history and physicochemical properties. This is the first report of TTBP-TAZ in North America.

Environmental concentrations and toxicology of 2,4,6-tribromophenol (TBP)

2,4,6-Tribromophenol is the most widely produced brominated phenol. In the present review, we summarize studies dealing with this substance from an environmental point of view. We cover concentrations in the abiotic and biotic environment including humans, toxicokinetics as well as toxicodynamics, and show gaps of the current knowledge about this chemical. 2,4,6-Tribomophenol occurs as an intermediate during the synthesis of brominated flame retardants and it similarly represents a degradation product of these substances. Moreover, it is used as a pesticide but also occurs as a natural product of some aquatic organisms. Due to its many sources, 2,4,6-tribromophenol is ubiquitously found in the environment. Nevertheless, not much is known about its toxicokinetics and toxicodynamics. It is also unclear which role the structural isomer 2,4,5-tribromophenol and several degradation products such as 2,4-dibromophenol play in the environment. Due to new flame retardants that enter the market and can degrade to 2,4,6-tribromophenol, this compound will remain relevant in future years - not only in aquatic matrices, but also in house dust and foodstuff, which are an important exposure route for humans.

Airborne particle-bound brominated flame retardants: Levels, size distribution and indoor-outdoor exchange

The quality of indoor environments has a significant impact on public health. Usually, an indoor environment is treated as a static box, in which physicochemical reactions of indoor air contaminants are negligible. This results in conservative estimates for primary indoor air pollutant concentrations, while also ignoring secondary pollutants. Thus, understanding the relationship between indoor and outdoor particles and particle-bound pollutants is of great significance. For this reason, we collected simultaneous indoor and outdoor measurements of the size distribution of airborne brominated flame retardant (BFR) congeners. The time-dependent concentrations of indoor particles and particle-bound BFRs were then estimated with the mass balance model, accounting for the outdoor concentration, indoor source strength, infiltration, penetration, deposition and indoor resuspension. Based on qualitative observation, the size distributions of ΣPBDE and ΣHBCD were characterized by bimodal peaks. According to our results, particle-bound BDE209 and γ-HBCD underwent degradation. Regardless of the surface adsorption capability of particles and the physicochemical properties of the target compounds, the concentration of BFRs in particles of different size fractions seemed to be governed by the particle distribution. Based on our estimations, for airborne particles and particle-bound BFRs, a window-open ventilated room only takes a quarter of the time to reach an equilibrium between the concentration of pollutants inside and outside compared to a closed room. Unfortunately, indoor pollutants and outdoor pollutants always exist simultaneously, which poses a window-open-or-closed dilemma to achieve proper ventilation.

Children's exposure to brominated flame retardants in indoor environments - A review

The aim of this review is to present up-to-date research on children's exposure to brominated flame retardants (BFRs) in indoor environments. Large geographical variations were observed for all BFRs [polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), tetrabromobisphenol A (TBBPA)], with the highest concentrations of PBDEs measured in North America (BDE-47) and Europe (BDE-209), where higher concentrations of PBDEs are present in dust from houses, daycare centers and primary schools. In Asia the highest PBDE concentrations were measured in China, near e-waste recycling areas. In the Middle East, Australia and Africa BFR levels were low in most indoor spaces. Asian countries also have the highest concentrations of TBBPA and HBCDD, followed by European countries. Fewer studies have been conducted measuring novel and emerging BFRs (NBFRs or EBFRs), of which decabromodiphenylethane (DBDPE) has the highest concentration in indoor environments, especially in China. The vast majority of children's exposure studies have been conducted in houses, sampling either dust or air, and considerably fewer in schools, daycare centers, cars and public facilities, despite BFR levels being comparable to (or sometimes even higher than) house dust. Relatively fewer studies focused on children's tissues such as serum, and only two studied exposure via mouthing toys. Alternative noninvasive sampling matrices that may act as surrogates for exposure to BFRs such as handwipes and silicone wristbands have recently started to gain momentum, because of the ease of sampling, faster collection time and better correlations to serum than house dust. Feces sampling is another promising alternative to children's serum that warrants further research. While many studies have associated different indoor environment characteristics, there is a knowledge gap on the association between children's behaviour and activity patterns and their exposure to BFRs, as well as data on infant exposure to BFRs via baby products. Results from the studies showed that dust ingestion was the dominant exposure pathway for most studied BFRs compared to indoor air inhalation and dermal contact, especially for infants and toddlers who have higher exposures than older children.

Anthropogenic and Naturally Produced Brominated Phenols in Pet Blood and Pet Food in Japan

Present study determined concentrations and residue patterns of bromophenols (BPhs) in whole blood samples of pet cats and pet dogs collected from veterinary hospitals in Japan. BPhs concentrations were higher in cat blood than in dog blood, with statistically insignificant differences (p = 0.07). Among the congeners, 2,4,6-tribromophenol (TBPh) constituted the majority of BPhs (>90%) detected in both species. Analysis of commercial pet food to estimate exposure routes showed that the most abundant congener in all pet food samples was 2,4,6-TBPh, accounting for >99% of total BPhs. This profile is quite similar to the blood samples of the pets, suggesting that diet might be an important exposure route for BPhs in pets. After incubation in polybrominated diphenyl ether (PBDE) mixtures (BDE-47, BDE-99 and BDE-209), 2,4,5-TBPh was found in dog liver microsomes but not in cat liver microsomes, implying species-specific metabolic capacities for PBDEs. Formation of 2,4,5-TBPh occurred by hydroxylation at the 1' carbon atom of the ether bond of BDE-99 is similar to human study reported previously. Hydroxylated PBDEs were not detected in cats or dogs; therefore, diphenyl ether bond cleavage of PBDEs can also be an important metabolic pathway for BPhs formation in cats and dogs.

New insight into the distribution pattern, levels, and risk diagnosis of FRs in indoor and outdoor air at low- and high-altitude zones of Pakistan: Implications for sources and exposure

Data regarding flame retardants (FRs) in indoor and outdoor air and their exposure to population are scarce and especially unknown in the case of Pakistan. The current study was designed to probe FR concentrations and distribution pattern in indoor and outdoor air at different altitudinal zones (DAZs) of Pakistan with special emphasis on their risk to the exposed population. In this study, passive air samplers for the purpose of FR deposition were deployed in indoor and outdoor air at the industrial, rural, and background/colder zones/sites. All the indoor and outdoor air samples collected from DAZs were analyzed for the target FRs (9.30-472.30 pg/m³), showing a decreasing trend as follows: ∑NBFRs > ∑PBDEs > ∑DP. However, significant correlations among FRs in the indoor and outdoor air at DAZs signified a similar source of FR origin that is used in different consumer goods. Furthermore, air mass trajectories revealed that movement of air over industrial area sources influenced concentrations of FRs at rural sites. The FR concentrations, estimated daily intake (EDI) and the hazard quotient (HQ), were recorded to be higher in toddlers than those in adults. In addition, indoor air samples showed higher FR levels, EDI and HQ, than outdoor air samples. An elevated FR concentrations and their prevalent exposure risks were recorded in the industrial zones followed by rural and background zones. The HQ for BDE-47 and BDE-99 in the indoor and outdoor air samples at different industrial and rural sites were recorded to be >1 in toddlers and adults, this further warrants a health risk in the population. However, FR investigation in indoor and outdoor air samples will provide a baseline data in Pakistan to take further steps by the government and agencies for its implementations.

Human exposure to HBCD and TBBPA via indoor dust in Korea: Estimation of external exposure and body burden

Human exposure to brominated flame retardants (BFRs) such as hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) mainly occurs through diet and dust ingestion. In this study, the BFR concentrations in 124 vacuum dust samples of six categories of indoor environments (homes, offices, kindergartens, cars, schools, and public indoor environments) and 32 surface dust samples were investigated. The median ΣHBCD concentrations ranged from 106.30ngg^-1 in home dust to 496.13ngg^-1 in office dust. The TBBPA concentrations in indoor dust (from 78.87 to 463.81ngg^-1) were among the highest compared to other countries because of the high market demand for this flame retardant in Korea. The TBBPA concentrations in surface dust of living rooms were significantly higher (p<0.05) than sleeping rooms, due to the presence of more electrical equipment in living rooms. The estimated daily intakes (EDI) of ΣHBCD and TBBPA (dust+diet) for toddlers were 6.18ngkg^-1bwd^-1 and 2.54ngkg^-1bwd^-1, respectively. In general, the ΣHBCD estimated body burden of Korean adults showed good agreement with the reported ΣHBCD median concentrations in their sera. Since the developmental health effect of exposure to HBCD was categorized as "high hazard" by the US Environmental Protection Agency, the estimated high body burden of ΣHBCD in Korean toddlers (7.91ngg^-1 lw) warns us of possible adverse effects on the development of essential systems in their bodies.

Characteristic accumulation of PCDD/Fs in pine needles near an MSWI and emission levels of the MSWI in Pearl River Delta: A case study

Pine needle samples were collected near a municipal solid waste incinerator (MSWI) in Pearl River Delta, southern China, as well as the stack gas and dust samples of the MSWI were simultaneously collected. Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) were analyzed following the USEPA Method 1613B. The concentration of PCDD/Fs in the pine needles (137-625 ng/kg, 25-51 ng I-TEQ/kg) is the highest level ever detected in China. Congener profile comparison and principal component analysis (PCA) confirmed the MSWI as an important emission source of environmental PCDD/Fs. The PCDD/Fs in the pine needles mainly depended on the atmospheric concentration, exposure time and also the wind direction. The accumulation of PCDD/Fs in this species did not occur at a steady rate, and the total concentrations covered up the actual photolysis information. Gas-phase partitioning of compounds in the atmosphere was the dominant process through which PCDD/Fs were adsorbed onto the pine needle surface in contrast with particle-phase deposition, and subsequent environmental behavior varied between the congeners. Photo-degradation was the major transformation process as PCDD/Fs were adsorbed onto the pine needle surfaces. Higher chlorinated PCDD/Fs were more recalcitrant to photo-degradation than those that were less chlorinated, and PCDDs were more resistant to photo-degradation than PCDFs. On the other hand, the strong ability of lipid-rich pine needles to accumulate dioxin compounds indicates they can be used as the absorption sink of PCDD/Fs in heavily polluted areas because it is easier to dispose of pine needles than it is to clean contaminated air.

Human Exposure to Legacy and Emerging Halogenated Flame Retardants via Inhalation and Dust Ingestion in a Norwegian Cohort

In this study, we estimated human exposure to polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), and several emerging flame retardants (EFRs) via inhalation and dust ingestion. Sixty indoor stationary air samples, 13 personal air samples, and 60 settled dust samples were collected from a Norwegian cohort during winter 2013. PBDEs showed the highest median concentration in dust (1200 ng/g), followed by EFRs (730 ng/g) and HBCDDs (190 ng/g). The PBDE concentrations in dust were mainly driven by BDE-209 and those of EFRs by bis(2-ethylhexyl) tetrabromophthalate. EFRs predominated in stationary air samples, with 2-ethylhexyl 2,3,4,5-tetrabromobenzoate and 4-(1,2-dibromoethyl)-1,2-dibromocyclohexane having the highest median concentrations (150 and 25 pg/m³ (sum of α- and β-isomers), respectively). Different profiles and concentrations were observed in personal air samples compared to the corresponding stationary air samples. In relation to inhalation exposure, dust ingestion appears to be the major exposure pathway to FRs (median total exposure 230 pg/kg bw/d, accounting for more than 65% of the total exposure) for the Norwegian cohort. The calculated exposure due to air inhalation was substantially lower when the stationary air concentrations were used rather than personal air concentrations (43 pg/kg bw/d versus 130 pg/kg bw/d). This suggests that other exposure situations (such as outdoors or in offices) contributed significantly to the overall personal exposure, which cannot be included by using only a stationary air sampling technique. The median and 95th percentile exposures for all target FRs did not exceed the reference dose.

Demographic and temporal trends of hexabromocyclododecanes (HBCDD) in an Australian population

Hexabromocyclododecanes (HBCDD) were measured in 67 pooled serum samples collected between 2002 and 2015 in South East Queensland, Australia. These data are the first report of HBCDD in Australian human serum. Temporal and demographic (age and gender) trends were investigated. HBCDD were detected in measurable concentrations in 69% of samples. The average ∑HBCDD concentration was 3.1ng/g lipid, whilst the range was <0.5 to 36ng/g lipid. α-HBCDD was the dominant stereoisomer making up an average of 60% of ∑HBCDD. The remainder was made up by γ-HBCDD. In contrast to another group of brominated flame retardants (BFRs, (polybrominated diphenyl ethers (PBDEs)), HBCDD were found in the lowest concentrations in pools from children aged 0-4 years. This could be attributed to differences in exposure, usage, and/ or the much lower half-life of HBCDD in the human body compared to PBDEs. HBCDD concentrations appear to be significantly higher in females than in males, however the reasons for this are unclear.

Emerging and Legacy Flame Retardants in UK Indoor Air and Dust: Evidence for Replacement of PBDEs by Emerging Flame Retardants?

Concentrations of 27 emerging (EFRs) and legacy flame retardants (LFRs) were measured in samples of indoor air (n = 35) and indoor dust (n = 77) from UK homes and offices. All target compounds were detected in indoor air and dust samples. Relatively volatile EFRs (e.g., tetrabromoethylcyclohexane-DBE-DBCH) were more frequently detected in indoor air (detection frequencies >60%), while less volatile EFRs (e.g., tetrabromobisphenolA-bis(2,3-dibromopropyl ether (TBBPA-BDBPE) and decabromodiphenyl ethane (DBDPE)) were predominant in dust. Concentrations of some EFRs (e.g., DBDPE) exceeded significantly those reported previously in UK dust (p < 0.05), while concentrations of BDE-209 in office dust were significantly lower (p < 0.05) than those reported previously in UK offices, consistent with the application of DBDPE as an alternative to the Deca-BDE formulation, of which BDE-209 is the principal constituent. Moreover, concentrations of BDEs-47 and -99 (both major constituents of the Penta-BDE product) in office air were significantly lower (p < 0.05) than those in previous UK studies. Our results constitute important early evidence that restrictions on PBDEs have increased demand for EFRs in the UK, with the result that human exposure to PBDEs in UK homes and offices has decreased while exposure to EFRs has risen.

Mutagenic Azo Dyes, Rather Than Flame Retardants, Are the Predominant Brominated Compounds in House Dust

Characterization of toxicological profiles by use of traditional targeted strategies might underestimate the risk of environmental mixtures. Unbiased identification of prioritized compounds provides a promising strategy for meeting regulatory needs. In this study, untargeted screening of brominated compounds in house dust was conducted using a data-independent precursor isolation and characteristic fragment (DIPIC-Frag) approach, which used data-independent acquisition (DIA) and a chemometric strategy to detect peaks and align precursor ions. A total of 1008 brominated compound peaks were identified in 23 house dust samples. Precursor ions and formulas were identified for 738 (73%) of the brominated compounds. A correlation matrix was used to cluster brominated compounds; three large groups were found for the 140 high-abundance brominated compounds, and only 24 (17%) of these compounds were previously known flame retardants. The predominant class of unknown brominated compounds was predicted to consist of nitrogen-containing compounds. Following further validation by authentic standards, these compounds (56%) were determined to be novel brominated azo dyes. The mutagenicity of one major component was investigated, and mutagenicity was observed at environmentally relevant concentrations. Results of this study demonstrated the existence of numerous unknown brominated compounds in house dust, with mutagenic azo dyes unexpectedly being identified as the predominant compounds.

Measurement and health risk assessment of PM2.5, flame retardants, carbonyls and black carbon in indoor and outdoor air in kindergartens in Hong Kong

Indoor air pollution is closely related to children's health. Polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DP) transmitted through indoor PM_2.5 and dust, along with carbonyl compounds and black carbon (BC) aerosol were analysed in five Hong Kong kindergartens. The results showed that 60% of the median PM_2.5 levels (1.3×10¹ to 2.9×10¹μg/m³ for indoor; 9.5 to 8.8×10¹μg/m³ for outdoor) in the five kindergartens were higher than the guidelines set by the World Health Organization (2.5×10¹μg/m³). Indoor PM_2.5 mass concentrations were correlated with outdoor PM_2.5 in four of the kindergartens. The PBDEs (0.10-0.64ng/m³ in PM_2.5; 0.30-2.0×10²ng/g in dust) and DP (0.05-0.10ng/m³ in PM_2.5; 1.3-8.7ng/g in dust) were detected in 100% of the PM_2.5 and dust samples. Fire retardant levels in the air were not correlated with the levels of dust in this study. The median BC concentrations varied by >7-fold from 8.8×10²ng/m^-3 to 6.7×10³ng/m^-3 and cooking events might have caused BC concentrations to rise both indoors and outdoors. The total concentrations of 16 carbonyls ranged from 4.7×10¹μg/m³ to 9.3×10¹μg/m³ indoors and from 1.9×10¹μg/m³ to 4.3×10¹μg/m³ outdoors, whilst formaldehyde was the most abundant air carbonyl. Indoor carbonyl concentrations were correlated with outdoor carbonyls in three kindergartens. The health risk assessment showed that hazard indexes (HIs) HIs of non-cancer risks from PBDEs and DPs were all lower than 0.08, whilst non-cancer HIs of carbonyl compounds ranged from 0.77 to 1.85 indoors and from 0.50 to 0.97 outdoors. The human intake of PBDEs and DP through inhalation of PM_2.5 accounted for 78% to 92% of the total intake. The cancer hazard quotients (HQs) of formaldehyde ranged from 4.5E-05 to 2.1E-04 indoors and from 1.9E-05 to 6.2E-05 outdoors. In general, the indoor air pollution in the five Hong Kong kindergartens might present adverse effects to children, although different schools showed distinct pollution levels, so indoor air quality might be improved through artificial measures. The data will be useful to developing a feasible management protocol for indoor environments.

Determination of the volatile fraction of phosphorus flame retardants in cushioning foam of upholstered furniture: towards respiratory exposure assessment

The purpose of this paper was to highlight potential exposure in indoor air to phosphorus flame retardants (PFRs) due to their use in upholstered furniture. For that, an analytical method of PFRs by headspace coupled to solid-phase micro-extraction (HS-SPME) was developed on cushioning foams in order to determine the PFRs' volatile fraction in the material. Tests on model foams proved the feasibility of the method. The average repeatability (RSD) is 6.3 % and the limits of detection range from 0.33 to 1.29 μg g(-1) of foam, depending on the PFRs. Results showed that some PFRs can actually be emitted in air, leading to a potential risk of exposure by inhalation. The volatile fraction can be high (up to 98 % of the total PFRs amount) and depends on the physicochemical properties of flame retardants, on the textural characteristics of the materials and on the temperature. The methodology developed for cushioning foams could be further applied to other types of materials and can be used to rate them according to their potential releases of phosphorus flame retardants.

Environmental occurrence, analysis and human exposure to the flame retardant tetrabromobisphenol-A (TBBP-A)-A review

TBBP-A is a high production volume chemical applied widely as a flame retardant in printed circuit boards. Recent studies have raised concern over potential harmful implications of TBBP-A exposure in human and wildlife, leading to its classification under group 2A "Probably carcinogenic to humans" by the International Agency for Research on Cancer. This article provides a comprehensive review of the available literature on TBBP-A analysis, environmental levels and human exposure. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been identified as the method of choice for robust, accurate and sensitive analysis of TBBP-A in different matrices. TBBP-A has been detected in almost all environmental compartments all over the world, rendering it a ubiquitous contaminant. Human exposure studies revealed dust ingestion and diet as the major pathways of TBBP-A exposure in the general population. Toddlers are likely to be more exposed than adults via accidental indoor dust ingestion. Moreover, exposure to TBBP-A may occur prenatally and via breast milk. There are no current restrictions on the production of TBBP-A in the EU or worldwide. However, more research is required to characterise human exposure to TBBP-A in and around production facilities, as well as in e-waste recycling regions.

Atmospheric occurrence and gas-particle partitioning of PBDEs at industrial, urban and suburban sites of Thessaloniki, northern Greece: Implications for human health

Air samples were collected during the cold and the warm period of the year 2012 and 2013 at three sites in the major Thessaloniki area, northern Greece (urban-industrial, urban-traffic and urban-background) in order to evaluate the occurrence, profiles, seasonal variation and gas/particle partitioning of polybrominated diphenyl ethers (PBDEs). The mean total concentrations of particle phase ∑12PBDE in the cold season were 28.7, 19.5 and 3.87 pg m(-3) at the industrial, urban-traffic and urban-background site, respectively, dropping slightly in the warm season (23.7, 17.5 and 3.14 pg m(-3)), respectively. The corresponding levels of gas-phase ∑12PBDE were 14.4, 7.15 and 4.73 pg m(-3) in the cold season and 21.2, 11.1 and 6.27 pg m(-3) in the warm season, respectively. In all samples, BDE-47 and BDE-99 were the dominant congeners. Absorption of PBDEs in the organic matter of particles appeared to drive their gas/particle partitioning, particularly in the cold season. The estimated average outdoor workday inhalation exposure to ∑12PBDE in the cold and the warm period followed the order: industrial site (288 and 299 pg day(-1)) > urban-traffic site (178 and 191 pg day(-1)) > urban-background site (58 and 63 pg day(-1)). The exposures to BDE-47, BDE-99, BDE-153 and ∑3PBDE via inhalation, for children outdoor worker and seniors were several orders of magnitude lower than their corresponding oral RfD values.

Airborne polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/furans (PBDD/Fs), and dechlorane plus (DP) in concentrated vehicle parking areas

This study investigated polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/furans (PBDD/Fs), and dechlorane plus (DP) in air around three concentrated vehicle parking areas (underground, indoor, and outdoor) in a metropolitan of South China. The parking areas showed higher concentrations of PBDEs, PBDD/Fs, and DP than their adjacent urban area or distinct congener/isomer profiles, which indicate their local emission sources. The highest PBDE and DP concentrations were found in the outdoor parking lot, which might be related to the heating effect of direct sunlight exposure. Multi-linear regression analysis results suggest that deca-BDEs without noticeable transformation contributed most to airborne PBDEs in all studied areas, followed by penta-BDEs. The statistically lower anti-DP fractions in the urban area than that of commercial product signified its degradation/transformation during transportation. Neither PBDEs nor vehicle exhaust contributed much to airborne PBDD/Fs in the parking areas. There were 68.1-100 % of PBDEs, PBDD/Fs, and DP associated with particles. Logarithms of gas-particle distribution coefficients (K ps) of PBDEs were significantly linear-correlated with those of their sub-cooled vapor pressures (p Ls) and octanol-air partition coefficients (K OAs) in all studied areas. The daily inhalation doses of PBDEs, DP, and PBDD/Fs were individually estimated as 89.7-10,741, 2.05-39.4, and 0.12-4.17 pg kg(-1) day(-1) for employees in the parking areas via Monte Carlo simulation.

Determination and human exposure assessment of polybrominated diphenyl ethers and tetrabromobisphenol A in indoor dust in South Africa

The concentration of TBBPA in dust samples from automobiles (n = 14), computer laboratories (n = 8), homes (n = 7), and offices (n = 7), and, also, PBDE concentrations in the indoor dust of 19 personal and previously owned automobiles in Durban, South Africa, were determined. Gas chromatography coupled with mass spectrometry was applied for the separation, identification, and quantitation of TBBPA and PBDEs. The median concentrations of TBBPA were 1156, 269, 120, and 492 ng g(-1) in automobiles, computer laboratories, homes, and offices, respectively. The ∑ n = 8 PBDE in 19 automobile samples ranged from 573 to 11,833 ng g(-1). BDE-209 accounted for approximately 42% of ∑ n = 8 PBDE in the samples. Household characteristics influenced the distribution of TBBPA in the various microenvironments. By assuming an average dust ingestion rate, and a median TBBPA concentration, the ∑DED (in ng kg(-1) bw day(-1)) of TBBPA is 0.08, 0.08, and 0.60, for an adult, teenager, and toddler, respectively. These doses are similar to dust ingestion intakes reported for Asian countries where there is a high demand for TBBPA as a flame retardant. Similarly, automobiles provide ample opportunity for human exposure to PBDEs via dust ingestion, particularly for toddlers and occupationally exposed adults.

A review of status of tetrabromobisphenol A (TBBPA) in China

Tetrabromobisphenol A (TBBPA), a currently intensively used brominated flame retardant (BFR), is employed primarily as a reactive flame retardant in printed circuit boards but also has additive applications in several types of polymers. TBBPA is a ubiquitous environmental contaminant that is observed in both abiotic and biotic matrices. This paper summarizes and critically reviews the published scientific data concerning the current pollution status of TBBPA in China. To provide an indication of the seriousness of the pollution levels of TBBPA in China, the data are compared with available existing data from other countries of the world. According to the available data, the sources of TBBPA in China are mainly derived from the primitive e-waste dismantling, TBBPA manufacturing and processing of TBBPA-based materials. The most serious cases of TBBPA pollution in China are in Guiyu, Guangdong (primitive e-waste dismantling site) with concentrations of TBBPA reaching 66,010-95,040 pg m(-3) in air, Shouguang, Shandong (TBBPA manufacturing site) with concentrations of TBBPA reaching 1.64-7758 ng g(-1) dry weight in soil, and Chaohu Lake, Anhui (industry concentration site) with concentrations of TBBPA reaching 850-4870 ng L(-1) in water. In general, China is the most polluted region as affected by TBBPA compared with other countries. The present review preliminarily reveals the research status of TBBPA in China.

Typical halogenated persistent organic pollutants in indoor dust and the associations with childhood asthma in Shanghai, China

Halogenated persistent organic pollutants (Hal-POPs) are significant contaminants in the indoor environment that are related to many human diseases. Ingestion of indoor dust is considered the major pathway of Hal-POP exposures, especially for children aged 3-6 years. Alongside a retrospective study on the associations between typical Hal-POP exposure and childhood asthma in Shanghai, indoor dust samples from asthmatic and non-asthmatic children's homes (n = 60, each) were collected. Polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured by GC-MS. BDE-209, PCB-8 and p,p'-DDE were the predominant components in each chemical category. The concentrations of most Hal-POPs were significantly higher in the asthmatic families. The associations between Hal-POP exposure and asthma occurrence were examined by calculating the odds ratios (ORs) using a logistic regression model. A positive association was found between p,p'-DDE in indoor dust and childhood asthma (OR = 1.825, 95%CI: 1.004, 3.317; p = 0.048). The average daily doses of Hal-POP intake were calculated using the method provided by the USEPA. Non-carcinogenic health risks were preliminarily assessed. Our study indicated that exposure to p,p'-DDE via indoor dust may contribute to childhood asthma occurrence. Non-carcinogenic health risks were not found with the intake of Hal-POPs via the ingestion of indoor dust.

Concentrations of legacy and emerging flame retardants in air and soil on a transect in the UK West Midlands

Passive air samples were collected monthly for 6 months from 8 sites along a transect of Birmingham, United Kingdom between June 2012 and January 2013. Soil samples were collected once at each site. Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in ambient air were 150, 49, and 180 pg m(-3), respectively. Atmospheric concentrations of PBDEs were negatively correlated with distance from the city centre, exhibiting an "urban pulse". The average ΣHBCDD air concentration was 100 pg m(-3), however concentrations were not correlated with distance from the city centre. Several emerging flame retardants (EFRs) were identified in air and/or soil samples: 2,3,4,5-tetrabromo-bis(2-ethylhexyl) phthalate (BEH-TEBP), 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane (TBECH or DBE-DBCH), allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DP or DDC-CO). Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in soil were 11, 3.6, and 15 ng g(-1) soil organic matter. PBDE concentrations in soil were higher at sites closest to the city centre, however correlations with distance from the city centre were not significant. BDEs-47 and -99 contributed more to ΣPBDEs in soil samples than air samples, but in both, the predominant congener was BDE-209. BATE was more abundant in air than soil but ATE was abundant in soil but not air.

Concentrations of polybrominated diphenyl ethers (PBDEs) and 2,4,6-tribromophenol in human placental tissues

Legacy environmental contaminants such as polybrominated diphenyl ethers (PBDEs) are widely detected in human tissues. However, few studies have measured PBDEs in placental tissues, and there are no reported measurements of 2,4,6-tribromophenol (2,4,6-TBP) in placental tissues. Measurements of these contaminants are important for understanding potential fetal exposures, as these compounds have been shown to alter thyroid hormone regulation in vitro and in vivo. In this study, we measured a suite of PBDEs and 2,4,6-TBP in 102 human placental tissues collected between 2010 and 2011 in Durham County, North Carolina, USA. The most abundant PBDE congener detected was BDE-47, with a mean concentration of 5.09ng/g lipid (range: 0.12-141ng/g lipid; detection frequency 91%); however, 2,4,6-TBP was ubiquitously detected and present at higher concentrations with a mean concentration of 15.4ng/g lipid (range:1.31-316ng/g lipid; detection frequency 100%). BDE-209 was also detected in more than 50% of the samples, and was significantly associated with 2,4,6-TBP in placental tissues, suggesting they may have a similar source, or that 2,4,6-TBP may be a degradation product of BDE-209. Interestingly, BDE-209 and 2,4,6-TBP were negatively associated with age (rs=-0.16; p=0.10 and rs=-0.17; p=0.08, respectively). The results of this work indicate that PBDEs and 2,4,6-TBP bioaccumulate in human placenta tissue and likely contribute to prenatal exposures to these environmental contaminants. Future studies are needed to determine if these joint exposures are associated with any adverse health measures in infants and children.

Tetrabromobisphenol A and heavy metal exposure via dust ingestion in an e-waste recycling region in Southeast China

This study was designed to investigate a prevalent brominated flame retardant tetrabromobisphenol A (TBBPA) and four heavy metals of Pb, Cr, As, Cd in dust samples (52 indoor and 52 outdoor) collected from residential houses in an e-waste recycling area in Southeast China. For TBBPA, the mean concentration in indoor dust (3435 ng/g, dw) was higher than that in outdoor dust (1998 ng/g, dw). For heavy metals, the mean concentrations of Pb, Cr, As, Cd were 399, 151, 48.13, and 5.85 mg/kg in indoor dust, respectively, and were 328, 191, 17.59, and 4.07 mg/kg in outdoor dust, respectively. Except for As, concentrations of TBBPA and other metals decreased with the increased distance away from the e-waste recycling center, suggesting significant contribution of e-waste activities. The daily exposure doses of TBBPA ranged from 0.04 to 7.50 ng/kg-bw/day for adults and from 0.31 to 58.54 ng/kg-bw/day for children, representing the highest values reported to date for TBBPA exposure via dust ingestion. Daily exposure doses of Cr, As, and Cd were all below the reference doses. However, daily exposure dose of Pb for children in areas near the e-waste processing center was above the reference dose, posing significant health concern for children in that region.

Brominated flame retardants, hexabromocyclododecane and tetrabromobisphenol A, affect proinflammatory protein expression in human bronchial epithelial cells via disruption of intracellular signaling

Hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) are widely used as brominated flame retardants (BFRs) in consumer products. Because humans can be exposed to BFRs mainly through air or dust, the effects of the BFRs on the respiratory system and the underlying mechanisms were investigated. HBCD exposure significantly increased the expression of intercellular adhesion molecule (ICAM)-1 and the production of interleukin (IL)-6 and -8 in human bronchial epithelial cells (BEAS-2B). TBBPA exposure significantly increased the expression of ICAM-1 and IL-6, but not IL-8. HBCD and TBBPA stimulated epidermal growth factor (EGF) production and EGF receptor (EGFR) phosphorylation. Inhibitors of EGFR-selective tyrosine kinase and the subsequent mitogen-activated protein kinase effectively blocked the increase in the expression of proinflammatory proteins. The activation of nuclear factor-kappa B (p50, p65) and activator protein 1 (c-Jun) was also observed following HBCD exposure. Furthermore, the modulation for nuclear receptors was investigated. TBBPA but not HBCD showed ligand activity for thyroid hormone receptor (TR) and TR antagonist significantly suppressed the TBBPA-induced increase of the expression of ICAM-1 and IL-6. In conclusion, HBCD and TBBPA can disrupt the expression of proinflammatory proteins in bronchial epithelial cells, possibly via the modulation of EGFR-related pathways and/or nuclear receptors.

A comparative assessment of human exposure to tetrabromobisphenol A and eight bisphenols including bisphenol A via indoor dust ingestion in twelve countries

Tetrabromobisphenol A (TBBPA) and eight bisphenol analogues (BPs) including bisphenol A (BPA) were determined in 388 indoor (including homes and microenvironments) dust samples collected from 12 countries (China, Colombia, Greece, India, Japan, Kuwait, Pakistan, Romania, Saudi Arabia, South Korea, U.S., and Vietnam). The concentrations of TBBPA and sum of eight bisphenols (ƩBPs) in dust samples ranged from <1 to 3600 and from 13 to 110,000 ng/g, respectively. The highest TBBPA concentrations in house dust were found in samples from Japan (median: 140 ng/g), followed by South Korea (84 ng/g) and China (23 ng/g). The highest ∑BPs concentrations were found in Greece (median: 3900 ng/g), Japan (2600 ng/g) and the U.S. (2200 ng/g). Significant variations in BPA concentrations were found in dust samples collected from various microenvironments in offices and homes. Concentrations of TBBPA in house dust were significantly correlated with BPA and ∑BPs. Among the nine target chemicals analyzed, BPA was the predominant compound in dust from all countries. The proportion of TBBPA in sum concentrations of nine phenolic compounds analyzed in this study was the highest in dust samples from China (27%) and the lowest in Greece (0.41%). The median estimated daily intake (EDI) of ∑BPs through dust ingestion was the highest in Greece (1.6-17 ng/kg bw/day), Japan (1.3-16) and the U.S. (0.89-9.6) for various age groups. Nevertheless, in comparison with the reported BPA exposure doses through diet, dust ingestion accounted for less than 10% of the total exposure doses in China and the U.S. For TBBPA, the EDI for infants and toddlers ranged from 0.01 to 3.4 ng/kg bw/day, and dust ingestion is an important pathway for exposure accounting for 3.8-35% (median) of exposure doses in China.

Polybrominated diphenyl ethers and polychlorinated biphenyls in indoor dust in Durban, South Africa

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in indoor dust of three microenvironments in Durban, South Africa. The sum of eight PBDEs and three PCBs were quantified by gas chromatography with mass spectral detection. The mean concentrations of ∑n = 8 PBDEs and ∑n = 3 PCBs in 10 homes, 11 offices, and 13 university students' computer laboratories were 1710, 1520, and 818 ng/g, and 891, 923, and 1880 ng/g for PBDEs and PCBs, respectively. The concentration of PCBs found in homes was independent (P = 0.0625) of building construction year. Similarly, no relationship was observed between PCB concentrations and floor type. The concentrations of PBDEs correlated (r = 0.60) with PCB concentrations in homes, thus assuming similar sources. The elevated concentrations of PBDEs and PCBs may have significant implications for human exposure.

Rapid identification of polystyrene foam wastes containing hexabromocyclododecane or its alternative polymeric brominated flame retardant by X-ray fluorescence spectroscopy

The brominated flame retardant hexabromocyclododecane (HBCDD) was added to Annex A of the list of persistent organic pollutants (POPs) of the Stockholm Convention. Thus, production and use of HBCDD will be banned, and the recycling of HBCDD-containing foam waste will be restricted. In reaction a special polymeric brominated flame retardant (PolyFR) was developed to replace HBCDD in expanded and extruded polystyrene foams for building and construction applications. A decision has to be made at some future time whether expanded and extruded polystyrene foam waste is to be subjected to incineration (with HBCDD) or to recycling (without HBCDD). Therefore, an appropriate and rapid field method is required to distinguish between foams containing HBCDD and foams free from HBCDD. Here we present a screening method for identifying HBCDD containing expanded and extruded polystyrene foams. The test principle is based on the fact that PolyFR (a brominated polymeric macromolecule) is not extractable whereas HBCDD (a low molecular weight substance) is extractable. Following rapid extraction of HBCDD the brominated flame retardant is identified and quantified via bromine analysis using a handheld X-ray fluorescence instrument. The method was applied successfully to 27 expanded and extruded polystyrene foam samples (foams and extruded polystyrene foam raw materials), which were provided without any information about the applied flame retardant. The presence of HBCDD was confirmed for all HBCDD-positive samples in the test. A robustness test revealed a high degree of correctness and a high repeatability for the test system: samples containing HBCDD and HBCDD-free samples were identified correctly with relative standard deviations of quantitative results below 14%. Moreover, X-ray fluorescence spectroscopy test results agree well with HBCDD determinations performed in a laboratory with a gas chromatograph coupled to a flame ionisation detector.

Pollution profiles and risk assessment of PBDEs and phenolic brominated flame retardants in water environments within a typical electronic waste dismantling region

The aim of this study was to assess the pollution profiles of various typical brominated flame retardants in water and surface sediment near a typical electronic waste dismantling region in southern China. We found that polybrominated diphenyl ethers (PBDEs), 2,4,6-tribromophenol (TBP), pentabromophenol (PeBP), tetrabromobisphenol A (TBBPA), and bisphenol A (BPA) were ubiquitous in the water and sediment samples collected in the study region. In water, Σ19PBDEs (sum of all 20 PBDE congeners studied except BDE-209, which was below the detection limit) levels ranged from 0.31 to 8.9 × 10(2) ng L(-1). TBP, PeBP, TBBPA, and BPA concentrations in the water samples ranged from not being detectable (nd-under the detection limit) to 3.2 × 10(2) (TBP), from nd to 37 (PeBP), from nd to 9.2 × 10(2) (TBBPA) and from nd-8.6 × 10(2) ng L(-1) (BPA). In sediment, Σ19PBDEs ranged from nd to 5.6 × 10(3) ng g(-1), while BDE-209 was the predominant congener, with a range of nd to 3.5 × 10(3) ng g(-1). Tri- to hepta-BDE concentrations were significantly (p < 0.01) correlated with each other, except for BDE-71 and BDE-183, and octa- to nona-BDEs concentrations were significantly (p < 0.05) correlated with each other, except for BDE-208. BDE-209 was not significantly correlated with tri- to nona-BDEs. Risk assessments indicated that the water and sediment across the sampling sites posed no estrogenic risk. However, different eco-toxicity risk degrees at three trophic levels did exist at most sampling sites.

Characterization of heavy metals and brominated flame retardants in the indoor and outdoor dust of e-waste workshops: implication for on-site human exposure

Forty-four indoor and outdoor dust samples were collected from e-waste workshops and were analyzed to characterize the heavy metals and brominated flame retardants (BFRs) as well as on-site human exposure. The results showed that the most abundant Polybrominated diphenyl ethers (PBDE) congener from three sites was deca-BDE, and it was penta-BDE for the other site. A significant and positive association was found between BDE-209 and decabromodiphenyl ethane (DBDPE). The high percentage of nona-BDE indicated the debromination of deca-BDE during e-waste recycling. The ratio comparison of BDE-47 to (BDE-100 + BDE-99) indicated that the outdoor dust went through more physiochemical processes. The enrichment factors for Cu and Pb were high in both the indoor and outdoor samples. Cd significantly exceeded the Chinese soil guideline grade III. The PCA results combined with the enrichment factor (EF) values suggested common sources and behaviours of Cu, Pb and Sb in the indoor dust. Co, Cr, Ni, Zn and Mn in the outdoor samples were more likely affected by crust. Strong correlations were found only for Pb and Sb with polybrominated diphenyl ethers (PBDEs). The hazard index for on-site human exposure to Pb was at a chronic risk. Despite the low deleterious risk of BFRs, concern should be given to DBDPE; the chronic toxicity of which is not known.

Polybrominated diphenyl ether (PBDE) concentrations and resulting exposure in homes in California: relationships among passive air, surface wipe and dust concentrations, and temporal variability

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in furniture foam, electronics, and other home furnishings. A field study was conducted that enrolled 139 households from California, which has had more stringent flame retardant requirements than other countries and areas. The study collected passive air, floor and indoor window surface wipes, and dust samples (investigator collected using an HVS3 and vacuum cleaner) in each home. PentaBDE and BDE209 were detected in the majority of the dust samples and many floor wipe samples, but the detection in air and window wipe samples was relatively low. Concentrations of each PBDE congener in different indoor environmental media were moderately correlated, with correlation coefficients ranging between 0.42 and 0.68. Correlation coefficients with blood levels were up to 0.65 and varied between environmental media and age group. Both investigator-collected dust and floor wipes were correlated with serum levels for a wide range of congeners. These two sample types also had a relatively high fraction of samples with adequate mass for reliable quantification. In 42 homes, PBDE levels measured in the same environmental media in the same home 1 year apart were statistically correlated (correlation coefficients: 0.57-0.90), with the exception of BDE209 which was not well correlated longitudinally.