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

Degradation processes of brominated flame retardants dispersed in high impact polystyrene under UV-visible radiation

In order to protect human health and the environment, several regulations have been introduced in recent years to reduce or even eliminate the use of some brominated flame retardants (BFRs) due to their toxicity, persistence and bioaccumulation. Dispersions of these BFRs in polymers are widely used for various applications. In this report, four different brominated molecules, decabromodiphenyl ether (DBDE), hexabromocyclododecane (HBCDD), decabromodiphenyl ethane (DBDPE) and tris(tribromophenoxy)triazine (TTBPT), were dispersed in the solid matrix of an industrial polymer, high impact polystyrene (HIPS). The possibility of degradation of these BFRs within HIPS under UV-visible irradiation in ambient air was investigated. The degradation kinetics of DBDE and HBCDD were followed by Fourier transform infrared spectroscopy (FTIR) and high-resolution two-step laser mass spectrometry (L2MS). The thermal properties of the pristine and irradiated polymer matrix were monitored by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), which showed that these properties were globally preserved. Volatile photoproducts from the degradation of DBDE, DBDPE and TTBPT were identified by headspace gas chromatography/mass spectrometry analysis. Under the chosen experimental conditions, BFRs underwent rapid degradation after a few seconds of irradiation, with conversions exceeding 50% for HIPS/DBDE and HIPS/HBCDD systems.

Eight novel brominated flame retardants in indoor and outdoor dust samples from the E-waste recycling industrial park: Implications for human exposure

As alternatives for legacy brominated flame retardants, novel brominated flame retardants (NBFRs) have a wide array of applications in the electronic and electrical fields. The shift of recycling modes of electronic and electrical waste (e-waste) from informal recycling family workshop to formal recycling facilities might come with the change the chemical landscape emitted including NBFRs, however, little information is known about this topic. This study investigated the occurrence characteristics, distribution, and exposure profiles of eight common NBFRs and their derivatives in an e-waste recycling industrial park in central China and illustrated the differences in various functional zones in the recycling park. The highest level of ΣNBFRs in dust samples was found in e-waste storage area at median concentration of 27,400 ng/g, followed by e-waste dismantling workshops (23,300 ng/g), workshop outdoor area (7770 ng/g), and residential area outdoor (536 ng/g). In the e-waste dismantling associated dust samples, tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), tetrabromobisphenol A (TBBPA) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) were the predominant components. This paper presented the first evidence regarding the occurrence characteristic and distribution of tetrabromobisphenol S (TBBPS), tetrabromobisphenol A bismethyl ether (TBBPA-BME) and tetrabromobisphenol S bis(2,3-dibromopropyl ether) (TBBPS-BDBPE) in the e-waste associated dust samples. By comparing with previous studies performed in China, this paper also noticed the significant decrease of TBBPA concentrations in the dust probably due to the shift of e-wastes sources and recycling modes. We further assessed the risk of occupational workers exposure to NBFRs. The median EDI (estimated daily intake) value of ΣNBFRs among e-waste dismantling workers was 9.71 ng/kg BW/d with the maximum EDI value being 19.6 ng/kg BW/d, hundreds of times higher than those exposed by general population. The study raises great concern for the health risk of occupational exposure to NBFRs in the e-waste recycling industrial park.

Brominated flame retardants in breast milk from the United States: First detection of bromophenols in U.S. breast milk

Brominated flame retardants (BFRs) are a class of compounds with many persistent, toxic, and bioaccumulative members. BFRs have been widely detected in breast milk, posing health risks for breastfeeding infants. Ten years after the phaseout of polybrominated diphenyl ethers (PBDEs) in the United States, we analyzed breast milk from 50 U.S. mothers for a suite of BFRs to assess current exposures to BFRs and the impact of changing use patterns on levels of PBDEs and current-use compounds in breast milk. Compounds analyzed included 37 PBDEs, 18 bromophenols, and 11 other BFRs. A total of 25 BFRs were detected, including 9 PBDEs, 8 bromophenols, and 8 other BFRs. PBDEs were found in every sample but at concentrations considerably lower than in previous North American samples, with a median ∑PBDE concentration (sum of 9 detected PBDEs) of 15.0 ng/g lipid (range 1.46-1170 ng/g lipid). Analysis of time trends in PBDE concentrations in North American breast milk indicated a significant decline since 2002, with a halving time for ∑PBDE concentrations of 12.2 years; comparison with previous samples from the northwest U.S region showed a 70% decline in median levels. Bromophenols were detected in 88% of samples with a median ∑12bromophenol concentration (sum of 12 detected bromophenols) of 0.996 ng/g lipid and reaching up to 71.1 ng/g lipid. Other BFRs were infrequently detected but concentrations reached up to 278 ng/g lipid. These results represent the first measurement of bromophenols and other replacement flame retardants in breast milk from U.S. mothers. In addition, these results provide data on current PBDE contamination in human milk, as PBDEs were last measured in U.S. breast milk ten years ago. The presence of phased-out PBDEs, bromophenols, and other current-use flame retardants in breast milk reflects ongoing prenatal exposure and increased risk for adverse impacts on infant development.

Novel Brominated Flame Retardants in Dust from E-Waste-Dismantling Workplace in Central China: Contamination Status and Human Exposure Assessment

Novel brominated flame retardants (NBFRs) have been widely used as alternatives to legacy BFRs. However, information on the contamination status and human exposure risks of electronic waste (e-waste)-derived NBFRs in the e-waste workplace is limited. In this study, six NBFRs and the legacy BFRs, hexabromocyclododecanes (HBCDs), were analyzed in 50 dust samples from an e-waste-dismantling workplace in Central China. The dust concentration of NBFRs in e-waste-dismantling workshops (median, 157−169 ng/g) was found to be significantly higher than those in an outdoor environment (17.3 ng/g) (p < 0.01). Differently, the highest median concentration of HBCDs was found in dust from the dismantling workshop for cellphones and computers (367 ng/g) among studied areas. The bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (BEHTBP) was the predominant compound, which contributed 66.0−88.0% of measured NBFR concentrations. NBFRs might originate from plastic and rubber materials in wastes based on the correlation and principal component analysis. Moreover, the total estimated daily intakes (average scenario) of NBFRs were calculated at 2.64 × 10−2 ng/kg bw/d and 2.91× 10−2 ng/kg bw/d for the male and female dismantling workers, respectively, via dust ingestion, inhalation, and dermal contact pathways, which were lower than the reference dose values, and thus indicated a limited human exposure risk for NBFRs at the current level. Although the dust concentrations and daily intakes of NBFRs were still lower than those of other emerging pollutants (e.g., organophosphate and nitrogenous flame retardants) measured in the same sampling set, the elevated levels of NBFRs suggested the progressive BFR replacement process in China, which deserves more attention regarding their adverse effects on both the environment and human health.

Comprehensive review of the impact of tris(2,3-dibromopropyl) isocyanurate (TBC or TDBP-TAZTO) on living organisms and the environment

Tris(2,3-dibromopropyl) isocyanurate (TBC or TDBP-TAZTO) belongs to the group of brominated flame retardants (BFRs). The production of this compound is increasing due to the growing demand and wide application in electrical, electronic, musical instrument, and automotive component industries. The properties of TBC, e.g., the high octanol-air partition coefficient (Koa), high octanol-water partition coefficient (Kow), and high bioconcentration factor (BCF), indicate a possibility of its spread in aquatic and terrestrial ecosystems and bioaccumulation in living organisms. The presence of TBC has been confirmed in soil, sediments, river water, and such materials as microplastic, curtains, and e-waste devices. The compound has potential to bioaccumulate in the food chain of living organisms. TBC has been demonstrated to exert a harmful effect mainly on the nervous and endocrine systems, lungs, and liver. The possible mechanism of toxicity of the compound in the nervous system is based on the generation of oxidative stress by TBC leading to apoptosis of neuronal cells, while mitochondrial damage is considered to be responsible for changes in the respiratory organ. Moreover, the potential of mussels and earthworms to be bioindicators of TBC has been proven. Therefore, the literature review is focused on TBC properties and analysis of the identification and impact of the compound on the environment, living organisms, and human cell lines. Given the many toxic effects of TBC highlighted in the literature, there is a need for more profound research on the safety of TBC and methods for identification and degradation of this compound.

ZIF-8/nitrogen-doped reduced graphene oxide as thin film microextraction adsorbents for simultaneous determination of novel halogenated flame retardants in crayfish-aquaculture water systems

Novel halogenated flame retardants (HFRs) have attracted much attention due to their environmental hazard and adverse effects on human health. In this study, a sensitive and simultaneous method for the determination of six novel HFRs was developed, including tetrabromobisphenol A (TBBPA), tetrachlorobisphenolA, TBBPA bis(2-hydroxyethyl ether), TBBPA bis(allyl ether), TBBPA bis(2,3-dibromopropyl ether) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine. ZIF-8 modified nitrogen-doped reduced graphene oxide (ZIF-8@N-rGO) was synthesized and coated onto a syringe filter to prepare a thin film microextraction (TFME) device. The adsorption capacities of ZIF-8@N-rGO for novel HFRs ranged from 50.98 to 112.84 mg g^-1, exhibiting good extraction efficiency through a combination of π-π, hydrophobic, and hydrogen bonding interactions. The TFME device was coupled to a high-performance liquid chromatography-ultraviolet detection system to simultaneously determine target HFRs in crayfish-aquaculture water systems. Under the optimal extraction parameters, the linearities ranged from 0.1 to 100 ng mL^-1. The method detection limits ranged from 0.030 to 0.14 ng mL^-1 and relative recoveries ranged from 88.6 to 106.2%. We found that novel HFRs were detected in water and crayfish samples and were primarily distributed in the viscera and head shell of the crayfish. The bioconcentration factors ranged from 0.25 to 19.20 L kg^-1, indicating non-bioaccumulation in the crayfish. This study provides valuable technology and information for potential health risks of exposure to novel HFRs from consuming crayfish.

Biotransformation of 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) can contribute to high levels of 2,4,6-tribromophenol (2,4,6-TBP) in humans

2,4,6-Tribromophenol (2,4,6-TBP) is a brominated flame retardant that accumulates in human tissues and is a potential toxicant. Previous studies found 2,4,6-TBP levels in human tissues were significantly higher than those of brominated flame retardants measured in the same samples. In contrast, the levels of 2,4,6-TBP in the environment and foodstuff are not elevated, suggesting a low potential for direct intake through environmental exposure or diet. Here, we hypothesized that high levels of 2,4,6-TBP in human tissues are partially from the indirect exposure sources, such as biotransformation of highly brominated substances. We conducted in vitro assays utilizing human and rat liver microsomes to compare the biotransformation rates of four highly brominated flame retardants, which could potentially transform to 2,4,6-TBP, including decabromodiphenyl ethane (DBDPE), 2,4,6-tris-(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and tetrabromobisphenol A (TBBPA). Our results show that TTBP-TAZ rapidly metabolizes in both human and rat liver microsomes with a half-life of 1.1 and 2.2 h, respectively, suggesting that TTBP-TAZ is a potential precursor of 2,4,6-TBP. In contrast, 2,4,6-TBP was not formed as a result of biotransformation of TBBPA, BTBPE, and DBDPE in both human and rat liver microsomes. We applied suspect and target screening to explore the metabolic pathways of TTBP-TAZ and identified 2,4,6-TBP as a major metabolite of TTBP-TAZ accounting for 87% of all formed metabolites. These in vitro results were further tested by an in vivo experiment in which 2,4,6-TBP was detected in the rat blood and liver at concentrations of 270 ± 110 and 50 ± 14 μg/g lipid weight, respectively, after being exposed to 250 mg/kg body weight/day of TTBP-TAZ for a week. The hepatic mRNA expression demonstrated that TTBP-TAZ significantly activates the aryl hydrocarbon receptor (AhR) and promotes fatty degeneration (18 and 28-fold change compared to control, respectively) in rats.

A review on the analytical procedures of halogenated flame retardants by gas chromatography coupled with single quadrupole mass spectrometry and their levels in human samples

Halogenated flame retardants (HFRs) market is continuously evolving and have moved from the extensive use of polybrominated diphenyl ether (PBDE) to more recent introduced mixtures such as Firemaster 550, Firemaster 680, DP-25, DP-35, and DP-515. These substitutes are mainly composed of non-PBDEs HFRs such as 2-ethyl-hexyl tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE). Other HFRs commonly being monitored include Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), Dechlorane 604 (Dec604), 5,6-dibromo-1,10, 11, 12,13,13-hexachloro- 11-tricyclo[8.2.1.02,9]tridecane (HCDBCO) and 4,5,6,7-tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-2,3-dihydro-1H-indene (OBTMPI). This review aims at highlighting the advances in the past decade (2010-2020) on both the analytical procedures of HFRs in human bio-specimens using gas chromatography coupled with single quadrupole mass spectrometry and synthesizing the information on the levels of these HFRs in human samples. Human specimen included in this review are blood, milk, stool/meconium, hair and nail. The review summarizes the analytical methods, including extraction and clean-up techniques, used for measuring HFRs in biological samples, which are largely adopted from those for analysing PBDEs. In addition, new challenges in the analysis to include both PBDEs and a wide range of other HFRs are also discussed in this review. Review of the levels of HFRs in human samples shows that PBDEs are still the most predominant HFRs in many cases, followed by DP. However, emerging HFRs are also being detected in human despite of the fact that both their detection frequencies and levels are lower than PBDEs and DP. It is clearly demonstrated in this review that people working in the industry or living close to the industrial areas have higher HFR levels in their bodies.

Endocrine disrupting potential of replacement flame retardants - Review of current knowledge for nuclear receptors associated with reproductive outcomes

BACKGROUND AND AIM

Endocrine disrupting chemicals (EDCs) constitute a major public health concern because they can induce a large spectrum of adverse effects by interfering with the hormonal system. Rapid identification of potential EDCs using in vitro screenings is therefore critical, particularly for chemicals of emerging concerns such as replacement flame retardants (FRs). The review aimed at identifying (1) data gaps and research needs regarding endocrine disrupting (ED) properties of replacement FRs and (2) potential EDCs among these emerging chemicals.

METHODS

A systematic search was performed from open literature and ToxCast/Tox21 programs, and results from in vitro tests on the activities of 52 replacement FRs towards five hormone nuclear receptors (NRs) associated with reproductive outcomes (estrogen, androgen, glucocorticoid, progesterone, and aryl hydrocarbon receptors) were compiled and organized into tables. Findings were complemented with information from structure-based in silico model predictions and in vivo information when relevant.

RESULTS

For the majority of the 52 replacement FRs, experimental in vitro data on activities towards these five NRs were either incomplete (15 FRs) or not found (24 FRs). Within the replacement FRs for which effect data were found, some appeared as candidate EDCs, such as triphenyl phosphate (TPhP) and tris(1,3-dichloropropyl)phosphate (TDCIPP). The search also revealed shared ED profiles. For example, anti-androgenic activity was reported for 19 FRs and predicted for another 21 FRs.

DISCUSSION

This comprehensive review points to critical gaps in knowledge on ED potential for many replacement FRs, including chemicals to which the general population is likely exposed. Although this review does not cover all possible characteristics of ED, it allowed the identification of potential EDCs associated with reproductive outcomes, calling for deeper evaluation and possibly future regulation of these chemicals. By identifying shared ED profiles, this work also raises concerns for mixture effects since the population is co-exposed to several FRs and other chemicals.

Occurrence and spatial distribution of legacy and novel brominated flame retardants in seawater and sediment of the South China sea

The occurrence and spatial distribution of polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in seawater and surficial sediment samples (N = 19 and 45, respectively) from the South China Sea (SCS) in 2018 were investigated, and the correlation between BFRs and site parameters (total organic carbon, depth, etc.) were assessed by principal component analysis. The concentration ranges of ΣPBDEs in seawater and sediments were 0.90-4.40 ng/L and 0.52-22.67 ng/g dry weight (dw), respectively, while those of ΣNBFRs were 0.49-37.42 ng/L and 0.78-82.29 ng/g dw, respectively. BDE-209 and decabromodiphenyl ethane were the predominant BFRs, accounting for 38.65% and 36.94% in seawater and 26.71% and 68.42% in sediments, respectively. Notably, tris(2,3-dibromopropyl)isocyanurate and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, seldomly detected in aquatic matrices worldwide, were detected for the first time in the study area, and their relatively high levels and detection frequencies indicate the ubiquitous application of these NBFRs in the Pearl River Delta. Zhuhai and Jiangmen are the main sources of NBFRs in the SCS. Preliminary risk assessment on NBFRs using hazard quotient indicates low to medium risks to marine organisms at some sites. The occurrence of NBFRs in the SCS highlights the prioritization of more toxicological information on these compounds.

Development and validation of a liquid chromatography-mass spectrometry method for simultaneous analysis of triazine-based brominated flame retardants in environmental samples

In the present study, a novel and reliable analytical method was developed and validated for the simultaneous determination of 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TDBP-TAZTO) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) in environmental samples using high-performance liquid chromatography coupled to a tandem mass spectrometer. Firstly, for optimization of the liquid chromatography separation, mobile phases, oven temperatures, modifiers, and buffers were varied. Afterwards, the extraction efficiency of sediment and fish samples was tested with different techniques (pressurized liquid, solid-liquid, ultrasound-assisted, and Soxhlet extraction). Additionally, cleanup using modified multilayer silica gel (sediment) and gel permeation chromatography as well as Florisil® columns (fish) with several solvent mixtures were performed. The best results were obtained with the pressurized liquid extraction (optimal conditions: extraction solvent 100% toluene, extraction time 20 min, cycles two, extraction temperature 100 °C, and flushing volume 60%) compared to other solvent extraction methods. On the basis of this optimized analytical procedure, the method was validated with satisfactory values of correlation coefficient (R²) between 0.998 and 0.999 for both matrices in the calibration range of 2.0-502.0 μg kg^-1 for TDBP-TAZTO and 16.6-770.6 μg kg^-1 for TTBP-TAZ in sediment samples as well as 4.8-303.5 μg kg^-1 and 47.4-742.5 μg kg^-1 in fish samples (bream), respectively. Mean recoveries (n = 5) were calculated for both analytes with spiked matrices at one concentration level (100 μg kg^-1) between 98 and 114% with intra-day relative standard deviations less than 11%. The inter-day precision (n = 15) was also acceptable for both compounds < 11%. It was found that the limit of detection and limit of quantification were in the range of 0.4-1.3 μg kg^-1 for TDBP-TAZTO and 10-28 μg kg^-1 for TTBP-TAZ in surface sediment samples and 7-25 μg kg^-1 and 22-80 μg kg^-1 in fish samples (bream), respectively. The results indicated that these analytical methods could provide reliable and efficient approaches for quantification of TDBP-TAZTO and TTBP-TAZ in sediment and fish samples. Graphical abstract.

Broad Exposure of the North American Environment to Phenolic and Amino Antioxidants and to Ultraviolet Filters

The present study provides a comprehensive investigation of three suites of commonly used synthetic additives: phenolic and amino antioxidants and ultraviolet filters. The concentrations of 47 such compounds and their transformation products were measured in 20 atmospheric particle samples collected in Chicago, in 21 Canadian e-waste dust samples, in 32 Canadian and United States' residential dust samples, and in 10 sediment samples collected from the Chicago Sanitary and Ship Canal. Despite their large production volumes in the United States, environmental data on antioxidants and UV filters in North America is limited. These compounds were detected in all the samples, indicating their ubiquitous distribution in the North American environment. The most prevalent compounds were 2,6-di-t-butyl-p-benzoquinone, diphenylamine, 4,4'-di-t-octyl diphenylamine, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. The e-waste dust contained significantly greater total concentrations of these compounds than the Canadian residential dust, while intermediate levels were detected in the United States residential dust. The sediment samples showed relatively high levels of N,N'-diphenylbenzidine, the source of which is unclear, and some benzotriazole UV filters. Daily intake rates by dust ingestion for these compounds ranged from 1-10 ng/(kg·day) for adults to 10-100 ng/(kg·day) for toddlers. Due to the wide distribution of these compounds in both the ambient and built environments, future research on their potential toxic effects on people and ecosystems is important.

Assessment of Occupational Exposure to Organic Flame Retardants: A Systematic Review

BACKGROUND

Flame retardants (FRs) are widespread in common goods, and workers in some industries can be exposed to high concentrations. Numerous studies describe occupational exposure to FRs, but the diversity of methods and of reported results renders their interpretation difficult for researchers, occupational hygienists, and decision makers.

OBJECTIVES

The objectives of this paper are to compile and summarize the scientific knowledge on occupational exposure to FRs as well as to identify research gaps and to formulate recommendations.

METHODS

Five databases were consulted for this systematic literature review (Embase, Medline [Pubmed], Global health, Web of Science, and Google Scholar), with terms related to occupational exposure and to FRs. Selected studies report quantitative measurements of exposure to organic FRs in a workplace, either in air, dust, or in workers' biological fluids. The Preferred Reporting Items for Systematic reviews and Meta-Analyses statement guidelines were followed.

RESULTS

The search yielded 1540 published articles, of which 58 were retained. The most frequently sampled FRs were polybrominated diphenyl ethers and novel brominated FRs. Offices and electronic waste recycling facilities were the most studied occupational settings, and the highest reported exposures were found in the latter, as well as in manufacturing of printed circuit boards, in aircrafts, and in firefighters. There were recurrent methodological issues, such as unstandardized and ill-described air and dust sampling, as well as deficient statistical analyses.

CONCLUSIONS

This review offers several recommendations. Workplaces such as electronic waste recycling or manufacturing of electronics as well as firefighters and aircraft personnel should be granted more attention from researchers and industrial hygienists. Methodical and standardized occupational exposure assessment approaches should be employed, and data analysis and reporting should be more systematic. Finally, more research is needed on newer chemical classes of FRs, on occupational exposure pathways, and on airborne FR particle distribution.

Polybrominated diphenyl ethers and organophosphate esters flame retardants in play mats from China and the exposure risks for children

A total of 41 play mats made from different raw materials, such as polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), chemical crosslinked polyethylene (XPE), and polyvinyl chloride (PVC), were obtained from Chinese markets and analyzed for flame retardants. Polybrominated diphenyl ethers (PBDEs) and their replacements, organophosphate esters (OPEs), were measured and the associated exposure risks for children were evaluated. The levels (range; median) of OPEs (6.6-7400; 200 ng g^-1) were generally 1-2 orders of magnitude higher than those of PBDEs (0.13-72; 13 ng g^-1), consistent with the production and usage trends of flame retardants. The concentrations of both PBDEs and OPEs were the lowest in XPE mats (0.13-5.6; 3.3 ng g^-1 for PBDEs and 6.6-320; 47 ng g^-1 for OPEs) compared to the other three types. Concentration comparison and compositional analysis suggested that PBDEs and OPEs in play mats were most probably from leaching of raw materials, during production, storage, and/or transport. Children's exposure to PBDEs and OPEs from play mats was estimated for three pathways, i.e., dermal contact, inhalation, and hand-to-mouth ingestion. The combined exposure was 5-6 orders of magnitude lower than the established reference dose values, suggesting no obvious health concern regarding the occurrence of PBDEs and OPEs in play mats. Nevertheless, selection of less contaminated, i.e., XPE mats among those under investigation, by consumers is strongly recommended to minimize any potential exposure risk.

Higher health risk resulted from dermal exposure to PCBs than HFRs and the influence of haze

To investigate the influence of haze on human dermal exposure to a series of halogenated flame retardants (HFRs) and polychlorinated biphenyls (PCBs), paired forehead wipes were collected from 46 volunteers (23 males, 23 females) using gauze pads soaked in isopropyl alcohol under heavy and light haze pollution levels. The median levels of ∑₂₇HFRs and ∑₂₇PCBs in all 92 samples were 672 and 1300ng/m², respectively. Decabromodiphenyl ether (BDE-209) (171ng/m²) and decabromodiphenylethane (DBDPE) (134ng/m²) were the dominant components of HFRs, indicating that dermal exposure may also be the significant pathway for non-volatile compounds. PCB-37 contributed the most to ∑₂₇PCBs, with a median concentration of 194ng/m², followed by PCB-60 (141ng/m²). Generally, PBDE, PCB and DD (dehalogenated derivatives of DPs) levels on the foreheads of female participants (291, 1340, 0.92ng/m²) were higher (p=0.037, 0.001, and 0.031, respectively) than those of male participants (226, 989, and 0.45ng/m²). A significant difference (p=0.001) in PCBs was found between light (1690ng/m²) and heavy (996ng/m²) haze pollution conditions. Nevertheless, HFR levels under heavy (median=595ng/m², ranging from 295 to 1490ng/m²) and light haze pollution conditions (ranging from 205 to 1220ng/m² with a median of 689ng/m²) did not show significant differences (p=0.269). The non-carcinogenic health risk resulting from dermal exposure to ∑₈HFRs and ∑₂₇PCBs was 8.72×10^-5 and 1.63×10^-2, respectively, raising more concern about populations' exposure to PCBs than HFRs.

Occurrence of two novel triazine-based flame retardants in an E-waste recycling area in South China: Implication for human exposure

The recent increase in the use of alternative flame retardants (FRs) in consumer products has led to emerging contaminants in the environment. Identification of novel FRs is urgently needed because the potential threat posed by these chemicals has provoked considerable attention, but the details of the threat are not yet widely understood. In this study, two novel triazine-based FRs, tris(2,3-dibromopropyl) isocyanurate (TDBP-TAZTO) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ), were identified in dust samples from an e-waste recycling area in China. Two legacy FRs, namely, tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD), were also analyzed for comparison. The mean level of TDBP-TAZTO in the e-waste dust samples was found to be much higher (2060 ng g^-1) than that of HBCDD (526 ng g^-1), while the mean level of TTBP-TAZ in residential dust samples was moderately higher (119 ng g^-1) than that of HBCDD (35.7 ng g^-1). A comparison of the TDBP-TAZTO and TTBP-TAZ concentrations with those of other alternative and legacy FRs indicated that TDBP-TAZTO is a major FR that is currently used in China. The estimated daily intake of TDBP-TAZTO via dust ingestion for occupational workers was much higher than that of HBCDD and was also much higher than for local adults and children. Exposure to TDBP-TAZTO poses a potentially high risk to the health of the local population, especially for the occupational workers, when the multicomponent chemical 'cocktail' effects are taken into account. More investigations on the environmental behaviors and risk factors of TDBP-TAZTO and TTBP-TAZ in various environmental matrices, as well as their toxicological effects, should be performed in the future.

Photodegradation of the novel brominated flame retardant 2,4,6-Tris-(2,4,6-tribromophenoxy)-1,3,5-triazine in solvent system: Kinetics, photolysis products and pathway

In this study the direct and indirect photolysis of the novel brominated flame retardant 2,4,6-Tris-(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) in an organic solvent mixture (60:30:10, ACN:MeOH:THF) under UV-(C) and simulated sunlight irradiation was investigated, and the formed photo-transformation products were identified for the first time. TTBP-TAZ was almost completely degraded within 10 min under UV-(C) irradiation. Due to the fast degradation no specific kinetic order could be observed. In comparison, the reaction under simulated sunlight irradiation was much slower and thus, the kinetic first-order could be determined. The observed photolysis rate constant k as well as the half-life time t_1/2 were estimated to be k = (0.0163 ± 0.0002) h^-1 and t_1/2 = 42.3 h, respectively. The addition of 2-propanol and hydrogen peroxide to investigate the influence of indirect photolysis under UV-(C) irradiation causes no influence on the degradation of TTBP-TAZ. Nevertheless, the removal of TTBP-TAZ under UV-(C) and simulated sunlight without additional chemicals (except solvent) indicates that the direct photolysis plays a significant role in the degradation mechanism of TTBP-TAZ. In both irradiation experiments, TTBP-TAZ was quantitatively degraded that involve the formation of previously unknown PTPs. Overall, two main PTPs were determined when irradiated with UV-(C) and eight sequential debromination products were observed when irradiated by simulated sunlight. These were determined by HPLC-DAD and - MS/(MS), respectively. Based on the chosen experimental conditions the consecutive debromination as well as photo-Fries rearrangement was confirmed as the main degradation pathway by high resolution mass spectrometry and X-ray diffraction.

Flame retardants and plasticizers in a Canadian waste electrical and electronic equipment (WEEE) dismantling facility

Here we report on the concentrations of 79 flame retardants (FRs) and plasticizers, including 34 polybrominated diphenyl ethers or PBDE congeners, 17 "novel" brominated FRs (NBFRs), 15 dechloranes, and 13 organophosphate esters (OPEs) in air (n = 9) and dust (n = 24) samples from an active waste electrical and electronic equipment (WEEE) dismantling facility in Ontario, Canada, collected in February-March 2017. This is the first study of its kind in North America. The facility processes a range of WEEE including monitors, computers, printers, phones, and toys. Of the 79 target compounds, at least 60 were detected at a frequency of at least 50% in both air and dust. Dust and air concentrations were dominated by three compounds: BDE-209 (median 110,000 ng/g and 100 ng/m³, respectively), DBDPE (median 41,000 ng/g and 41 ng/m³), and TPhP (median 42,000 ng/g and 27 ng/m³). Levels of PBDEs, NBFRs, and dechloranes were close to two orders-of-magnitude higher in dust from the dismantling facility than in residential homes, while OPEs were one order-of-magnitude higher. Congener profiles of PBDEs indicated debromination of BDE-209. We calculated that a total mass of 44 ± 1 mg day^-1 of 79 target analytes were released to air from WEEE processed in the dismantling hall and a further 270 ± 91 mg day^-1 were released to dust. It is clear that WEEE dismantling facilities are a serious concern as a source of emissions for a wide range of FRs at relatively high concentrations to both workers and the immediate environment.

Brominated and organophosphate flame retardants along a sediment transect encompassing the Guiyu, China e-waste recycling zone

e-Waste recycling using crude techniques releases a complex, yet incompletely characterized mixture of hazardous materials, including flame retardants (FRs), to the environment. Their migration downstream and the associated risks also remain undocumented. We examined 26 FRs (18 brominated (BFRs: 12 polybrominated diphenyl ether (PBDE) congeners, plus 6 alternatives) and 8 organophosphate esters (OPEs)) in surficial sediments of the Lian River. Sampling encompassed the river's origin, through the Guiyu e-waste recycling zone, to its mouth, as well as associated tributaries. OPE exceeded BFR concentrations in most sediments, despite their far greater water solubilities. Among OPEs, tris(1-chloro-2-propyl) phosphate dominated upstream, but shifted to triphenyl phosphate in Guiyu and downstream sediments. For PBDEs, Deca-BDE dominated upstream, but Penta-BDE prevailed in Guiyu and at many downstream sites. Among emerging alternative BFRs, decabromodiphenyl ethane dominated upstream, transitioning to 1,2-bis(2,4,6,-tribromophenoxy)ethane in Guiyu sediments. Penta-BDE (BDE-47 + -99, 668-204,000 ng g^-1, ∑PBDEs 2280-287,000 ng g^-1), tetrabromobisphenol A (2,720-41,200 ng g^-1), 1,2-bis(2,4,6,-tribromophenoxy)ethane (222-9870 ng g^-1) and triphenyl phosphate (4260-1,710,000 ng g^-1, OPEs 6010-2,120,000 ng g^-1) concentrations in Guiyu sediments were among the highest reported in the world to date. The continuing dominance of these e-waste indicative FRs in sediments downstream of Guiyu suggested that FR migration from Guiyu occurred. Hazard quotients >1.0 indicated that the extreme sediment concentrations of individual FRs posed ecological risks in most Guiyu reach and downstream areas. Simultaneous exposure to multiple FRs likely increased risks. However, risks may be mediated if FRs were associated with strong sorbents, e.g. carbon black from burned debris, hydrophobic polymer fragments, or resided as additives within polymer fragments.

Tri(2,4-di- t-butylphenyl) Phosphate: A Previously Unrecognized, Abundant, Ubiquitous Pollutant in the Built and Natural Environment

Using high-resolution mass spectrometry, we identified tri(2,4-di- t-butylphenyl) phosphate (TDTBPP) in e-waste dust. This is a previously unsuspected pollutant that had not been reported before in the environment. To assess its abundance in the environment, we measured its concentration in e-waste dust, house dust, sediment from the Chicago Ship and Sanitary Canal, Indiana Harbor water filters, and filters from high-volume air samplers deployed in Chicago, IL. To provide a context for interpreting these quantitative results, we also measured the concentrations of triphenyl phosphate (TPhP), a structurally similar compound, in these samples. Median concentrations of TDTBPP and TPhP were 14 400 and 41 500 ng/g, respectively, in e-waste dust and 4900 and 2100 ng/g, respectively, in house dust. TDTBPP was detected in sediment, water, and air with median concentrations of 527 ng/g, 3700 pg/L, and 149 pg/m³, respectively. TDTBPP concentrations were generally higher or comparable to those of TPhP in all media analyzed, except for the e-waste dust. Exposure from dust ingestion and dermal absorption in the e-waste recycling facility and in homes was calculated. TDTBPP exposure was 571 ng/kg bw/day in the e-waste recycling facility (pro-rated for an 8-h shift), and 536 ng/kg bw and 7550 ng/kg bw/day for adults and toddlers, respectively, in residential environments.