Alternative Flame Retardant, 2,4,6-Tris(2,4,6 ... - ACS Publications

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Cite This: Environ. Sci. Technol. XXXX, XXX, XXX−XXX

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 Jiehong Guo,† William A. Stubbings,† Kevin Romanak,† Linh V. Nguyen,‡ Liisa Jantunen,§,∥ Lisa Melymuk,⊥ Victoria Arrandale,#,¶ Miriam L. Diamond,∥,‡,# and Marta Venier*,† †

School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, United States Department of Physical and Environmental Science, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada § Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, Ontario M3H 5T4, Canada ∥ Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada ⊥ Research Centre for Toxic Compounds in the Environment (RECETOX), Masaryk University, Kamenice 753/5, pavilion A29, 62500 Brno, Czech Republic # Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario M5G 1X3, Canada ¶ Occupational Cancer Research Centre, Cancer Care Ontario, Ontario M5G 2L3, Canada ‡

S Supporting Information *

ABSTRACT: 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(2,3dibromopropyl) 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.

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INTRODUCTION Flame retardants have been widely used in a wide variety of various consumer products and building materials to comply with flammability standards. Brominated flame retardants (BFRs) are among the most widely used group, accounting for ∼20% of global production of flame retardants in 2004.1 Triazine based polymers are a relatively new group of flame retardants used both as charring agents and as foaming agents in intumescent flame retardants.2 For example, 2,4,6-tris(2,4,6tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) has been used in styrenic copolymers in house and office electric and electronic equipment.3 Tris(2,3-dibromopropyl) isocyanurate (TBC) is added to various materials, such as glass fiber reinforced plastics, polyurethane polyolefin films (or mulches) © XXXX American Chemical Society

used in agriculture, polyvinyl chloride, polyphenyl alkenes, acrylonitrile butadiene styrene, unsaturated polyester, and synthetic rubber.4 Other brominated triazine compounds (e.g., 1,3-bis(2,3-dibromopropyl)-5-(2-propen-1-yl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and 1-(2,3-dibromopropyl)-3,5di-2-propen-1-yl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione) have been found in consumer plastic products (e.g., switch box of a new table lamp) from the Swiss market.5,6 Received: November 29, 2017 Revised: February 19, 2018 Accepted: February 21, 2018

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DOI: 10.1021/acs.est.7b06139 Environ. Sci. Technol. XXXX, XXX, XXX−XXX

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Environmental Science & Technology

analysis. Details of sample treatment and extraction are reported in the SI. Briefly, dust samples were sieved and sonicated with hexane in acetone 1:1 (v:v) three times. The air PUF sandwich and filter samples were extracted separately in an accelerated solvent extraction system (Dionex ASE350, Thermo Fisher Scientific, Inc.) using a mix of hexane in acetone 1:1 (v:v). Extracts were fractionated on a 3.5% (by weight) water deactivated silica gel column using 25 mL of hexane, 25 mL hexane in dichloromethane 1:1 (v:v), and 25 mL of dichloromethane in acetone 3:7 (v:v) as eluting solvents. Each fraction was then concentrated to 1 mL and spiked with known amount of internal standards. The target compounds were in the second fraction. The U.S. residential dust samples (n = 30) were collected from bedrooms and living rooms of 20 houses in Bloomington Indiana, U.S. in 2013 and were processed according to previously published methods.18 The following outdoor samples were screened: air particle (n = 146, whole year data, analyzed at the same time as PBDEs) and precipitation samples from the Integrated Atmospheric Deposition Network (IADN) collected in 2015 (n = 3−4 for each of the six sites), Ponar grab sediments from Chicago’s Sanitary and Ship Canal (CSSC) collected in 2013 (n = 5), Ponar grab sediments from Indiana Harbor and Ship Canal (IHSC) collected in 2006 (n = 6), and water particulate samples in the IHSC collected in 2015 (n = 2). Details of sample collection and analysis for air, sediments and water are reported elsewhere.19−23 Instrumental Analyses. Target compounds were quantitated on an Agilent 7890 series gas chromatograph (GC) coupled to an Agilent 5975C mass spectrometer (MS) operating in the electron capture negative ionization (ECNI) mode using an RTX-1614 (15 m, 250 μm i.d., and 0.1 μm film thickness) fused silica capillary GC column (Restek Corporation, Bellefonte, CA). The instrumental details are the same as those for other flame retardants.21,24 More details are given in the SI. The full scan mass spectra of the TBC standard were obtained on an Agilent 6890 series GC coupled to an Agilent 5973 MS operating in the electron impact ionization (EI) mode. A Restek RTX-OP-Pesticides-2 (30 m, 250 μm i.d., 0.25 μm film thickness) column was used, and the mass spectrometer was scanned from m/z 50 to m/z 800. The instrument details are given in the SI. The TTBP-TAZ and TBC standards, and one e-waste dust sample were also screened on a MAT-95 XL magnetic sector high resolution mass spectrometer (Thermo Electron Corporation) in the EI mode (70 V electron energy) to confirm the structure. This instrument was operated at a mass resolution 18 000. More details are given in the SI. Quality Control. Procedural blanks (n = 5 for both e-waste and residential dust, and n = 3 for e-waste air) and field blanks (n = 2 for e-waste dust, n = 4 for both air PUF and filter, and n = 3 for U.S. residential dust) were processed along with samples. Precleaned glassware treated with the same procedure as the corresponding samples was used for procedural blanks. Field blanks were precleaned polyester socks (for dust), and PUF sandwich and filters (for air), which had been exposed by unsealing the aluminum foil wrap during sample retrievals. TTBP-TAZ and TBC were not detected in any of these blanks. 2,4,6-TBP was detected in the range N.D. to 0.9 ng for e-waste samples, and 0.01 to 0.08 ng for residential dust samples. The average recoveries of the surrogate standards BDE-77 and 13 C12-BDE-209 were 60 ± 18% and 87 ± 29% in e-waste dust,

These halogenated or halo-alkyl triazine derivatives have the potential for being persistent organic pollutants.7 TBC was reported in abiotic and biotic samples near a manufacturing facility in China,4 mollusks from the Chinese Bohai Sea,8 sediments from Yellow River and Jiaozhou Bay of China,9,10 and curtains from Japanese markets.11 TBC can cause neurotoxicity to rats,12 induce reproductive and endocrine toxicity in zebrafish,13 and prevent the growth of algae.14 TTBP-TAZ has been found in the plastic casings of electrical and electronic equipment and in dust samples collected in The Netherlands.15 TTBP-TAZ was estimated to have a persistence of ∼17 years in a modeled indoor environment,16 and similar long-range transport potential as PBDEs,17 due to its long halflives in the atmosphere and water. No studies have reported environmental concentrations of these compounds in North America. During the analysis of BFRs in e-waste samples, we noticed a late eluting peak which was not in our standards which we identified as TTBP-TAZ and then optimized our GC−MS analytical method to measure it. Because this compound has not yet been reported in North America, our goal was to screen for its presence in the North American environment by measuring the concentrations of TTBP-TAZ and two related compounds, TBC and 2,4,6-tribromophenol (TBP, an impurity in the TTBP-TAZ standard), in dust and air samples from an ewaste facility in Ontario, Canada, in house dust from the U.S., as well as in various abiotic samples from the Great Lakes (i.e., air, sediment and water). This is the first report of TTBP-TAZ in the North American indoor and outdoor environment. Our second goal was to optimize a GC−MS analytical method so that this brominated flame retardant can be screened with other compounds during routine analyses of PBDEs and other halogenated flame retardants; previous analysis has been by liquid chromatography mass spectrometry (LC/MS).15

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MATERIAL AND METHODS Chemicals. The target compounds, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ, CAS 25713-60-4, 97% purity), tris(2,3-dibromopropyl) isocyanurate (TBC, CAS 52434-90-9, 97% purity) and 2,4,6-tribromophenol (TBP, CAS 118-79-6, 100% purity), internal standard BDE-118 (BDE-118S), and surrogate BDE-77 (BDE-77S), were purchased from AccuStandard (New Haven, CT, USA). The internal standards BDE-181 and BB-209, surrogate 13C labeled BDE-209, and BFR-PAR mixture containing various PBDE congeners and non-BDE flame retardants were purchased from Wellington Laboratories (Guelph, ON, Canada). 3,3′,5,5′tetrabromobisphenol A bis(2,3-dibromopropyl) ether (TBBPABDBPE, CAS 21850-44-2) was purchased from Chiron AS (Trondheim, Norway). Additional details on the materials are given in the Supporting Information (SI). Sampling and Sample Treatment. The e-waste air and dust samples were collected from an e-waste facility in Ontario, Canada in 2016. Dust from the floor (n = 3) and the top of work benches where dismantling took place (n = 4) was collected using a vacuum cleaner fitted with precleaned polyester socks inserted at the end of the hose attachment. Four active low-volume air samplers, which consisted of a glass fiber filter (GFF, pore size 0.7 μm) followed by a PUF/XAD/ PUF sandwich (ORBO; Sigma-Aldrich, Oakville, ON, Canada), were deployed on a shelf (∼1.5 m high) near the dismantling benches and run for 8 to 30 h with sampling rates of 5.5 to 10 L/min. All the samples were stored at −20 ◦C until chemical B


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Figure 1. Partial GC/MS-ECNI gas chromatograms on a 15 m column for a floor dust sample collected at an e-waste recycling facility in Ontario in May 2016. The m/z values of the monitoring ions are 330 for 2,4,6-TBP, 81 for BDE-47 and TBBPA-BDBPE, 649.8 for TBC, 488.8 for BDE-209, and 753.7 for TTBP-TAZ. The standards are from AccuStandard or Wellington Laboratories. Abbreviations: 2,4,6-TBP: 2,4,6-tribromophenol (CAS 118-79-6); BDE: brominated diphenyl ether; TBC: tris(2,3-dibromopropyl) isocyanurate (CAS 52434-90-9); TBBPA-BDBPE: 3,3′,5,5′tetrabromobisphenol A bis(2,3-dibromopropyl) (CAS 21850-44-2); TTBP-TAZ: 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (CAS 25713-604).

and 91 ± 22% and 64 ± 22% in e-waste air samples. The surrogate recoveries for the U.S. residential dust were previously reported and are within the range of 50−150%.18 Based on the smallest detected GC peaks, the estimated detection limits for TTBP-TAZ and 2,4,6-TBP were 0.6 and 0.06 ng/g for dust, and 0.003−0.02 and 0.0003−0.002 ng/m3 for air, respectively. One of the e-waste dust samples was analyzed in triplicate and the relative standard deviation was 34% for TTBP-TAZ and 17% for 2,4,6-TBP. Blank samples (silica gel for dust and precleaned PUF sandwich and filters for air) spiked with known amount of PBDEs and other BFRs were also processed along the samples and the recoveries were in the range of 67−140% for dust and 69−139% for air. The National Institute of Standard Technology (NIST) Standard Reference Material 2585 (house dust) was analyzed in triplicate and the PBDE average recoveries were in the range 86% to 109%. Although triazine compounds are not included in the reference material, efficiencies similar to those of PBDEs are expected also based on a previous report.15 Data Analysis. Descriptive statistical analyses were completed with Microsoft Excel 2016. One-way analyses of variance (ANOVA) for the comparison of logarithmical transformed chemical concentrations were completed in Minitab 17 (State College, PA). Results were considered statistically significant at the 95% confidence interval (p < 0.05).

decabromodiphenylethane (DBDPE) and 3,3′,5,5′-tetrabromobisphenol A bis(2,3-dibromopropyl) ether (TBBPA-BDBPE), a previously identified late eluting compound25 when monitoring bromide ions at m/z 79 and 81 on a 15-m RTX-1614 column (Figure 1). This unknown compound was found in most of the e-waste dust samples. To determine the structure of this compound, full scan (m/z range of 35−1050) mass spectra in the ECNI mode were obtained for one e-waste dust sample. The most abundant ion cluster was found to center at m/z 754, which shows an isotopic pattern corresponding to exactly 6 bromine atoms (Figure 2). This cluster is likely a fragment from a large molecule because most chemicals eluting near or later than BDE-209 have molecular weights >900 and have more than 8 bromines. For example, BDE-209 has a molecular weight (MW) of 959.17 and 10 bromines, DBDPE has MW of 971.22 and 10 bromines, and TBBPA-BDBPE has a MW of 943.60 and 8 bromines. When the same dust sample was scanned at high resolution mass spectrometry (HRMS) with an EI source, an ion cluster centered at 987.3789 was found, with an isotopic pattern corresponding to 8 bromine atoms (Figure 2). In a literature search to identify possible candidate molecules, we found that Covaci et al.26 reported a molecule named TTBP-TAZ which had a MW of 1068.40 and 9 bromines and which was not in our standard list. The structure of this compound is shown in Figure 3. TTBP-TAZ nominal mass is 1059.00 and the most abundant ion of the molecular ion cluster is 1066.3 (see the SI for more details on the difference between MW and nominal mass). TTBP-TAZ can lose one bromine atom to form an ion cluster centered at m/z 987, or lose one of its three brominated

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RESULTS AND DISCUSSION Structure Identification. During the analysis of brominated flame retardants in dust from an e-waste facility we noticed one unknown GC peak eluting after BDE-209, C


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Figure 2. Electron capture negative ionization mass spectra (ECNI) and high-resolution mass spectrometry electron impact ionization mass spectra (HRMS EI) of TTBP-TAZ from the standard (AccuStandard) and the floor dust from an e-waste facility in Ontario, Canada. The m/z value for the most abundant ion in each ion cluster is labeled along with our elemental composition assignments. The molecular ion M has an elemental composition of C21H6Br9N3O3. The branch chain R has an elemental composition of C6H2Br3.

Figure 3. Structures of TTBP-TAZ, 2,4,6-TBP, and TBC. Abbreviations: TTBP-TAZ, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (CAS 2571360-4); 2,4,6-TBP, 2,4,6-tribromophenol (CAS 118-79-6); TBC, tris(2,3-dibromopropyl) isocyanurate (CAS 52434-90-9).

rings (R = C6H2Br3) to form an ion cluster centered at m/z 754. The protonated molecular ion [M+H]+ (centered at m/z 1067.3) of this compound has been found in the positive atmospheric pressure chemical ionization (APCI) mode, and the ion [M−C6H2Br3−H]− (m/z 753.5) has been found in the negative APCI mode.15 We then purchased a commercial standard of TTBP-TAZ from AccuStandard to confirm the hypothesis that the unknown peak was indeed TTBP-TAZ. The gas chromatogram of this standard material is shown in Figure 1, and the ECNI and HRMS EI mass spectra of the peak are shown in Figure 2.

The GC retention time and the mass spectra (Figures 1 and 2) matched those of the unknown peak. To confirm this compound, we also compared the exact masses of the dominant clusters in the spectra acquired with HRMS EI both in the standard and in three samples (two dust and one air filter; since the results were very similar, only one of the dust samples is presented here, see Figure 2). The exact mass of the [M−Br]+ cluster in the standard was similar to that in the sample: 987.37943 vs 987.37894 for the most abundant ion. Differences of other ions are within the range of 0.05), which suggests that dust samples in this facility were well mixed. E


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captured by gas-phase sampling media at similar percentages.28 Estimates of the vapor pressure (Pa) of TTBP-TAZ ranges from −12.5 to −21.9 (log vapor pressure estimated using EPI Suite v4.1 and SPARC, respectively) and log KOA ranges from 21.5 to 25.2 (EPI Suite and Absolv, respectively).4,17 Also, TBC was not detected in any of the e-waste air samples. Concentrations of 2,4,6-TBP in the e-waste dust were 0.3 to 12% of those of TTBP-TAZ. Median air concentrations of 2,4,6-TBP were 4.45 ng/m3, comparable to those of TTBPTAZ (Table S1). These concentrations in air of the e-waste recycling facility were one to 2 orders of magnitude higher than those in the indoor air from two Japanese houses, which were in the 0.1−1 ng/m3 range.29 However, the dust concentrations of 2,4,6-TBP from the e-waste facility (median: 145 ng/g) were in the same range of those reported in Japanese house and office dust samples (15 to 620 ng/g).29,30 Residential Dust. TTBP-TAZ was detected in 21 out of 30 samples with concentrations ranging from 0.43 to 92 ng/g (Table S2), which were 2 to 3 orders of magnitude lower than the concentrations in the e-waste dust. TTBP-TAZ concentrations were not significantly different from the concentrations of 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), but were 1 order of magnitude lower than those of DBDPE and BDE-47, and 2 orders of magnitude lower than those of BDE-209 (Figure 4). These TTBP-TAZ concentrations in U.S. house dust were similar to the concentrations in Dutch floor dust ( 0.05) between rooms, suggesting well-mixed environments. Similar findings were reported for PBDEs and other brominated flame retardants.18 TBC was not detected in any of the residential dust samples. 2,4,6-TBP was detected in all the 30 U.S. house dust samples, ranging from 0.9 to 129 ng/g (Table S2). The concentrations of 2,4,6-TBP in our house dust were similar to those in Japanese house dust (16−130 ng/g).29,30 Outdoor Environment. TTBP-TAZ was detected in 0.05). For residential dust, TTBP-TAZ, 2,4,6-TBP and TBBPA-BDBPE were measured in this study while other compounds were measured previously.18 Abbreviations: TTBP-TAZ, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine; 2,4,6-TBP, 2,4,6-tribromophenol; BTBPE, 1,2bis(2,4,6-tribromophenoxy)ethane; TBBPA-BDBPE, 3,3′,5,5′-tetrabromobisphenol A bis(2,3-dibromopropyl); DBDPE, decabromodiphenylethane; BDE, brominated diphenyl ether.

The measured TTBP-TAZ concentrations were similar to the concentrations in dust collected on electronics (1070− 22 150 ng/g) and generally higher than the concentrations of dust collected in the vicinity of electronic equipment (220− 3950 ng/g) in Dutch houses.15 These results confirm that electrical and electronic equipment are a major source of TTBP-TAZ to indoor environments. The log transformed concentrations of TTBP-TAZ were marginally significantly correlated with those of BDE-209 (p = 0.068) in the e-waste dust samples. Given the high MW and number of bromines, TTBP-TAZ may have similar application to BDE-209, DBDPE and TBBPA-BDBPE.27 TBC was not detected in any of the ewaste dust samples. TTBP-TAZ was also detected in all the four air samples obtained with low-volume active samplers deployed in the ewaste facility; the median concentration of TTBP-TAZ was 5.75 ng/m3 (sum of PUF sandwich and filter), which is 20 times lower than that of BDE-209, and 10 times higher than that of BDE-47 (Table S1). More than 70% of TTBP-TAZ was found in the filter in all the four samples and the remaining ∼30% in the XAD. TTBP-TAZ is expected to be entirely in the particle phase given its physical-chemical properties (extremely low, but also highly uncertain, vapor pressure and high KOA). Finding TTBP-TAZ in filter and gas-phase sorbent is not surprising; rather, it is similar to what happens also with BDE209, another rather large molecule with low vapor pressure that is also found predominantly in the particle phase but which is F


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Environmental Science & Technology may have started recently. For example, TTBP-TAZ was found in Dutch house dust samples collected in 2013 but not in those collected in 2006.15 IHSC sediment was sampled in 200621 which could predate its presumed significant use (see below). The CSSC sediment was collected in 2013; however, a small surface amount of recently deposited TTBP-TAZ could have been diluted by decades old sediment in the 10 cm depth grab sample.20 similarly to TTBP-TAZ, TBC was not detected in any of the environmental samples. TBC has been found in very high concentrations in river water (2 to 200 ng/L), surface sediments (up to 6 μg/g dw), soils (20−700 ng/g dw), earthworms (10 to 80 ng/g dw) and fish (carp) samples (10 to 600 ng/g dw) collected near a TBC manufacturing plant in Southern China before 2009.4 TBC was also detected in 77% of mollusks from the Chinese Bohai Sea (median range 0.07 to 1.01 ng/g dw),8 and sediments from the Yellow River Delta wetland (0.20 to 29.03 ng/g dw) and the Jiaozhou Bay wetland (1.20 to 8.76 ng/g dw) of China.9,10 In indoor samples, TBC was found in 10 out of 40 curtains purchased from the Japanese market at concentrations up to 23 700 μg/g.11 There are no reports of TBC in environmental samples outside of Asia, which may be due to its low production and use outside of Asia. The peak of 2,4,6-TBP was visible in some precipitation and sediment samples but the concentrations were relatively low and was not quantified. Production and Use. TTBP-TAZ was developed jointly by the Japanese Company Dai-Ichi Kogyo Seiyaku (DKS) and by the Israeli Dead Sea Bromine Group (ICL), although each company commercialized it under different trade names (Pyroguard SR 245 at DKS and FR-245 at ICL).3 TBC, TBBPA-BDBPE and even hexabromocyclododecane (HBCDD) were also produced by DKS with trade names Pyroguard SR-750, Pyroguard SR720N and Pyroguard SR-103, respectively.33 The relatively novel flame retardant TBBPABDBPE is also manufactured by ICL with the trade name FR720.25 TTBP-TAZ is mainly employed in acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS) which are used to fabricate casings of televisions, audio and video equipment, computer monitors, and the casings of other electric equipment.34 According to the U.S. Toxic Substances Control Act (TSCA) Inventory, TTBP-TAZ was not manufactured in the U.S. but was imported by several companies. One of those is the electronic product manufacturer LG International America Inc., with an annual imported volume of TTBP-TAZ of 345 000 kg/ yr in 2012 and 565 000 kg/yr before 2012. TTBP-TAZ was also imported into the U.S. by ICL but the imported volume is unknown.35 Three U.S. patents claim that TTBP-TAZ was used as flame retardant to produce flame-retarded foamable resin beads for insulating materials of household electrical appliances, cars, buildings and houses, and to produce curable epoxy resin for fabricating circuit boards.36−38 In Canada, TTBP-TAZ was added to the Non-Domestic Substances List in 2005.39 In Europe, TTBP-TAZ is listed in the European List of Notified Chemical Substances (ELINCS).5 According to LookChem, China has 59 TTBP-TAZ suppliers, 12 of which are direct manufacturers. Several of these companies sell TTBP-TAZ with a minimum purchase on the order of metric tonnes.40 Given its high production volume in China, it is surprising that no studies have reported TTBP-TAZ in Chinese environmental samples although it was detected in our North American indoor samples and Dutch house dust.15

The U.S. production volume of 2,4,6-TBP was 4500−23 000 t in 2006. It is considered a High Production Volume chemical (HPV) by the Europe Union.26 2,4,6-TBP is produced by Chemtura under the trade name PH-73FF and by ICL Industrial Products under the trade name FR-613.26 2,4,6TBP is on the Domestic Substances List under Canada’s Chemical Management Plan.41 Japanese production was 3600 t in 2001.42 In China, 2,4,6-TBP is manufactured by 72 companies.43 2,4,6-TBP may also be an impurity in TTBP-TAZ because the former was found in almost all the plastic samples and because there was a significant correlation between the concentrations of these two chemicals in the plastic of electronic products.15 Similarly to Ballesteros et al.,15 no correlation between 2,4,6-TBP and TTBP-TAZ was found in dust in our study. This finding could have been due to the multiple sources contributing to TTBP-TAZ and 2,4,6-TBP in e-waste and house dust. 2,4,6-TBP also could be a degradation product of other flame retardants.44,45 For example, 2,4,6-TBP was found as an impurity in tetrabromobisphenol A (TBBPA),46 which was very abundant in our e-waste samples. TBC has been on the Domestic Substances List of Canada since 1994.41 Lookchem lists 52 suppliers of this compound in China.47 The production of TBC started in the mid-1980s and the annual production was ∼500 t/yr in 1996 in China.4 TBC is considered a Low Production volume chemical in the European Union.26 No information on production/imported volumes has been found in the U.S. Interestingly, TBC was included on Minnesota’s Chemicals of High Concern List.48 Despite claims from the manufacturers that TTBP-TAZ poses no human and environmental risks, this compound can easily degrade to 2,4,6-TBP, which has shown acute toxicity to fish and rodents, and genetic, reproductive and developmental toxicity to mice and rodents at μg/g levels.49 Based on their high production and imported volumes, their wide usage in many countries, and their potential persistence and toxicity, triazine flame retardants are likely to be a group of emerging chemicals of concern. The high concentrations of TTBP-TAZ in the Canadian e-waste facility and its prevalence in U.S. homes clearly demonstrates the potential for human exposure. Furthermore, it is anticipated that TTBP-TAZ will eventually circulate in the environment like BDE-209 and DBDPE based on its similarities with these compounds. Further studies are needed to better understand the sources and emissions, environmental transport and fate, and the ecotoxicity and impact on human health of these triazine flame retardants. Further measurements of TTBP-TAZ by GC/MS should include labeled standards, which are now available, and analytical methods optimized specifically for this compound (i.e., frequent changes of liner, fast oven temperature ramps, short and thin film columns) to provide a more accurate estimate of its presence in the environment.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.7b06139. Experimental details (PDF)

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AUTHOR INFORMATION

Corresponding Author

*M. Venier. E-mail: [email protected]. G


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Environmental Science & Technology ORCID

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Liisa Jantunen: 0000-0003-0261-9539 Victoria Arrandale: 0000-0002-9587-4207 Miriam L. Diamond: 0000-0001-6296-6431 Marta Venier: 0000-0002-2089-8992 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work is funded by Ontario Ministry of Labour Research Opportunities Program, Czech-American Scientific Cooperation Program (AMVIS/KONTAKT II, LH12074), and U.S. Environmental Protection Agency Great Lakes National Program Office (Grant GL 00E01422, Todd Nettesheim and Vergel Santos, project officers). We are grateful to all participants and researchers involved in the U.S. dust study. We thank Jonathan A. Karty from Department of Chemistry of Indiana University Bloomington for conducting the highresolution mass spectrometry scan. We also thank Ronald A. Hites for helpful discussions on the mass spectrometry.

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