Letter pubs.acs.org/journal/estlcu
Cite This: Environ. Sci. Technol. Lett. XXXX, XXX, XXX−XXX
Children’s Car Seats Contain Legacy and Novel Flame Retardants Yan Wu,† Gillian Z. Miller,‡ Jeff Gearhart,‡ Kevin Romanak,† Viorica Lopez-Avila,§ and Marta Venier*,† †
School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, United States Ecology Center, Ann Arbor, Michigan 48104, United States § Agilent Technologies, Santa Clara, California 95051, United States ‡
Environ. Sci. Technol. Lett. Downloaded from pubs.acs.org by YORK UNIV on 12/03/18. For personal use only.
S Supporting Information *
ABSTRACT: Brominated and phosphorus-based flame retardants (PFRs) were measured in foam and fabric samples from 18 newly marketed children’s car seats. The concentrations of two cyclic phosphonates {PMMMPs, 5-ethyl-2methyl-2-oxido-1,3,2-dioxaphosphinan-5-yl)methyl methyl methylphosphonate and bis[(5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl] methyl phosphonate p,p′-dioxide} were quantitatively measured for the first time in the North American environment and were much higher than those of other flame retardants. Median PMMMP concentrations were 73.6 μg/g, accounting on average for 52% of the total FR concentrations, indicating an intentional addition of PMMMPs during the manufacturing process of these car seats. Two other emerging PFRs [tris(2,4-di-Hi Katie,tbutylphenyl) phosphate (TDTBPP) and resorcinol bis(diphenyl phosphate) (RDP)] were detected for the first time in baby products at median levels of 1.11 and 6.15 μg/g, respectively. Other frequently detected PFRs included triethyl phosphate (TEP), triphenyl phosphate (TPHP), and tris(2-butoxyethyl) phosphate (TBOEP). Among the brominated flame retardants monitored, decabromodiphenyl ethane (DBDPE), with a median concentration of 128 μg/g, was the only halogenated FR measured at levels suggesting intentional use. Other brominated FRs such as hexabromobenzene (HBB) and 2,3-dibromo 2,4,6tribromophenyl ether (DPTE) were sporadically detected with median concentrations of 0.23 and 0.18 μg/g, respectively. Despite being phased out in the United States starting in 2013, polybrominated diphenyl ethers (PBDEs) were still observed in 75% of our samples, although at modest levels (median total PBDE levels of 0.24 μg/g). Trace PBDE levels suggest background contamination rather than intentional use. The high levels of FRs measured in these children’s car seats together with the negative health effects associated with some of these compounds are a cause for concern for children’s health.
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INTRODUCTION Children’s car seats (hereafter “seats”) are required by law to meet the performance-based, open flame flammability standards created for car interiors rather than those for children’s products. In particular, seats need to comply with Federal Motor Vehicle Safety Standard 302 (FMVSS302), which was written in 1971 by the National Highway Traffic Safety Administration (NHTSA) and has remained unchanged. While this regulation does not specifically call for the use of chemical additives, flame retardants (FRs) are routinely added to seats as a cost-effective way to meet the standard. Polybrominated diphenyl ethers (PBDEs) make up one of the most well-known group of FRs. In North America, pentaand octa-BDE were phased out at the end of 2004, while decaBDE was withdrawn from the market at the end of 2013, because of rising concerns about their persistent, bioaccumulative, and toxic potentials. This phase-out of PBDEs has stimulated the use of alternative FRs to meet flammability standards. Novel FRs include compounds such as decabromo© XXXX American Chemical Society
diphenylethane (DBDPE), bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), dechlorane-related substances (Dechloranes), and organophosphate esters (OPEs).1 OPEs have been used for more than 150 years, and they have recently been applied as plastic additives and FRs in consumer products.2 Their usage has significantly increased in the past decade or so as a result of the ban on halogenated flame retardants in some consumer products in the United States.3 Infants and toddlers have FR burdens higher than those of adults because of their limited metabolic capacity, lower body weight, more frequent object/hand-to-mouth behaviors, and higher contact with floors.4 Animal tests and epidemiological studies have documented several adverse health effects caused Received: October 26, 2018 Revised: November 15, 2018 Accepted: November 16, 2018
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DOI: 10.1021/acs.estlett.8b00568 Environ. Sci. Technol. Lett. XXXX, XXX, XXX−XXX
Letter
Environmental Science & Technology Letters by pre- and postnatal exposure to flame retardants, including decreased birth weight/length, endocrine disruption, neurodevelopmental toxicity, liver damage, and cancer.5−7 Moreover, early life exposure to FRs and their metabolites may be associated with prolonged health risks to the exposed subjects later in life.6,8 Children’s car seats are a potential FR source for children because their breathing zone is in the proximity of infant products containing these chemicals; this might result in higher inhalation exposures.9 Direct contact of the child’s skin with the seat’s upholstery is also a potential source of exposure, although there are no data about this. Hoffmann et al. hypothesized that baby products, and specifically car seats, could be contributing to children’s high exposure to phosphorus-based flame retardants (PFRs), in particular to tris(1,3-dichloro-2-propyl) phosphate (TDCPP).9,10 The independent nonprofit organization Ecology Center routinely tests children’s car seats for FR chemicals. Recently, their self-published research has raised concerns about unidentified brominated compounds and cyclic phosphonates in these products.11,12 In the work presented here, we measured the concentration of FRs in fabric and foam from 18 seats purchased in 2018 by the Ecology Center. The goals of the study were to identify FRs, measure their concentrations in these children’s car seats, and track market shifts in the use of FRs.
negative ionization (Agilent 7890B GC-5977B ECNI-MS). Both GC−MS instruments were operated in selected ion monitoring (SIM) mode. For confirmation of cyclic phosphonates, reference materials and 10 representative children’s car seat samples were scanned on a model 7250 GC/Q-TOF instrument in positive chemical ionization (PCI) mode. Detailed analytical procedures, including the highresolution MS analyses, are presented in the Supporting Information. A summary of the limits of detection (LODs) and qualifier and quantifier ions used in the analyses are reported in Table S2. Procedural blanks consisting of sodium sulfate (previously baked at 300 °C for 12 h) were treated along with the seat samples to evaluate the background contamination from laboratory operations. The reported concentrations were corrected by subtracting the blanks on a mass basis. Blank levels are reported in Table S3. Surrogate standards were not added to these samples because of the need for sequential dilutions due to high concentrations of the target chemicals. Matrix spike recoveries were between 70 and 120%, confirming that this analytical protocol is suitable. Statistical analyses and plotting were performed using OriginPro 2017 (OriginLab Corp.) or Excel 2016 (Microsoft Corp.). Prior to statistical analyses, all data were logarithmically transformed to guarantee normal distributions and equal variances across groups, which were confirmed using the Shapiro−Wilk test and the Brown−Forsythe test, respectively. The correlation between variables was evaluated using Kendall’s tau test. A significance level of α = 0.05 was applied to all analyses.
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MATERIALS AND METHODS Fabric samples were collected from each of 18 car seats, including 31 total fabric samples (15 stand-alone fabrics and 16 laminated composites of foam and fabric) and five soft foam samples (four polyurethane foams and one polyethylene foam). Children’s car seats were purchased by the Ecology Center and shipped to Indiana University for analyses. These seats were manufactured from January 2017 to February 2018. Nine and two seats were manufactured in China and Canada, respectively, and the remaining ones were produced in the United States with global components (Table S1). At least one sample from each seat was analyzed. Detailed sample information is provided in Table S1. Samples were shipped to Indiana University for analyses and then cut into pieces using scissors precleaned with isopropanol; 50−200 mg of the cut sample was transferred into a precleaned test tube and sonicated twice with 5 mL of hexane and acetone (50/50, v/v). Then, 100 μL aliquots of each extract were spiked with internal standards and solvent-exchanged into either hexane or methanol depending on the instrument used for analysis (100-fold dilution). Another 10-fold dilution was performed for some compounds [e.g., PMMMPs, tris(2-butoxyethyl) phosphate (TBOEP), and triphenyl phosphate (TPHP)] for which the concentration was initially outside the range of the calibration curve. Blank samples were prepared following the same protocol and analyzed in parallel for each dilution step. The complete list of target analytes is included in Table S2. PFRs, except TDTBPP and tris(2,4-di-tert-butylphenyl) phosphite (TDTBPPO), were analyzed on an ultraperformance liquid chromatograph coupled to a triple-quadrupole mass spectrometer (Agilent 1290 Infinity II UPLC-6470 QQQ-MS) with positive electrospray ionization (ESI+). TDTBPP and TDTBPPO were analyzed using gas chromatography and mass spectrometry (GC−MS) in electron impact mode (Agilent 6890 GC-5973 EI-MS). The remaining target compounds were analyzed via GC−MS with electron-capture
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RESULTS AND DISCUSSION PBDEs. Seventy-five percent of the children’s car seat samples contained at least one BDE congener above the detection limit, and the median total PBDE concentrations were 0.08, 0.29, and 0.20 μg/g in foams, fabrics, and composites, respectively. BDE-28, -47, and -49 were the predominant congeners in all samples with medians of 0.19, 0.041, and 0.44 μg/g, respectively. Detecting PBDEs despite their phase-out in 2013 is somewhat surprising, but the modest levels detected suggest that PBDEs were not added intentionally but were impurities. Likely, PBDE residues are still in older products’ components or in parts containing recycled materials.13 A survey of FR levels in gymnastic studios also found that PBDE levels were significantly lower in newly introduced foam blocks.14 NBFRs. Seven of 18 targeted NBFRs (i.e., DBDPE, three tribromophenoxy FRs, and three bromobenzenes) were detected in these samples, albeit at detection frequencies of
