Metabolites of Organophosphate Flame Retardants and 2‑Ethylhexyl Tetrabromobenzoate in Urine from Paired Mothers and Toddlers Craig M. Butt, †,§ Johanna Congleton, ‡,§ Kate Hoffman, † Mingliang Fang, † and Heather M. Stapleton* ,† † Nicholas School of the Environment, Duke University, Box 90328, Levine Science Research Center, Room A220, Durham, North Carolina 27708, United States ‡ Environmental Working Group, Washington, DC 20009, United States * S Supporting Information ABSTRACT: As a result of the polybrominated diphenyl ether (PBDE) ban in the mid-2000s, the chemical flame retardant market has moved toward alterative compounds including chlorinated alkyl and nonchlorinated aryl organophosphate flame retardants (OPFRs) as well as aromatic brominated compounds such as Firemaster 550 (FM550). Recent studies have shown that the OPFRs and Firemaster 550 components are frequently detected in polyurethane foams and in indoor dust. Some OPFRs are considered carcinogenic and/or neuro- developmental toxicants, and children’s exposure to these compounds is a concern. OPFRs are readily metabolized and excreted in the urine as their dialkyl and diaryl compounds which function as biomarkers for OPFR exposure. Limited research has shown that adults are broadly exposed to OPFRs, but nothing is known about children’s exposure. Similarly, 2-ethylhexyl-2,3,4,5-tetrabromoben- zoate (EH-TBB), a FM550 component, is metabolized to tetrabromobenzoic acid (TBBA). The current study measured levels of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(1-chloro-2-propyl) phosphate (BCIPP), diphenyl phosphate (DPHP), 2 alkylated DPHPs, and TBBA in urine collected in 2013 from 21 US mother-toddler pairs. BDCIPP, DPHP, and ip-DPHP were detected in 100%, 98%, and 96% of all individuals, whereas BCIPP and tert-butyl-DPHP (tb-DPHP) were only detected in 8% and 13%. Further, TBBA was detected in 27% of adults but 70% of children. Overall, children had higher urinary levels of BDCIPP, DPHP, ip-DPHP, and TBBA as compared to their mothers, suggesting higher exposure. For example, on average, BDCIPP levels in children were 4.9 times those of mothers. BDCIPP and DPHP levels in mother’s urine were also significantly correlated with levels in children’s urine, suggesting similar exposure routes, likely in the home environment. Various potential predictors of OPFR exposure were assessed using a questionnaire. In children some predictors of hand-mouth exposure were associated with elevated BDCIPP and DPHP levels (e.g., less frequent hand washing for BDCIPP). Overall, these trends are consistent with higher flame retardant levels in children as a result of increased hand-mouth behavior and elevated dust exposure. ■ INTRODUCTION Chemical flame retardants (FRs) are often added to household products such as furniture foam, textiles, and electronics to meet strict flammability standards. A key regulation was California Technical Bulletin 117 (TB 117), which has recently undergone revision and no longer requires open flame test requirements. 1 The more stringent open flame test led to the high application rates of FRs in polyurethane foam in furniture, but the revised standard - TB117-2013 - focuses on smoldering ignition sources, the main cause of furniture fires, and is expected to reduce the use of FR additives in foam. For many years the dominant FR used in polyurethane foam was the polybrominated diphenyl ether (PBDE) pentaBDE commercial mixture. 2 Concerns regarding their bioaccumula- tion in human tissues, and potential health effects, resulted in a phase-out of the pentaBDE and octaBDE mixtures in both Europe and the United States during the mid-2000s. To continue to meet the flammability standards following the pentaBDE phase-out, manufacturers have relied on an increasing variety of alternative FRs. A major class of alternative compounds is the organophosphate flame retardants (OPFRs) which are broadly comprised of the chlorinated alkyl phosphates and nonchlorinated aryl phosphates. 3 Representa- tive OPFR chemicals include tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP). In addition, TPHP has been used as a plasticizer and lubricant. 3 An additional alternative is Firemaster 550 (FM550), which is comprised of TPHP, various isopropylated TPHPs isomers, 2- ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), and bis(2- ethylhexyl)-2,3,4,5-tetrabromophtalate (BEH-TEBP). 4 Recent studies from the United States show that OPFRs and FM550 components are the most frequently detected flame retardants in foams from baby products 5 and residential sofas. 2 Received: May 27, 2014 Revised: July 29, 2014 Accepted: August 4, 2014 Published: August 4, 2014 Article pubs.acs.org/est © 2014 American Chemical Society 10432 dx.doi.org/10.1021/es5025299 | Environ. Sci. Technol. 2014, 48, 10432-10438