Research | Children’s Health Serum PBDEs in a North Carolina Toddler Cohort: Associations with Handwipes, House Dust, and Socioeconomic Variables Heather M. Stapleton,1 Sarah Eagle,1 Andreas Sjödin,2 and Thomas F. Webster 3 1Nicholas School of the Environment, Duke University, Durham, North Carolina, USA; 2Centers for Disease Control and Prevention, National Center for Environmental Health, Division for Laboratory Sciences, Atlanta, Georgia, USA; 3Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts, USA Background : Polybrominated diphenyl ethers (PBDEs) are persistent, bioaccumulative, and endocrine-disrupting chemicals. o Bjectivs : We used handwipes to estimate exposure to PBDEs in house dust among toddlers and examined sex, age, breast-feeding, race, and parents’ education as predictors of serum PBDEs. Methods : Eighty-three children from 12 to 36 months of age were enrolled in North Carolina between May 2009 and November 2010. Blood, handwipe, and house dust samples were collected and analyzed for PBDEs. A questionnaire was administered to collect demographic data. r sulte : PBDEs were detected in all serum samples (geometric mean for ∑pentaBDE in serum was 43.3 ng/g lipid), 98% of the handwipe samples, and 100% of the dust samples. Serum ∑pentaBDEs were significantly correlated with both handwipe and house dust ∑pentaBDE levels, but were more strongly associated with handwipe levels (r = 0.57; p < 0.001 vs. r = 0.35; p < 0.01). Multivariate model estimates revealed that handwipe levels, child’s sex, child’s age, and father’s education accounted for 39% of the variation in serum ∑BDE3 levels (sum of BDEs 47, 99, and 100). In contrast, age, handwipe levels, and breast-feeding duration explained 39% of the variation in serum BDE 153. c onclusi : Our study suggests that hand-to-mouth activity may be a significant source of expo- sure to PBDEs. Furthermore, age, socioeconomic status, and breast-feeding were significant pre- dictors of exposure, but associations varied by congener. Specifically, serum ∑BDE3 was inversely associated with socioeconomic status, whereas serum BDE-153 was positively associated with dura- tion of breast-feeding and mother’s education. k ey words : children, exposure, handwipes, house dust, PBDEs. Environ Health Perspect 120:1049–1054 (2012). http://dx.doi.org/10.1289/ehp.1104802 [Online 23 May 2012] Polybrominated diphenyl ethers (PBDEs) are flame retardant chemicals that have been used to reduce the flammability of polymers and resins found in commercial products such as furniture, electronics (e.g., TVs, cell phones, business equipment), and electrical wiring and in some textile applications. Historically three different commercial mixtures, known as pentaBDE, octaBDE, and decaBDE, were sold by different companies under differ- ent trade names. However, the persistence, bioaccumulation, and potential toxicity of components in the pentaBDE and octaBDE mixtures resulted in their phase out in many regions of the world, including the United States (Tullo 2003). PBDE congeners found in the pentaBDE commercial mixture are commonly found in human tissues (Schecter et al. 2005; Sjödin et al. 2003, 2008). This mixture was used pri- marily in polyurethane foam found in fur- niture, and most of the pentaBDE used in furniture was manufactured in the United States and Canada (Hale et al. 2003). The high use of pentaBDE in North America may explain why these populations have some of the highest PBDE levels ever recorded in non-occupationally exposed populations (Hites 2004). In the 2003–2004 NHANES (National Health and Nutrition Examination Survey) survey of the U.S. population (≥ 12 years of age), > 97% of the population had detectable levels of PBDE in their blood. Concentrations in 12- to 19-year-olds were higher than in older age groups, suggesting that adolescents experienced a higher exposure level than adults (Sjödin et al. 2008). More recent studies have examined PBDE levels in younger children (Rose et al. 2010; Roze et al. 2009; Toms et al. 2008; Windham et al. 2010). Rose et al. (2010) measured PBDEs in serum from 2- to 5-year-old children in California and found that their levels were 2–10 times higher than most adults in the US. Children are likely exposed to PBDEs from many sources. Exposure modeling sug- gests that most exposures occur from diet, inhalation, and contact with contaminated house dust (Jones-Otazo et al. 2005; Lorber 2008). House dust is often contaminated with numerous chemicals, and previous stud- ies have linked children’s exposure to lead with exposure from contaminated house dust (Butte and Heinzow 2002; Rhoads et al. 1999). PBDEs are often detected in house dust and they have also been measured in handwipe samples (Rudel et al. 2003; Stapleton et al. 2008). This suggests that children with more hand-to-mouth contacts may also be more exposed to contaminants from their hand-to-mouth activities. In U.S. adults, both diet and exposure to dust have Environmental Health Perspectives • volume 120 | number 7 | July 2012 been shown to be associated with pentaBDE body burdens (Fraser et al. 2009; Wu et al. 2007); however, more recently, studies in the United States suggest that dust exposure may have more of an influence than diet on serum PBDE levels (Johnson et al. 2010; Watkins et al. 2012). The most significant sources of PBDE exposure in children are currently unknown; however, dust and diet are both hypothesized to play major roles, although such estimates are complicated by the uncer- tainty surrounding exposure factors for dust ingestion (Lorber 2008; Rose et al. 2010). Children’s exposure to PBDEs is of con- cern because of PBDEs’ known endocrine- disrupting and neurodevelopmental properties as observed in animal studies. PBDEs have chemical structures similar to thyroid hor- mones, such as thyroxine. This similarity in structure may explain why PBDE exposure in animals has been linked to significant changes in circulating thyroid hormone levels (Fernie et al. 2005; Tomy et al. 2004; Zhou et al. 2002). In addition, in vitro studies have shown that PBDEs and their oxidative metabolites are potent competitors with thyroid hormones for binding to transthyretin (Meerts et al. 2000) and human type 1 deiodinase, which metabolizes thyroid hormones (Butt et al. 2011). PBDEs and their metabolites have also been shown to affect spontaneous behavior in rodents and affect cholinergic function and calcium signaling in the brain (Dingemans et al. 2010a, 2010b; Viberg et al. 2002, 2003). Recent human studies have also reported Address correspondence to H. Stapleton, Nicholas School of the Environment, Duke University, LSRC, Box 90328, Durham, NC 27708 USA. Telephone: (919) 613-8717. Fax: (919) 684-8741. E-mail: heather.stapleton@duke.edu Supplemental Material is available online (http:// dx.doi.org/10.1289/ehp.1104802). We thank B. Patterson for her assistance with recruitment. We also thank all of our participants in this study. This study was supported by a research grant to H.M.S. from the National Institute of Environmental Health Sciences, R01 ES016099. T.F.W. is supported in part by R01 ES015829. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention or the Agency for Toxic Substances and Disease Registry. The authors declare they have no actual or potential competing financial interests. Received 1 December 2011; accepted 14 May 2012. 1049