title: Serum polybrominated diphenyl ether concentrations and thyroid function in young children.
abstract: Thyroid hormones are essential for proper neurodevelopment in early life. There is evidence that exposure to polybrominated diphenyl ethers (PBDEs) affects thyroid function, but previous studies have been inconsistent, and no studies among children have been conducted in the United States where PBDE levels are particularly high. Serum levels of seven PBDE congeners and thyroid hormones and other thyroid parameters were measured in 80 children aged 1-5 years from the southeastern United States between 2011 and 2012. Parents of the children completed questionnaires with details on demographics and behaviors. Multivariate linear regression models were used to estimate the associations between serum PBDE levels, expressed as quartiles and as log-transformed continuous variables, and markers of thyroid function. BDE-47, 99, 100 and 153 were detected in >60% of samples, and were summed (∑PBDE). PBDE congeners and ∑PBDE were positively associated with thyroid-stimulating hormone (TSH). A log-unit increase in ∑PBDE was associated with a 22.1% increase in TSH (95% CI: 2.0%, 47.7%). Compared with children in the lowest quartile of ∑PBDE exposure, children in higher quartiles had greater TSH concentrations as modeled on the log-scale (second quartile: β=0.32, 95% confidence interval (CI): -0.09, 0.74; third quartile: β=0.44, 95% CI: 0.04, 0.85; and fourth quartile: β=0.49, 95% CI: 0.09, 0.89). There was also a tendency toward lower total T4 and higher free T3 with increasing PBDE exposure. Results suggest that exposure to PBDEs during childhood subclinically disrupts thyroid hormone function, with impacts in the direction of hypothyroidism.
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: mhymanjacobson@emory.edu.
authors.forename: Melanie H
authors.initials: MH
authors.lastname: Jacobson
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: dbbarr@emory.edu.
authors.forename: Dana B
authors.initials: DB
authors.lastname: Barr
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA; Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: mmarcus@emory.edu.
authors.forename: Michele
authors.initials: M
authors.lastname: Marcus
authors.affiliation: Department of Pediatrics, Division of Endocrinology, Emory University School of Medicine, Atlanta, GA 30322, USA. Electronic address: abmuir@emory.edu.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Muir
authors.affiliation: Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: rlyles@emory.edu.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Lyles
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. Electronic address: phoward@emory.edu.
authors.forename: Penelope P
authors.initials: PP
authors.lastname: Howards
authors.affiliation: National Center for Environmental Assessment, U.S. Environmental Protection Agency, Washington, DC 20004, USA. Electronic address: larissapardo2@gmail.com.
authors.forename: Larissa
authors.initials: L
authors.lastname: Pardo
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA; Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA; School of Community Health Sciences, University of Nevada, Reno, NV 89557, USA. Electronic address: ldarrow@emory.edu.
authors.forename: Lyndsey A
authors.initials: LA
authors.lastname: Darrow
mesh_terms: D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D005845:Georgia; D055768:Halogenated Diphenyl Ethers / Q000097:blood*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood*
chemical_list: D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D013972:Thyrotropin
keywords: Brominated flame retardants; Endocrine disruption; PBDEs; Thyroid function; Thyroid hormones