title: Polybrominated diphenyl ether (PBDE) flame retardants and thyroid hormone during pregnancy.
abstract: BACKGROUND
  Human exposure to polybrominated diphenyl ether (PBDE) flame retardants has increased exponentially over the last three decades. Animal and human studies suggest that PBDEs may disrupt thyroid function. Although thyroid hormone (TH) of maternal origin plays an essential role in normal fetal brain development, there is a paucity of human data regarding associations between exposure to PBDEs and maternal TH levels during pregnancy.
  
  
  OBJECTIVE
  Our goal was to determine whether PBDE serum concentrations are associated with TH levels in pregnant women.
  
  
  METHODS
  We measured the concentration of 10 PBDE congeners, free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in 270 pregnant women around the 27th week of gestation.
  
  
  RESULTS
  Serum concentrations of individual PBDE congeners with detection frequencies > 50% (BDEs 28, 47, 99, 100, and 153) and their sum (ΣPBDEs) were inversely associated with TSH levels. Decreases in TSH ranged between 10.9% [95% confidence interval (CI), -20.6 to 0.0] and 18.7% (95% CI, -29.2 to -4.5) for every 10-fold increase in the concentration of individual congeners. Odds of subclinical hyperthyroidism (low TSH but normal T4) were also significantly elevated in participants in the highest quartile of ΣPBDEs and BDEs 100 and 153 relative to those in the first quartile. Associations between PBDEs and free and total T4 were not statistically significant. Results were not substantially altered after the removal of outliers and were independent of the method used to adjust for blood lipid levels and to express ΣPBDEs.
  
  
  CONCLUSIONS
  Results suggest that exposure to PBDEs is associated with lower TSH during pregnancy. Findings may have implications for maternal health and fetal development.
authors.affiliation: Center for Children's Environmental Health Research, School of Public Health, University of California-Berkeley, Berkeley, California 94704-7392 , USA. chevrier@berkeley.edu
authors.forename: Jonathan
authors.initials: J
authors.lastname: Chevrier
authors.forename: Kim G
authors.initials: KG
authors.lastname: Harley
authors.forename: Asa
authors.initials: A
authors.lastname: Bradman
authors.forename: Myriam
authors.initials: M
authors.lastname: Gharbi
authors.forename: Andreas
authors.initials: A
authors.lastname: Sjödin
authors.forename: Brenda
authors.initials: B
authors.lastname: Eskenazi
mesh_terms: D000328:Adult; D005260:Female; D005411:Flame Retardants / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers / Q000097:blood / Q000633:toxicity*; D006801:Humans; D011247:Pregnancy; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D005411:Flame Retardants; D055768:Halogenated Diphenyl Ethers; D013963:Thyroid Hormones