title: Thyroid hormone levels of pregnant inuit women and their infants exposed to environmental contaminants.
abstract: BACKGROUND
  An increasing number of studies have shown that several ubiquitous environmental contaminants possess thyroid hormone-disrupting capacities. Prenatal exposure to some of them, such as polychlorinated biphenyls (PCBs), has also been associated with adverse neurodevelopmental effects in infants.
  
  
  OBJECTIVE
  In this study we examined the relationship between exposure to potential thyroid hormone-disrupting toxicants and thyroid hormone status in pregnant Inuit women from Nunavik and their infants within the first year of life.
  
  
  METHODS
  We measured thyroid hormone parameters [thyroid stimulating hormone (TSH), free thyroxine (fT(4)), total triiodothyronine (T(3)), thyroxine-binding globulin (TBG)] and concentrations of several contaminants [PCB-153, hydroxylated metabolites of PCBs (HO-PCBs), pentachlorophenol (PCP) and hexachlorobenzene (HCB)] in maternal plasma at delivery (n = 120), in umbilical cord plasma (n = 95), and in infant plasma at 7 months postpartum (n = 130).
  
  
  RESULTS
  In pregnant women, we found a positive association between HO-PCBs and T(3) concentrations (beta = 0.57, p = 0.02). In umbilical cord blood, PCB-153 concentrations were negatively associated with TBG levels (beta = -0.26, p = 0.01). In a subsample analysis, a negative relationship was also found between maternal PCP levels and cord fT(4) concentrations in neonates (beta = -0.59, p = 0.02). No association was observed between contaminants and thyroid hormones at 7 months of age.
  
  
  CONCLUSIONS
  Overall, there is little evidence that the environmental contaminants analyzed in this study affect thyroid hormone status in Inuit mothers and their infants. The possibility that PCP may decrease thyroxine levels in neonates requires further investigation.
authors: Public Health Research Unit, Centre Hospitalier Universitaire de Québec-CHUL, Québec City, Québec, Canada.
authors: Renée
authors: R
authors: Dallaire
authors: Gina
authors: G
authors: Muckle
authors: Eric
authors: E
authors: Dewailly
authors: Sandra W
authors: SW
authors: Jacobson
authors: Joseph L
authors: JL
authors: Jacobson
authors: Torkjel M
authors: TM
authors: Sandanger
authors: Courtney D
authors: CD
authors: Sandau
authors: Pierre
authors: P
authors: Ayotte
mesh_terms: D000328:Adult; D004781:Environmental Exposure; D004785:Environmental Pollutants; D005260:Female; D006581:Hexachlorobenzene; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D004930:Inuit; D011078:Polychlorinated Biphenyls; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000097:blood; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D013963:Thyroid Hormones; D013975:Thyroxine-Binding Proteins; D014284:Triiodothyronine; D006581:Hexachlorobenzene; D013972:Thyrotropin; D011078:Polychlorinated Biphenyls; D013974:Thyroxine