title: Association of thyroid hormone concentrations with levels of organochlorine compounds in cord blood of neonates.
abstract: BACKGROUND
  Thyroid hormones are important regulators of brain development. During critical periods of development, even transient disorders in thyroid hormone availability may lead to profound neurologic impairment. Animal experiments have shown that certain environmental pollutants, including heavy metals and organochlorine compounds such as polychlorinated biphenyls (PCBs) and dioxins, can interfere with thyroid hormone homeostasis. Whether these contaminants can affect circulating levels of thyroid hormones in humans is unclear, however, because the results of available studies are inconsistent.
  
  
  OBJECTIVE
  The aim of the present study is to examine the possible relationships between concentrations of environmental pollutants and thyroid hormone levels in human umbilical cord blood.
  
  
  METHODS
  We measured concentrations of environmental pollutants [including selected PCBs, dioxin-like compounds, hexachlorobenzene, p,p'-DDE (dichlorodiphenyldichloroethylene), cadmium, lead] and thyroid hormones in the cord blood of 198 neonates.
  
  
  RESULTS
  A statistically significant inverse relationship between concentrations of organochlorine compounds and levels of both free triiodothyronine (fT3) and free thyroxine (fT4), but not thyroid-stimulating hormone, was observed. We found no association between concentrations of heavy metals and thyroid hormone levels.
  
  
  CONCLUSIONS
  Our results suggest that environmental chemicals may affect the thyroid system of human neonates. Although the differences in fT3 and fT4 levels associated with the organochlorine compounds were within the normal range, the observed interferences may still have detrimental effects on the neurologic development of the individual children, given the importance of thyroid hormones in brain development.
authors: Toxicological Centre, University of Antwerp, Wilrijk, Belgium. Johan.Maervoet@ua.ac.be
authors: Johan
authors: J
authors: Maervoet
authors: Griet
authors: G
authors: Vermeir
authors: Adrian
authors: A
authors: Covaci
authors: Nicolas
authors: N
authors: Van Larebeke
authors: Gudrun
authors: G
authors: Koppen
authors: Greet
authors: G
authors: Schoeters
authors: Vera
authors: V
authors: Nelen
authors: Willy
authors: W
authors: Baeyens
authors: Paul
authors: P
authors: Schepens
authors: Maria K
authors: MK
authors: Viaene
mesh_terms: D000328:Adult; D004785:Environmental Pollutants / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000097:blood*; D007231:Infant, Newborn; D011247:Pregnancy; D012044:Regression Analysis; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D004785:Environmental Pollutants; D006843:Hydrocarbons, Chlorinated; D013963:Thyroid Hormones