title: Prenatal exposure to endocrine disrupting chemicals in relation to thyroid hormone levels in infants - a Dutch prospective cohort study.
abstract: BACKGROUND
  Endocrine disrupting chemicals (EDCs) present in the environment may disrupt thyroid hormones, which in early life are essential for brain development. Observational studies regarding this topic are still limited, however as the presence of chemicals in the environment is ubiquitous, further research is warranted. The objective of the current study was to assess the association between exposure markers of various EDCs and thyroxine (T4) levels in newborns in a mother-child cohort in the Netherlands.
  
  
  METHODS
  Exposure to dichlorodiphenyldichloroethylene (DDE), three di-2-ethylhexyl phthalate (DEHP) metabolites, hexachlorobenzene (HCB), polychlorinated biphenyl (PCB)-153, perfluorooctanesulfonic acid (PFOS), and perfluorooctanoic acid (PFOA) was determined in cord plasma or breast milk, and information on T4 levels in heel prick blood spots was obtained through the neonatal screening programme in the Netherlands. Linear regression models were composed to determine associations between each of the compounds and T4, which were stratified for gender and adjusted for a priori defined covariates.
  
  
  RESULTS
  Mean T4 level was 86.9 nmol/L (n = 83). Girls in the highest quartile of DDE and PFOA exposure showed an increased T4 level compared to the lowest quartile with both crude and fully adjusted models (DDE > 107.50 ng/L, +24.8 nmol/L, 95% CI 0.79, 48.75; PFOA > 1200 ng/L, +38.6 nmol/L, 95% CI 13.34, 63.83). In boys a lower T4 level was seen in the second quartile of exposure for both PFOS and PFOA, however after fully adjusting the models these associations were attenuated. No effects were observed for the other compounds.
  
  
  CONCLUSIONS
  DDE and perfluorinated alkyl acids may be associated with T4 in a sex-specific manner. These results should however be interpreted with caution, due to the relatively small study population. More research is warranted, as studies on the role of environmental contaminants in this area are still limited.
authors.affiliation: VU University, Section Health and Life Sciences, Faculty of Earth and Life Sciences, De Boelelaan 1085, 1081HV Amsterdam, The Netherlands. m.de.cock@vu.nl.
authors.forename: Marijke
authors.initials: M
authors.lastname: de Cock
authors.forename: Michiel R
authors.initials: MR
authors.lastname: de Boer
authors.forename: Marja
authors.initials: M
authors.lastname: Lamoree
authors.forename: Juliette
authors.initials: J
authors.lastname: Legler
authors.forename: Margot
authors.initials: M
authors.lastname: van de Bor
mesh_terms: D017738:Alkanesulfonic Acids / Q000032:analysis / Q000097:blood; D002210:Caprylates / Q000032:analysis / Q000097:blood; D052244:Endocrine Disruptors / Q000032:analysis* / Q000097:blood; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis* / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005466:Fluorocarbons / Q000032:analysis / Q000097:blood; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000032:analysis / Q000097:blood; D007231:Infant, Newborn; D008297:Male; D008431:Maternal-Fetal Exchange; D008895:Milk, Human / Q000737:chemistry; D009426:Netherlands / Q000453:epidemiology; D010795:Phthalic Acids / Q000032:analysis / Q000097:blood; D011247:Pregnancy; D011446:Prospective Studies; D013963:Thyroid Hormones / Q000097:blood*
chemical_list: D017738:Alkanesulfonic Acids; D002210:Caprylates; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D005466:Fluorocarbons; D006843:Hydrocarbons, Chlorinated; D010795:Phthalic Acids; D013963:Thyroid Hormones; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid