title: Effect of environmental perchlorate on thyroid function in pregnant women from Córdoba, Argentina, and Los Angeles, California.
abstract: OBJECTIVE
  To determine whether environmental perchlorate exposure adversely affects thyroid function in women in the first trimester of pregnancy.
  
  
  METHODS
  First-trimester pregnant women were recruited from prenatal clinics in the Los Angeles County Hospital, Los Angeles, California, and in the Hospital Universitario de Maternidad dependent Universidad Nacional de Córdoba, Córdoba, Argentina, between 2004 and 2007. Spot urine and blood specimens were obtained during the clinic visit. Urinary perchlorate, iodine, and creatinine were measured, and thyroid function tests were performed.
  
  
  RESULTS
  The study included 134 pregnant women from Los Angeles, California (mean gestational age ± SD = 9.1 ± 2.2 weeks), and 107 pregnant women from Córdoba, Argentina (mean gestational age = 10.0 ± 2.0 weeks). Median urinary iodine values were 144 μg/L in California and 130 μg/L in Argentina. Urinary perchlorate levels were detectable in all women (California: median, 7.8 μg/L [range, 0.4-284 μg/L] and Argentina: median, 13.5 μg/L [range, 1.1-676 μg/L]). Serum thyroperoxidase antibodies were detectable in 21 women from California (16%) and in 17 women from Argentina (16%). Using Spearman rank correlation analyses, there was no association between urinary perchlorate concentrations and serum thyrotropin, free thyroxine index, or total triiodothyronine values, including within the subset of women with urinary iodine values less than 100 μg/L. In multivariate analyses using the combined Argentina and California data sets and adjusting for urinary iodine concentrations, urinary creatinine, gestational age, and thyroperoxidase antibody status, urinary perchlorate was not a significant predictor of thyroid function.
  
  
  CONCLUSIONS
  Low-level perchlorate exposure is ubiquitous, but is not associated with altered thyroid function among women in the first trimester of pregnancy.
authors.affiliation: University School of Medicine, Boston, MA, USA. elizabeth.pearce@bmc.org
authors.forename: Elizabeth N
authors.initials: EN
authors.lastname: Pearce
authors.forename: Carole A
authors.initials: CA
authors.lastname: Spencer
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Mestman
authors.forename: Richard H
authors.initials: RH
authors.lastname: Lee
authors.forename: Liliana M
authors.initials: LM
authors.lastname: Bergoglio
authors.forename: Paula
authors.initials: P
authors.lastname: Mereshian
authors.forename: Xuemei
authors.initials: X
authors.lastname: He
authors.forename: Angela M
authors.initials: AM
authors.lastname: Leung
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Braverman
mesh_terms: D001118:Argentina / Q000453:epidemiology; D002140:California / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D007455:Iodine / Q000652:urine; D015141:Los Angeles / Q000453:epidemiology; D010472:Perchlorates / Q000009:adverse effects* / Q000494:pharmacology / Q000652:urine; D011247:Pregnancy; D011248:Pregnancy Complications / Q000139:chemically induced / Q000453:epidemiology; D011261:Pregnancy Trimester, First / Q000097:blood / Q000187:drug effects; D037841:Pregnant People; D013959:Thyroid Diseases / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology / Q000652:urine; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000009:adverse effects / Q000494:pharmacology
chemical_list: D010472:Perchlorates; D014874:Water Pollutants, Chemical; D007455:Iodine; C494474:perchlorate