title: Exposure to free and conjugated forms of bisphenol A and triclosan among pregnant women in the MIREC cohort.
abstract: BACKGROUND
  Bisphenol A (BPA) and triclosan (TCS) are two nonpersistent chemicals that have been frequently measured in spot urine samples from the general population but less so in pregnant women; however, data are limited on the free (bioactive) and conjugated forms of these phenols.
  
  
  OBJECTIVE
  The Maternal-Infant Research on Environmental Chemicals (MIREC) Study addressed these data gaps by utilizing stored maternal urine samples from a large multicenter cohort study of Canadian pregnant women.
  
  
  METHODS
  Concentrations of free and conjugated forms of BPA and TCS were measured in about 1,890 first-trimester urine samples by ultra performance liquid chromatography-tandem mass spectrometry using isotope dilution.
  
  
  RESULTS
  The glucuronides of BPA and TCS were the predominant forms of these chemicals measured (detected in 95% and 99% of samples, respectively), whereas the free forms were detected in 43% and 80% of samples, respectively. The geometric mean urinary concentrations for glucuronides of BPA and TCS were 0.80 μg/L (95% CI: 0.75, 0.85) and 12.30 μg/L (95% CI: 11.08, 13.65), respectively. Significant predictors of BPA included maternal age < 25 vs. ≥ 35 years, current smoking, low vs. high household income, and low vs. high education. For TCS, urinary concentrations were significantly higher in women ≥ 25 years of age, never vs. current smokers, and women with high household income and high education.
  
  
  CONCLUSIONS
  The results from this study represent the largest national-level data on urinary concentrations of free and conjugated forms of BPA and TCS in pregnant women and suggest that maternal characteristics predicting elevated urinary concentrations of these phenols largely act in opposite directions.
authors.affiliation: Population Studies Division, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada.
authors.forename: Tye E
authors.initials: TE
authors.lastname: Arbuckle
authors.forename: Leonora
authors.initials: L
authors.lastname: Marro
authors.forename: Karelyn
authors.initials: K
authors.lastname: Davis
authors.forename: Mandy
authors.initials: M
authors.lastname: Fisher
authors.forename: Pierre
authors.initials: P
authors.lastname: Ayotte
authors.forename: Patrick
authors.initials: P
authors.lastname: Bélanger
authors.forename: Pierre
authors.initials: P
authors.lastname: Dumas
authors.forename: Alain
authors.initials: A
authors.lastname: LeBlanc
authors.forename: René
authors.initials: R
authors.lastname: Bérubé
authors.forename: Éric
authors.initials: É
authors.lastname: Gaudreau
authors.forename: Gilles
authors.initials: G
authors.lastname: Provencher
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Faustman
authors.forename: Eric
authors.initials: E
authors.lastname: Vigoren
authors.forename: Adrienne S
authors.initials: AS
authors.lastname: Ettinger
authors.forename: Michael
authors.initials: M
authors.lastname: Dellarco
authors.forename: Susan
authors.initials: S
authors.lastname: MacPherson
authors.forename: William D
authors.initials: WD
authors.lastname: Fraser
mesh_terms: D000328:Adult; D000367:Age Factors; D001559:Benzhydryl Compounds / Q000633:toxicity / Q000652:urine*; D015331:Cohort Studies; D004785:Environmental Pollutants / Q000633:toxicity / Q000652:urine*; D005260:Female; D020719:Glucuronides / Q000652:urine; D006801:Humans; D018811:Maternal Exposure; D010636:Phenols / Q000633:toxicity / Q000652:urine*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012907:Smoking; D012959:Socioeconomic Factors; D014260:Triclosan / Q000633:toxicity / Q000652:urine*; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D004785:Environmental Pollutants; D020719:Glucuronides; D010636:Phenols; D014260:Triclosan; C006780:bisphenol A; D000098826:Bisphenol A Compounds