title: Direct measurement of Bisphenol A (BPA), BPA glucuronide and BPA sulfate in a diverse and low-income population of pregnant women reveals high exposure, with potential implications for previous exposure estimates: a cross-sectional study.
abstract: BACKGROUND
  Bisphenol A (BPA) is a ubiquitous, endocrine-disrupting environmental contaminant that increases risk of some adverse developmental effects. Thus, it is important to characterize BPA levels, metabolic fate and sources of exposure in pregnant women.
  
  
  METHODS
  We used an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytic method to directly and simultaneously measure unconjugated BPA (uBPA), BPA glucuronide and BPA sulfate in the urine of a population of ethnically and racially diverse, and predominately low-income pregnant women (n = 112) in their second trimester. We also administered a questionnaire on dietary and non-dietary sources of exposure to BPA.
  
  
  RESULTS
  We found universal and high exposure to uBPA and its metabolites: median concentrations were 0.25, 4.67, and 0.31 μg/g creatinine for uBPA, BPA glucuronide, and BPA sulfate, respectively. The median Total BPA (uBPA + BPA in glucuronide and sulfate forms) level was more than twice that measured in U.S. pregnant women in NHANES 2005-2006, while 30 % of the women had Total BPA levels above the 95th percentile. On average, Total BPA consisted of 71 % BPA in glucuronide form, 15 % BPA in sulfate form and 14 % uBPA, however the proportion of BPA in sulfate form increased and the proportion of uBPA decreased with Total BPA levels. Occupational and non-occupational contact with paper receipts was positively associated with BPA in conjugated (glucuronidated + sulfated) form after adjustment for demographic characteristics. Recent consumption of foods and beverages likely to be contaminated with BPA was infrequent among participants and we did not observe any positive associations with BPA analyte levels.
  
  
  CONCLUSIONS
  The high levels of BPA analytes found in our study population may be attributable to the low-income status of the majority of participants and/or our direct analytic method, which yields a more complete evaluation of BPA exposure. We observed near-universal exposure to BPA among pregnant women, as well as substantial variability in BPA metabolic clearance, raising additional concerns for effects on fetal development. Our results are consistent with studies showing thermal paper receipts to be an important source of exposure, point to the difficulty pregnant women have avoiding BPA exposure on an individual level, and therefore underscore the need for changes in BPA regulation and commerce.
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA.
authors.forename: Roy R
authors.initials: RR
authors.lastname: Gerona
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA.
authors.forename: Janet
authors.initials: J
authors.lastname: Pan
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA.|Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, 950 New Hampshire Avenue NW, Suite 414, Washington, DC, 20052, USA.
authors.forename: Ami R
authors.initials: AR
authors.lastname: Zota
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA.
authors.forename: Jackie M
authors.initials: JM
authors.lastname: Schwartz
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Friesen
authors.affiliation: Division of Biological Sciences, University of Missouri-Columbia, 114 Lefevre Hall, Columbia, MO, 65211, USA.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Taylor
authors.affiliation: School of Molecular Biosciences and Center for Reproductive Biology, Washington State University, PO Box 647521, Pullman, WA, 99164-7521, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Hunt
authors.affiliation: Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, Mailstop 0132, 550 16th Street, 7th Floor, San Francisco, CA, 94143, USA. tracey.woodruff@ucsf.edu.
authors.forename: Tracey J
authors.initials: TJ
authors.lastname: Woodruff
mesh_terms: D000293:Adolescent; D000328:Adult; D001559:Benzhydryl Compounds / Q000652:urine*; D003430:Cross-Sectional Studies; D004032:Diet; D052244:Endocrine Disruptors / Q000652:urine*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D020719:Glucuronides / Q000652:urine*; D006801:Humans; D018811:Maternal Exposure; D008875:Middle Aged; D010636:Phenols / Q000652:urine*; D011203:Poverty; D011247:Pregnancy; D013431:Sulfates / Q000652:urine*; D011795:Surveys and Questionnaires; D055815:Young Adult; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D020719:Glucuronides; D010636:Phenols; D013431:Sulfates; C512161:bisphenol A glucuronide; D000098826:Bisphenol A Compounds; C006780:bisphenol A
keywords: Bisphenol A; Children’s environmental health; Exposure sources; Liquid chromatography-tandem mass spectrometry (LC-MS/MS); Pregnant women