title: Isomer profiles of perfluorochemicals in matched maternal, cord, and house dust samples: manufacturing sources and transplacental transfer.
abstract: BACKGROUND
  Perfluorochemicals (PFCs) are detectable in the general population and in the human environment, including house dust. Sources are not well characterized, but isomer patterns should enable differentiation of historical and contemporary manufacturing sources. Isomer-specific maternal-fetal transfer of PFCs has not been examined despite known developmental toxicity of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in rodents.
  
  
  OBJECTIVE
  We elucidated relative contributions of electrochemical (phased out in 2001) and telomer (contemporary) PFCs in dust and measured how transplacental transfer efficiency (TTE; based on a comparison of maternal and cord sera concentrations) is affected by perfluorinated chain length and isomer branching pattern.
  
  
  METHODS
  We analyzed matching samples of house dust (n = 18), maternal sera (n = 20), and umbilical cord sera (n = 20) by isomer-specific high-performance liquid chromatography tandem mass spectrometry.
  
  
  RESULTS
  PFOA isomer signatures revealed that telomer sources accounted for 0-95% of total PFOA in house dust (median, 31%). This may partly explain why serum PFOA concentrations are not declining in some countries despite the phase-out of electrochemical PFOA. TTE data indicate that total branched isomers crossed the placenta more efficiently than did linear isomers for both PFOS (p < 0.01) and PFOA (p = 0.02) and that placental transfer of branched isomers of PFOS increased as the branching point moved closer to the sulfonate (SO3-) end of the molecule.
  
  
  CONCLUSIONS
  Results suggest that humans are exposed to telomer PFOA, but larger studies that also account for dietary sources should be conducted. The exposure profile of PFOS and PFOA isomers can differ between the mother and fetus-an important consideration for perinatal epidemiology studies of PFCs.
authors.affiliation: Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Beesoon
authors.forename: Glenys M
authors.initials: GM
authors.lastname: Webster
authors.forename: Mahiba
authors.initials: M
authors.lastname: Shoeib
authors.forename: Tom
authors.initials: T
authors.lastname: Harner
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Benskin
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Martin
mesh_terms: D017738:Alkanesulfonic Acids / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D002210:Caprylates / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004391:Dust / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D004785:Environmental Pollutants / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D005260:Female; D005312:Fetal Blood / Q000737:chemistry* / Q000187:drug effects; D005466:Fluorocarbons / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D006801:Humans; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D053719:Tandem Mass Spectrometry
chemical_list: D017738:Alkanesulfonic Acids; D002210:Caprylates; D004391:Dust; D004785:Environmental Pollutants; D005466:Fluorocarbons; C023036:perfluorooctanoic acid; C076994:perfluorooctane sulfonic acid