title: Half-life of serum elimination of perfluorooctanesulfonate,perfluorohexanesulfonate, and perfluorooctanoate in retired fluorochemical production workers.
abstract: BACKGROUND
  The presence of perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHS), and perfluorooctanoate (PFOA) has been reported in humans and wildlife. Pharmacokinetic differences have been observed in laboratory animals.
  
  
  OBJECTIVE
  The purpose of this observational study was to estimate the elimination half-life of PFOS, PFHS, and PFOA from human serum.
  
  
  METHODS
  Twenty-six (24 male, 2 female) retired fluorochemical production workers, with no additional occupational exposure, had periodic blood samples collected over 5 years, with serum stored in plastic vials at -80 degrees C. At the end of the study, we used HPLC-mass spectrometry to analyze the samples, with quantification based on the ion ratios for PFOS and PFHS and the internal standard (18)O(2)-PFOS. For PFOA, quantitation was based on the internal standard (13)C(2)-PFOA.
  
  
  RESULTS
  THE ARITHMETIC MEAN INITIAL SERUM CONCENTRATIONS WERE AS FOLLOWS: PFOS, 799 ng/mL (range, 145-3,490); PFHS, 290 ng/mL (range, 16-1,295); and PFOA, 691 ng/mL (range, 72-5,100). For each of the 26 subjects, the elimination appeared linear on a semi-log plot of concentration versus time; therefore, we used a first-order model for estimation. The arithmetic and geometric mean half-lives of serum elimination, respectively, were 5.4 years [95% confidence interval (CI), 3.9-6.9] and 4.8 years (95% CI, 4.0-5.8) for PFOS; 8.5 years (95% CI, 6.4-10.6) and 7.3 years (95% CI, 5.8-9.2) for PFHS; and 3.8 years (95% CI, 3.1-4.4) and 3.5 years (95% CI, 3.0-4.1) for PFOA.
  
  
  CONCLUSIONS
  Based on these data, humans appear to have a long half-life of serum elimination of PFOS, PFHS, and PFOA. Differences in species-specific pharmacokinetics may be due, in part, to a saturable renal resorption process.
authors.affiliation: Medical Department, 3M Company, St. Paul, Minnesota 55144, USA. gwolsen@mmm.com
authors.forename: Geary W
authors.initials: GW
authors.lastname: Olsen
authors.forename: Jean M
authors.initials: JM
authors.lastname: Burris
authors.forename: David J
authors.initials: DJ
authors.lastname: Ehresman
authors.forename: John W
authors.initials: JW
authors.lastname: Froehlich
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Seacat
authors.forename: John L
authors.initials: JL
authors.lastname: Butenhoff
authors.forename: Larry R
authors.initials: LR
authors.lastname: Zobel
mesh_terms: D000368:Aged; D017738:Alkanesulfonic Acids / Q000097:blood*; D002210:Caprylates / Q000097:blood*; D002617:Chemical Industry; D005260:Female; D005466:Fluorocarbons / Q000097:blood*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D012179:Retirement; D013451:Sulfonic Acids / Q000097:blood*