Half-Life of Serum Elimination of Perfluorooctanesulfonate, Perfluorohexanesulfonate, and Perfluorooctanoate in Retired Fluorochemical Production Workers Geary W. Olsen,1 Jean M. Burris,1 David J. Ehresman,1 John W. Froehlich,2,* Andrew M. Seacat,1,# John L. Butenhoff,1 and Larry R. Zobel1 1Medical Department, 3M Company, St. Paul, Minnesota, USA; 2Pace Analytical Laboratory, St. Paul, Minnesota, USA 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°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 18O2-PFOS. For PFOA, quantitation was based on the internal standard 13C2-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. Key words: biomonitoring, perfluoroalkyl acids, perfluorohexanesulfonate, perfluorooctanesulfonate, perfluorooctanoate, PFHS, PFOA, PFOS, pharmacokinetics. Environ Health Perspect 115:1298–1305 (2007) . doi:10.1289/ehp.10009 available via http://dx.doi.org/ [Online 12 June 2007] Address correspondence to G.W. Olsen, 3M Company, Medical Department, Mail Stop 220-6W-08, St. Paul, MN 55144 USA. Telephone (651) 737-8569. Fax (651) 733-9066. E-mail: gwolsen@mmm.com *Current address: Department of Chemistry, University of California at Davis, Davis, California, USA. #Current address: Amylin Pharmaceuticals, Inc., San Diego, California, USA. We acknowledge the dedicated participation of the subjects during the 5-year follow-up period. We thank D. Madsen, J. Mandel, J. Schumpert, C. Simpson, and K. Young for their assistance at various times during the study. During this study, all authors were employed by or under contract with the 3M Company, which produced the three polyfluoroalkyl acids and related products. Received 18 December 2006 ; accepted 12 May 2007. The full version of this article is available for free in HTML or PDF formats. |