title: Accumulation and clearance of perfluorooctanoic acid (PFOA) in current and former residents of an exposed community.
abstract: BACKGROUND
  Perfluorooctanoic acid (PFOA) is a perfluoroalkyl acid found in > 99% of Americans. Its health effects are unknown. Prior estimates of serum half-life range from 2.3 to 3.8 years.
  
  
  OBJECTIVE
  We assessed the impact of years of residence and years since residing in the study area on serum PFOA concentration in a sample of current and former residents who were exposed to PFOA emissions from an industrial facility in six water districts in West Virginia and Ohio.
  
  
  METHODS
  Serum samples and questionnaires, including residential history, were collected in 2005-2006. We modeled log serum PFOA (nanograms per milliliter) for current residents as a function of years of residence in a water district, adjusted for a variety of factors. We modeled the half-life in former residents who lived in two water districts with high exposure levels using a two-segment log-linear spline.
  
  
  RESULTS
  We modeled serum PFOA concentration in 17,516 current residents as a function of years of residence (R2 = 0.68). Years of residence was significantly associated with PFOA concentration (1% increase in serum PFOA/year of residence), with significant heterogeneity by water district. Half-life was estimated in two water districts comprising a total of 1,573 individuals. For the participants included in our analyses, we found that years since residing in a water district was significantly associated with serum PFOA, which yielded half-lives of 2.9 and 8.5 years for water districts with higher and lower exposure levels, respectively.
  
  
  CONCLUSIONS
  Years of residence in an exposed water district is positively associated with observed serum PFOA in 2005-2006. Differences in serum clearance rate between low- and high-exposure water districts suggest a possible concentration-dependent or time-dependent clearance process or inadequate adjustment for background exposures.
authors.affiliation: Department of Environmental and Occupational Health, Emory University, Atlanta, Georgia, USA. rseals@hsph.harvard.edu
authors.forename: Ryan
authors.initials: R
authors.lastname: Seals
authors.forename: Scott M
authors.initials: SM
authors.lastname: Bartell
authors.forename: Kyle
authors.initials: K
authors.lastname: Steenland
mesh_terms: D000328:Adult; D000368:Aged; D002210:Caprylates / Q000032:analysis / Q000097:blood*; D004781:Environmental Exposure / Q000032:analysis* / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D005260:Female; D005466:Fluorocarbons / Q000032:analysis / Q000097:blood*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009820:Ohio; D012111:Residence Characteristics / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000097:blood*; D014881:Water Supply / Q000032:analysis; D014903:West Virginia; D055815:Young Adult
chemical_list: D002210:Caprylates; D005466:Fluorocarbons; D014874:Water Pollutants, Chemical; C023036:perfluorooctanoic acid