title: Investigation of the associations between low-dose serum perfluorinated chemicals and liver enzymes in US adults.
abstract: OBJECTIVE
  Perfluorinated chemicals (PFCs) have been largely used for years in a variety of products worldwide. However, the toxic effect of PFCs on exposure to the liver in the general population has not yet been determined.
  
  
  METHODS
  In this study, 2,216 adults (18 years of age or older) were recruited in a National Health and Nutrition Examination Survey (NHANES) in 1999-2000 and 2003-2004 to determine the relationship between serum level of PFCs and the levels of liver enzymes. The data were adjusted for all other confounding variants.
  
  
  RESULTS
  After performing mathematical analysis, we determined when serum log-perfluorooctanoic acid (PFOA) increases in one unit, the serum alanine aminotransferase (ALT) concentration (U/l) increases by 1.86 units (95% confidence interval (CI), 1.24-2.48; P=0.005), and the serum log-gamma-glutamyltransferase (GGT) concentration (U/l) is 0.08 unit higher (95% CI, 0.05-0.11; P=0.019). The association between PFOA and liver enzymes was more evident in obese subjects, as well as subjects with insulin resistance and/or metabolic syndromes. When dividing the serum PFOA into quartiles in the fully adjusted models in subjects with a body mass index>or=30 kg/m2, the ALT level trend across the serum PFOA quartiles was significant (P=0.003).
  
  
  CONCLUSIONS
  On the basis of these data, we conclude that a higher serum concentration of PFOA may cause liver enzymes to increase abnormally in the general population, particularly in obese individuals. Further studies are warranted to clarify the casual relationship between PFCs and these liver enzymes.
authors.affiliation: Department of Internal Medicine, En Chu Kong Hospital, Taipei County, Taiwan, and Institute of Occupational Medicine and Industrial Hygiene, National Taiwan University College of Public Health, Taipei, Taiwan.
authors.forename: Chien-Yu
authors.initials: CY
authors.lastname: Lin
authors.forename: Lian-Yu
authors.initials: LY
authors.lastname: Lin
authors.forename: Chih-Kang
authors.initials: CK
authors.lastname: Chiang
authors.forename: Wei-Jie
authors.initials: WJ
authors.lastname: Wang
authors.forename: Yi-Ning
authors.initials: YN
authors.lastname: Su
authors.forename: Kuan-Yu
authors.initials: KY
authors.lastname: Hung
authors.forename: Pau-Chung
authors.initials: PC
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000410:Alanine Transaminase / Q000097:blood; D002210:Caprylates / Q000009:adverse effects*; D056486:Chemical and Drug Induced Liver Injury / Q000097:blood / Q000201:enzymology*; D004781:Environmental Exposure; D004785:Environmental Pollutants; D005260:Female; D005466:Fluorocarbons / Q000009:adverse effects*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008099:Liver / Q000201:enzymology; D008297:Male; D024821:Metabolic Syndrome / Q000201:enzymology; D008875:Middle Aged; D009765:Obesity / Q000201:enzymology; D014481:United States; D055815:Young Adult; D005723:gamma-Glutamyltransferase / Q000097:blood
chemical_list: D002210:Caprylates; D004785:Environmental Pollutants; D005466:Fluorocarbons; C023036:perfluorooctanoic acid; D005723:gamma-Glutamyltransferase; D000410:Alanine Transaminase