title: Validation of questionnaire-based long-term dietary exposure to polychlorinated biphenyls using biomarkers.
abstract: METHODS
  The health consequences of lifelong low-level exposure to polychlorinated biphenyls (PCBs) via food are largely unknown, mainly due to the lack of large population-based prospective studies addressing this issue. We validated long-term food frequency questionnaire (FFQ)-based dietary PCB exposure against concentrations of six PCB congeners in serum.
  
  
  RESULTS
  Dietary PCB exposure was estimated in the Swedish Mammography Cohort by constructing a recipe-based database of CB-153, an indicator for total PCBs in food. The Spearman rank correlation (adjusted for within-person variability) was assessed between concurrent (2004-2006), past (1997), and long-term (mean of 1997 and 2004-2006) FFQ-based dietary PCB exposure, respectively, and the following serum PCB congeners, CB-118, CB-138, CB-153, CB-156, CB-170, and CB-180, in women (56-85 years of age, n = 201). The correlation between FFQ-based dietary PCB exposure and serum CB-153 was 0.41 (p < 0.001) for the concurrent (median 1.6 ng/kg body weight) and 0.34 (p < 0.05) for the past (median 2.6 ng/kg body weight) exposure assessment. Long-term validity of FFQ-based PCB estimates and the six serum PCB congeners ranged from 0.30 to 0.58 (p < 0.05).
  
  
  CONCLUSIONS
  FFQ-based PCB exposure estimates show acceptable validity in relation to PCB concentrations in serum, justifying their use in large-scale epidemiological studies.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Bergkvist
authors.forename: Agneta
authors.initials: A
authors.lastname: Akesson
authors.forename: Anders
authors.initials: A
authors.lastname: Glynn
authors.forename: Karl
authors.initials: K
authors.lastname: Michaëlsson
authors.forename: Panu
authors.initials: P
authors.lastname: Rantakokko
authors.forename: Hannu
authors.initials: H
authors.lastname: Kiviranta
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
authors.forename: Marika
authors.initials: M
authors.lastname: Berglund
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood*; D004032:Diet; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011078:Polychlorinated Biphenyls / Q000097:blood* / Q000633:toxicity*; D011795:Surveys and Questionnaires; D013548:Sweden
chemical_list: D015415:Biomarkers; D011078:Polychlorinated Biphenyls