title: Estimating Time-Varying PCB Exposures Using Person-Specific Predictions to Supplement Measured Values: A Comparison of Observed and Predicted Values in Two Cohorts of Norwegian Women.
abstract: BACKGROUND
  Studies on the health effects of polychlorinated biphenyls (PCBs) call for an understanding of past and present human exposure. Time-resolved mechanistic models may supplement information on concentrations in individuals obtained from measurements and/or statistical approaches if they can be shown to reproduce empirical data.
  
  
  OBJECTIVE
  Here, we evaluated the capability of one such mechanistic model to reproduce measured PCB concentrations in individual Norwegian women. We also assessed individual life-course concentrations.
  
  
  METHODS
  Concentrations of four PCB congeners in pregnant (n = 310, sampled in 2007-2009) and postmenopausal (n = 244, 2005) women were compared with person-specific predictions obtained using CoZMoMAN, an emission-based environmental fate and human food-chain bioaccumulation model. Person-specific predictions were also made using statistical regression models including dietary and lifestyle variables and concentrations.
  
  
  RESULTS
  CoZMoMAN accurately reproduced medians and ranges of measured concentrations in the two study groups. Furthermore, rank correlations between measurements and predictions from both CoZMoMAN and regression analyses were strong (Spearman's r > 0.67). Precision in quartile assignments from predictions was strong overall as evaluated by weighted Cohen's kappa (> 0.6). Simulations indicated large inter-individual differences in concentrations experienced in the past.
  
  
  CONCLUSIONS
  The mechanistic model reproduced all measurements of PCB concentrations within a factor of 10, and subject ranking and quartile assignments were overall largely consistent, although they were weak within each study group. Contamination histories for individuals predicted by CoZMoMAN revealed variation between study subjects, particularly in the timing of peak concentrations. Mechanistic models can provide individual PCB exposure metrics that could serve as valuable supplements to measurements.
authors.affiliation: Department of Community Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.
authors.forename: Therese Haugdahl
authors.initials: TH
authors.lastname: Nøst
authors.forename: Knut
authors.initials: K
authors.lastname: Breivik
authors.forename: Frank
authors.initials: F
authors.lastname: Wania
authors.forename: Charlotta
authors.initials: C
authors.lastname: Rylander
authors.forename: Jon Øyvind
authors.initials: JØ
authors.lastname: Odland
authors.forename: Torkjel Manning
authors.initials: TM
authors.lastname: Sandanger
mesh_terms: D000293:Adolescent; D000328:Adult; D004032:Diet; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D020387:Food Chain; D006801:Humans; D008875:Middle Aged; D015233:Models, Statistical; D009664:Norway / Q000453:epidemiology; D011078:Polychlorinated Biphenyls / Q000097:blood*; D017698:Postmenopause; D011247:Pregnancy; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls