title: Persistent organic pollutants in Norwegian men from 1979 to 2007: intraindividual changes, age-period-cohort effects, and model predictions.
abstract: BACKGROUND
  Longitudinal monitoring studies of persistent organic pollutants (POPs) in human populations are important to better understand changes with time and age, and for future predictions.
  
  
  OBJECTIVE
  We sought to describe serum POP time trends on an individual level, investigate age-period-cohort effects, and compare predicted polychlorinated biphenyl (PCB) concentrations to measured values.
  
  
  METHODS
  Serum was sampled in 1979, 1986, 1994, 2001, and 2007 from a cohort of 53 men in Northern Norway and analyzed for 41 POPs. Time period, age, and birth cohort effects were assessed by graphical analyses and mixed-effect models. We derived the predicted concentrations of four PCBs for each sampling year using the CoZMoMAN model.
  
  
  RESULTS
  The median decreases in summed serum POP concentrations (lipid-adjusted) in 1986, 1994, 2001, and 2007 relative to 1979 were -22%, -52%, -54%, and -68%, respectively. We observed substantial declines in all POP groups with the exception of chlordanes. Time period (reflected by sampling year) was the strongest descriptor of changes in PCB-153 concentrations. Predicted PCB-153 concentrations were consistent with measured concentrations in the study population.
  
  
  CONCLUSIONS
  Our results suggest substantial intraindividual declines in serum concentrations of legacy POPs from 1979 to 2007 in men from Northern Norway. These changes are consistent with reduced environmental exposure during these 30 years and highlight the relation between historic emissions and POP concentrations measured in humans. Observed data and interpretations are supported by estimates from the CoZMoMAN emission-based model. A longitudinal decrease in concentrations with age was evident for all birth cohorts. Overall, our findings support the relevance of age-period-cohort effects to human biomonitoring of environmental contaminants.
authors.affiliation: Department of Community Medicine, University of Tromsø, Tromsø, Norway.
authors.forename: Therese Haugdahl
authors.initials: TH
authors.lastname: Nøst
authors.forename: Knut
authors.initials: K
authors.lastname: Breivik
authors.forename: Ole-Martin
authors.initials: OM
authors.lastname: Fuskevåg
authors.forename: Evert
authors.initials: E
authors.lastname: Nieboer
authors.forename: Jon Øyvind
authors.initials: JØ
authors.lastname: Odland
authors.forename: Torkjel Manning
authors.initials: TM
authors.lastname: Sandanger
mesh_terms: D000367:Age Factors; D015988:Cohort Effect; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000097:blood*; D008401:Gas Chromatography-Mass Spectrometry; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D009664:Norway / Q000453:epidemiology; D011078:Polychlorinated Biphenyls / Q000097:blood; D052616:Solid Phase Extraction; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls; C014024:2,4,5,2',4',5'-hexachlorobiphenyl