title: The Northern Norway Mother-and-Child Contaminant Cohort (MISA) Study: PCA analyses of environmental contaminants in maternal sera and dietary intake in early pregnancy.
abstract: BACKGROUND
  Although predictors of contaminants in serum or whole blood are usually examined by chemical groups (e.g., POPs, toxic and/or essential elements; dietary sources), principal component analysis (PCA) permits consideration of both individual substances and combined variables.
  
  
  OBJECTIVE
  Our study had two primary objectives: (i) Characterize the sources and predictors of a suite of eight PCBs, four organochlorine (OC) pesticides, five essential and five toxic elements in serum and/or whole blood of pregnant women recruited as part of the Mother-and-Child Contaminant Cohort Study conducted in Northern Norway (The MISA study); and (ii) determine the influence of personal and social characteristics on both dietary and contaminant factors.
  
  
  METHODS
  Recruitment and sampling started in May 2007 and continued for the next 31 months until December 2009. Blood/serum samples were collected during the 2nd trimester (mean: 18.2 weeks, range 9.0-36.0). A validated questionnaire was administered to obtain personal information. The samples were analysed by established laboratories employing verified methods and reference standards. PCA involved Varimax rotation, and significant predictors (p≤0.05) in linear regression models were included in the multivariable linear regression analysis.
  
  
  RESULTS
  When considering all the contaminants, three prominent PCA axes stood out with prominent loadings of: all POPs; arsenic, selenium and mercury; and cadmium and lead. Respectively, in the multivariate models the following were predictors: maternal age, parity and consumption of freshwater fish and land-based wild animals; marine fish; cigarette smoking, dietary PCA axes reflecting consumption of grains and cereals, and food items involving hunting. PCA of only the POPs separated them into two axes that, in terms of recently published findings, could be understood to reflect longitudinal trends and their relative contributions to summed POPs.
  
  
  CONCLUSIONS
  The linear combinations of variables generated by PCA identified prominent dietary sources of OC groups and of prominent toxic elements and highlighted the importance of maternal characteristics.
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway. Electronic address: anna.sofia.veyhe@uit.no.
authors.forename: Anna Sofía
authors.initials: AS
authors.lastname: Veyhe
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway; Institute of Health and Society, University of Oslo, Norway.
authors.forename: Dag
authors.initials: D
authors.lastname: Hofoss
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway.
authors.forename: Solrunn
authors.initials: S
authors.lastname: Hansen
authors.affiliation: National Institute of Occupational Health (NIOH) , Oslo, Norway.
authors.forename: Yngvar
authors.initials: Y
authors.lastname: Thomassen
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway; Norwegian Institute for Air Research (NILU), Fram Centre, Tromsø, Norway.
authors.forename: Torkjel M
authors.initials: TM
authors.lastname: Sandanger
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway.
authors.forename: Jon Øyvind
authors.initials: JØ
authors.lastname: Odland
authors.affiliation: Department of Community Medicine, Faculty of Health Science, The Arctic University of Norway, Norway; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Evert
authors.initials: E
authors.lastname: Nieboer
mesh_terms: D000293:Adolescent; D000328:Adult; D001151:Arsenic / Q000097:blood; D002104:Cadmium; D015331:Cohort Studies; D004435:Eating; D004522:Educational Status; D004785:Environmental Pollutants / Q000097:blood*; D005260:Female; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000097:blood; D007854:Lead / Q000097:blood; D008423:Maternal Age; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D008628:Mercury / Q000097:blood; D015999:Multivariate Analysis; D009664:Norway; D010575:Pesticides / Q000097:blood; D011078:Polychlorinated Biphenyls / Q000097:blood; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000097:blood*; D025341:Principal Component Analysis; D017747:Seafood; D012643:Selenium / Q000097:blood; D012907:Smoking; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D002104:Cadmium; D007854:Lead; D011078:Polychlorinated Biphenyls; D008628:Mercury; D012643:Selenium; D001151:Arsenic
keywords: Food Frequency Questionnaire (FFQ); Persistent Organic Pollutants (POPs); Pregnant women; Principal Component Analysis (PCA); The Northern Norway Mother-and-Child Contaminant Cohort Study (MISA); Toxic and essential elements