title: Time trends of persistent organic pollutants in Sweden during 1993-2007 and relation to age, gender, body mass index, breast-feeding and parity.
abstract: BACKGROUND
  Persistent organic pollutants (POPs) are lipophilic chemicals that bioaccumulate. Most of them were resticted or banned in the 1970s and 1980s to protect human health and the environment. The main source for humans is dietary intake of dairy products, meat and fish. Little data exist on changes of the concentration of POPs in the Swedish population over time.
  
  
  OBJECTIVE
  To study if the concentrations of polychlorinated biphenyls (PCBs), DDE, hexachlorobenzene (HCB) and chlordanes have changed in the Swedish population during 1993-2007, and certain factors that may influence the concentrations.
  
  
  METHODS
  During 1993-2007 samples from 537 controls in different human cancer studies were collected and analysed. Background information such as body mass index, breast-feeding and parity was assessed by questionaires. Wilcoxon rank-sum test was used to analyse the explanatory factors specimen (blood or adipose tissue), gender, BMI, total breast-feeding and parity in relation to POPs. Time trends for POPs were analysed using linear regression analysis, adjusted for specimen, gender, BMI and age.
  
  
  RESULTS
  The concentration decreased for all POPs during 1993-2007. The annual change was statistically significant for the sum of PCBs -7.2%, HCB -8.8%, DDE -13.5% and the sum of chlordanes -10.3%. BMI and age were determinants of the concentrations. Cumulative breast-feeding >8 months gave statistically significantly lower concentrations for the sum of PCBs, DDE and the sum of chlordanes. Parity with >2 children yielded statistically significantly lower sum of PCBs.
  
  
  CONCLUSIONS
  All the studied POPs decreased during the time period, probably due to restrictions of their use.
authors.affiliation: Department of Oncology, University Hospital, SE-701 85 Orebro, Sweden. elin.hardell@orebroll.se
authors.forename: Elin
authors.initials: E
authors.lastname: Hardell
authors.forename: Michael
authors.initials: M
authors.lastname: Carlberg
authors.forename: Marie
authors.initials: M
authors.lastname: Nordström
authors.forename: Bert
authors.initials: B
authors.lastname: van Bavel
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001942:Breast Feeding / Q000706:statistics & numerical data; D002706:Chlordan / Q000097:blood / Q000378:metabolism*; D003710:Demography; D003633:Dichlorodiphenyl Dichloroethylene / Q000097:blood / Q000378:metabolism*; D004781:Environmental Exposure / Q000032:analysis / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000097:blood / Q000378:metabolism*; D004787:Environmental Pollution / Q000706:statistics & numerical data; D005260:Female; D006581:Hexachlorobenzene / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010298:Parity; D011078:Polychlorinated Biphenyls / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D012737:Sex Factors; D013548:Sweden; D013995:Time; D055815:Young Adult
chemical_list: D004785:Environmental Pollutants; D002706:Chlordan; D003633:Dichlorodiphenyl Dichloroethylene; D006581:Hexachlorobenzene; D011078:Polychlorinated Biphenyls