title: Insights into PBDE Uptake, Body Burden, and Elimination Gained from Australian Age-Concentration Trends Observed Shortly after Peak Exposure.
abstract: BACKGROUND
  Population pharmacokinetic models combined with multiple sets of age-concentration biomonitoring data facilitate back-calculation of chemical uptake rates from biomonitoring data.
  
  
  OBJECTIVE
  We back-calculated uptake rates of PBDEs for the Australian population from multiple biomonitoring surveys (top-down) and compared them with uptake rates calculated from dietary intake estimates of PBDEs and PBDE concentrations in dust (bottom-up).
  
  
  METHODS
  Using three sets of PBDE elimination half-lives, we applied a population pharmacokinetic model to the PBDE biomonitoring data measured between 2002-2003 and 2010-2011 to derive the top-down uptake rates of four key PBDE congeners and six age groups. For the bottom-up approach, we used PBDE concentrations measured around 2005.
  
  
  RESULTS
  Top-down uptake rates of Σ4BDE (the sum of BDEs 47, 99, 100, and 153) varied from 7.9 to 19 ng/kg/day for toddlers and from 1.2 to 3.0 ng/kg/day for adults; in most cases, they were--for all age groups--higher than the bottom-up uptake rates. The discrepancy was largest for toddlers with factors up to 7-15 depending on the congener. Despite different elimination half-lives of the four congeners, the age-concentration trends showed no increase in concentration with age and were similar for all congeners.
  
  
  CONCLUSIONS
  In the bottom-up approach, PBDE uptake is underestimated; currently known pathways are not sufficient to explain measured PBDE concentrations, especially in young children. Although PBDE exposure of toddlers has declined in the past years, pre- and postnatal exposure to PBDEs has remained almost constant because the mothers' PBDE body burden has not yet decreased substantially.
authors.affiliation: Safety and Environmental Technology Group, Swiss Federal Institute of Technology Zurich (ETH Zurich), Zurich, Switzerland.
authors.forename: Tenzing
authors.initials: T
authors.lastname: Gyalpo
authors.forename: Leisa-Maree
authors.initials: LM
authors.lastname: Toms
authors.forename: Jochen F
authors.initials: JF
authors.lastname: Mueller
authors.forename: Fiona A
authors.initials: FA
authors.lastname: Harden
authors.forename: Martin
authors.initials: M
authors.lastname: Scheringer
authors.forename: Konrad
authors.initials: K
authors.lastname: Hungerbühler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000378:metabolism / Q000493:pharmacokinetics; D001315:Australia; D001822:Body Burden; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004391:Dust / Q000032:analysis*; D004781:Environmental Exposure; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000378:metabolism* / Q000493:pharmacokinetics; D005260:Female; D005506:Food Contamination / Q000032:analysis*; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism / Q000493:pharmacokinetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D004391:Dust; D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers