title: Toxicokinetic modeling of persistent organic pollutant levels in blood from birth to 45 months of age in longitudinal birth cohort studies.
abstract: BACKGROUND
  Despite experimental evidence that lactational exposure to persistent organic pollutants (POPs) can impact health, results from epidemiologic studies are inconclusive. Inconsistency across studies may reflect the inability of current methods to estimate children's blood levels during specific periods of susceptibility.
  
  
  OBJECTIVE
  We developed a toxicokinetic model to simulate blood POP levels in children from two longitudinal birth cohorts and aimed to validate it against blood levels measured at 6, 16, and 45 months of age.
  
  
  METHODS
  The model consisted of a maternal and a child lipid compartment connected through placental diffusion and breastfeeding. Simulations were carried out based on individual physiologic parameters; duration of breastfeeding; and levels of POPs measured in maternal blood at delivery, cord blood, or breast milk. Model validity was assessed through regression analyses of simulated against measured blood levels.
  
  
  RESULTS
  Simulated levels explained between 10% and 83% of measured blood levels depending on the cohort, the compound, the sample used to simulate children's blood levels, and child's age when blood levels were measured. Model accuracy was highest for estimated blood POP levels at 6 months based on maternal or cord blood levels. However, loss in model precision between the 6th and the 45th month was small for most compounds.
  
  
  CONCLUSIONS
  Our validated toxicokinetic model can be used to estimate children's blood POP levels in early to mid-childhood. Estimates can be used in epidemiologic studies to evaluate the impact of exposure during hypothesized postnatal periods of susceptibility on health.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Solna, Sweden. marcandre.verner@channing.harvard.edu
authors.forename: Marc-André
authors.initials: MA
authors.lastname: Verner
authors.forename: Dean
authors.initials: D
authors.lastname: Sonneborn
authors.forename: Kinga
authors.initials: K
authors.lastname: Lancz
authors.forename: Gina
authors.initials: G
authors.lastname: Muckle
authors.forename: Pierre
authors.initials: P
authors.lastname: Ayotte
authors.forename: Éric
authors.initials: É
authors.lastname: Dewailly
authors.forename: Anton
authors.initials: A
authors.lastname: Kocan
authors.forename: Lubica
authors.initials: L
authors.lastname: Palkovicová
authors.forename: Tomas
authors.initials: T
authors.lastname: Trnovec
authors.forename: Sami
authors.initials: S
authors.lastname: Haddad
authors.forename: Irva
authors.initials: I
authors.lastname: Hertz-Picciotto
authors.forename: Merete
authors.initials: M
authors.lastname: Eggesbø
mesh_terms: D002675:Child, Preschool; D015331:Cohort Studies; D004785:Environmental Pollutants / Q000633:toxicity*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007774:Lactation; D008137:Longitudinal Studies; D008895:Milk, Human; D008962:Models, Theoretical
chemical_list: D004785:Environmental Pollutants