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Insights into PBDE Uptake, Body Burden, and Elimination Gained from Australian Age-Concentration Trends Observed Shortly after Peak Exposure.

Gyalpo T, Toms LM, Mueller JF, Harden FA, Scheringer M, Hungerbühler K - Environ. Health Perspect. (2015)

Bottom Line: 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).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.In the bottom-up approach, PBDE uptake is underestimated; currently known pathways are not sufficient to explain measured PBDE concentrations, especially in young children.

View Article: PubMed Central - PubMed

Affiliation: Safety and Environmental Technology Group, Swiss Federal Institute of Technology Zurich (ETH Zurich), Zurich, Switzerland.

ABSTRACT

Background: Population pharmacokinetic models combined with multiple sets of age-concentration biomonitoring data facilitate back-calculation of chemical uptake rates from biomonitoring data.

Objectives: 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.

No MeSH data available.


Related in: MedlinePlus

Overview of the approach employed in this work.
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f1: Overview of the approach employed in this work.

Mentions: Part 1. Top-down approach for uptake. The time-variant population PK model originally presented by Ritter et al. (2011) was applied (step 1 in Figure 1). All model equations are provided in the Supplemental Material (Equations S1–S4). Briefly, single individuals are represented as a single well-mixed lipid compartment that receives PBDEs via uptake and loses PBDEs via elimination (excretion and/or metabolism). The size of the lipid compartment varies as a function of age and reflects age-dependent changes in body weight and lipid fraction (Australian Bureau of Statistics 1998; International Commission on Radiological Protection 2002; World Health Organization 2006). The PK model calculates longitudinal concentrations of chemicals as a function of age for representative females and males born in 1-year intervals from 1921 until 2020. Uptake rates (step 2) are age and time dependent and represent the internal dose, (i.e., the amount of chemical that passes absorption barriers such as skin, lung tissue, and gastrointestinal tract wall), whereas the chemicals’ intrinsic elimination half-lives are age-independent (step 3). These two parameters define the longitudinal PBDE concentration profile in each individual.


Insights into PBDE Uptake, Body Burden, and Elimination Gained from Australian Age-Concentration Trends Observed Shortly after Peak Exposure.

Gyalpo T, Toms LM, Mueller JF, Harden FA, Scheringer M, Hungerbühler K - Environ. Health Perspect. (2015)

Overview of the approach employed in this work.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4590757&req=5

f1: Overview of the approach employed in this work.
Mentions: Part 1. Top-down approach for uptake. The time-variant population PK model originally presented by Ritter et al. (2011) was applied (step 1 in Figure 1). All model equations are provided in the Supplemental Material (Equations S1–S4). Briefly, single individuals are represented as a single well-mixed lipid compartment that receives PBDEs via uptake and loses PBDEs via elimination (excretion and/or metabolism). The size of the lipid compartment varies as a function of age and reflects age-dependent changes in body weight and lipid fraction (Australian Bureau of Statistics 1998; International Commission on Radiological Protection 2002; World Health Organization 2006). The PK model calculates longitudinal concentrations of chemicals as a function of age for representative females and males born in 1-year intervals from 1921 until 2020. Uptake rates (step 2) are age and time dependent and represent the internal dose, (i.e., the amount of chemical that passes absorption barriers such as skin, lung tissue, and gastrointestinal tract wall), whereas the chemicals’ intrinsic elimination half-lives are age-independent (step 3). These two parameters define the longitudinal PBDE concentration profile in each individual.

Bottom Line: 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).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.In the bottom-up approach, PBDE uptake is underestimated; currently known pathways are not sufficient to explain measured PBDE concentrations, especially in young children.

View Article: PubMed Central - PubMed

Affiliation: Safety and Environmental Technology Group, Swiss Federal Institute of Technology Zurich (ETH Zurich), Zurich, Switzerland.

ABSTRACT

Background: Population pharmacokinetic models combined with multiple sets of age-concentration biomonitoring data facilitate back-calculation of chemical uptake rates from biomonitoring data.

Objectives: 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.

No MeSH data available.


Related in: MedlinePlus