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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

PBDE uptake rates of different age groups in 2005 derived from both the top-down approach with different elimination half-lives and the bottom-up approach. Note the different scale on the y-axis for infants 0–3 months of age.
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f3: PBDE uptake rates of different age groups in 2005 derived from both the top-down approach with different elimination half-lives and the bottom-up approach. Note the different scale on the y-axis for infants 0–3 months of age.

Mentions: Bootstrapping. To preserve the empirical variability in the biomonitoring data, we ran the optimization process 100 times with 100 different biomonitoring data subsets for each PBDE congener and each elimination half-life (scenarios A, B, and C; Table 1). Each subset was bootstrapped (step 7 in Figure 1) from the full set of biomonitoring data; we randomly selected 1 pool per age group and survey (throughout the five surveys, the number of pools per age group varied from 2 to 9). Each subset consisted of 29 pools (five age groups from survey 2002–2003; six age groups from the other surveys). The variability in body concentrations originating from the 100 simulations is shown as shaded areas for the female population in Figure 2. The 100 simulations resulted in 100 optimized uptake rates; the average uptake rates for each age group for the year 2005 are shown in Figure 3. We refer to the uptake rates from the model fit as “top-down” uptake rates.


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)

PBDE uptake rates of different age groups in 2005 derived from both the top-down approach with different elimination half-lives and the bottom-up approach. Note the different scale on the y-axis for infants 0–3 months of age.
© Copyright Policy - public-domain
Related In: Results  -  Collection

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

f3: PBDE uptake rates of different age groups in 2005 derived from both the top-down approach with different elimination half-lives and the bottom-up approach. Note the different scale on the y-axis for infants 0–3 months of age.
Mentions: Bootstrapping. To preserve the empirical variability in the biomonitoring data, we ran the optimization process 100 times with 100 different biomonitoring data subsets for each PBDE congener and each elimination half-life (scenarios A, B, and C; Table 1). Each subset was bootstrapped (step 7 in Figure 1) from the full set of biomonitoring data; we randomly selected 1 pool per age group and survey (throughout the five surveys, the number of pools per age group varied from 2 to 9). Each subset consisted of 29 pools (five age groups from survey 2002–2003; six age groups from the other surveys). The variability in body concentrations originating from the 100 simulations is shown as shaded areas for the female population in Figure 2. The 100 simulations resulted in 100 optimized uptake rates; the average uptake rates for each age group for the year 2005 are shown in Figure 3. We refer to the uptake rates from the model fit as “top-down” uptake rates.

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