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Tissue distribution of dioxin-like compounds: potential impacts on systemic relative potency estimates
Karin I van Ede1, Lesa L Aylward, Patrik L Andersson
1Institute for Risk Assessment Sciences, Utrecht University, Yalelaan 104, 3584 CM Utrecht, The Netherlands. k.i.vanede@uu.nl
Toxicology Letters
|May 18, 2013
Summary
Relative effect potencies (REPs) for dioxins are crucial for human risk assessment. Using extra-hepatic concentrations, like in blood or adipose tissue, offers a more accurate prediction of dioxin potency in humans compared to liver-based estimates.
Area of Science:
- Environmental Chemistry
- Toxicology
- Risk Assessment
Background:
- Relative effect potencies (REPs) are vital for assessing risks of dioxins and related compounds.
- Previous studies calculated (systemic)REPs based on tissue or internal doses.
Purpose of the Study:
- To calculate (systemic)REPs for specific dioxins and dioxin-like compounds.
- To compare congener distribution patterns between rodent models and humans.
- To evaluate the influence of hepatic sequestration on human risk assessment.
Main Methods:
- Calculated (systemic)REPs using plasma, adipose tissue, or liver concentrations in rats and mice after a single oral dose.
- Analyzed compound-specific distribution, accumulation, and elimination patterns.
- Compared rodent distribution data with human population data.
Main Results:
- Distribution patterns for tested congeners were similar across studies and dosing regimens.
- TCDD responding concentrations in single-dose studies aligned with subchronic studies.
- Human distribution data showed minimal hepatic sequestration compared to rodents.
Conclusions:
- Hepatic sequestration in rodents may mislead human risk assessment due to differences in bioavailability and CYP1A2 binding.
- Extra-hepatic concentrations (blood serum/plasma, adipose tissue) provide more accurate human risk predictions.
- Extra-hepatic responses are recommended for more reliable relative potency estimations in humans.
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