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Physiologically Based Pharmacokinetic Modeling in Risk Assessment: Case Study With Pyrethroids
Pankajini Mallick1, Gina Song1, Alina Y Efremenko1
1ScitoVation, LLC, Durham, North Carolina 27713.
Children show lower or equal internal exposure to pyrethroid insecticides than adults. Physiologically based pharmacokinetic (PBPK) modeling confirms no additional safety factor is needed for age-related differences in risk assessment.
Area of Science:
- Environmental Health
- Toxicology
- Pharmacokinetics
Background:
- Assessing risks to sensitive populations is crucial in risk assessment.
- Age-related sensitivity to pyrethroid insecticides is a key concern.
Purpose of the Study:
- To predict age-dependent changes in target tissue exposure to eight pyrethroids.
- To calculate a Data-derived Extrapolation Factor (DDEF) for age-related pharmacokinetic differences in humans.
Main Methods:
- Developed a generic human physiologically based pharmacokinetic (PBPK) model for pyrethroids.
- Utilized in vitro to in vivo extrapolation and life-stage modeling.
- Modeled exposure to eight different pyrethroids.
Main Results:
- Age-related differences in brain exposure to pyrethroids are primarily due to metabolic capacity and physiological variations between children and adults.
- Internal pyrethroid concentrations in children are equal to or lower than in adults for identical external exposures.
- Data-derived Extrapolation Factor (DDEF) values were close to 1 for all eight pyrethroids.
Conclusions:
- No additional adjustment factor is required for age-related pharmacokinetic differences in pyrethroid risk assessment.
- The study provides a robust framework for evaluating age-specific pesticide exposure.
- Findings support current risk assessment protocols for pyrethroids regarding pediatric populations.
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