Reproductive toxicity in birds predicted by physiologically-based kinetics and bioenergetics modelling.

Area of Science:

• Ecotoxicology
• Environmental Risk Assessment (ERA)
• Computational Toxicology

Background:

• Pesticide effects on avian reproduction are critical for environmental risk assessment (ERA).
• Dynamic energy budget-toxicokinetic-toxicodynamic (DEB-TKTD) models offer mechanistic predictions for ERA.
• Case studies are needed to validate DEB-TKTD models for avian risk assessment.

Purpose of the Study:

• To model the effects of benzamide, a fluopyram metabolite, on northern bobwhite quail (Colinus virginianus).
• To demonstrate the application of DEB-TKTD models in avian reproductive toxicity assessment.
• To integrate exposure modeling with toxicodynamic modeling for improved ERA predictions.

Main Methods:

• Parametrization of a DEB-TKTD model using an egg injection study for northern bobwhite quail embryos.
• Development of a physiologically-based toxicokinetic (PBK) model to predict internal egg exposure from dietary intake.
• Integration of DEB-TKTD and PBK models to predict effects on hatchling and chick weight.

Main Results:

• Model calibration indicated benzamide uptake via yolk and stress on energy assimilation/mobilization.
• The combined DEB-TKTD and PBK models accurately predicted observed weight reductions in chicks.
• Different TKTD assumptions required specific endpoint data (survival, growth, yolk utilization) for model discrimination.

Conclusions:

• DEB-TKTD models, supported by experimental data and exposure models, can reliably predict pesticide impacts on bird reproduction.
• This approach enhances the utility of mechanistic models in avian environmental risk assessment.
• The study provides a validated framework for using DEB-TKTD models in avian ERA.