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THE INDOOR FUGACITY MODEL
Citation:
Bennett, D. H. AND E J. Furtaw Jr. THE INDOOR FUGACITY MODEL. Presented at Society of Environmental Toxicology and Chemistry 2001 Annual Meeting, Baltimore, MD, November 11-15, 2001.
Impact/Purpose:
Research will be conducted to develop and apply integrated microenvironmental, and physiologically-based pharmacokinetic (PBPK) exposure-dose models and methods (that account for all media, routes, pathways and endpoints). Specific efforts will focus on the following areas:
1) Develop the Exposure Related Dose Estimating Model (ERDEM) System.
Includes: Updating the subsystems and compartments of the ERDEM models with those features needed for modeling chemicals of interest to risk assessors;
Designing and implementing the graphical user interface for added features.
Refining the exposure interface to handle various sources of exposure information;
Providing tools for post processing as well as for uncertainty and variability analyses;
Research on numerical and symbolic mathematical/statistical solution methods and computational algorithms/software for deterministic and stochastic systems analysis.
2) Apply ERDEM and other quantitative models to understand pharmacokinetics (PK) and significantly reduce the uncertainty in the dosimetry of specific compounds of regulatory interest.
Examples of the applications are:
exposure of children to pesticides
study design
route-to-route extrapolation
species extrapolation
experimental data analysis
relationship between parametric uncertainty and the distribution of model results
validity of scaling methods within species
validity of scaling methods from one species to another species
reduction of uncertainty factors for risk assessment
Description:
Dermal and non-dietary pathways are potentially significant exposure pathways to pesticides used in the home. The exposure pathways include dermal contact through the hands and skin, ingestion from hand to mouth activities, ingestion through contact with toys and other items, and absorption of pesticides into food. A limited amount of data has been collected on pesticide concentrations in the home following an application; however, a model is needed that can predict concentrations of other pesticides based on their chemical properties. A model based on fugacity principles is presented in this talk. The compartments included in the mass balance are the air (both gas phase and aerosols), carpet, smooth flooring, and walls. The concentrations on furniture and toys, and in food, are also considered as these are possible exposure media. The fugacity capacity and transfer rate coefficients between compartments are calculated and used in a dynamic mass-balance model. The concentrations predicted by the model are compared to measured concentrations found in homes following an application.
This work has been funded in part by the United States Environmental Protection Agency under Interagency Agreement No. DW-89938190 with Lawrence Berkeley National Laboratory. It has been subjected to Agency review and approved for publication.