Aerosol deposition modeling using ACSL

An aerosol deposition model has been written for inclusion into physiologically based pharmacokinetic (PBPK) models, allowing PBPK model based risk assessments to be performed for aerosolized materials. Previously, PBPK models could only treat inhaled gases and vapors. The deposition model employs a semi-empirical equation to describe extrathoracic deposition and employs data concerning the geometry of the thoracic conducting airways as well as that of the gas exchange regions of the lung to compute the deposited aerosol mass based on aerosol diffusion, sedimentation, and impaction. Provisions are made to allow calculations for polydisperse aerosols whose size distribution and mass vary with time. Variations in the model subject's respiration can be accommodated through selection of respiratory parameters at model startup as well as through consideration of carbon dioxide stimulation of respiration. The model is compared with other similar calculations and experimental data to validate the calculations. An example model application is presented in the form of a comparison of two inhalation atmospheres, one from an inhalation toxicity study and one from a similar atmosphere produced for fire extinguishing agent testing.