Estimation of particle size distribution parameters in animal lungs

Abstract

A constant of specific solubility of 2·5 × 10 −8 g cm −2day −1 was determined for fused aluminosilicate particles, by observing in vivo retention kinetics after intravenous injection into rats. Studies over the past years in this laboratory, in which dogs and rats have inhaled labeled aerosols of these particles, have shown retention half-lives in the lung of 460 and 285 days, respectively. By applying these values for solubility and half-life to Mercer's theory of dissolution from the deep lung, the initial distribution of particles deposited in the pulmonary regions of dogs and rats following inhalation was calculated. From an inhaled aerosol with a mass median diameter, D m, of 1·0 μm and σ o = 1·7, a distribution described by D m = 0·51 μm and σ o's ranging from 1·16–1·48 was estimated to have been deposited in the Beagle dog lung. and a D m =< 0·32 μm and σ o's ranging from 1·18–1·29 was similarly calculated for rats.