Respiratory tract deposition of inhaled polydisperse aerosols in beagle dogs

Abstract

Respiratory tract deposition patterns were measured in 5 Beagle dogs following inhalation of 140La-labeled aerosols ranging in size distribution from 0·42 to 6·6 μm activity median aerodynamic diameter (AMAD). Each dog was exposed to a series of aerosols within the above particle size range, and respiratory tract deposition patterns were assessed by radioactivity profile scanning for several days following inhalation. The aerosols were polydisperse with particle sizes which were satisfactorily described by log-normal distributions with geometric standard deviations ranging from 1·3 to 2·8. The fractions of the inhaled aerosols deposited in the nasopharyngeal, tracheobronchial and pulmonary regions of the respiratory tract were found similar to calculated deposition fractions for humans using deposition fractions for single particle sizes from the Task Group on Lung Dynamics. The results indicate that the Beagle dog represents a satisfactory biological model for man in inhalation toxicity studies, especially with regard to the initial dose distribution.