The spatial and temporal distribution of inhaled UO2 particles in the respiratory tract of the rat. I. Pulmonary tissue.

An analysis is described of the mass distribution of inhaled UO2 particles in the pulmonary tissue of rats by random sampling of fields in autoradiographs of histological sections. The degree of nonrandomness is compared between fields, between sections, and between lobes and interpreted in terms of the physical distribution of UO2. The error in the estimate of the mean number of charged-particle tracks from UO2 per field in the pulmonary tissue by selective tissue sampling is related to the degree of nonrandomness of the UO2 distribution. Estimates of this error in the lungs from nine animals range from 5.2 to 8.4%. When estimating this error, it is concluded that, in the case of the rat, sections should be taken at intervals of 3 mm or less throughout the lobes.