Effect of Time Post-exposure on the Effectiveness of Bronchopulmonary Lavage in Removing Inhaled 144Ce in Fused Clay from Beagle Dogs

Abstract

The effectiveness of a single, unilateral bronchopulmonary lavage in removing relatively insoluble radioactive material from the lung was evaluated at various times after inhalation exposure to radioactive aerosol in dogs. Twenty-seven beagle dogs exposed to aerosols of 144Ce fused clay achieved initial lung burdens ranging from 23 to 73 pCi/kg body weight. The dogs were divided into nine groups of three dogs each and each group was given a single bronchopulmonary lavage of the right lung at one of the following times after exposure; 2 hr, 2,4,7, 14,28,56,128 and 196 days. Mean percentages of the right lung burden recovered in the lavage fluid were: 45, 25, 22, 19, 25, 12, 17, 14 and 17%, respectively. After the lung lavage, the dogs were sacrificed, dissected, and the tissues analyzed. At least 93 % ofthesacrifice body burden was found in the lungs out to 56 days after exposure. At 128 and 196 days after exposure, lung burdens were means of 88 and 81 % of the sacrifice body burden, respectively.The results indicate that a sizable percentage of the insoluble particles in the lung remains accessible to removal by bronchopulmonary lavage for periods up to 6 months after exposure; however, translocation from the lungs to other tissues increases with time. Also, depending on the isotope, the total radiation dose delivered to lung before lavage can become so large at longer times after exposure that removal of material from the lung has little effect in reducing total cumulative dose to tissues.

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4

“…Results were not analysed here, but there did not appear to be a marked difference in absorption from the lungs to blood between dogs exposed at 3 months of age (immature) or at 18 months of age (young adult), although, as expected, there was greater deposition in the skeleton of the immature dogs. Other studies investigated the effectiveness of lung lavage at reducing lung content and radiation effects (Boecker et al., 1974b; Felicetti et al., 1975). (171) Studies of the biokinetics of 144 Ce following inhalation of 144 Ce-FAP have also been conducted in mice.…”

Consensus Report: Mutagenicity and Carcinogenicity of Car Exhausts and Coal Combustion Emissions

“…This is a dynamic situation such that particles in macrophages may be recovered from the alveolar spaces by lavage even when several hundred days have elapsed between inhalation of the particles and lavage or washing of the lung (100). However, with deposition of large quantities, the clearance rate from the pulmonary compartment is considerably reduced.…”