The Clearance of Uranium Dioxide Dust from the Lungs Following Single and Multiple Inhalation Exposures

Abstract

A study of uranium-238 dioxide and uranium-235 dioxide aerosols in dogs revealed that the clearance of the lungs differs markedly after single and multiple inhalation exposures, namely approximately 180 and 340 days for the respective biological half-times. In vivo counting of the 186-keV gamma rays was the basic measurement employed for both aerosols. Additional data were obtained by excreta and tissue analyses. Some difficulties with in vivo counting of animals subjected to prolonged uranium exposures are discussed, as well as a description of several possible mechanisms whereby the clearance of the pulmonary region might be influenced by the type and frequency of aerosol exposure.