Total and regional lung retention of monodisperse cobalt compound aerosols after a single inhalation.

After a single short term inhalation of monodisperse cobalt compound aerosols with preselected physical and chemical parameters the long term retention in beagle dogs is determined measuring their radioactive Co-57 label by a gamma camera. Additionally the major clearance pathways are estimated by excretion analyses. The biological variability of the lung retention is small but it depends clearly on the physiochemical properties of the inhaled aerosol particles. The predominant clearance mechanism in the lung is a moderate dissolution process depending on the specific surface area of the particles. So cobalt oxide particles with an adjustable solubility in the lung can be used for studies of distinct dissolution processes in the lung. Using a gamma camera the dynamics of particle accumulation in the tracheobronchial lymph nodes and the subsequent clearance are analysed on single dogs.