Biokinetics of inhaled 239PuO2 in the Beagle dog: effect of aerosol particle size

Young adult Beagle dogs received single brief inhalation exposures to one of three monodisperse aerosols of 239PuO2 (0.72, 1.4 or 2.8 μm) activity median aerodynamic diameter (AMAD). Results indicate long term retention of a substantial percentage of the intitial pulmonary burden (IPB), and that the retention was affected by particle size. The percentage of the initial pulmonary lung burden retained in the long term component and its effective half time (TAUsub(E)) were 90% with TAUsub(E) = 680 days for the 0.72 m AMAD aerosol, 68% with TAUsub(E) = 1400 days for the 1.4 μm AMAD aerosol and 82% with TAUsub(E) = 1800 days for the 2.8 μm AMAD aerosol. The major route of elimination from lung was via the faeces, but significant amounts were also translocated to thoracic lymph nodes (approx. 15% IPB by 2 years). Small amounts were translocated to liver (0.2% IPB) and skeleton (0.1% IPB) by 2 years after exposure. The average γ-radiation dose to the lung was projected to be twice as large for the 2.8 μm AMAD group as for the 0.72 μm AMAD group at 10 years after exposure. (U.K.)