Fragmentation of inhaled 238PuO2 particles in lung.

Beagle dogs were exposed by inhalation to monodisperse aerosols of 238PuO2. Autoradiographs of lung sections were studied for nine dogs sacrificed from 4 to 730 days after exposure. Fragmentation of particles in lung was observed autoradiographically. A simple mathematical model fitted to the fragmentation and lung retention data for dogs suggests that lung clearance from intact particles (65%) and particle fragments (32%) were important to the removal of 238PuO2 deposited in the lung by inhalation. The increased surface area resulting from fragmentation should increase dissolution and risk to other organs from irradiation by translocated plutonium.