The mobility of curium-244 dioxide in the bronchially intubated rat

The mobility of curium dioxide in the rat after pulmonary intubation was investigated by administering suspensions containing different particle size ranges of the oxide. A major factor influencing the movement of curium from lungs to blood was the formation of hydroxide or hydrous oxide particles about 0.001 μm in diameter. This process was sufficiently rapid for the lung clearance kinetics of the dioxide to resemble those of a soluble compound more closely than those of an insoluble one. Filtration of 0.001 μm particles through the kidneys resulted in considerably enhanced excretion of curium relative to administered curium citrate. It was concluded that current metabolic models, which assume that solubility in the lung is a prerequisite for transport in body fluids, do not adequately describe the behaviour of curium from the standpoint of radiological protection. (author)