Studies on the Metabolic Behaviour of Industrial Actinide-bearing Aerosols after Deposition in the Rat Lung: An Experimental Basis for Interpreting Chest Monitoring Data and Assessing Limits on Intake for Workers

The metabolism of ²³⁹Pu and ²⁴¹Am in 3 site-specific industrial dusts has been studied after their deposition in the rat lung. A comparative experiment has also been carried out with a mixture of these actinides inhaled as their nitrates. The aim of this study was to provide an experimental basis for assessing limits on intake and to establish whether the ²³⁹Pu content in the lungs could be interpolated from measurements of ²⁴¹Am. The results:

1 demonstrate the wide differences in the lung retention kinetics of the actinides and in the absolute and relative amounts translocated to the blood that can occur for industrially produced materials;

2 show that the annual limits on intake (ALIs) for the different materials vary between those postulated for class W and Y compounds by the International Commission on Radiological Protection;

3 indicate that acute intakes of ²³⁹Pu equivalent to the ALI can, depending on the nature of the dust, be estimated from ²⁴¹Am chest monitoring data at times from a few days up to about 3 years after exposure.