Case Application of
Time-Dependent Dissolution Data
into Inhalation Intake Evaluations
Using ICRP 66 Lung Model

William M. Findley and Thomas R. La Bone

Westinghouse Savannah River Company,

Seven workers at the Savannah River Site were exposed to airborne weapons-grade plutonium in September 1999 with resultant small systemic intakes. Post incident bioassay indicated an insoluble form of plutonium that behaved quite differently than predicted using the inhalation classes and lung model defined in Publication 30 of the International Commission on Radiological Protection (ICRP), consequently the intakes were evaluated using the ICRP 66 lung model and ICRP 67 systemic model. One of the major advances of the ICRP 66 lung model is the allowance for the incorporation of time dependent dissolution data into the model. This data is important since respiratory tract clearance rates determine not only doses to tissues in the respiratory tract itself, but also doses resulting from deposition in other organs following systemic intake. This data can be essential in accurately assigning the magnitude of the intake and the resultant dose, especially for insoluble materials. An air sampling filter paper from the event was packaged and sent to Lovelace Respiratory Research Institute for laboratory analysis of the dissolution properties of the contaminants. Results from the analysis will be presented and compared to the solubility assumptions selected for the preliminary evaluations.

*This paper was prepared in connection with work done under Contract Number DE-AC09-96SR18500 with the United States Department of Energy.