Two studies of acute internal exposure to man involving cerium and tantalum radioisotopes.

Abstract

Abstract Actual exposures of humans to internal radioactive contamination provide our most valuable data in determining the behavior of these substances in man. Two recent exposures at the National Reactor Testing Station demonstrate the markedly different behavior that can result from inhalation of insoluble particulates. In one incident, an individual received a body burden of 36 μCi of 141Ce, 27 μCi of 144Ce and 13.5 μCi of 95Zr-95Nb. Over 99.7% of his total body burden was eliminated in only 4 days, all of which was through the gastrointestinal tract with a total dose of about 10.3 rems to the lower large intestine. In the other incident, an individual received a body burden of 30 μCi of 182Ta and 150 μCi of 183Ta. Approximately 93% of the activity was eliminated in 7 days, the elimination being entirely in the feces. The remaining activity decreased at a rate not statistically different than the 115-day radiological half life of 182Ta, resulting in a dose of 13 rems to the lungs. The actual biological elimination could be detected only on large samples of feces and amounted to less than 0.05%/day. The major contaminants were not detected in 24-hr urines in either incident.