Pathology of Multiple Intravenous Doses of Polonium

Abstract

The author has reviewed the literature on the pathology and hematology of single intravenous or oral doses of polonium-210 in other papers of the Supplement (1-3). The literature cited at this point in the present paper is concerned with effects of multiple intravenous doses of polonium-210. Data on the distribution and excretion of polonium and on the mortality, life span, and growth of rats in the present study have been reported by Stannard et al. in other papers of this Supplement (4,5). Spoerl and Anthony (6) have summarized the effects of multiple intravenous injections of polonium-210 observed in experiments performed at Mound Laboratory. These included an experiment in which rats were injected with polonium at a dosage level of 2 ,uc/kg of body weight every 2 weeks for a total of ten injections, and an experiment in which rats were injected throughout life at 28-day intervals with doses of polonium (averaging 0.006 ,c/kg/mo) calculated to maintain an average body burden of 0.01 A,c/kg of body weight. The rats in the latter low-doselevel experiment were indistinguishable from their control rats in all examinations for histopathological changes. In comparison of rats injected with 2 auc/kg every 2 weeks with rats receiving single injections of doses of similar total magnitude, it was observed that the pathologic changes appeared earlier and were more marked in the multiple-dose animals, and also involved marked damage of the liver, which was not markedly affected in single-dose experiments. The present experiment on rats was performed to study effects of maintained body burdens of polonium-210 over a dosage or body burden range between a level expected, on the basis of previous experience, to cause little or no effect and a level expected to cause marked damage.