Reassessment of Human and Beagle Dog Pu Excretion Data Based on Reevaluation of Human Pu Excretion Data

Abstract

Abstract Experiments conducted in 1945–1946, by administering small amounts of Pu to humans, provided data for modeling short-term Pu excretion vs. retention. This experiment was justified on the basis that workers handling kilogram quantities of Pu at Los Alamos were showing positive amounts of Pu in their urine. Plutonium, like 226Ra, had been shown to produce bone tumors in animals. Because of possible latent bone-tumor risk caused by Pu deposited in bone, studies using beagle dogs were performed at the University of Utah in 1950. From this study, which paralleled the human Pu injection studies of 1945–1946, long-term animal excretion data were obtained. In order to compare long-term beagle excretion data with long-term human Pu excretion data, additional urine samples were collected in 1950 from two of the human subjects injected with 239Pu. A comparison of the beagle and human excretion data indicated that human Pu excretion was less than that of the dogs over a 5-y study period. In contrast to the single power function model developed to describe human excretion. the beagle Pu excretion data were modeled using a two-term power function model. A review of the human injection study data shows that urine bioassay results obtained from the two persons sampled in 1950 were subject to a bias because of chemical losses. Failure to recognize this source of error in the reported data resulted in the data being in error on the low side. This bias had a large influence on the development of the Langham one-term power function excretion model for Pu in urine. Identification of these assay errors provides evidence that human Pu excretion, following injection intake, is better described by a two-term power function model. This new information demonstrates that human retention is less than predicted by a single power function model and that human excretion data are more comparable to beagle excretion data for both short-term and long-term sampling periods. Based on the revised human excretion data, short-term and long-term Pu urine excretion models were developed and were presented.