Review of Pu-239 and Ra-226 effects in beagles

A long term biological study has been completed that was designed to assess the predicted effects in humans of internally deposited Pu-239 by comparis on with Ra-226 in beagles Herein we summarize for the first time results of several previous reports about the effects of these two radionuclides in o ur beagles in an attempt to elucidate what has been learned since the begin ning of the study in the early 1950's. Perhaps the most important finding w as that bone surface-seeking plutonium is more toxic at equal mean skeletal radiation doses (<3 Gy for Pu-239, < 20 Gy for Ra-226) than bone volume-se eking radium for the induction of skeletal malignancy by about a factor of 16 for a single intravenous injection of monomeric Pu-239. In addition, anc illary studies have shown that when plutonium transfers continuously onto b one surfaces from a depot of particulate Pu-239 in phagocytic cells, its re lative toxicity per Gy average skeletal dose is enhanced by about a factor of 2. juvenile animals or dogs injected as mature adults were only about ha lf as sensitive for equal mean skeletal doses as dogs injected as young adu lts. Male and female dogs were about equally sensitive to radiation of the skeleton by either radionuclide. Findings about radiation-induced fractures are summarized as well as data on the induction of soft-tissue malignancie s by Pu-239 or Ra-226. Natural survival was not affected at the lower dosag e levels of either Ra-226 Or Pu-239 as compared with control dogs given no radioactivity, but the survival of animals at higher levels was reduced. No additional life-shortening effects beyond those attributable to occurrence of radiation-induced malignancies or other radiation-induced effects were suggested by analysis of data for low dosage levels.