Bone cancer occurrence among beagles given 239Pu as young adults.

The occurrence of skeletal malignancies has been documented among 234 young adult beagles given single intravenous injections of monomeric 239Pu citrate. Occurrence has also been documented among 132 comparable control group animals surviving the minimum latent time period of 2.79 y for radiation-induced bone cancer, who were maintained for lifespan observation. Injected amounts ranged from about 0.02-106 kBq kg-1 body mass with factors of 2 or 3 between dose levels. There were 84 radiographically apparent bone tumors in 76 plutonium-injected dogs and one tumor in a control group dog. Most of these were osteosarcomas except for seven chondrosarcomas, one liposarcoma, and one plasma cell myeloma of bone. The relationship between percent of dogs at any dose level with bone malignancy and average skeletal dose at the presumed time of tumor initiation of 1 y before death appeared to be linear below about 1.3 Gy average skeletal dose. The observed data can be approximated by the expression A = 0.76 + 75 D, where A = percent of dogs with bone cancer at any dose level, D = average skeletal dose in Gy (for doses up to 1.3 Gy) at tumor initiation, and 0.76 represents the percent tumor response in the control animals not given plutonium. Similar analysis of our corresponding data for beagles given 226Ra, excluding the two highest dose levels (approximately 100% occurrence), yielded the expression A = 0.76 + 4.7 D, where D = the average skeletal dose in Gy (for doses up to 20 Gy) at 1 y before death. The ratio of coefficients indicates the effectiveness for bone cancer induction of 239Pu relative to 226Ra, or [(75 +/- 22.5)(4.7 +/- 0.47)-1] = 16 +/- 5 for a single, brief intake of either nuclide into blood.