CARCINOGENESIS BY IONIZING RADIATIONS 



1159 



Experimental studies on the carcinogenicity of radioisotopes obtained 

 from fission products were begun by investigators of the Manhattan 

 Project. The following observations were made by Lisco et at. (1947): 

 Tumors of the colon followed ingestion of an insoluble Y 91 compound by 



Fig. 18-5. X-ray picture of the pelvis of a dial painter with primary osteosarcoma of 

 the pubic bone (after Martland, 1931). 



Fig. 18-6. Radiation osteitis. In the bone marrow, areas of hyperplasia alternate 

 with areas of fibrosis. There is an increased osteoblastic activity (after Martland 1931). 



rats. When Y 91 was injected subcutaneously into mice as phosphate, 

 epidermoid carcinoma and fibrosarcoma were induced. When yttrium 

 phosphate was injected as a suspension intravenously, it induced osteo- 

 genic sarcoma in the long bones of rats. Plutonium as nitrate or citrate 

 injected subcutaneously into mice induced fibrosarcoma at the site of 

 injection and osteogenic tumors in distant bones. When plutonium was 



