Tumours of the skin and other delayed effects of external beta irradiation of mice using 90Sr and 32P.

Abstract

The histological type and incidence of skin tumors in mice were studied in mice after external beta irradiation from either a P32 or a Sr90 source. Almost one quarter of the animals exposed to Sr90 radiation died of late complications of acute damage to their skin and small intestine. To overcome variations in the amount of skin irradiated the incidence of tumors is expressed as the number per 100 cm2 of irradiated skin: Squamous-cell carcinomas increased from none in the controls to just under 0.1 per 100 cm2 in irradiated animals. Fibrosarcomas increased from 0.04 per 100 cm2 in control mice to 2.0 per 100 cm2 after doses of 3000 rads and above, i.e., the incidence increased 50 times. Tumor incidence was not correlated with the severity of residual radiation damage of the skin and was about the same in both strains of mice used and in males and females. Radiation induced fibrosarcomas occurred earlier than those occurring in the control animals. Some of the human implications of the data are briefly discussed.