The Dose-Response Relationships of Beta-Ray-Induced Skin Tumors in the Rat

Abstract

Single doses of beta radiation from Yttrium 91 sources were applied to 35 cm2 skin areas on the backs of young male rats. The resultant dose-tumor incidence curves were highly non-linear. There was a marked increase in tumor production at about 2000 r which corresponded to the dosage producing mild to moderate skin damage. A maximum tumor yield was observed at about 4000 r; the incidence declined at higher doses which were markedly pilocidal. There was little dose dependence in the appearance time of tumors in contrast to the magnitude of tumor incidence. Epidermoid carcinonas predominated at the higher doses and adnexal tumors were most common in the mid-dose range. The frequency distribution of tumors in individual rats suggested that the presence of some tumors in the irradiated skin does not markedly affect the formation of others.