Beta-ray induced skin tumor formation in mice

The summation theory of carcinogenic mechanism, proposed by Druckrey, was developed by Nakahara and Fukuoka into the summation theory of syncarcinogenic effects by chemical carcinogens in submanifestational dose. Submanifestational doses of 4-nitroquinoline 1-oxide and β-rays, applied in either order demonstrated the summation effect on skin tumor formation in mice. The findings suggest that the effects of these carcinogens are qualitatively equivalent in tumor formation. In 10 minutes irradiation groups, the rates of skin tumor formation of one-year interval group and 10-day interval group were 1/15 and 6/50 respectively. These data indicate that the syncarcinogenic effects of beta-irradiation persisted for one year. (auth.)