Incidence of Radiation-induced Skin Tumours in Mice and Variations with Dose Rate

Abstract

Mice were exposed to weakly penetrating beta-particles from an external source, using 12 different surface doses ranging from 5.4 to 260 Gy and given at four different dose rates from 200 to 1.7 cGy/min. As in previous investigations, both epidermal and dermal tumours occurred with the latter predominating. The lowest surface dose to produce a statistically significant increase in skin tumours was 21.7 Gy, no effect being detected with doses of 5.4-16.3 Gy. The dose-response curves rose steeply when obvious increases occurred. Consideration of these findings and the fact that radiation-induced skin tumours can have an exceptionally long latent period leads to the suggestion that there is some relatively radioresistant factor which normally restrains potential radiation-induced cancer cells in the skin from becoming tumours until the skin is subjected to high local doses. Tumour-induction was unaffected by reducing the highest dose rate by a factor of 10 and the dose-response curves were almost identical. Further reductions of dose rate, encompassing a further factor of 10, in general resulted in fewer tumours.

ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection

“…However, in the experiments of Coggle and Williams (1990), no reduction in effectiveness was found over a 1000-fold range of -radiation doses down to 0.1 Gy min À1 . In contrast, Hulse et al (1983) did find a reduction from a total of 30 tumours to five in comparable numbers of mice when the dose rate was reduced from 1.1-2.0 Gy min À1 to 0.017-0.024 Gy min À1 . Neither the dose rate nor the total dose was low in terms of radiological protection or carcinogenesis in the experiments of Hulse et al (1983) and Williams et al (1986).…”

“…In contrast, Hulse et al (1983) did find a reduction from a total of 30 tumours to five in comparable numbers of mice when the dose rate was reduced from 1.1-2.0 Gy min À1 to 0.017-0.024 Gy min À1 . Neither the dose rate nor the total dose was low in terms of radiological protection or carcinogenesis in the experiments of Hulse et al (1983) and Williams et al (1986). Thus, it is possible, as the experiments of Hulse et al (1983) suggested, that with very low dose rates, say 0.01 Gy day À1 , the reduction in effectiveness may be considerable.…”

“…Neither the dose rate nor the total dose was low in terms of radiological protection or carcinogenesis in the experiments of Hulse et al (1983) and Williams et al (1986). Thus, it is possible, as the experiments of Hulse et al (1983) suggested, that with very low dose rates, say 0.01 Gy day À1 , the reduction in effectiveness may be considerable.…”

“…Type of exposure and radiation quality (F30) Experimental results suggest that reduction in dose rate reduces the carcinogenic effect to some degree. The data of Hulse et al (1983) and Papworth and Hulse (1983) suggested an acute threshold of approximately 16 Gy for induction of epidermal tumours in rats. The resistance to the induction of SCC by protracted irradiation was well illustrated by the finding that 0.75 Gy given three times a week over their lifetime induced only a 3% incidence of SCC, whereas higher doses per fraction resulted in a 100% incidence.…”

Biokinetics of nuclear fuel compounds and biological effects of nonuniform radiation.

“…Albert et al (180) showed that the rat skin tumor yield after grid and sieve nonuniform radiation exposure was markedly delayed compared with uniform exposure. Hulse and colleagues (181)(182)(183) irradiated CBA mice with thallium-204 (204T1) particles using 12 different surface doses (5.4-260 Gy) and 4 different dose rates (1.7-200 cGy/min). The average latent period for tumor formation was 7 months, and more than 70% of the tumors were of dermal origin, 30% epidermal, and more than 60% were malignant.…”