Neutron carcinogenesis in mice: a study of the dose-response curves

Several experimental studies have been conducted with the objective to improve our knowledge of the types of dose-response relationships for radiation carcinogenesis in mice exposed to single acute doses. The experimental results on tumor induction have already been published and are here summarized with emphasis on the dependence on radiation quality, age at irradiation, and sex. These data indicate that the bone marrow, liver, and ovaries of the mice tested have an appreciable susceptibility to radiation carcinogenesis. However, the shape of the dose-response relationship depends on the tissue exposed. The data also confirm that a linear relationship is adequate for a conservative description of the dose-effect curves after exposure to low dose of neutrons, while a purely quadratic dependence is not inconsistent with the experimental data obtained using low-LET radiation. Other information which stems from the present analysis is that the susceptibility to radiation induction of liver tumor by fission neutrons decreases in old age. Finally, the experimental data on induction of ovarian tumors suggest a threshold-like dose response.