Host: The Japan Radiation Research Society
Co-host: City of Kitakyushu, University of Occupational and Environmental Health, Japan
The Janus Program at Argonne National Laboratory involved a large-scale mouse study of 49,000 animals exposed to a variety of doses of neutrons and gamma-rays administered at a range of dose rates. The database for these tissues is available at www.janus.northwestern.edu and tissues from the study are also available. In this work, a retrospective statistical analysis of data obtained from the Janus Program on cancerous and non-cancerous diseases of irradiated B6CF1 mice was performed in order to assess the effects of low-dose chronic radiation, with 2-40 cGy of Janus reactor fission neutrons or 100-600 cGy of gamma rays, given in 60 fractions. We specifically assessed: (1) the difference of individual tissue toxicities due to each radiation dose; (2) the effect of gender on a tissue toxicity within a given dose; (3) the effect of neutron and gamma ray irradiations at doses with presumably similar relative biological effectiveness (RBE); we did this by comparing risk for individual toxicities and toxicity incidence rate ratios for organ systems; (4) the incidence rate ratio of organ system failure due to each radiation dose; and (5) the relationship between multiple organ systems failure, radiation type, and radiation dose. The results from our per-toxicity analyses support previous findings that radiation increases the overall incidence of both neoplastic and non-neoplastic tissue toxicities, however the data also suggest that the effects of radiation are tissue-type specific. Additionally, our data also showed that gender has a role in the response to radiation. When analyzing the toxicities grouped as affecting whole organ systems, the data provided useful information supporting the theoretical model of linear no-threshold effect for neutron irradiation, and the concept of adaptive for gamma ray and neutron irradiation.
