Overview and analysis of internal radiation dose estimates in experimental animals in a framework of international studies of the sprayed neutron-induced (56)Mn radioactive microparticles effects

The aim of overview is to present the pooled data of published internal dose estimates and the results of corresponding analysis of internal irradiation features of experimental mice and rats after exposure to sprayed neutron activated radioactive (56)MnO(2). These dose estimates were conducted in a framework of multicenter international study to investigate biological effects as a result of exposure to sprayed radioactive (56)MnO(2) microparticles. Radionuclide (56)Mn (T(1/2) = 2.58 h) is one of the main gamma-beta emitters during the first hours after neutron activation of soil following nuclear explosion. It was concluded that there are three groups of organs of mice and rats, the radiation doses of which differ by approximately an order of magnitude: the group with the highest radiation doses (large and small intestine, stomach, skin and lungs), the group with lowered radiation doses (eyes, esophagus, trachea), the group with the lowest radiation doses (liver, heart, kidneys). The radiation doses to organs are proportional to the activity of the sprayed radioactive powder. The distribution of internal radiation doses among organs of experimental mice of different strains but of the same age was practically the same in case of exposure to the same activity of sprayed (56)MnO(2) powder. Doses of internal irradiation of experimental mice substantially exceed the doses of internal irradiation of experimental rats exposed to the same activities of the sprayed (56)MnO(2) powder. The data presented in the overview can be helpful for further investigation and for interpretation of the biological effects of this type of irradiation.