The experiment was performed in support of a Japanese initiative to investigate the biological effects of irradiation from residual neutron-activated radioactivity that resulted from the A-bombing. Radionuclide ⁵⁶Mn (T_1/2 = 2.58 h) is one of the main neutron-activated emitters during the first hours after neutron activation of soil dust particles. In our previous studies (2016–2017) related to irradiation of male Wistar rats after dispersion of ⁵⁶MnO₂ powder, the internal doses in rats were found to be very inhomogeneous: distribution of doses among different organs ranged from 1.3 Gy in small intestine to less than 0.0015 Gy in some of the other organs. Internal doses in the lungs ranged from 0.03 to 0.1 Gy. The essential pathological changes were found in lung tissue of rats despite a low level of irradiation. In the present study, the dosimetry investigations were extended: internal doses in experimental mice and rats were estimated for various activity levels of dispersed neutron-activated ⁵⁶MnO₂ powder. The following findings were noted: (a) internal radiation doses in mice were several times higher in comparison with rats under similar conditions of exposure to ⁵⁶MnO₂ powder. (b) When 2.74 × 10⁸ Bq of ⁵⁶MnO₂ powder was dispersed over mice, doses of internal irradiation ranged from 0.81 to 4.5 Gy in the gastrointestinal tract (small intestine, stomach, large intestine), from 0.096 to 0.14 Gy in lungs, and doses in skin and eyes ranged from 0.29 to 0.42 Gy and from 0.12 to 0.16 Gy, respectively. Internal radiation doses in other organs of mice were much lower. (c) Internal radiation doses were significantly lower in organs of rats with the same activity of exposure to ⁵⁶MnO₂ powder (2.74 × 10⁸ Bq): 0.09, 0.17, 0.29, and 0.025 Gy in stomach, small intestine, large intestine, and lungs, respectively. (d) Doses of internal irradiation in organs of rats and mice were two to four times higher when they were exposed to 8.0 × 10⁸ Bq of ⁵⁶MnO₂ (in comparison with exposure to 2.74 × 10⁸ Bq of ⁵⁶MnO₂). (e) Internal radiation doses in organs of mice were 7–14 times lower with the lowest ⁵⁶MnO₂ amount (8.0 × 10⁷ Bq) in comparison with the highest amount, 8.0 × 10⁸ Bq, of dispersed ⁵⁶MnO₂ powder. The data obtained will be used for interpretation of biological effects in experimental mice and rats that result from dispersion of various levels of neutron-activated ⁵⁶MnO₂ powder, which is the subject of separate studies.

为了支持日本的一项倡议，进行了该实验，以研究A轰炸产生的残留中子活化放射性所产生的辐射的生物学效应。 中子活化土壤尘埃颗粒后的最初几个小时，放射性核素⁵⁶ Mn（T _1/2 = 2.58 h）是中子活化的主要辐射源之一。在我们之前的研究（2016-2017）中，与⁵⁶ MnO ₂分散后的雄性Wistar大鼠辐射有关老鼠体内的剂量非常不均匀：不同器官之间的剂量分布范围从小肠的1.3 Gy到其他一些器官的0.0015 Gy以下。肺内剂量范围为0.03至0.1 Gy。尽管辐射水平低，但在大鼠的肺组织中发现了基本的病理变化。在本研究中，剂量学研究得到了扩展：在实验小鼠和大鼠中的内部剂量针对分散的中子活化的⁵⁶ MnO ₂粉末的各种活性水平进行了估算。注意到以下发现：（a）在相似的⁵⁶ MnO ₂暴露条件下，小鼠的内部辐射剂量是大鼠的几倍。粉末。（b）当将2.74×10 ⁸  Bq的⁵⁶ MnO ₂粉末分散在小鼠身上时，胃肠道（小肠，胃，大肠）的内部照射剂量为0.81至4.5 Gy，肺部为0.096至0.14 Gy ，在皮肤和眼睛中的剂量分别为0.29至0.42 Gy和0.12至0.16 Gy。小鼠其他器官的内部辐射剂量要低得多。（c）在相同的暴露于⁵⁶ MnO ₂粉末活性的大鼠器官中，内部辐射剂量显着降低（2.74×10 ⁸ Bq）：分别在胃，小肠，大肠和肺中为0.09、0.17、0.29和0.025 Gy。（d）当暴露于8.0×10 ⁸  Bq的⁵⁶ MnO _2中时，大鼠和小鼠器官的内部辐射剂量要高出_2-4倍（与暴露于⁵⁶ MnO _2的2.74×10 ⁸  Bq相比）。（e）小鼠体内的内部辐射剂量 比分散的⁵⁶ MnO ₂ 的最高量8.0×10 ⁸ Bq低，而最低的⁵⁶ MnO ₂量（8.0×10 ⁷ Bq）低7-14倍。粉末。所获得的数据将用于解释由不同水平的中子活化的⁵⁶ MnO ₂粉末分散而产生的实验小鼠和大鼠的生物学效应，这是单独研究的主题。