The Center for Peace Hiroshima University, 730-0053, Hiroshima, Japan.
Hiroshima University, 739-8527, Japan.
J Radiat Res. 2022 Aug 13;63(Supplement_1):i38-i44. doi: 10.1093/jrr/rrac003.
At the detonation of the atomic bombing in Hiroshima and Nagasaki, a significant amount of radionuclides was produced by the neutron induced activation. The residual radiation from the explosion is crucial to the health risk of the people who entered these cities after the bombing and might have inhaled these radioactive materials. Because 56Mn is one of the major radionuclides produced in soil and have not been studied until now, we had conducted a series of experiments using rats to investigate the biological impacts of exposure of 56MnO2 particles. In these experiments, the rats' spontaneous locomotor activity was also assessed to examine the possible effects of 56Mn on their behavior. However, the locomotor activity data obtained from an individual experiment failed to identify radiation effects due to the large variation among animals and the small sample size. In the present study, all available data from our previous studies on 56MnO2 exposure (0.02-0.15 Gy of whole-body doses) as well as 60Co-γ exposure (at 2-5 Gy of whole-body doses) were pooled. Our statistical method, which takes into account individual differences and daily fluctuations, successfully identified a decrease in locomotor activity caused by 56MnO2 exposure, where the changes were gradual and reached the maximum reduction around 2 weeks after exposure. In contrast, exposure to 60Co-γ rays produced the highest decline of activity within one day. These results suggest that internal exposure to 56Mn at whole-body doses of even less than 0.15 Gy may have a long-lasting impact on locomotor activity.
在广岛和长崎的原子弹爆炸中，大量的放射性核素通过中子诱导激活产生。爆炸产生的残余辐射对那些在爆炸后进入这些城市并可能吸入这些放射性物质的人来说，是健康风险的关键。由于 56Mn 是土壤中产生的主要放射性核素之一，直到现在还没有进行过研究，我们使用大鼠进行了一系列实验，以研究 56MnO2 颗粒暴露对生物的影响。在这些实验中，还评估了大鼠的自发运动活动，以检查 56Mn 对其行为可能产生的影响。然而，由于动物之间的变异很大，而且样本量很小，因此从单个实验中获得的运动活动数据未能确定辐射的影响。在本研究中，我们汇集了之前关于 56MnO2 暴露（全身剂量 0.02-0.15Gy）和 60Co-γ 暴露（全身剂量 2-5Gy）的所有可用数据。我们的统计方法考虑到了个体差异和日常波动，成功地识别出了 56MnO2 暴露引起的运动活动减少，这种变化是逐渐的，在暴露后大约 2 周达到最大减少。相比之下，60Co-γ 射线暴露在一天内产生了最高的活动下降。这些结果表明，全身剂量甚至低于 0.15Gy 的 56Mn 内暴露可能对运动活动产生持久影响。
