The Center for Peace, Hiroshima University, Higashi-senda-machi, Naka-ku, Hiroshima 730-0053, Japan.
J Radiat Res. 2022 Aug 13;63(Supplement_1):i1-i7. doi: 10.1093/jrr/rrac020.
Investigation into the risks associated with radiation exposure has been carried out on those exposed to radiation in Hiroshima and Nagasaki, Semipalatinsk and other parts of the world. These risks are used as a guidance standard for the protection for radiation workers and the general public when exposed to radiation, and it sets upper regulatory limits for the amount of radiation exposure. However, the effects of internal exposure to radioactive microparticles have not been considered in these studies. These effects cannot be ignored since the exposure dose increases are inversely proportional to the square of the distance to the vicinity of the particles and can exceed tens of thousands of mGy. So far, only retrospective studies of people who have been exposed to radiation have been conducted, therefore we hypothesized that animal experiments would be necessary to investigate these effects. As a result, we found specific effects of radioactive microparticles. One particularly noteworthy finding was that internal exposure to radioactive microparticles resulted in pathological changes that were more than 20 times greater than those caused by the same level of external exposure. In contrast, there were other results that showed no such effects, and the reasons for this discrepancy need to be clarified. We also conducted RNA expression experiments and found that there was a difference between external exposure to 60Co gamma rays and internal exposure to 56Mn microparticles. In the future, we will need to study the mechanisms behind these findings. If the mechanism can be confirmed, it is expected to lead to the development of protective and therapeutic methods.
对广岛和长崎、塞米巴拉金斯克和世界其他地区受到辐射照射的人进行了与辐射相关风险的调查。这些风险被用作辐射工作人员和公众暴露于辐射时的防护标准，并为辐射暴露量设定了上限监管限值。然而，这些研究并未考虑放射性微颗粒的内暴露效应。由于暴露剂量的增加与距颗粒附近的距离的平方成反比，并且可以超过数万 mGy，因此这些效应不容忽视。到目前为止，仅对已经暴露于辐射的人进行了回顾性研究，因此我们假设需要进行动物实验来研究这些效应。结果，我们发现了放射性微颗粒的特定效应。一个特别值得注意的发现是，放射性微颗粒的内暴露导致的病变比相同水平的外暴露导致的病变大 20 多倍。相比之下，还有其他结果表明没有这种效应，需要澄清这种差异的原因。我们还进行了 RNA 表达实验，发现 60Co 伽马射线外照射和 56Mn 微颗粒内照射之间存在差异。未来，我们将需要研究这些发现背后的机制。如果可以证实该机制，有望开发出保护和治疗方法。
