Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana, USA.
Department of Preventive Medicine & Population Health, University of Texas Medical Branch, Galveston, Texas, USA.
J Environ Sci Health C Toxicol Carcinog. 2021;39(2):113-128. doi: 10.1080/26896583.2021.1897273.
The space radiation environment is a complex combination of fast-moving ions derived from all atomic species found in the periodic table. The energy spectrum of each ion species varies widely but is prominently in the range of 400-600 MeV/n. The large dynamic range in ion energy is difficult to simulate in ground-based radiobiology experiments. Most ground-based irradiations with mono-energetic beams of a single one ion species are delivered at comparatively high dose rates. In some cases, sequences of such beams are delivered with various ion species and energies to crudely approximate the complex space radiation environment. This approximation may cause profound experimental bias in processes such as biologic repair of radiation damage, which are known to have strong temporal dependencies. It is possible that this experimental bias leads to an over-prediction of risks of radiation effects that have not been observed in the astronaut cohort. None of the primary health risks presumably attributed to space radiation exposure, such as radiation carcinogenesis, cardiovascular disease, cognitive deficits, etc., have been observed in astronaut or cosmonaut crews. This fundamentally and profoundly limits our understanding of the effects of GCR on humans and limits the development of effective radiation countermeasures.
空间辐射环境是一个由来自元素周期表中所有原子种类的高速移动离子组成的复杂组合。每个离子种类的能量谱变化很大，但主要集中在 400-600 MeV/n 的范围内。离子能量的大动态范围难以在地面放射生物学实验中模拟。大多数基于地面的辐射实验是用单一离子种类的单能束进行的，剂量率相对较高。在某些情况下，会使用各种离子种类和能量的束序列进行粗略模拟，以近似复杂的空间辐射环境。这种近似可能会导致生物学修复辐射损伤等过程中的实验偏差，这些过程具有很强的时间依赖性。可能正是这种实验偏差导致了对宇航员队列中未观察到的辐射效应风险的过高预测。在宇航员或航天员机组人员中，没有观察到据推测归因于空间辐射暴露的主要健康风险，例如辐射致癌、心血管疾病、认知缺陷等。这从根本上严重限制了我们对 GCR 对人类影响的理解，并限制了有效辐射对策的发展。
