Effects of neutron radiation on pharmaceuticals in deep space-like environments - general anesthesia in space

In deep space environments such as the Moon and Mars, secondary radiation generated by interactions between galactic cosmic rays and spacecraft walls or planetary surfaces presents a significant challenge. In particular, the effects of neutron radiation remain insufficiently understood. This study investigates the impact of neutron radiation on pharmaceuticals, specifically the general anesthetic propofol (2,6-Diisopropylphenol). Neutron irradiation experiments were conducted using the RIKEN Accelerator-driven compact Neutron Source (RANS), employing fast neutrons with energies of 1-5 MeV at doses up to 4 Gy. Analyses employing nuclear magnetic resonance (NMR), colorimetric assessment, micelle particle size measurement via optical microscopy, and high-performance liquid chromatography (HPLC) detected no discernible alterations in the molecular structure of propofol. Furthermore radiological activation analysis using Geiger-Müller (GM) counters and γ-ray spectral analysis with the germanium detector (Ge) indicated minimal radionuclide generation in the pharmaceutical itself, however significant activation was observed in glass vials. These findings highlight container activation as a critical risk factor in the storage and transportation of pharmaceuticals in space environments.