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

Abstract

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.

Keywords: Anesthesia propofol; Deep space radiation; Effects of neutron irradiation; Fast neutron.