Is the Adaptive Response an Efficient Protection Against the Detrimental Effects of Space Radiation?

Exposure to high-energy neutrons, protons and HZE particles during a deep space mission, needs an efficient protection against the detrimental effects of space ra-diation. Recent findings concerning the induction of adaptive response by neutrons and high cumulative doses of gamma radiation in human cells have opened a new horizon for possible implications of adaptive response in radiation protection and especially in pro-tection against detrimental effects of high levels of radiation during a long-term space journey. We demonstrated significant adaptive response in humans after exposure to high levels of natural radiation. Individuals whose cumulative radiation doses were up to 950 mSv, showed a significant adaptive response after exposure to 1.5 Gy gamma radiation. These doses are much lower than those received by astronauts during a six-month space mission. Screening the adaptive response of candidates for long-term space missions will help scientists identify individuals who not only show low radiation suscep-tibility but also demonstrate a high magnitude of radioadaptive response. In selected individuals, chronic exposure to elevated levels of space radiation during a long-term mission can considerably decrease their radiation susceptibility and protect them against the unpredictable exposure to relatively high radiation levels due to solar activity.