A bespoke health risk assessment methodology for the radiation protection of astronauts

Abstract

An alternative approach that is particularly suitable for the radiation health risk assessment (HRA) of astronauts is presented. The quantity, Radiation Attributed Decrease of Survival (RADS), representing the cumulative decrease in the unknown survival curve at a certain attained age, due to the radiation exposure at an earlier age, forms the basis for this alternative approach. Results are provided for all solid cancer plus leukemia incidence RADS from estimated doses from theoretical radiation exposures accumulated during long-term missions to the Moon or Mars. For example, it is shown that a 1000-day Mars exploration mission with a hypothetical mission effective dose of 1.07 Sv at typical astronaut ages around 40 years old, will result in the probability of surviving free of all types of solid cancer and leukemia until retirement age (65 years) being reduced by 4.2% (95% CI 3.2; 5.3) for males and 5.8% (95% CI 4.8; 7.0) for females. RADS dose–responses are given, for the outcomes for incidence of all solid cancer, leukemia, lung and female breast cancer. Results showing how RADS varies with age at exposure, attained age and other factors are also presented. The advantages of this alternative approach, over currently applied methodologies for the long-term radiation protection of astronauts after mission exposures, are presented with example calculations applicable to European astronaut occupational HRA. Some tentative suggestions for new types of occupational risk limits for space missions are given while acknowledging that the setting of astronaut radiation-related risk limits will ultimately be decided by the Space Agencies. Suggestions are provided for further work which builds on and extends this new HRA approach, e.g., by eventually including non-cancer effects and detailed space dosimetry.

Towards sustainable human space exploration—priorities for radiation research to quantify and mitigate radiation risks

“…Applying this approach, a 1000-day Mars exploration mission with a hypothetical effective dose of ~1 Sv received at a typical astronaut age of 40 years old, was found to result in the probability of surviving free of all types of solid cancer and leukemia until retirement age (65 years) being reduced by 4.2% (95%CI: 3.2; 5.3) for males and 5.8% (95%CI: 4.8; 7.0) for females 32 .…”

“…The development of ESA radiation risk models, to better characterize the mission radiation risks to astronauts, was recently recommended in a paper on research plans in Europe for radiation hazard assessments in space 19 . In line with this recommendation and the radiation protection initiative for astronauts at the ESA-Astronaut Centre, the first stage of a space radiation risk module for Astronaut’s health risk assessment was developed and verified 32 . This risk module built on previous work 33 , 34 was based on radiation-related health risk assessment for the detrimental health effect outcomes of incidence of all solid cancer, leukemia, lung and female breast cancer from estimated radiation exposures accumulated during long term missions to the Moon or Mars.…”

Dose Limits and Countermeasures for Mitigating Radiation Risk in Moon and Mars Exploration

“…Following the Topical Team recommendations, European scientists have recently proposed a space radiation risk model based on a different metric [42], the radiationattributed decrease of survival (RADS), defined as:…”

Application of multi-method-multi-model inference to radiation related solid cancer excess risks models for astronaut risk assessment

“…Recent developments, not yet adopted for operational use by national agencies, relate to the quantity Radiation Attributed Decrease of Survival (RADS) [4] , [5] . RADS has been pointed out to provide more accurate risk estimates for astronauts, because in this calculation method, fewer types of population specific rates from the general population are integrated, where such rates represent a major source of uncertainty (Walsh et al [6] ). Generally, it is important to assess uncertainties and to optimize their magnitude if possible to generate reliable risk assessments.…”