Space Radiation and Astronaut Health Managing and Communicating Cancer Risks (2021) / Chapter Skim
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1 Introduction
1 Introduction
Pages 19-32
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From page 19... ...
NASA has long recognized that crewed space missions carry a range of unique hazards and challenges, including health-related risks. As NASA prepares for space exploration missions that extend to greater distances into our solar system and for longer durations, including missions to near-Earth objects, the Moon, and Mars, as well as prolonged stays on the International Space Station (ISS)
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From page 20... ...
To protect astronauts from unacceptable risks due to space radiation exposure, NASA has set space permissible exposure limits (SPELs)
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From page 21... ...
In the near future, as NASA prepares for a crewed space mission to the Moon and, eventually, Mars, the agency is proposing changes to its health standard for space radiation exposure limits and its approach to managing and communicating the cancer and non-cancer risks associated with space radiation exposure. There are a number of reasons why NASA feels these changes are necessary.
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From page 22... ...
. The other reasons presented to the committee for revising the standard and associated risk management are the following: • NASA is aware that recent updates from epidemiological and ra diobiological studies on sex differences in radiation-induced cancer risks may affect its cancer risk assessment model and what is an ac ceptable level of radiation exposure for astronauts (see Box 1-1 and Figure 1-1)
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From page 23... ...
FIGURE 1-1 Female astronauts have lower permissible mission duration than male astronauts owing to differing assessed cancer risks under the current NASA risk model. NOTE: ISS = International Space Station; NASA = National Aeronautics and Space Administration; NSCR = NASA Space Cancer Risk; PMD = permissible mission duration; REIC = risk of exposure-induced cancer; REID = risk of exposure-induced death; SPEL = space permissible exposure limit.
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From page 24... ...
The study committee was not asked to develop a new radiation exposure health standard or to perform a detailed evaluation of the NASA stochastic cancer model that informs the standard. To accomplish the task, the National Academies empaneled a committee of 18 members with expertise in the areas of radiation and cancer biology; 2 A copy of a document prepared by NASA summarizing the discussion of this advisory panel may be requested by contacting the National Academies' Public Access Records Office (PARO@nas.edu)
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From page 25... ...
Provide a written report with recommendations on the best process and strategies for NASA to use in addressing and managing the uncertainties of long-term cancer risks due to radiation exposure in crewed space missions beyond low Earth orbit. In conducting the review, the committee will consider the following: • N ASA's present processes for assessing uncertainty from radiation risk exposure in crewed space missions compared to terrestrial methods for clinical applications, and how data from ground-based research on the relationship between radiation exposure and cancer risk should inform NASA's approach to risk management for crewed missions.
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From page 26... ...
and email communications. At the first public session in January 2021, NASA provided more specifics on its objectives for the study; factors considered and background on the proposed radiation standard; health and medical risk characterization; sex difference considerations; cancer incidence within the NASA Astronaut Corps; and a crew perspective (see Appendix A for the public session agendas)
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From page 27... ...
In the March white paper, NASA provided the final proposed language for the updated standard, which utilized the mean REID to set the career total dose limit (universal for sex and age)
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NASA has asked the committee to confirm whether these considerations have been addressed adequately in its proposed standard and in the assessment, management, and communication of radiation-induced cancer risks. NASA has acknowledged that under current conditions, a mission to Mars would expose all astronauts to space radiation that exceeds the SPEL, despite taking measures to keep radiation exposure as low as reasonably achievable (the ALARA principle)
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From page 29... ...
from cancer -- The probability that an indi vidual will die from cancer associated with the radiation exposure (UNSCEAR, 2000)
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An exposure limit is defined in a health standard. It has the primary functions of preventing in-flight risks that would jeopardize mission success and limiting chronic risks to acceptable levels based on legal, ethical, moral, and financial considerations (Cucinotta, 2010)
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From page 31... ...
Chapter 3 considers NASA's proposed changes to its radiation exposure standard, and provides the committee's recom mendations on the implementation and application of the updated standard and on risk assessment for cancer risks associated with radiation exposure during crewed space missions. Chapter 4 considers the aims and methods of communicating to astronauts the cancer risk from ionizing space radiation, and offers conclusions and recommendations on communicating cancer risks associated with radiation exposure during crewed space missions, as well as considerations of waivers for missions that exceed the radiation exposure standard.
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From page 32... ...
Presenta tion to the Committee on Assessment of Strategies for Managing Cancer Risks Associated with Radiation Exposure During Crewed Space Missions, January 25. Shields, P
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