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Combined effects of space flight factors and radiation on humansThe probability that a dose of ionizing radiation kills a cell is about 10,000 times the probability that the cell will be transformed to malignancy. On the other hand, the number of cells killed required to significantly impact health is about 10,000 times the number that must be transformed to cause a late malignancy. If these two risks, cell killing and malignant transformation, are about equal, then the risk that occurs during a mission is more significant than the risk that occurs after a mission. The latent period for acute irradiation effects (cell killing) is about 2-4 weeks; the latent period for malignancy is 10-20 years. If these statements are approximately true, then the impact of cell killing on health in the low-gravity environment of space flight should be examined to establish an estimate of risk. The objective of this study is to synthesize data and conclusions from three areas of space biology and environmental health to arrive at rational risk assessment for radiations received by spacecraft crews: (1) the increased physiological demands of the space flight environment; (2) the effects of the space flight environment on physiological systems; and (3) the effects of radiation on physiological systems. One physiological system has been chosen: the immune response and its components, consisting of myeloid and lymphoid proliferative cell compartments. Best-case and worst-case scenarios are considered. In the worst case, a doubling of immune-function demand, accompanied by a halving of immune capacity, would reduce the endangering dose to a crew member to around 1 Gy.
Document ID
20040141712
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Todd, P.
(Campus Box 429, University of Colorado Boulder, CO, United States)
Pecaut, M. J.
Fleshner, M.
Clarkson, T. W.
Date Acquired
August 22, 2013
Publication Date
December 6, 1999
Publication Information
Publication: Mutation research
Volume: 430
Issue: 2
ISSN: 0027-5107
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: RO1 CA35370
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Environmental Health

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