Background: Expanding human presence in space through long-duration exploration missions and commercial space operations warrants improvements in approaches for quantifying crew space radiation health risks. Currently, risk assessment models for radiogenic cancer and cardiovascular disease consider age, sex, and tobacco use, but do not incorporate other modifiable (e.g., body weight, physical activity, diet, environment) and non-modifiable individual risk factors (e.g., genetics, medical history, race/ethnicity, family history) that may greatly influence crew health both in-mission and long-term. For example, clonal hematopoiesis of indeterminate potential (CHIP) is a relatively common age-related condition that is an emerging risk factor for a variety of diseases including cardiovascular disease and cancer. CHIP carrier status may therefore exacerbate health risks associated with space radiation exposure.
Methods: In the present study, published CHIP hazard ratios were used to modify background hazard rates for coronary heart disease, stroke, and hematologic cancers in the National Aeronautics and Space Administration space radiation risk assessment model. The risk of radiation exposure-induced death for these endpoints was projected for a future Mars exploration mission scenario.
Results: Here we show appreciable increases in the lifetime risk of exposure-induced death for hematologic malignancies, coronary heart disease, and stroke, which are observed as a function of age after radiation exposure for male and female crew members that are directly attributable to the elevated health risks for CHIP carriers.
Conclusions: We discuss the importance of evaluating individual risk factors such as CHIP as part of a comprehensive space radiation risk assessment strategy aimed at effective risk communication and disease surveillance for astronauts embarking on future exploration missions.
Space radiation exposure is a major hazard of spaceflight that may increase cancer and cardiovascular disease risks for future astronauts exploring the moon and Mars. There is a need for accurate risk assessment that considers individual risk factors to support informed consent and medical management of these risks. Clonal hematopoiesis of indeterminate potential (CHIP) is a condition that occurs when copies of variant cells accumulate in the blood of otherwise healthy individuals. CHIP is an emerging risk factor linked with blood cancers and cardiovascular disease. We evaluated how CHIP can alter space radiation health risks in astronauts for a Mars exploration mission scenario. We find large increases in lifetime risk of space radiation exposure-induced death for hematologic malignancies and cardiovascular disease in CHIP carriers. These results suggest that increased screening may help facilitate better management of radiation risks.
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