Radiation Exposure and Mortality from Cardiovascular Disease and Cancer in Early NASA Astronauts

Abstract

Understanding space radiation health effects is critical due to potential increased morbidity and mortality following spaceflight. We evaluated whether there is evidence for excess cardiovascular disease or cancer mortality in early NASA astronauts and if a correlation exists between space radiation exposure and mortality. Astronauts selected from 1959-1969 were included and followed until death or February 2017, with 39 of 73 individuals still alive at that time. Calculated standardized mortality rates for tested outcomes were significantly below U.S. white male population rates, including all-cardiovascular disease (n = 7, SMR = 33; 95% CI, 14-65) and all-cancer (n = 7, SMR = 43; 95% CI, 18-83), as anticipated in a healthy worker population. Space radiation doses for cohort members ranged from 0-78 mGy. No significant associations between space radiation dose and mortality were found using logistic regression with an internal reference group, adjusting for medical radiation. Statistical power of the logistic regression was <6%, remaining <12% even when expected risk level or observed deaths were assumed to be 10 times higher than currently reported. While no excess radiation-associated cardiovascular or cancer mortality risk was observed, findings must be tempered by the statistical limitations of this cohort; notwithstanding, this small unique cohort provides a foundation for assessment of astronaut health.

Figure 1

Individual Astronaut Dosimetry. Summary of individual dosimetry and vital status for all NASA crew in astronaut selection groups 1–7. Dosimetry, presented as total mean skin dose in mGy, was obtained from published records; median dose was 2 mGy with a range of 0–74.1 mGy. Living astronauts are indicated by (+); while deaths are distinguished by major cause into three groups, cardiovascular disease (▲), cancer (■) or other (•).