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CVD-related deaths high in Apollo astronauts
New research suggests that exposure to deep space radiation may be associated with the higher rate of CVD-related death that has been observed among astronauts in the Apollo space program.
Michael D. Delp, PhD, and fellow investigators discuss in Scientific Reports the effects of exposure to galactic cosmic radiation, which can manifest as CVD later in life.
“The human experience with spaceflight has shown that space exploration comes with various health risks,” Delp, from the department of nutrition, food and exercise sciences at Florida State University, and colleagues wrote in Scientific Reports. “Despite the potential to be more biologically damaging, the long-term effect of space radiation on CV health has received little attention.”
This study is the first to analyze mortality among Apollo astronauts, according to the investigators. The Apollo space program ran from 1961 to 1972, with 11 manned flights into space between 1968 and 1972. Nine of those flew beyond Earth’s orbit into deep space. The program is most notable for landing men on the moon, as well as the failed mission of Apollo 13, according to a press release.
The goal was to determine whether mortality rates due to CVD, cancer, accidents or other causes differed among Apollo lunar astronauts (n = 7; all men), astronauts who flew only in low Earth orbit (n = 37; 30 men, 5 women) and astronauts who never flew orbital missions in space (n = 35; 32 men, 3 women). Using the NASA Johnson Space Center Lifetime Surveillance of Astronaut Health database, Delp and colleagues were able to determine the cause of death among all Apollo astronauts, 97% of low Earth orbit astronauts and 49% of non-flight astronauts.
Causes of death were categorized as related to CVD (HF, MI, stroke, brain aneurysm, venous thromboembolism), cancer (malignant neoplasms), accident (fatal unintentional injuries including orbiter destruction and plane, automobile, motorcycle, boat or bicycle accidents) or “other.”
Overall, 43% of Apollo astronauts died as a result of CVD, a rate that was significantly higher than that among low Earth orbit astronauts (11%) and non-flight astronauts (9%). Deaths related to cancer and accidents were highest among low Earth orbit astronauts (31% and 49%, respectively).
Of the 24 men who traveled into deep space on the Apollo lunar missions, eight died and seven were included in this study. The eighth died after the data analysis had been completed, according to the release.
"We know very little about the effects of deep space radiation on human health, particularly on the CV system," Delp said in the release. "This gives us the first glimpse into its adverse effects on humans.”
The investigators also exposed mice to the type of radiation that Apollo astronauts would have experienced. After 6 months — the equivalent of 20 human years — the mice had sustained vascular endothelial cell dysfunction, according to the release.
Delp is working with NASA to conduct additional research on the CV health of Apollo astronauts. – by Dave Quaile
Disclosure: The research was funded by the National Space and Biomedical Research Institute and the NASA Space Biology Program. The researchers report no relevant financial disclosures.