The popular press has picked up on a story about cosmic rays and cardiovascular disease in astronauts who landed on the moon. The Voice of America has a particularly breathless account of a study, Apollo Lunar Astronauts Show Higher Cardiovascular Disease Mortality: Possible Deep Space Radiation Effects on the Vascular Endothelium, published in the online journal Scientific Reports. The study concludes that “the CVD mortality rate among Apollo lunar astronauts (43%) was 4–5 times higher than in non-flight and low earth astronauts.” How many Apollo lunar astronauts were studied? Seven! This is the definition of an underpowered study.
The New York Times has a more thoughtful account of this “study” and its limitations. The paper’s lead author Michael D. Delp from Florida State University when challenged on the study’s weakness said, “What it does is point to the fact that we need a lot more study on this,” he said. “One of the things that NASA and others have been most concerned about with space radiation is cancer. The cardiovascular system has barely gotten mentioned.” He didn’t mention, nor has any other account that I’ve seen, that overall mortality in this miniscule account doesn’t seem to be different from the reference group, but the data are presented such that I can’t be sure this is so.
Human exposure to extraterrestrial environments is fraught with potential hazards. As we enter the space age we will have to carefully study the health effects of this new environment on the humans who live in it. So Dr Delp is correct that we need more information. But we would have gotten it even if this tiny and utterly inconclusive study had been put in the trash bin. If it can be studied, it will be.