From the dawn of space travel more than half a century ago, it was feared space travellers would contract cancers and heart disease at a higher rate than on Earth due to greater exposure to radiation.
After all, it’s well understood that exposure to ionising radiation can increase risk of death from cancers and evidence is emerging of a role of radiation in cardiovascular disease (CVD).
But a new study by American and Russian researchers has found no noticeable increase in either cancer or heart disease in US astronauts and Russian cosmonauts.
“So far, investigations into astronaut mortality have demonstrated no discernible excess mortality risk from cancer or CVD for astronauts in comparison to either the general population or professional athletes,” according to the study, which was published in the journal Nature’s Scientific Reports.
The study considered all NASA astronauts since 1959, a total of 301, and all Soviet or Russian cosmonauts since 1961, a total of 117. All had travelled into space before July 2018 in the case of astronauts and December 2017 for cosmonauts.
Of that group, 89 had since died – 53 astronauts and 36 cosmonauts – from various causes.
The researchers, led by Robert Reynolds from Mortality Research and Consulting Inc. in California, were only interested in cancer and heart disease deaths, which could potentially be linked to radiation exposure.
They found 30 per cent of the 53 US astronauts died from cancer and less than 15 per cent from heart disease. The mortality profile for cosmonauts was different – half the 36 deaths were attributable to heart disease and 28 per cent to cancer.
That might seem a lot but it’s not much different to the overall population, which has never been to space.
“If ionising radiation is impacting the risk of death due to cancer and cardiovascular disease, the effect is not dramatic,” Reynolds said.
That’s the good news. With the exception of those relatively few astronauts involved in the moon missions, all astronauts and cosmonauts went no further than Earth orbit where the Earth’s magnetic field provides significant protection against exposure to ionising radiation.
It’s likely to be very different in future as man ventures far beyond Earth, first to Mars. That will involve long voyages with far greater exposure to radiation, which could take years off astronaut lives.
“It is important to note that future missions of deep space exploration will likely offer much greater doses of space radiation than have historical doses, which will lead to a different risk profile for future astronauts and cosmonauts,” the study said.
“In the years to come it is imperative that epidemiologists continue to surveil the astronaut and cosmonaut populations for potential harmful effects of exposure to space radiation, using methods both novel and familiar. Doing so will be integral to supporting human ambitions for further exploration and eventual colonization of our solar system.”
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