Cosmic radiation damages astronauts' hearts

Posted by Kate Taylor

Long-distance space travel could harm astronauts' arteries, say University of Alabama at Birmingham researchers.

They've found that cosmic radiation accelerates the development of atherosclerosis in mice, regardless of their cholesterol levels or circulating white blood cells. It also made existing atherosclerotic lesions worse.

"It’s well known that prolonged exposure to radiation sources here on Earth, including those used in cancer treatment, excessive occupational exposure and atomic bombs, are associated with an increased risk for atherosclerosis," says Dennis Kucik of the Department of Pathology.

"But cosmic radiation is very different from X-rays and other radiation found on Earth. The radiation risks of deep-space travel are difficult to predict, largely because so few people have been exposed."

The only people who have been exposed to high levels of cosmic radiation are the 24 astronauts who have been to the moon as part of NASA’s Apollo missions in the late 1960s and early 1970s.

The team exposed the mice to a particle beam of high-velocity iron ions, similar to those found in space. They analyzed the mice after 13 and 40 weeks.

"At 13 weeks it was surprising and quite remarkable that we already could see permanent damage — an irreversible thickening of the artery wall where it had been exposed to radiation," says co-author Janusz Kabarowski.

"The irradiation had no significant effect on the frequency of circulating immune and inflammatory white blood cells or plasma lipid profile."

Knowing the effects of cosmic radiation on the heart health of deep-space astronauts will help meet the unique challenges of treatment and prevention posed by missions of long duration, says Kabarowski.

X-rays can be blocked by lead shields; however, cosmic radiation ions can actually become more dangerous when they interact with metals. And although other materials do work, they wouldn't be easy to incorporate into spacesuits.

"Our future research will look at the mechanisms causing the damage, and we will try to find a way to target those mechanisms to correct the damage or prevent it altogether," says Kabarowski