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Space Radiation a Risk for Astronauts

Risk of colon cancer, premature aging poses worries for manned missions to moon, Mars

TUESDAY, April 15, 2008 (HealthDay News) -- Astronauts may be at increased risk of colon cancer and premature aging from the high-energy radiation found in space, a new report says.

The study, expected to be presented Tuesday during the American Association for Cancer Research annual meeting in San Diego, has implications for the long-term space travel necessary for Project Constellation, the recently launched NASA program to return humans to the moon and then on to Mars.

"Radiation exposure, either intentional or accidental, is inevitable during our lifetimes," study author Kamal Datta, an assistant professor at the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center, said in a prepared statement. "But with plans for a mission to Mars, we need to understand more about the nature of radiation in space. There is currently no conclusive information for estimating the risk that astronauts may experience."

Researchers exposed mice to the high linear energy transfer (LET) radiation similar to that found in space. They found that it created a highly oxidative cellular environment in the gastrointestinal tract over prolonged periods of time, a condition favorable for cancer development.

High-LET radiation is found in solar flares. The earth's atmosphere blocks much of this radiation from reaching us.

The radiation produced free radicals that damage a cell's DNA. Over time, accumulated damage can lead to mutations -- and, in some cases, malignant tumors. Datta and colleagues also noted the cell's stress response to the free radical damage continued up to two months after exposure to the high-LET radiation.

Also, the mice exposed to the high-LET radiation aged prematurely, researchers said. Datta said their fur became prematurely gray, an observation the team plans to follow-up with MRI brain scans.

This is not the first possible link between space travel and cancer. The National Academies reported in 2004 that it had found the frequency of cancer in the astronaut population was higher than the incidence among the general U.S. population.

More information

The American Association of Retired Persons has more about how free radicals affect the body.

SOURCE: Georgetown University, news release, April 15, 2008
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