Study Shows High-Energy Particles Damage Cells : Space Travel Could Pose Risk of Cancer

A new study suggests exposure to radiation during very long-term travel in outer space may cause cancer, a scientist says.

Experiments at the Lawrence Berkeley Laboratory show that the type of particles that are found in cosmic radiation caused more damage to animal cells in a laboratory dish than cancer-causing X-rays, biophysicist Tracy Yang reported.

“In general, we have found that heavy charged particles, like the ones that bombard everything passing through space, are far more effective than even X-rays in turning normal cells into cancer cells,” he said.

“In addition, whereas cells can repair some of the genetic damage caused by X-rays, they cannot repair damage from these very high-energy particles, which are found in cosmic radiation.”

Implications for Space Travelers

The implication is that with enough exposure, space travelers may develop cancer, Yang told experts from around the world at the Symposium on Heavy Charged Particles in Research and Medicine.

But, he said in an interview, he is optimistic that scientists will find ways to minimize the risks by the time people are taking prolonged space trips.

During the four-year study, Yang and his colleagues simulated the outer space environment by bombarding cells of mouse embryos with heavy ion particles produced by the laboratory’s powerful Bevalac accelerator.

A healthy cell grows in a single layer until it fills up a laboratory dish, then stops dividing, Yang said.

“This is known as the density inhibition of growth. A cancer cell loses this property and keeps growing even though there’s no more room in the dish, spilling over into layer upon layer,” he said.

“Using a dye, you can easily see these multilayer, dense spots springing up, indicating the cell has become cancerous.”

Injected Cells Into Mice

Yang and his team found such a transformation took place when they bombarded the healthy mouse cells with the heavy charged particles. They then injected the transformed cancer-like cells into mice.

“The animals produced tumors, showing the cells were indeed true cancer cells,” Yang said.

The team found that up to a certain point, the heavy charged particles caused greater damage more rapidly than equivalent doses of X-rays.

“We hope these tests will give us a better assessment of the risks faced by people who will travel for prolonged periods in space and a better understanding of carcinogenesis in general,” Yang said.

“Prolonged space travel will be harmful, that’s for sure, but I’m confident we will find ways to minimize the risks. Once we understand how certain chemicals inhibit the cancer process, we can design drugs suitable for human use.”

Already, scientists have had preliminary success in using nontoxic concentrations of chemicals such as dimethyl sulfoxide, or DMSO--which is used for arthritis--and vitamin A in animals to suppress the cancer process, even after it has already begun, Yang said.