Radiation Exposure: Timing Also Important

A U.S. government study suggests it doesn’t just matter how much radiation an astronaut is exposed to, the time and order of exposure also is important.

Researchers at the Department of Energy’s Brookhaven National Laboratory found human cells are three times more likely to develop properties similar to those in the initial stages of cancer when they are exposed to two types of high-energy particles within a short period of time.

The radiation field in space contains high levels of high-energy protons and much lower levels of high atomic number, high-energy particles, or HZE, such as iron and titanium.

Most people studying the effects of space radiation have looked at the effects of just one type of particle, either the protons or the HZE particles, said Brookhaven biologist Betsy Sutherland, the paper’s lead author. This is one of the first studies to try to imitate real space radiation conditions closely, where, on average, a cell will be hit by a proton first and then by an HZE particle.

The study’s results are detailed in the September edition of the journal Radiation Research.