Does high speed travel change human DNA?

Answered by Marianne Baker, Barts Cancer Institute. There's probably no effects on DNA from high-speed travel itself, but there is a known effect on DNA from cosmic radiation at high altitudes - one long-haul flight is roughly the equivalent radiation exposure of a couple of chest X-rays. So if you spend a lot of time at high-altitude, rather than high speed, you'd be increasing the chances of damaging your DNA, and therefore slightly increasing your cancer risk. As SeanB points out on the Naked Scientists forum, if high-speed travel had an effect it would have been seen already - astronauts have to go at 12km per second to obtain enough energy to reach earth orbit as well, and, as they are probably the most studied people around, any effects would have been seen since the 1960's when the first people orbited the earth.