We have Canadian Chris Hadfield on the space station right now where he must be getting extra exposure to radiation. Do astronauts get enough exposure for there to be a long term effect?
Certainly astronauts are exposed to greater levels of radiation than those of us on earth. This also tends to be higher energy cosmic radiation, which is relatively more damaging compared to say, x-rays. However, astronauts are all adults - meaning their cells are primarily non-dividing (compared to say a baby or child). Non-dividing cells are more resistant to damage and mutation, and so studies of astronauts have not found a significant long-term impact from cosmic radiation.
Answered By: Dr. Aaron Goodarzi
For more about how radiation effects the human body, see the CurioCity Backgrounders: Radiation Effects on the Body, Radiation Effects on Cells and DNA and Radiation & Human Space Exploration.