[xiaoma]

Possibly. The largest human study ever done on the effects of chronic low-level radiation found them to be beneficial.

The researcher involved proposed a radiation hormesis model, in which the body adapts to the destructive effects of radiation by upgrading its self-repair response. US regulatory groups adhere to a linear no-threshold model in which all radiation, regardless of how weak it may be, leads to cumulative damage. It's not a resolved issue however. The French Academy of Sciences & National Academy of Medicine, for one, cited the study linked below in an argument against the LNT model.

http://www.scienceboard.net/community/perspectives.122.html