The cell can repair certain levels of cell damage. At low doses, such as that received every day from background radiation, cellular damage is rapidly repaired.

http://web.princeton.edu/sites/ehs/osradtr...

The cell can repair certain levels of cell damage

http://www.research.ucdavis.edu/home.cfm?i...

Most cells have the ability to repair some damage

http://www.state.nj.us/dep//rpp/llrw/downl...

Cells can often repair radiation damage,

These are divided into two categories:
threshold effects and non-threshold effects.
Threshold effects appear after a certain level
of radiation exposure is reached and enough
cells have been damaged to make the effect
apparent. Non-threshold effects can occur at
lower levels of radiation exposure.

http://www.jlab.org /

French Academy of Sciences,
National Academy of Medicine
Joint Report (2005)
“…this report raises doubts on the
validity of using the LNTfor evaluating
the carcinogenic risk of low doses…”
Exact opposite conclusion from BEIR VII
(Phase 2)Report.

The conclusion of the French Report is that the linear no-threshold relationship (LNT) may greatly overestimate the carcinogenic effect of low doses (<100 mSv) and even more that of very low doses (<10 mSv), such as those delivered during X-ray examinations. Conversely, the conclusion of the BEIR VII report is that LNT should be used for assessing the detrimental effects of these low and very low doses. The causes of these diverging conclusions should be carefully examined. They seem to be mostly associated with the interpretation of recent biological data. The point of view of the French Report is that these recent data are incompatible with the postulate on which LNT is implicitly based, namely the constancy of the carcinogenic effect per unit dose, irrespective of dose and dose rate.