ASSUMPTIONS about the safety of medical X-rays are being challenged by the finding that cells exposed to low doses of radiation don’t bother to repair damaged DNA. That casts doubt on the validity of current estimates of safe doses, which are calculated from high-dose experiments.
A team at the University of Saarland in Homburg, Germany, exposed human lung cells to a range of X-ray doses. At higher doses of about 200 milligrays, cells repaired 95 per cent of their damage within a day. But cells receiving around 1 milligray – equivalent to a normal X-ray – did not perform any…
