: "Radiation is only one of many different phenomena that can lead to cell damage. A healthy cell's metabolism naturally produces free radicals, which can break one of a DNA molecule's two strands 10,000 times in a day and break both strands 8 times in the same period. By comparison, a very high dose of radiation (say 1 gray) can damage one strand 1,000 times and both strands 40 times in a very concentrated area for a brief space of time. Damage done to one strand can easily be repaired, but the body finds it much more difficult to repair DNA molecules where both strands are broken." (After Maurice Tubiana, "L'effet des faibles doses", le dossier du nucleaire, la Jaune et la Rouge, November 2001)