Pregnancy and ionising radiation: most occupational exposure adds little to background levels. (Editorial)

Most occupational exposure adds little to background levels

About a quarter of a million people are occupationally exposed to ionising radiation in Britain.[1] A fifth of these are women, nearly all working in the health services or as aircrew. What advice should they be given about pregnancy?

Large doses of radiation are harmful, yet we cannot accurately determine the risks of small doses because any small increase in cancer or inherited disease is masked by the natural variation in these conditions. The effects of small doses of ionising radiation are probably not analogous to small insults of heat, cold, trauma, or poison, which have thresholds below which no injury occurs. Ionising radiation deposits its energy in very small, subatomic sized volumes. At a point of ionisation the energy deposited per unit mass is similar to that at the centre of an atomic explosion. It causes injury to chromosomes, and this injury occurs at very low doses.[2] Trends of increasing rates of cancer are seen in workers in the atomic power industry exposed at low dose rates and to low doses.[3]

The harm done by ionising radiation depends on two factors: the effect per unit dose and the dose received. …