How are risks from ionising radiation estimated?
If the dose of radiation to which people have been exposed is known, then it is possible to calculate the probability that harmful health effects would ensue. This is done using risk factors and our primary source of risk factors is the population that survived the A-bombs in Hiroshima and Nagasaki. These have been exhaustively studied and, although we do not know the exact radiation dose which each individual received, the risk factors for different cancers and other end-points are now known with a reasonable degree of accuracy. A-bomb survivors are not our only source of information, however. There are many other studies involving people who have received high doses (such as patients given radiotherapy), moderate to low doses (such as patients given certain diagnostic procedures and radium dial painters), and low doses spread out over long periods (such as workers in the nuclear industry). These studies involve exposure to radiations of different types. In addition to these epidemiol
