Exposure to ionising radiation leads to a radiation dose. The main health effect of low levels of radiation dose is an increased risk of developing cancer. This document provides an introduction to the risks from exposure to low doses of radiation and explains the derivation of the radiation risk factors used in radiation protection.
The estimated values of risk factors are largely based on epidemiological studies of the Japanese atomic-bomb survivors, many of whom received medium to high doses of ionising radiation. These are supported by studies of other populations such as patients given medical exposures and workers receiving exposures at work. The International Commission on Radiological Protection used these estimates of radiation risk as the basis for their radiation protection system and made adjustments to allow for lower doses and lower dose rates.
The studies of the Japanese atomic-bomb survivors include many features of good epidemiological studies and the findings from studies of other populations are in reasonable agreement with them.