Some recent statistical analyses of two long-term studies of exposure to ionizing radiation.

Two long-term studies of cancer mortality in population exposed to high doses of ionizing radiation are described briefly. Statistical analysis plays a key role in establishing to what extent it is appropriate to generalize from the experience of these populations to that of other populations who have been exposed, usually at lower doses. Two examples of recent analyses are given. First, a detailed comparison of the cancer mortality experience in the two studies has been carried out; this has shown a high level of agreement between them. In the second example the relation between the radiogenic risk and the baseline age-specific cancer risk in the two populations has been studied. Results are again in good agreement and show that for a group of epithelial tumours of non-sex-specific sites exposure to radiation multiplies the baseline risk.