New findings of long-term radiation effects on cancer and non-cancer risks among atomic bomb survivors and the need for animal experiments

After 50 years of studies important new findings are continuing to emerge from the Radiation Effects Research Foundation's ongoing epidemiological studies of the long term health effects of radiation exposure on the atomic-bomb survivors. Recent analyses of cancer risks have made it clear that the dose-related increases in cancer risk continues throughout life following acute exposure to radiation and that the excess rates appear to increase with attained age. These observations may provide some useful clues about the nature of radiation carcinogenesis. The survivor data also indicate that, with current dose estimates, the solid cancer dose response is remarkably linear in dose. In recent years it is also becoming clear that increasing dose is associated with increases in death and incidence rates for a variety of noncancer diseases in the survivors. While there are considerable uncertainties about the nature of the dose of the dose response at low doses (less than 0.5 Sv), these elevated risks are not limited to the highest doses (say above 1.5 Sv) as was thought in the past and cannot be explained on the basis of confounding with other factors (e.g. smoking). There is clearly a need for animal experiments and other studies that can help further our understanding of the mechanisms for radiation effects on non-neoplastic diseases. (author)