Radiation-related cancer risks at low doses among atomic bomb survivors

To clarify the information in the Radiation Effects Research Foundation dat a regarding cancer risks of low radiation doses, we focus on survivors with doses less than 0.5 Sv. For reasons indicated, we also restrict attention mainly to survivors within 3,000 m of the hypocenter of the bombs. Analysis is of solid cancer incidence from 1958-1994, involving 7,000 cancer cases among 50,000 survivors in that dose and distance range. The results provide useful risk estimates for doses as low as 0.05-0.1 Sv, which are not overe stimated by linear risk estimates computed from the wider dose ranges 0-2 S v or 0-4 Sv. There is a statistically significant risk in the range 0-0.1 S v, and an upper confidence limit on any possible threshold is computed as 0 .06 Sv. It is indicated that modification of the neutron dose estimates cur rently under consideration would not markedly change the conclusions. (C) 2 000 by Radiation Research Society.