The problem arises, in part, because the general public—and even most scientists—are not aware that exposure to ionizing radiation is only weakly carcinogenic. The evidence comes from a number of different studies. Among the 82,000 survivors of the Hiroshima-Nagasaki bombing, for example, an average exposure of 27 rem only raised the number of cancer deaths by 6% over the number expected in the absence of such exposure. Radiation-induced leukemia among the survivors began to appear two to three years after exposure, reached a peak at five to six years, and declined thereafter.
Studies in experimental animals have shown that the duration of the exposure, not just overall dose, is important. Acute exposure generally results in a much higher incidence of tumors than does the same dose delivered over a period of hours to days. It is possible that the Chernobyl accident may provide a direct answer about dose-rate effects in ...
