1966 年 1 巻 2 号 p. 64-70
Reduction of radiation injury and evaluation of risks following exposure are both of great importance in the peaceful use of nuclear energy.
In this paper discussions are given to the latter and relevant problems are listed as to the former.
For the practical purpose of radiation protection against radiation hazards it often becomes neccessary to establish levels as to the expected exposure dose, for which not only scientific but also social and economical considerations have to be taken into account. There are three categories of effect to be considered in biological evaluation: 1, early effect due to acute exposure, 2, late effect and 3, genetic effect in the population at large.
Evaluation of risks requires a quantitative information about dose-effect relationship, as to which two contrastic hypotheses are available, i. e., the one which assumes a linearity and the other which proposes a threshhold dose. Present state of knowledge, in which no mechanisms of biological effect of radiation are erucidated, has to acknowledge both hypotheses to be practical and useful approach, each being complementary to another. Dose-effect relationship with regard to late effect, which is of vital importance in man, is discussed from currently available data. Several research themes which may contribute to the biological evaluation of risks are illustrated.