acute irradiations are of major concern in human radiation protection. some research workers Also, [G1, G6] point out other advantages, like the linearity of the relationship between the log mean after-survival of the animals and the daily exposure level. This property might facilitate the description of the effect and justify comparisons between various animal species or various types of radiation. 98. On the contrary, others believe that the terminated exposure technique, rather than the exposure to death might be more apt to give unbiased answers. Based on evidence on irradiated DBA mice Mole M6] examined the concept of what he called "wasted radiation" for exposure to death, that is, the amount of radiation administered in excess of that strictly required to kill the animals. Mole showed that under some conditions of exposure the wasted radiation would amount to over one-half of the mean accumulated dose. This implied that the duration-of-life exposure conditions would be unsuitable to establish precise dose-time relationships for life-shortening. Actually, the mean accumulated dose would be overestimated on account of the wasted radiation and the mean survival time would be put in doubt by the fact that each specific biological response to radiation might take a different and characteristic time to deve- lop. According to Mole.[M6], for all these reasons terminated exposure con- ditions should preferably be used. 99. The concept of wasted radiation was utilized by many research workers in the field, although often without much experimental ground, to account for data that could not otherwise be explained. The concept stems from the notion that each specific disease or pathologic condition has a latency time between induction and clinical manifestation; there is also more time intervening between the appearance of the disease and its development into a lethal condition. The biological arguments underlying the concept of wasted radiation are indeed well founded but there are different views as to the practical importance of this concept since the amount of wasted radiation appears to be neg- ligible [L7] or very substantial [M6] under different experimental conditions. Sacher and Grahn [Sk], Grahn and Sacher [G1] and Sacher |S23] have repeatedly criticized the concept of wasted radiation pointing out that it does not lend itself to any easily testable implications. In their opinion, there are in- deed changes in the effectiveness of a given dose with an increase of the protraction time (see paragraphs 151-191) and under appropriate circumstances