survivors where any life-shortening action observed over more than 30 years can reasonably and entirely be accounted for by the induction of neopiastic conditions. And the differences of exposure between the United States radio- logists and the A-bomb survivors were such thet, on the basis of general radiobiological knowledge, non-specific life-shortening would rather have been expected from the latter than from the former series. 390. Pending further evidence therefore, it should be concluded that radia- tion-induced life-shortening in man is essentially due to the induction of specific neoplastic conditions. Non-specific effects on the life-span, sug- gested in one instance, have not been proven beyond doubt: the weight of these data is therefore insufficient to modify the above conclusions.