-6Page 4, lines 3-24 - "There is an increasing body of published experimental evidence that reflects this t pd. "Speiss and Mays 622) observed that for Ra alpha radiation induced bone sarcoma in man, the tumor incidence per rad approximately doubled for a four-fold increase in the spacing of ““‘*Ra injections and that the observed incidence of bone tumors s per rad in children was nearly twice that for adults. Upton et al. 23) show a significantly higher incidence of tumors in mice for a given neutron dose at more protracted periods of exposure. Moskalev and Buldakov(24) showed that fractionation of the administered Pu dose over larger periods of time increased bone tumor induction. The higher tumor incidence per rad for the smaller lung burdens of crushed 239pu0, microspheres observed by Sanders seems best explained by the limited alpha irradiation of large numbers of cells by numerous very small, mobile particles of low acticity Bor particle (see below). Hamsters subjected to low alpha doses from 10p distributed quite homogeneously in the bronchiolar-alveolar region show a marked increase in the lung tumor incidence per rad at very low doses and dose rates\*’/?, And the incidence of bronchial cancer in uranium miners reflects a higher tumor risk per rad at the lower doses(2®) for this, jow dose rate exposure group. The tobacco radioactivity results +) indicate a significant tumor risk for the cumulative alpha radiation dose from 1059 in insoluble particles in the bronchi of smokers, involving much lower dose rates." Comments: Here the author indicates that "there is an increasing body of " published experimental evidence that reflects this trend", i.e., referring to "marked inverse dose-rate vs. risk relationship." Then the author cites various reports to support this. It is well known that fractionation or protraction (reduction of dose rate) of doses that as intensive doses are in the range of high doses that are relatively inefficient (per rad) for carcinogenesis (i.e., in the declining part of the dose-incidence curve following the peak at the most efficient dose level), owing to excessive cell sterilization or destruction, will increase the efficiency of such doses, It is also well known that fractionation or protraction of a dose that as an intensive dose is in the rapidly rising portion of a dose-squared doseincidence relationship (an efficient dose) will reduce the