Ques to the present discussion of beta exposure .1° One summarizing statement of the short-term effects stated, "=-though the gastrointestinal tract is one of the sensitive systems to ionizing radiation, it also has a most remrkable regenerative and reperetive capacity. It takes doses of well over a thousand roentgens to damage the gut permanently in most mammals studied, and it is capable of rapid,-. dramatic recovery of anatomical and functional integrity with doses in the lethal range." Evaluating the data from dogs exposed to whole-body X- radiation the authors said, "--- it 1s suggested that doses of approximately 1,100 to 1,500 r may represent the upper limit of the possible efficacy of supportive measures in the treatment of the syndrome of acute radiation jmjury. With greater doses the damage to the intestinal mucosa appears irreparable and of an extent incompatible with lite "12 At the same time, it has been repeatedly indicated that the irradiation of the gastrointestinal tract plays a major role in gross whole-body effects associated with radiation syndrome. 11, ? 12, » 13,13, 14, » 115, 16, 17,17, 18, 2 19, 19; 20 In fact one author 3 . Bummarizes several experimental findings, "In producing acute intestinal radiation death, irradiation of any major portion of the exteriorized small intestine alone is almost equivalent to whole-body irradiation---." Graph Five suggests the relative doses to the parts of the gastrointestinal tract, from ingestion of fallout material. The available ex- perimental data does not permit a conclusive statement as to whole-body effects to be expected from such ratios of exposures. Most of these experiments are related to the criterion of death, but they do suggest - 10 - DOE ARCHIVES /¥3 a