REOTEeT to the present dtecussion of beta exposure. One sumerizing statement of the short-term effects stated, So ee though the gastrointestinal tract is one of the sensitive systems to ionizing radiation, it also bas se most remarkable regenerative and reparative 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 seid, "--- it is 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 | znjury. With greater doses the damage to the intestinal mucosa appears irreparable and of an extent incompatible with uite."12 at the same time, it has been repeatedly indicated that the 4rradistion of the gastrointestiral tract plays a major role in gross whole-body effects associated with radis- tion syndrome 1» 12, 13, 14, 15, 16, 17, 18, 19, 20 Tn fact one author?3 summarizes several exp2rimental findings, "In producing acute intestinal radiation death, irradiation of any major portion cf the exteriorized small intestine alone is almost equivalect to whole-body irradiation---." Graph Five suggests the relative doses to the parts of the gastrointestinal tract, from ingestion cf fallout material. The available ex- perimental ceta 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 tke criterion of death, but they do suggest DOE ARCHIVES VN ™~N - 10 -