-1Q0- were done on post exposure day 3, at which time a drop in total white count was evident. The count then fluctuated perhaps as a result of the beta lesions, with no severe depression over the first 4 weeks. occurred, reaching minimum levels at 6 weeks. of the unexposed populations by 2 years. A marked depression then The counts approached the levels The time course of neutrophil count changes followed closely that of the total white count. .Lymphocyte depression was early and profound with gradual return toward normal. The counts remained below that of the unexposed groups up until 11 years post exposure (See Fig. 19). The platelet count reached a low at approximate ly 4& weeks with fairly rapid initial recovery followed by secondary depression and slow return toward normal. The hematocrits at no time were remarkedly different from the unexposed levels. At times of peak depression, some individuals had neutrophil counts below 1000 per mm? and platelet counts below 75,000 per mn? No infections attributable to the neutropenia were observed, however and an epidemic of upper respiratory infections at approximately the time of the maximum neutrophil depression was equally severe in the heavily and mildly exposed groups. No severe hemorrhagic phenomena could be attributed to the platelet depression except that menorrhagia occurred in 3 women. All individuals were ambulatory throughout, and no therapy (other than skin lesions) beyond that routinely required for any large group of individuals was necessary or administered because of the radiation exposure. Except for radiation-induced lesions of the skin, patchy epilation, and early gastrointestinal symptoms, no clear cut disease processes or symptoms were noted which could be related directly to radiation exposure. During the first few months post exposure about two-thirds of the exposed people exhibited loss of weight of several pounds. This may possibly have been related to their radiation exposure, ‘although it was difficult to rule out effects due 5001301