the unomposed populations by 2 years. The time course of neutrophil count changes foliowed clescly that of the total white count. Lyapkocyte depressioa was early and profound (fig. 9) with craducl retucn tewaecd nozmal. that of the umemposed groups as 3 years. The counts remained below The ‘platelet count reached a low at approzinately 4 weeks (fig. 10) with faisly rapid initial recovery follLowed by a seconcary depression and slow return towards noemal. platcliet counts were At three years the moan stiii slishtiy celow the mean of the unexpoced populaticn. Tanz hematocrits at no tine wore remeochably different from the unexposed levels. As the tines of peak depression, some individuals had neutrophil counts belew CS0/am> and pistelet counts. beloy 75,000fan. No infections attributable to the neutzopenia were observed, however, ond an epidemic of upper sespirctozy Iintectica at eppromimately the time cf maximum neutrophil depression was cquaiiy scavily and mildly exposed groups. the platelet depression. severe in the No hemorzshacic phenomena could be attributed to Ail individuals were ambulatory throughout, and no therapy Cother than for the skin Lesicns) beyond that routinely required for any lazge groups of individuals was necessasy or administered becouse of the radiation expos- ure. The £3indings aticu accurate documentation of the response of the huran being to total-body gamma exposure in the bish subicthal ranse, not possible in the Japanese exposed at Hiroshima and Nesecsati. aspects from that scen in nm Inborstory animals, early rise, vith only minimel Acvering The total white count shows aa mtit masimum depression occurs at apnromd- A simiZas trend is secon with tha neutrophil count. ymohocytes is carly and severe. oO mately 6 wees. The time course differs in important The droy in The platelet count fatis in a secuins fashion, seaching a Low at approwinately 53 days. The rate of recovery is considerably siewer than would be anticipated fren laboratory animal data and is incempicte at wm 3 years. These findings ore consistent with the incomplete data available on the

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