ofthe total while blooel cent (coefficien! of Correlation of 0.9). count were due to changes ib the neatrophiie count. ape proups., Thas (lacethuctasatais wo total This was true of both the older ined younger Tecan be seen from Table 4.2 that (he neutrophtle count’ was cousistently preater than the lymphocyte count in the older age group. In the younger groups, differences in the neu. frophile and lymphocyte count were less marked and on six occastons the lyinphoeyvie count wies older are proups were Approximately 70 per cent of the control group (Fig. 4.4). Following this, the platelet count fell reaching a low of approximately 35 per cent of control value during the fourth week. The platelet count rose during the 5th week and reached the value noted for the initial counts on the 40th day. A second decrease in the platelet count (P< 0,01) developed dur ing the 7th and 8th weeks, and values remained at approximately 70 per cent of the control troup during the remainder of the observation period. The pattern of platelet counts in the below 15-year group was remarkably similar to that noted in the older age groups. Differences between the age groups were jess apparent if the platelet counts were expressed as per cent of the control group. 4.6 cote ee ewe ay ee ee ete grevler than the neutrophile count. Platelets were first counted _10 days after exposure, at which lime platelet values of the AILINGINAE GROUP in this proup there wore only three individuals below age 5, For this reason, remarks will be confined essentially to the older aye proup. The absolute neutrophife count fluctuated around the control value for the first six weeks of observation (Table 4.3), At this time the counts began to fall, and a value approximately 75 per cent of the control count was reached and maintained throughout the duration of the obser- i vation period. The lymphocytes in this group fell to a value of 55 per cent of normal during the first week. The counts then Siuctuated around this value throughout the period of observatic n, and no definite upward trend of the lymphocyte count was noted during the period of observa- _ tion. . AS was noted in the Rongelap group the lymphocyte counts remained at an essentially constant low level throughout the period of observation. The total leukocyte count in this grour also reflected changes in the neutrophile count. 7 The platelet counts in the Ailinginae group were low, approximately 75 per cent of normal, when first enumerated on post-exposure day 10. The counts remained at this level during the second and third week; a low value 45 per cent value approximatcly 70 the observation period. 4.7 however, a definite fall in count was noted during the fourth week when of control was attained. The counts returned during the fifth week toa per cent of the control level, where they remained for the duration of A secondary fall, as observed in the Rongelap group was not detected. UTIRIK GROUP In the ¢reater than 5 age group the total white blogd cell and neutrophile counts were depressed slightly below control values during the first and second weeks (Table 4.4). The lymphocyte counts were below control levels consistently, and the total white count equal to the control value obtained on day 29 was due to a neutrophilic leukocytosis. Platelet counts on the 29th day were significantly lower than on the 19th day and were lower than control values. The 29th day coincides with the time of maximum depression for the more heavily exposed groups. 4.8 RONGERIK GROUP (AMERICANS) The neutrophile count in generai reflected the time course of the total leukocyte count (Fig. 4.5). Neutrophiles accounted almost entirely for the marked rise in total count on postexposure day one, and the values for absolute neutrophile count fluctuated near the contro} 80 '