4 graph. The data are handled somewhatdifferently this year: because of certain differences noted in age and sex groups between the exposed and the unexposed, in addition to the comparisons of mean levels for entire groups, comparisons are also made for the age and sex groups of age 7 to 15. 16 to 40, and >40 years. The data are summarized in Tables 12 and 13 and in Figures 34 to 30. In Appendices ! and 2 are classified according to age andsex, andin thescat- tergram (Figure 36) showing the larger number of individual counts belowrather than above the mean line of the unexposed. A cumulative per- centage distribution curve of counts combining the vounger and older males ( Figure 38) shows the curve for exposed males definitely displaced to the left of the curve for unexposed males of the same age groups. Among the females, onlyin the older presented summaries of the mean blood counts of group were the neutrophils slightly depressed (see son populations since exposure in March 195+. In Appendix 3 are listed the individual blood counts tor 1961. It should be noted that in 1960 onlythe exposed group were examined: therefore, the last complete data on both exposed and unexposed groups are for 1959. In Appendix +4 the individual alkaline phosphatase and basophil counts are presented. both sexes showedslightly higher neutrophil levels the exposed population and the various compari- Leukocytes The mean leukocvte levels in 1961 were some- what belowthe 1959 levels in the population at large, while both exposed groups (the only groups examined in 1960) showed a slight increase over the 1960 level. Changing neutrophil and lympho- cyte mean levels were generally parallel. As will be brought out. a slight deficit in both neutrophils and lymphocytes in certain age groups of the more Figures 35 and 37). In groups aged 15 to 40 vears. than unexposed people ofthe same age. Lymphocytes As with neutrophils. the exposed population at large showeda slight (6.3%) deficit of lymphocytes compared with the unexposed population (see Table 12 and Figure 39). Among the males, onlv the vounger age group showed slightly lower levels, while the three female groupsall showed lower levels. This maybe seen in the-histogram (Figure 35), the scattergrams(Figures +0 and +1), and the cumulative percentage distribution curve| Figure 42), Eosinophils, Monocytes, and Basophils These all showed slightly lower levels than in 1959. The levels of monocytes and eosinophilsin heavily exposed Rongelap people largely accounted for the lower leukocyte levels. The Ailingnae the exposed group were somewhat lower than in the unexposed group. As has been noted previous- various leukocytes as the unexposed group. The mean level of leukocytes in the exposed Rongelap people (175 r) was about 6% below that in the unexposed group. The percentage distribution ofthe various white cell levels in all groups was not very different from that previously reported. Table 12 and Figure 34 showleukocyte levels. were common in both groups. Neutrophils remained below the unexposed level by about 12°¢. Age distribution scattergramsfor the individual platelet counts in both males and females of the exposed population showed more counts below than above the unexposed mean curves(see Figures 44 and +5). This was also borne out by comparison of the cumulative distribution curves of the exposed and unexposed populations, the former showing a continued displacementto theleft (Figure 46). The platelet levels showed most depression in the exposed male groups of ages 7 to 15 group (69 r) showed about the samelevels of the The mean neutrophil count for the exposed population wasslightly (7.3%) below the mean count of the unexposed comparison population. (See Table 12 and Figure 34.) However, examination of the mean counts bv age and sex groups made it apparent that the deficit was largely accountedfor in the voung (age 7 to 15) and older males (age >+40 years). This is demonstrated in the histogram (Figure 35) showing the percentage differences in the exposed and unexposed groups ly, eosinophil counts >5 of the total white count Platelets The mean levels of platelets in the various age groups in both exposed and unexposed popula- tions were about the same as twoyears previously (see Table 12 and Figure 43). However, the level in the exposed group as a whole, as in the past.