qi qa platelet counts were done. The hematocrit levels wereslightly increased overlevels of3. years ago, possibly indicating a better state of nutrition. None of the mean counts were very different from those of the unexposed comparison population (1965 counts) except for leukocytes, which were somewhathigher in the Utirik people. Appendix 10 showslevels of blood elements at various times since exposure. 50; _ T I T T FEMALES 1965 T I | 1 r 1 - 1 “er 1 Se HEMATOCRIT % t, e [ 40 i 4 4 e e e _ _ 4 4 | 35+ 4 * ° roo F ee rp 1 4 J 4 a -4 * F e : sob t 20 : 40 30 ] L 50 60 AGE (YEARS) ! 70 - l 80 1 90 Figure 63. Hematocrit values of Rongelap exposed females plotted against age. Solid line represents mean level of unexposed female population, 1965. $0,L e T-—e a ! e TT MALES 1965 I L - 4 4 Le 4 ase HEMATOCRIT Ve = IL L F 40 4 7 = 7 4 4 4 Le A 35h a 1 la 4 4 : 4 oy : 30! 4 1 20 30 L 40 l 50 60 AGE (YEARS) . | 70 1 on ~=—80té«é‘aD Figure 64. Hematocrit vaiues of Rongelap exposed males plotted against age. Solid line represents mean level of unexposed male population, 1965. Children of Exposed Parents Children of exposed parents born sincethefallout showed levels of peripheral blood elements about the sameasthose of children of unexposed parents of the same age range. Leukemia Survey No evidence of preleukemia or leukemicstate was detected in any of the people examined, either from the biood picture or from physical examination. Counts of 4000 whitecells for percent basophils revealed no abnormally high levels (see Appendix 13). Subject No. 3, a 13-year-old boy, continues to show about twice the numberof basophils (1.13%) noted in other Rongelapese. He has developed marked hypothyroidism during the past 2 years but shows no evidenceofincipient leukemia. Statistical Analysis of Rongelap Blood Data In the last report’® a factorial analysis ofvariance of Rongelap blood data over the previous 4 years indicated that the slight depression of blood elements (leukocytes and platelets) of the exposed population over this period was highly significant. However, a similar analysis of the 1965 hematological data showsthat at this time there was no significant difference (at the 5% level) of platelets, leukocytes, neutrophils, or lymphocytes between the exposed and unexposed Rongelap population.* This was also true for the Ailingnae population. The significantly greater platelet level in this group is unexplained. There was evidence that the leukocyte and platelet levels of the youngest age group in all populations were higher than in adults. No sex differences could be demonstrated in any of the 1965 data. The percent difference in blood levels between exposed and unexposed groupsts presented in Table 24 and Figure 65. It can be seen that at 11 years there is no substantial difference between the groups. CHROMOSOMESTUDIES Since chromosomeaberrations have been dem- onstrated in cultured blood cells from various groups of people exposed to radiation, even years after exposure, it was of interest to see whether any such aberrations were present in the people of *Weare grateful to Mr. Keith Thompson of Brookhaven Na- tional Laboratory for the statistical analysis of these data.