Since blood-formingcells are among the most radiosensitive cells in the body, hematologicalexaminations have been emphasized in both exposed and unexposed populations. Evidence of such sensitivity in the exposed Rongelap people was provided by the early acute depression of leukocytes and platelets and by possible residual effects on hemopoiesis indicated by a lag tn recovery of blood elements to the levels of the unexposed population. The developmentofa fatal case of leukemia mayalso be evidenceofresidualeffect. Leukocytes and neutrophils x 10-4 oo a C. HEMATOLOGICAL FINDINGS —~~ * Vth * -*} 4+— iL, a, ae A ‘de’ * ‘pH ae-oe Bay , one th w Neutrophils | 1234356789 1} 10 Days 1. Procedures Mo (3 2) 35 oT4 iF lo Iu 18 2 Years Timeafter exposure Figure 10. Mean neutrophil and white cell counts of Rongelap people from the time of exposure through 20 vears post exposure. Stars represent mean values of comParison population. Until 1972 vearly measurements were made of peripheral! blood elements, including WBC,differential white counts, RBC and hematocrit and/or hemoglobin, and platelet counts. Since a case of leukemia was found in 1972, such measurements have been made twice a year. The counts were done under a microscope until electronic means cameinto use (Coulter counter and Genera] Sci- ence Haema-Count MK 3 and MK instru- ments). Reticulocyte and bone marrow examinations have been done on several occasions by stan- * 10 + T mre TT TT TT r 2 8- a ‘n % 6~ Z a et dard procedures.* A numberofspecial hematological examinations over the years have includedtests for leu- w & oy at OLit pei ot yd tf 08 24 40 36 726123436789 ke mia (i.e., special scanning of blood smears for Days immature forms, basophil counts in 4000 cells, alkaline phosphatase staining of neutrophils,** analysis for Australiaantigens),’ studies ofred cell and plasma volume, chromosome analysis, etc. Plasma and red cell samples have been brought back for special studies in laboratories in the United States. These studies are further discussed Mo it Jl 13 35 1O 12 V4 dm ts ' os Years Time after exposure Figure 11. Mean lymphocyte counts of Rongelap peopie from time of exposure through 20 vears post expxsure Stars represent mean values of comparison pupulation 2. Recovery of Hemopoiesis In Figures 10 to 12 the mean blood counts of the combined (Rongelap and Ailingnae) exposed group are compared with those of the unexposed group overthe 20-year period. Data arelisted in Table 12 for the past 5 years, and in Appendix 6 for the entire 20 years. Figure 13 shows the cu*Mr. N. McDaniel of SUNYat Stony Brook has done thedifferential counts for the past several years. **Dr. W. Moloney and Mrs. L. Tullin at Harvard Medical School did the alkaline phosphatase staining of neutrophils in penpheral blood smears. *Dr. B.S. Blumberg, Institute for Cancer Research, Phila- deiphia, did the studies for Australia antigens. Platelets x 10-4 in later sections, where relevant. Out ee O08 244056726 1234567489 Il 10 Days Mo 12 13 _—- 15 14 17 16 19 18 Years Timeafter exposure Figure 12. Mean platelet counts of Rongelap people from time of exposure through 20 years post exposure. Stars "epresent mean counts of unexposed comparison popula . -ns. 2