11 diation, but the caustic nature of the fallout may have contributed. The G.I. symptoms in the Rongelap people consisted of anorexia and nausea (in about twothirds of them) and to a lesser extent of vomiting and diarrhea (in one-tenth of them). Only a few in the Ailingnae group complained of these symptoms, and no one in the Rongerik and Utirik groups. The gamma exposureis thought to have been sufficient to accountfor the G.I. symptoms, but the ingested radioactive material (estimated at about 3 mCi) may have contributed. The G.I. symptoms were more prevalent in the Rongelap children (see Table 4). These symptomslasted only about two days and had largely disappeared by the time the people arrived at Kwajaletn. depression was greater in the children, particu- larly those exposed at <5 years of age (see Table 5). The changes are enumerated below in more detail. Lymphopenia to about half the level of the com- parison Marshallese population was evident when the Rongelap people were first examined 3 days after exposure. In children <5 years of age the lymphocytes dropped to 25% of the level of the comparison children but showeda slight rise dur- Appendix 6 and graphically in Section III. C. The showed a slight increase by one year. The early sequent years are presented in tabular form in early findings are summarized here and thelater ones in Section ITI. C. Oneof the earliest findings in the Marshallese indicative of significant exposure was lowering of leukocyte and platelet levels in the peripheral blood. This was most marked in the 64 people on Rongelap who had received 175 rads and less so in other groups receiving less exposure. The hemopoietic depression was roughly proportional to the gamma dose of radiation received. Even in the 157 Uturik people who received only an estimated Table 4 Nausea and Vomiting in Rongelap Group™ Incidence, % Age at exposure, yr No. Nausea Vomiting <5 26 13 51 85 44 38 4 Table 5 Mean Blood Counts at Peak Depression in Rongelap Group”? Percent of control Age <5 Neutrophils 7 CD cc" Lymphocytes Platelets tN - radiation, since it was not considered likely that the dose from internally absorbed radionuciides contributedto it significantly. The hematological hematological findings and the fAndings in sub- b. Depression of Blood Elements. cD 14 rads, it was possible to distinguishslight platelet depression in the group as a whole. The smaller groups on Ailingnae and Rongerik showed peripheral blood levels between those of the high and low exposure groups. The hematological depression was thought to be due entirely to gamma 36 25 23 Age >5 64 35 34 ing the following weeks. The lymphocytelevels Veutrophil levels showed considerable fluctuation during the first month, possibly related to the prevalence of beta burns of the skin during that period. Neutrophil depression became evident by 3 to 6 weeks post exposure, the level dropping to abouthalf the control level in adults andslightly lower in children aged <5 (Table 5). Neutrophils recovered more rapidly than lymphocytes and reached near contro]levels by one year. Early platelet counts showed less fluctuation than other blood counts and decreased to about 30% of control levels by the fourth week. A spurt of recovery to about 75% of control levels occurred during the next few weeks, followed by slower recovery with mean levels never exceeding 90 to 95% of control levels during the first vear. The platelet count is probably the most sensitive index of the severity of radiation exposure in the sublethal range. ; Erythropotetic depression has not been a consistent finding, and radiation effects on these cells have not been demonstrable by peripherai blood counts. Morphologtcal changes. During the period when neutropenia was most severe, some people were found to have peculiar monocytic leukocytes that were thoughtto be large lymphocytes. These cells were not found subsequently, although an occasional binucleated lymphocyte was seen. ¢. Clinical Findings. The developmentofsig- nificant depression of peripheral blood leukocytes and platelets during the first 6 weeks was cause for considerable apprehension among the medical