TT 1111 ou “<3 zn 65 an TIT 3 TT 1111 3 COUNTS / MIN PER 50->kev BAND 3 17 1 Po te 23 4 5 6 7 8 9 10 14 12:13 14:15 ENERGY Mev Figure 17. Net in vive gamma-ray spectra of Marshallese. acute or subacute effects and late or long-term effects. The discussion will concern largely the 64 Rongelap people whoreceived the highest dose (175 r) of whole-body radiation. ACUTE AND SUBACUTE EFFECTS Penetrating Radiation Symptoms. The only symptomatological evidence of acute effect from the penetrating radiation was the occurrence of anorexia and nausea, and ina few individuals vomiting and diarrhea, during the first two days after exposure. That these symptoms were unequivocally related to radiationis validated by the fact that they did not occurin the groups receiving lower exposure. Other than these early ones, however, during the three years of examinations there have been no symptomsthat appeared to berelated to radiation effects, except those associated with superficial irradiation to the skin. Hematological effects. The early significantreduction of lymphocytes followed by depression of other leukocytes and platelets indicated that serious radiation exposure had occurred. Only a slight effect on erythropoiesis was observed in the form of a slight drop in the hematocrit levels during the first 6 to 8 weeks. The degree of the hematopoietic depression was consistent with the calculated dose of 175 r whole-body penetrating radiation. Determination of degree of hematopoietic recovery during the past two years has been in- creasingly difficult because of problemsin selec- tion of unexposed “control” populationsas outlined earlier; apparent changes in bloodlevels from yearto yearin different control groups; and closer proximity of the blood levels in the exposed groupsto those in the unexposed population. The general lowering of leukocytes in the exposed group this year would be disturbing except that the unexposed groupalso showedsimilar lower counts when comparedwith the control population used last year. One must consider the possibility that a downward trend in the white blood cell level of the whole population may be occurring such as has been reported in the Japanese people over the past 10 years."' If this is true in the case of the Marshallese, it would not seem that such a trend had affected the more isolated Utirik people, whose blood levels were more comparable with those of last year’s controls (Rita or B,). Determination of white blood cell levels of these groupsat the next annual medical survey at four years post-exposure will no doubthelp clarify this issue. It seemslikely that a slight lag in recoveryof lymphocytes and platelets does persist three years post-exposure when valuesfor these elements are compared with the unexposed grouplevels. In contrast to the leukocytes, the platelets showed a slight increase overlast year’s values. Negative results in bone marrow examinations(carried out at 6 months and during this survey) do not negate the possibility of a slight degree of impairment of hematopoiesis, since a slight depression of elements noted would not be likely to be detectable in the bone marrow examinations. The lowerlevels of hematocrits appearto parallel the reduction of leukocytes, and an explanation based on decreased erythrocyte production as a radiation effect does not seem likely, since erythropoietic depression was not a prominentfeature of the radiation effects and hematocrits are also low in the unirradiated population. Theslight anemic tendency maypossibly be related to blood loss associated with chronic parasitic infestation and other forms of chronic infection. Nutritional deficiency such as iron deficiency, low dietary protein, or interference with absorption of vitamin B,, are possibilities, but there is no good evidence that these factors are involved. They will, however, be given careful consideration in the next survey. Response to infection. The Marshallese experience has made it clear that nature has endowed human