43. pulation is difficult to explain, Evidence for residual bone marrow injury mayalso be associated with continued slight depression of the peripheral blood elements noted above,the finding of bizarre nuclear forms and binucleated forms in bone mar- row examinations, anda slight increase in incidence of aneuploidy and 2-hit aberrations in chromosomestudies of cultures of the peripheral blood lymphocytes. ‘ounts of exposed 15-year period OT POSURE Summaryof Findings in Rongelap People Over the Past 15 Years The effects of fallout radiation on the exposed Marshallese can be categorized as prodomal, acute, andlate effects. Somespecial studiesare also discussed below. PRODROMAL RADIATION EFFECTS io 20 8 ATELETS x to-* ibution curves »ple in 1969. the comparison ‘and Figure 41. oted in the popived a very low to compare the ition with those 3 because of difssibly in ethnic d cells revealed al lymphocytes, ition. Thesecells xcytes orslightly ophilic, and the h no indentation were present in oup, 30% of the of the unexposed irik population. »osed Rongelap diation exposure, 1 of the exposed During the first 24 to 48 hr after exposure, about % of the people experienced anorexia and nausea. A few vomited and had diarrhea, many also experienced itching and burningof the skin, and a few complained of lacrimation and burning of the eyes. None of these symptomswas noted in the Utirik people (14-rad group). Followingthis, the people remained asymptomatic until about 2 weeksafter the accident when cutaneouslesions andloss of hair developed, due largely to betairradiation of the skin. It was apparent when the people were first examined, a few days after exposure, that the lymphocytes were considerably depressed andthatsignificant doses of radiation had probably been received. In addition to the whole-body dose of radiation and the beta irradi- ation of the skin, radiochemical analyses of the urine showed that measurable amounts of radioactive material had also been absorbedinternally. “ACUTE EFFECTS Penetrating Radiation _Oneoftheearliest findings indicative ofa significant exposurein these people was lowering of levels of leukocytes and platelets of the peripheral blood. This was most marked in the 64 people on Rongelap whohad received 175 rads andless so in the other groups receiving less exposure. The hemopoietic depression was roughly proportional 5006300 to the dose of radiation received. Even in the 157 Utirik pepole whoreceived only an estimated i4 rads, it was possible to distinguish slight 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 chronological records of blood findings in the group exposed on Rongelap are presented in Figures 38 to 41 and Appendix 8. Lymphopenia of about half the level of the comparison Marshallese population was evident when the people exposed on Rongelap werefirst examined on their arrival at Kwajalein 3 days after exposure (see Figures 39 and 41). In children <5 years of age the lymphocytes dropped to 25% of the levels in the comparison children, but showed slight rise during the following weeks. The lymphocyte level showeda slight increase by 1 year. In the following year mean counts approachedthelevels of the comparison population but remainedslightly belowit. Neutrophil levels fluctuated considerably during the first month; possibly this was related to the prevalence of beta burns of the skin during that period. Neutrophil depression became evident by 5 and 6 weeks post exposure (see Figures 38 and 41) with levels reaching about half that of the comparison population in the adults andslightly lowerin the children <5 years of age. This degree of neutropenia wasinsufficient to result in any apparent increased infectious processes, and,indeed, it was noted that neutrophilic leukocytosis was possible in people showingcasual infections at this time. Neutrophil levels recovered more rapidly than lymphocyte levels and reached near control levels by 1 year. Subsequent annual surveys have revealed that recovery does not appear to have been complete, particularly in younger and older age groups, during the 15-year period. Early platelet counts showedless fluctuation than other blood counts and fairly consistently showed increasing depression, reachinglevels of about 30% that of the comparison population by the 4th week. A spurt of recovery to about 75% of comparison levels occurred during the following few weeks, which was followed by slower recovery but with mean levels never reaching higher than 90 to 95% that of the comparison population during the 15 years post exposure (see Figures 40 and 41). Erythropotetic depression has not been a consistent finding as with the leukocytes and thrombo- , oe