neePe hieCees ngFade Sn ‘> sie aneBe NS agagtS ae wetwalm SPF ate ie om a se en et reenact ce ene FR Aah me Bee meme The accumulation of data from these surveysis occurred from year to year in the peripheral blood levels of the comparison populations as well as of of raw data, much of it in appendices, so that others may have an opportunity to make further calculationsif desired. tion levels occurred as follows. report, therefore, includes a considerable amount Summaryof Past Findings Reports have been published on the findings of surveys madeat the following times after exposure: initial examination,’ 6 months,” 1 year,’ 2 years,’ 3 years,’ 4 years,° and 5 and 6 years.’ The following is a brief summary of the findings previously reported. During the first 24 to 48 hr after exposure, about % of the Rongelap people experienced anorexia and nausea. A few vomited and had diarrhea, Many also experienced itching and burningof the skin, and a few complained of lach- rymation and burningof the eyes. Following this, the people remained asymptomatic until about 2 weeksafter the accident, when cutaneous lesions and loss of hair developed, due largely to betair- radiation of the skin. It was apparent when the people were first examined, a fewdays after exposure, that the lymphocytes were considerablydepressed andthat significant doses of radiation had probably been received. In addition to the wholebody dose of radiation and the beta irradiation of the skin, radiochemical analyses of the urine showed that measurable amountsof radioactive material had also been absorbed internally. The effects of the radiation can best be summarized underthree headings according to the modeofexposure: penetrating irradiation, skin irradiation, and internal irradiation. PENETRATING IRRADIATION The changesin the peripheral blood of the more heavily exposed Rongelap people who received 175 r will be reviewed in the section on hematological examinations (see Figures 34, 39, and 43. and Appendices | and 2). The changes in the Ailingnae and Utirik groups were similar but less 1kcracerentie nese ete marked. Certain unexplained fluctuations have becoming increasingly voluminous. Since conditions have not been favorable for performance of extensive statistical analyses or use of electronic computing procedures to store and manipulate the data, the annual survey reports published bythis Laboratory are made as complete as possible. This the exposed groups. The mean leukocyte level of the exposed group showed a marked decreaseat the time of the 1960 survey (no unexposed people were examined). Depression of the peripheral blood elements as represented by mean populaLymphocytesfell promptly and bythe third day were about 35% of the control values in adults, and slightly lower in children. There was only slight recovery after six months. At 2 years, although further recovery was evident, the mean values of these cells were still found to be below the comparison population levels (75 to 80%). At 3 years the mean lymphocyte counts wereslightly below those of the comparison population. At 4 years the mean level appeared to be about the same as that of the comparison population, but many counts remained lower. However, at 5 years, lymphocyte levels appearedfor the first time to equal those of the unexposed group, except that analyses showed more counts belowthe average of the unexposed group. Neutrophil levels fluctuated considerably during the first few weeks but fell gradually to a low of about 50% of comparison population levels by the 6th week after exposure. Slow recoveryensued, but at 6 monthsthey werestill slightly below the unexposed levels. However, by 1 year post exposure they had returnedto the level of the comparison population and have remained so, with the possible exception of those of children <12 years old, which generally have been lower than those of the unexposed children of comparable age. Platelets fell to about 30%of the unexposed values by the 4th week. By 6 months they had reached 75%of the controls; at 1 year the mean platelet count wasstill belowthat of the control population but higher than at the 6-month survey. Although further increases were apparentat the 2-, 3-, and 4-year examinations, the levels were still below those of the comparison population. At 5 years post exposure, exposed people still had mean platelet levels 10 to 15% belowthose of the unexposed group. Changes in hematocrit were not remarkable in anyof the groups during the period of maximum depression of leukocytes. However, it appeared 4