where 144 people were examined. Theship served as a base of operations and laboratory (Figure 2). The physical examinations at Utirik were carried out in tents ashore (Figure 3). Several unfavorable factors associated with the examinations should be mentioned: 1) The language barrier made the examinations difficult since very little English is spoken by the Marshallese. However, sufficient interpreters have been available to assist the medical team. 2) The lack ofvital statestics from the Marshallese imposes a serious difficulty in interpretation and evaluation of the medical data. Such statistics would be extremely helpful in evaluating the long-term effects of radiation. In recent years records ofbirths, deaths, etc., have been kept by the health aids or magistrates and supposedly forwarded to the district administrator; however, such records have been poorly kept or lost and thusvital statistics are practically nonexistent. 3) Another factor was the uncertainty ofexact ages of some of the Marshallese, particularly in the older groups, largely due to lack of written birth records. Exceptfor the first, birthdaysarelitte observed. 4) The medicalstatusis also complicated by unhygtenic living conditions evidenced by the presence of parasitic infestation, chronic skin diseases, and extremely poor oral hygiene. Possibly dietary deficiencies also exist (this will be further evaluated on later surveys). 5) During the course of these studies over the past three years, difficulties have been encountered in 0btaining what could be considered as entirely adequate populations to act as comparison groupsfor the irradiated people. Two separate comparison groups had been used in the past, each comparableto the exposed groupin size and closely matched for age and sex. These groups are represented in hematological graphs of this report as A and 8 (8, and B,). The A population was chosen at Majuroat the time of the initial examinations, but at six months post- exposureit was found necessary to select another group,the B, group, since many members of the A group were missing (had migrated to otherislands, etc.). At the two-year examination, the B group (8, ) was used again even though about one-third of the group was missing. The people in the 4 and B groups were mostly Marshallese from the eastern chain of the Marshall Islands andare considered to be anthropologicallyslightly different from people of the western island chain to which the Rongelapese understudy belong.’ At the time of the present survey,it was found that during the preceding year the Rongelap pop- ulation had doubled at Majuro Atoll by the influx of other Rongelap people who had been away from the island atthe timeofthe accident but had since returned. This situation was mostfortunate, since this group of people was of the samestock (blood relatives) and was living with the population under study under the same environmental conditions. These people provided a uniquely appropriate groupto serve as a comparison popula- tion. Moreover, they matched reasonably weilfor age and sex and would be available for furure examinations since they planned to return to Rongelap Islandto live. This group is represented as C in the graphs. For the growth and development studies, as many of the old B-group children as could be found were examined in addition to the Rongelap children in order to expand the number. for comparison and furnish further longitudinal data for yearly studies. EXAMINATIONS Histories were taken by a Marshallese practitioner with particular emphasis on theinterval history during the past year. Complete physical examinations were carried out including examination ofthe skin with color photography and biopsies of selected lesions; ophthalmological studies includingslit-lamp observations, visual acuity, and accommodanion; growth and development studies in children (less than 20 years of age) including anthropometric measurements and x-ray examinationsof the left wrist and hand for bone developmentstudies; audiometer examinations on all over 30 vears of age; ECG records on all over 40 years of age; and x-ray examinatons as deemednecessary. Hematotogical examinations included three complete blood analyses including WBC, differential, platelet counts (phase microscopy), and hematocrit (microhematocrit method) done at about weekly intervals. (Only one complete blood study was carried out on the Uurik people except for repeat examinations on those with abnormal counts.) In addition, sickling tests (sodium bisulfide technique) were run, and smears were obtained for reticulocyte counts, alkaline phos-

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