1.3 GENERAL METHODS; CONTROL POPULATION The facilities of the Marshall Island Memorial Hospital in the Trust Territory Headquarters were made available for the clinical and laboratory examinations. The resurvey included the establishment of a control group of unexposed Marshallese, in addition to obtaining interval histories, complete physical examinations, hematological studies, and radioactivity excretion studies on all the exposed individuals. Similar examinations were conducted on this control group for immediate comparison of findings and to serve as a base line for comparing growth and other future changes in the two groups. The control patients were obtained principally from amongthe residents of the village of Rita, located about 2 miles from the hospital. This population was chosen on the basis of its similarity with respect to the living conditions of the exposed people, its relative permanence, and its accessibility to the Memorial Hospital. The individuals were selected on the basis of age and sex to be paired with the members of the exposed group. Thus, each individual of the exposed group was assigned a control individual of the same sex and approximately the same age. The age distribution of the exposed and control populations is given with the hematological results in Chap. 4. The age distribution of the exposed and control groups was the same, except that suitable controls were not found for two women of reported ages 60 and 100, nor were controls established for the three babies born to members of the exposed group since March, 1954. Numbers were assigned to the controls by adding 1000 to the numberof the corresponding member of the exposed group. For example, Labnir, number 1011, was the control for Antak, number 11. REFERENCE 1. E, P. Cronkite et al., Study of Response of Human Beings Accidentally Exposed to Significant Fallout Radiation, Operation Castle final report of Project 4.1. 10

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