some degree of residual skin changelargely in the form of pigment aberrations with atrophy and scarring. Numerous histopathological studies have been made, and the changes found have been consistent with radiation damage. However, at no time have changes been observed either grossly or microscopically indieative of malignantor premalignant change. Thespotty epilation on the heads was shortlived, regrowth of hair occurring about 3 months after exposure and complete regrowth of normal hair by 6 months post-exposure. No furtherevidence of epilation has been seen. An interesting observation was the appearance of a bluish-brown pigmentation of the semilunar areas of the fingernails and toenails in about 90% of the people beginning about 3 weeks after exposure. By 6 months, however, the pigmentation had largely grown out with the nail and had disappeared in most cases. The cause of this phenomenon has not been explained. Internal Irradiation Radiocchemicai analysis of numerous urine samples of the exposed population showed some degree of internal absorption of radioactive mate- tials, probably brought about largely through eating and drinking contaminated food and water. Calculations of the body burdensof these mate- rials, however, showed that the concentrations were too low to result in any serious effects, and the levels found at 2 and 3 years post-exposure were far below the accepted maximum permis- sible body level. The results of numerousradiochemical examinationsof the urines over the past + years, and of gammaspectroscopy over the past 2 years, will be reviewed in greater detail below. Present Survey BACKGROUND MATERIAL Organization The medical team consisted of 8 physicians. 5 scientists, and 6 technicians from various labo- ratories in the United States. A Marshallese practitioner and 2 medical technicians from Majuro Atoll assisted the team, as did someof the Rongelap people (see Figure 2). A groupofsix scientists from the University of Washington, headed by Dr. E.E. Held, accom- panied the team to collect soil, marine, and plant Figure 2. Medical team personnel.

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