3 uals of the same age groups showed no apparent differences. A biological age score was calculated for individuals and groupsby use of an average percentagescore. Life shortening effects of radiation have not been apparent. As noted, the mortality rate was about the same in the exposedasin the unexposed people: Development of thyroid pathology was noted in 1963 when a teen-age exposedgirl was found to have a nodule of the thyroid gland. In 1964, two additional teen-age girls were found to have nodules. These cases were operated upon, and the nodules were found to be benign adenomatoid goiters. These abnormalities are believed to be the result of exposureof the thyroid to radioiodines from the fallout and to the gamma radiation. The dose to the child’s thyroid was estimated as between 700 and 1400 rads from radioiodines and an additional 175 rads from gammaradiation for the group exposed to 175 rads. No nodules were detected in the unexposed children. . Twocases of cancer have developed in the exposed group. Thefirst appeared at 5 years post exposure, too soon, it is believed, to have been radia- tion induced. The second occurred at 8 years post exposure. Leukemia surveys including physical findings, studies of leukocyte counts and morphology, alkaline phosphatase staining, and basophil counts of 4000 white cells showed no evidence of leukemia or leukemic tendency. Onechild in the irradiated grouphas hadslightly elevated basophil counts but no other positive findings. The cardiovascular and arthritis surveys, as well as the general results of the physical examinations, have not shown any apparent increased incidenceof degenerative diseases in the exposed people. No radiation-induced cataracts have been observedin any of the exposed people. Genetic effects have not been specifically studied because of the small numberof people involved. No apparentradiation-induced genetic changes have been detected on routine physical examina- tions in the first-generation children of exposed parents, with the possible exception of suggestive evidence of increased miscarriages andstillbirths in the exposed women. BETA IRRADIATION OF THE SKIN It was impossible to get.an accurate estimate of the radiation dose to the skin. Beta burnsofthe skin and epilation appeared about 2 weeksafter exposure, largely on parts of the bodynot covered by clothing. About 90% of the people exposed on Rongelap had these burns, and a smaller number developed spotty epilation of the scalp. Mostofthe lesions were superficial; they exhibited pigmentation anddry, scaly desquamation, and were associated with itching and burning sensations. Rapid healing and repigmentation followed. Some lesions were deeper, showed wet desquamation, and were morepainful. A few burns became secondarily infected and had to be treated with antibiotics. Repigmentation of the lesions gradually took place in most instances, and the skin appeared normal within a few weeks. However, in about 15% of the people, deeper lesions, particularly on the dorsum ofthe feet, continued to show lack of repigmentation with varying degrees of scarring and atrophyofthe skin. At 10 years these conditions werestill evident in a numberofcases. During the past several years an increased number of pigmented maculae and moles have been noted in previously irradiated areas of the skin, but these have appeared to be quite benign. Numeroushistopathological studies have been made,’:*° and the changes found have been con- sistent with radiation damage. At no time have changes been observed either grossly or microscopically indicative of malignant or premalignant change. Spotty epilation on the heads was short lived, regrowth of hair occurring about 3 months after exposure and complete regrowth of normal hair by 6 months. Nofurther evidenceofepilation has been seen. Aninteresting observation noted duringthefirst few monthsafter exposure was the development of bluish-brown pigmentation of the semilunar areas of the fingernails and toenails in about 90% of the people exposed on Rongelap. By 6 monthsthis pigmentation had disappeared, having grown out with the nail. The cause of this phenomenonhas not been explained. INTERNAL IRRADIATION Radiochemical analyses of numerous urine samples of the exposed population showed internal absorption of radioactive materials, probably brought about largely through eating and drink- ing contaminated food and water and to lesser extent through inhalation. During the first few