SKIN LESIONS AND EPILATION 39 the vast majority of cases. Such changes have been generally observed prior to the development of radiation cancer. (c) The lack of any marked histological damage 6 months after exposure implies good repair. (d) Since lowenergy radiation was chiefly responsible for the skin lesions, the prognosis appears better because none of 1,100 individuals exposed to low voltage X-ray for dermatological conditions developed epidermoid carcinoma5 to 23 years after treatment (27). (e) Furthermore epitheliomata rarely develop after a single dose of radiation to the skin (12). (f) Lastly the incidence of skin cancer in Negroes is one-sixth to one-ninth the incidence in Caucasians (28) in the United States. Other factors make the outlook less favorable: (a) Deeper lesions of the feet and neck continued to show pigment aberrations and slight atrophy at 1 year, and one severe ear lesion showed marked atrophy and scarring at this time. (b) It is not known whether or not radiation of the epidermis per se can predispose to malignant change. Since the epidermis was heavily irradiated in these cases, compared to the dermis, this becomes an important consideration. (c) Since many children and young adults were involved, the life expectancy of a large numberof the individuals will exceed the long induction period for the development of radiation cancer observed in radiologists. (d) Exposure to tropical sunlight, potentially carcinogenic in itself, may increase the probability of neoplastic change. (e) The influence of the sublethal whole-body exposure received by these people on induction of skin cancer is not known. The regrowth of hair, beginning about 9 weeks after exposure in the Marshallese, was at about the same time as noted in the Japanese exposure corresponds roughly to the time of appearanceof epilation in the Japanese exposed to gammaradiation at Hiroshima and Nagasaki Fo.Low1nG THE DETONATION of a thermonuclear device significant amountsof visible radioactive material were deposited on inhabited atolls producing skin lesions, whole-body radiation injury and some internal deposition of radionu- The occurrence of epilation 2 to 3 weeks after (29, 30). Since the greater amount of epila- tion occurred over a period of a week to 10 days there was apparently no phasic response dependent on the growth cycle of the follicles (in- active, or telogen and active, or anagenfollicles) as has been reported (81, 32). S041 24 fisherman (11), and slightly later than the time of regrowth (6 to 8 weeks) noted in the Japanese bomb casualties. In contrast to the marked pigmentation changes noted in the irradiated skin of the Marshallese, there were no pigment aberrations in the new hair, which was observed to be of normal texture and abundance at 6 months. Increased graying has been reported in animals (83-36) but has not been seen in human beings. Neither was there any appearance of dark hair in aged individuals whoalready had gray hair as has been reported in humanbeings (32, 37, and 38). In the Japanese bomb casualties (30) and the Japanese fishermen (11) the new hair was also normal in color, texture, and abundance. , The nature of the bluish-brown transverse bands of pigmentation that developed beneath the nails is not known. Since it occurred in the majority of the more heavily exposed Marshallese groups and in all 5 of the American Negroes, but none of the white Americans, it appeared to be a response peculiar to darkskinned races. The phenomenon was apparently produced by gammaradiation with a dosage as low as 75 r since this was the estimated dose that the American Negroes received in the absence of significant contamination of the hands. Sutton (39) has reported a case of simi- lar fingernail pigmentation which developed in a negress, following 150 r of soft X-irradiation to the hands. 3.8 clides. Summary The skin lesions in the more heavily contaminated groups were characterized by itching and burning of the skin for 2448 hours. Epilation and skin lesions were observed, be-