SKIN LESIONS AND EPILATION voltage X-ray for dermatological conditions developed epidermoid carcinoma 5 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 numberofthe 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 proba- bility 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 occurrence of epilation 2 to 3 weeks after exposure corresponds roughly to the time of appearance of epilation in the Japanese exposed to gammaradiation at Hiroshima and Nagasaki (29, 30). Since the greater amount of epilation occurred over a period of a week to 10 days there was apparently no phasic response dependenton the growth cycle of thefollicles (inactive, or telogen andactive, or anagenfollicles) as has been reported (31, 32). The regrowth of hair, beginning about 9 weeks after exposure in the Marshallese, was at about the same time as noted in the Japanese 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 (33-36) 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 human beings (32, 37,and 38). In the Japanese bomb casualties (30) and the Japanese fishermen (11) the new hair was also normalin 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 Mar- shallese groups and in all 5 of the American Negroes, but none of the white Americans, it appeared to be a response peculiar to dark- skinned races. The phenomenon was appar- ently 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 Summary FoLLowine THE Detonation of a thermonuclear device significant amounts of visible radioactive material were deposited on inhabited atolls producing skin lesions, whole-body radiation injury and someinternal deposition of radionuclides. 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- y. 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 monthsafter exposure implies good repair. (d) Since low energy radiation was chiefly responsible for the skin lesions, the prognosis appears better because none of 1,100 individuals exposed to low 39