SKIN LESIONS AND EPILATION Biopsies of three pigmented lesions were taken from 2 of the white Americans of the Rongerik group. Only 1 of 3 showed evidence of dumage, which wasslight and confined to the epidermis. Third series—6th month post-exposure. Sec- tions of skin at this time revealed some changes persisting in the epidermis and to a lesser extent in the dermis (Plates 28 and 29). Epidermis. The following changes were found to varying degrees: focal atrophy of the stratum granulosum; slight focal pigmentary disturbances in cells of the basal layer; slight to moderate hyperkeratinization; and slight disturbances in polarity of epithelial cells in the still persistent basal papillary projections. Dermis. In the dermis, telangiectasis superficially persisted from a slight to moderate degree in most of the sections, and contributed the only abnormality noted. 3.33 Epilation and Nail Pigmentation E’pilation. The incidence and time of appear- ance of epilation in the various groupsisillus- trated in Tables 3.1 and 3.2, and Figure 3.1. Epilation was first observed of the fourteenth post-exposure day in the Rongelap group, and somewhatlater in the other groups. It was of a spotty nature and was confined almost entirely to the head region. Epilation was divided arbitrarily into 3 degrees of severity. “1+” indicated loss of hair without obvious thinning; “2+” indicated loss of hair sufficient to cause thin spots; and “3+” indicated an extensive epilation with bald spots. Table 1 illustrates that there was a greater degree of epilation in the children (0 to 15 years), with over 90 percent developing epilation to some degree as compared to only 28 percent in the older age group. The preponderance of scalp lesions in the areas of epilation indicated that radiation from the fallout material on the skin was primarily responsible for the epilation. Only three cases of mild epilation developed in the Ailinginae children, and questionable epilation 33 occurred in one of the Americans, characterized by loose hair upon combing but without areas of alopecia. Regrowth of hair in all individuals commenced sometime during the third monthafter exposure. .\t the 6 months’ examination complete regrowth of hair, normal in color, texture, and abundance had taken place. Plates 13-15, 17, 18, and 19 showepilation and regrowth of hair. Vail Pigmentation. An unusual observation was the appearanceof a bluish-brown pigmentation of the fingernails which wasfirst well documented on the 23rd post-exposure day. The «iscoloration began in the semilunar area of the fingernails (to a lesser extent in the toenails), and spread outward sometimes in streaks. .\s the discolored area grew distally the semilunar area usually became clear. Plate 20 shows pigmented bands in the nails at 77 days. At six months, pigmentation had grown out with the nails, and was no longer evident except in three cases which still showed pigment at the distal end of the nail. The pigment was on the under side of the nail plate. Discoloration of the nails was seen in a large proportion of the two higher exposure groups (Tables 3.1 and 3.2). The phenomenon appeared to be a radiation response peculiar to the dark-skinned races since it was seen in all of the exposed American Negroes und none of the white Americans supposedly receiving the same exposure. This lesion was not observed in the Utirik people or in unexposed Marshallese. Since the nail pigmentation occurred in individuals without skin lesions, it appeared to be the result of a more penetrating gamma componentof radiation. 3.4 Therapy Tue Treatment Or the skin lesions was largely non-specific. Most of the superficial lesions were treated with calamine lotion with one percent phenol, which in most cases relieved the itching and burning. .\ few of the hyperpigmented lesions not relieved by calamine with phenol were treated with pontocaine