exposure day in the Rongelap group and was confined to the head. The epilation was divided arbitrarily into three degrees of severity. “1+” epilation indicates loss of hair without obvious thinning; “2+” indicates a loss of hair sufficient to cause obvious thin Spots; and “3+" indicates an extensive epilation withbald spots. Table 3.1 illustrates that there was a greater degree of epilation in the children (0 to 15 years). Over 90 per cent developed epilation of some degree inthe 0 to 15 years group, Compared to only 28 per cent in the older age group. ‘The preponderiace of scalp lesions tn the areas of epilation indicates that radiation from the fathout ma Table 3.20 LESIONS IN ATLINGINAB AND RONGERIK GROUPS A(finginne (18 people) Kongerih (28 people) Por Cent of Total with Lesions Mean Sime of Appearance ® G7 27 Scalp & Face Neck and 38.9 26 10.7 32 Shoulders Back Axilla Antecubltal 61.0 0.0 22,2 27 24 14.3 7.1 3.5 30 28 23 Fossue id 28 25.0 3.5 47 16.7 5.6 33 44 3.5 0.0 43 77.7 38 17.9 40 Type of Lesion Epilation Per Cent of Total with Lestons 3.51 Mean Time of Appearance 42 Lesions of, Hane & Wrist Feet Legs 5.6 38 29 Nail Disc Voration (All Negroes) * Days post -expusure. }One case clatmed slight epilation. Questionable, terial on the skin is primarily responsible for the epilation. In the Ailinginae group only three cases of mild epilation developed in children (Table 3.2). Slight regrowth of hair was observed in all individuals nine weeks after exposure. Hair regrowth wag complete and normal six months after exposure. 3.4 NAILPIGMENTATION An unexpected observation was the discovery of a bluish-brown pigmentation of the finger- nails which was first well documented on the 23rd post-exposure day. The discoloration began in the semilunar area of the fingernails (to a lesser extent in the toenails), and tended to spread outward sometimes in streaks. As the discolored area grew outwards the semilunar area usually became clear. In a few cases, detachment of the end of the nail from the nail bed was observed when the pigmentation reached the end of the nail. Plate 3.17 shows pigmented bands in the nails at 77 days. The discoloration of the nails was seen in 89 per cent of the Rongelap and 78 per cent of the Ailinginae group. It appeared to be a radiation response peculiar to the dark-skinned races since it was seen in all of the American Negroes in the Rongerik group and in none of the white men. This fesion wag not observed in the Utirik group nor in the control Marshallese. Since the nail pazmentation occurred in individuals without skin lesions, it ap~ peared to be the result of a more penetrating component of radiation than contact radiation which predominantly produced the skin lesions. 40