In Table 3.1 is tabulated the incidence of the various types of lesions in the Rongelap peroup with a breakdown as to age and the median time of appearance. Similar data are presented in Table 3.2 for the Ailinginae and Rongerik groups. 3.2.2 Description and Ilustration of Specific Lesions The scalp and forehead lesions appeared 12 to 14 days following exposure along with epiJation in the Rongelap group. The skin lesions were maculopapular with a spotty distribution. They were concentratedin (he areas of epilation. These lesions are illustrated in Plates 3.12 to 3.16. Scalp lesions continued their appearance over a period of about a month. Thus, groups of lesions in various stages were present in the same individual. This was particularly notable among the children, ‘The incidence of scalp lesions wis greatest in the 0 to 15 year group (see Table 3.1). The neck lesions were the most common and began their appearance a few days after the scalp lesions, These lesions appeared as hyperpigmented macules and papules which spread and coalesced into raised plaques, The fesions usually appeared first on the side and front of the neck and spread backwards. They were more common and more severe in women, Plates 3.1 through 3.4 and 3.9 illustrate neck lesiong in the various stages of development. Someof the deeper neck lestons tended to occur in women where their thick hair touched their necks. Axillary lesions were maculopapular, less abundant, and developed simultaneously with the neck lesions. These lesions are illustrated in Plates 3.10 and 3.11. The axillary lesions were more commonin the young children. Antecubital fossae lesions appeared about a week later than did the neck and axillary lesions. These are illustrated in Plates 3.9 and 3.10. The foot lesions developed later than the lesions of the antecubital fossae. These lesions were located mainly on the dorsum of the foot between or on the toes. They wereinitially characterized by large pigmented plaques with subsequent bullous formation and in eight cases raw crusting lesions of varying degree followed the bullae. The foot lesions were not as common in children under 5 years of age as in the older age groups. Sequential lesions in a 14year old girl are shown on Plates 3.5 to 3.7. One of the more severe foot lesions is shown in Plate 3.8. ~ Lesions of the hands, arms, legs, and trunk were less common, less severe, and developed later. Areas of increased pigmentation were scattered over the abdomen, chest, arms, legs, and face. Increaged pigmentation of the sides of the face is illustrated in Plate 3.4. A striking early lesion was an erythematous, weeping, excoriating lesion surrounding the anus which oc- curred in several of the babies and a few of the older people. These lesions were severe initially but healed rapidly. Most of the Marshallese had multiple lesions. The combination of epilation and the contrasting hyperpigmented and depigmented areas adjacent to normal skin presented a striking appearance. The multiple lesions are illustrated in Plates 3.8 to 3.11. 3.2.3 Severity and Time Appearance of Lesions in theVariousExposure Groups It is not feasible tu quantify accurately the severity and extensiveness of the skin lesions in the various groups. However, it was the uniform opinion of all observers that the most severe and extensive lesions occurred in the Rongelap group. The lesions that developed in the Ailinginae group were much less severe and extensive, and the Rongerik group (Americans) had only mild lesions. Skin lesions were completely absent in 60 per cent of the Rongerik group, as opposed to approximately 10 per cent in both the Rongelap and Ailinginae groups. Transepidermal necrosis occurred in 20 per cent of the Rongelap and in 5 per cent of the Ailinginae people. No lesions of this severity were seen in the Rongerik group. The lesions appeared earlier in the Rongelap group suggesting a higher dose. The comparison of the incidence of epilation and neck lesions and time of appearance is illustrated in aeecee Fig. 3.1 for the Rongelap and Ailinginae groups.