28 EFFECTS OF IONIZING RADIATION were absent until the visible lesions developed. During the early stages of development of the lesions, itching, burning and slight pain were experienced with the more superficial lesions. With deeper lesions pain was more severe. The deeper foot lesions were the most painful and caused some of the people to walk on their heels for several days during the acute stages. Some of the more severe lesions of the neck and axilla were painful when turning the head or raising the arms. The lesions did not produce any constitutional symptoms. 3.3. 3.31 Description of Skin Lesions* Gross Appearance The time of appearance and the severity of the lesions varied with the degree of skin contaminationin the different groups. The Ronge- lap group, which showed greatest radioactive contamination of the skin (according to instrument readings) were the first to develop lesions and epilation at about 12 to 14 days after the accident. They also had the mostsevere lesions. Skin lesions in the lesser exposed Ailinginae and Rongerik groups developed approximately one week after fhose in the Rongelap group, and were less severe and extensive. The Utirik group did not develop any lesions which could be attributed to irradiation of the skin. The incidence of ulcerating lesions in the different groupsreflected the relative severity of the skin injury. Twenty percent of the Rongelap people developed ulcerative lesions while only five percent-of the Ailinginae and none of the Rongerik people developed ulcerative lesions. Ninety percent of the Rongelap and Ailinginae groups developed lesions, compared to only forty per- cent of the Rongerik group. There were more lesions per individual in the Rongelap group than in the Ailinginae or Rongerik groups. A comparison of the incidence and time of appearance of epilation and neck lesions in the two groupsis illustrated graphically in Figure 3.1. * The description of lesions refers to the Marshallese unless otherwise indicated. Nearly all of the lesions were spotty and developed on exposed parts of the body not covered by clothing during the fallout. The ma- jority of individuals developed multiple lesions (particularly the Rongelap group), most of which were superficial. There was a difference of several days in the latent period before developmentof lesions on various skin areas. The order of appearance was roughly as follows: scalp (with epilation), neck, axillary region, antecubital fossae, feet, arms, legs, and trunk. Lesions on the flexor surfaces in general preceded those on the extensor surfaces. Tables 3.1 and 3.2 show incidence according to age and time of appearance of lesions in the various groups. In the early stages all lesions were characterized by hyperpigmented macules, papules, or raised plaques. (Plate 1.) These frequently were small, 1-2 mm.areasatfirst, but tended to coalesce in a few days into larger lesions, with a dry, leathery texture. The pigmented stage of the superficial lesions within several days was followed by dry, scaly desquamation which proceeded from the center part of the lesion outward, leaving a pink to white thinned epithelium. As the desquama- tion proceeded outward, a characteristic ap- pearance of a central depigmented area fringed with an irregular hyperpigmented zone was seen (Plates2 and 3). Repigmentation beganin the central area and spread outward over the next few weeks leaving skin of relatively nor. mal appearance. Plates 3, 4, 11, and 12 show superficial lesions as they appeared initially anc six months later. The mildest manifestation o: skin injury was the development of a blotchy increased pigmentation of the skin with barely perceptible desquamation. Such lesions wer most often noted on the face and trunk. Epilation was usually accompanied by scal) lesions (Plates 13, 17 and 19). Some indi viduals developed new scalp lesions over | period of about a month. Neck lesions usuall: had a “necklace” distribution, beginning anteri orly and spreading posteriorly. These wer more severe in women in whom thick hai