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 deeperlesions 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 contamination in the different groups. The Rongelap group, which showed greatest radioactive contamination of the skin (accordingto instru- ment readings) were thefirst to develop lesions and epilation at about 12 to 14 daysafter the accident. They also had the mostseverelesions. 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 notdevelop any lesions which could be attributed to irradiation of the skin. The incidence of ulcerating lesions in the different groups reflected 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 percent 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. cH oD Crt * 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 cov- ered by clothing during the fallout. The majority 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 development of 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 showincidence 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.areasat first, 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 desquamation proceeded outward, a characteristic appearance of a central depigmented area fringed with an irregular hyperpigmented zone was seen (Plates 2and 3). Repigmentation began in the central area and spread outward over the next few weeks leaving skin of relatively normal appearance. Plates 3, 4, 11, and 12 show superficial lesions as they appearedinitially and six months later. The mildest manifestation of skin injury was the development of a blotchy increased pigmentation of the skin with barely perceptible desquamation. Such lesions were most often noted on the face and trunk. Epilation was usually accompanied by scalp lesions (Plates 13, 17 and 19). Some individuals developed new scalp lesions over a period of about a month. Neck lesions usually had a “necklace” distribution, beginning anteri- orly and spreading posteriorly. These were more severe in women in whomthick hair