3.1 Introduction Faucout or Raptwacrive material commenced approximately 4-6 hours after detonation of the thermonuclear device. On the most heavily contaminated island, Rongelap, the fallout was described as x powdery material, “snowlike,” which fell over a period of several hours and whitened the hair and adhered to the skin. Less striking fallout described us “mist-like” was observed on Ailinginae and Rongerik. Fallout was not visible on Utirik, which was contaminated to only a mild degree. The severity of the skin manifestations was roughly proportional to the amountof fallout observed. The population of the four island groups and incidence of the skin lesions were as follows: Geour | are am nee ae ee Comrosrnos eee me we ee ee a, 3.2 Signs and Symptoms Durine Tix First 24-48 hours after exposure, about 25 percent of the Marshallese in the two higher exposure groups experienced itching and a burning sensation of the skin. .\ few also complained of burning ofthe eyes with lachrymation. These symptoms were present to u lesser extent in the Americans on Rongerik Atoll who were aware of the danger, took shelter in aluminum buildings, bathed and changed clothes. These precautions greatly reduced the subsequent development of skin lesions in this group. The people on Utirik, the farthest from the detonation, had no early skin sympFaLLout Onsgaven en ee ae oe Rongelap.-_._.__ 64 Marshallese........-. Ailinginae.__,...., 18 Marshallese_._....... Rongerik....._._.| 23 White Americans...._| 5 Negro Americans. —e <n EXTENSIVENESS OFSuIN LESIONS AND -_ ——ee ee ee Heavy (snowlike)..-.-.-- Extensive. Moderate (mistlike)- . --- , extensive. Moderate (mistlike) ....- Slight. Utirik. 222.2222 7 | 157 Marshallese. ____.__. | None. .....-.-.-------- Evacuation of exposed personnel to Kwajalein, where medical facilities were available, was accomplished one to two days after the event. Decontamination of the skin was commenced aboard ship, and completed after arrival at Kwajalein. Skin examinations were carried out almost daily during the first 11 weeks and then again at & months, | and 2 years after the accident. Examinations of unexposed Americans and native personnel were also carried out for comparntive purposes. Color photographs and biopsies of lesions in various stages of development were taken. No skin lesions or epilation. toms. All skin symptoms subsided within 1 to 2 days. On arrival of the medical team on the ninth post-exposure day, the exposed personnel appeared to be in good health. The skin appeared normal. However, evidence of cutaneous radiation injury_appeared about 2 weeks after exposure when epilation and skin lesions commenced. Erythema of the skin was not observed either during the early examinations when a primary erythema might be expected, or later when a secondary erythema might be expected. After subsidence of the initial skin symptoms, further symptoms referrable to the skin 27