Chopter § ACCIDENTAL EXPOSURE OF HUMAN BEINGS TO FALLOUT Immediately after the accidental exposure of human beings on Rongelap, Ailinginae, Rongerik, and Uterik to the fallout from Shot 1, Project 4.1 was organized to (1) evaluate the severity of the radiation injury to the human beings exposed, (2) provide for ajl necessary medical care, and (3) conduct a scientific study of radiation injuries to human beings. This project represented the first observations by Americans on human beings exposed to excessive doses of radiation from fallout (mixed fission products). The groups of exposed individuals were sufficiently large to provide good statistics. Although no pre-exposure clinical studies or blood counts were available, it was possible to study Marshallese and American control groups that matched and exposed population closely with regard to age, sex, and background. The exposures involved far exceeded the normal permissible dosage. Calculations indicated that 28 Americans on Rongerik Atoll received a total gamma dosage of 86 r, 64 Marshallese on Rongelap Atoll 182 r, 18 Marshallese in the neighborhood of Ailinginae 81 r, and 157 Marshallese on Uterik Atoll 13 r. The external gamma dosage was deliver- ed primarily by radiation energies of 100, 700, and 1,500 kev. The beta dosage was delivered by beta radiation with maximum energies of 0.3 and 1.8 Mev. The exposures occurred between 4 and 78 hours after the detonation, and the fallout was of about 12-hour duration. The internal dosage was due mostly to ingested material rather than inhaled material. The physical effects of the radiation on individuals were typical of those normally ex- pected. A significant number of individuals on Rongelap suffered from mild nausea, and one or two individuals vomited on the day of exposure. With the exception of nausea in one Ailinginae individual, there were no other definite gastrointestinal symptoms in the other Marshallese or the Americans. The Marshallese on Rongelap and Alilinginae and the Americans experienced, to a varying degree, burning of the eyes and itching of the skin for from 1 to 3 days. Later signs of radiation injury included definite loss of hair (epilation) in the Rongelap and Ailinginae groups, and the development of spotty, super- ficial, hyperpigmented skin lesions that peeled off (desquamated) from the center of the lesions outwards. In some cases the skin damage was sufficient to result in raw weeping lesions. There was no full-thickness destruction (necrosis) of the skin. The Americans developed only minor skin lesions without ulceration; there were no skin lesions in the Uterik natives. All lesions healed rapidly, with no further breakdown of the skin noted during the period of observation. Microscopic examination of biopsies of the lesions showed changes usually associated with radiation injury. Fully clothed individuals and those remaining inside of buildings or huts were protected to various degrees from development of lesions. Hematologic changes were definite in the Rongelap, Ailinginae, and American groups. Lymphopenia appeared promptly and persisted for a prolonged period of time. Neutro- penia occurredin all the individuals, with initial minimum values occurring around the 11th day followed by an increase in the counts and a secondary minimum aroundthe 40th to 45th day. The most consistent hematologic change was the depression in the platelet counts. Platelets were below normal when first counted on the 10th day after exposure 71