. . ‘ . . . CIRa A a . yXe ro fey NC: . tte Aa al tlaae Rete hal ele So ee due almost entirely to the more penetrating beta component (average energy, 600 kev). There— fore, the surface dose in rep from this component alone must have been of the order 4 to 5 times this depth dose, i.e., roughly 2,000-5,000 rep. The soft component (average energy, 100 kev) must have contributed a considerably larger share to the surface dose though with only superficial penetration. 3. Protective Factors. The following factors were found to afford some degree of protection: a. Shelter. — Those individuals who remained indoors or under the trees during the fall- b. Bathing. - Those who bathed during or shortly after the fallout were protected to out period showed some degree of protection as compared with those who were in the open during that period. varying degrees. Small children who went wading in the ocean developed fewer foot lesions. Most of the Americans who were more aware of the danger of the fallout, took shelter in their butler-—type buildings, bathed and changed clothes and consequently developed only very mild beta lesions. c. Clothing. - Clothing, even a single layer of cotton material offered almost conplete protection, as was demonstrated by the fact that lesions developed almost entirely on the ex- posed parts of the body. 4, Factors favoring the development of lesions. a, Areas of more profuse perspiration. — Lesions were more numerous in areas where per— spiration is abundant such as the folds of the neck, axillae, and antecubital fossae. b. Delay in decontamination. - There was a delay of one to two days before satisfactory decontamination was possible. The prolonged contact of radioactive materials on the skin during this period increased the dose to the skin. However, the dose rate fell off rapidly and decon— tamination would have to have been prompt in order to have been very effective. CORRELATION WITH HEMATOLOGICAL FINDINGS Attenpts were made at correlation of the severity and extensiveness of skin lesions with maximum depression of platelet, lymphocyte, and neutrophile counts for individuals in the Rongelap group. No positive correlation was found. Thus, the contamination of the skin apparently did not significantly contribute to the total-body dose of irradiation. It is possible that the skin lesions may have been partly responsible for the fluctuation in leukocyte counts during the period when the lesions were most acute. ~ DISCUSSION There has been little previous experience with radiation dermatitis resulting from ex- posure to fallout material from nuclear detonations, and the general consensus until this event has been that the hazard from fallout material was negligible. From the present experi-— ence it is evident that following detonation of a large scale device close to the ground, seri- ous exposure of personne] with resulting radiation lesions of the skin may occur from fallout material, even at considerable distances from the site of detonation. This incident is the first example of large numbers of radiation burns of human beings produced by exposure to fall- out material. With the Hiroshima and Nagasaki detamations fallout was not a problem since the bombs were detonated high in the air. The flash burns of the Japanese were due to thermal radiation only. Following the Alamogordo atomic detonation there were a number of cattle that developed lesions on their backs due to the deposit of fallout material (4). Also, following a deton- Crd 433