arte te ee ee Bt we ge There wag a delay of two and one-half days before satisfactory decontamination wis possible. The presence of radioactive materials on the skin during this period increased the dose to the skin, However, (he dose rate fell off rapidly and decontamination would have to have been very prompt in order to be effective. 3.6 CORRELATION WITH HEMATOLOGICALFINDINGS Attempts at correlation of the severity and extensiveness of skin lesions with maximum depression of platelet, lymphocyte, and neutrophile counts were made for individuals in the Rongelap group. No positive correlation was found. Thus the contamination of the skin appar- ently did not significantly contribute to the total-body dose of irradiation. 3.7 DISCUSSION There has been little previous experience with radiation dermatitis resulting from exposure to fallout material from nuclear detonations, and the general consensus until now has been that the hazard from fallout material was negligible. With the Hiroshima and Nagasaki detonafions, fallout material was.nota problem since the bombs were exploded high in the air. The flash burns of the Japanese were purely thermal, Fromthe present experience it is quite evident that following detonation of a large scale device close to the ground, serious exposure of personnel may occur from fallout material, even at considerable distances from the site of detonation. The incident described in this paper is the first example of large numbers of radiation burns produced by exposure to suchfallout material. Knowlton,et al. described burns of the hands of four individuals who were handling fis- sion product material following an experimental detonation. Also, following the Alamogordo detonation, there were a number of cattle that developed lesions due to deposit of fallout material on their backs.’ In addition, there were a number of sheep that developed lesions closely resembling radiation burns following a Nevada detonation. However, Lushbaugh® reported that the histopathological characteristics of these lesions did not conform in all respects to radiation dermatitis. It is of considerable interest to compare the present experience with that accepted in the past as the typical course of radiation burns of the skin. The gross lesions of the hands described by Knowlton, et al. occurred from an exposure of about one hour, resulting in doses between 3000 and 16,000 rep of beta radiation (maximum energy about 1 Mev) with a small gamma component considered to be insignificant. The lesions were described as developing in four phases: (1) An initial phase which began almost immediately after exposure and consisted of an erythema with tingling and burning of the hands, reaching a peak in 48 hours and subsiding rapidly so that by 3 to 5 days there was a relative absence of signs; (2) A second phase which occurred from about the 3rd to the 6th or 8th day and was characterized by a more severe erythema; (3) The third phase at 8 to 12 days, which was characterized by vesicle and bullae formation. The erythema spread to new areas during the following two weeks, and the active process subsided by 24 to 32 days. The bullac dried up, and desquamation and epithelization took place in less severely damaged areas; (4) The fourth phase or chronic stage was characterized by further breakdown of skin with necrosis in areas which were damaged sufficiently to compromise the blood supply. Atrophy of the epidermis and loss of epithelial structures took place, which necessitated skin grafting in some cases. Robbins, et al.’ reported six cases accidentally exposed to scattered cathode rays (beta) from a 1200 kv primary beam with exposure time of about 2 minutes and a rough estimation of dose to the skin of between 1000 and 2000 rep. The lesions described were similar to those reported by Knowlton, et al.‘ witha primary erythema developing within 36 hours; secondary erythema with vesiculation and bullae formation appearing about 12 to 14 days later; and, in the more severely affected, a tertiary phase characterized by further breakdown of the skin. In comparisor. with severe roentgen ray reactions these investigators stress the unique periodicity of cathode ray burns, relative absence of deep damageto the skin, less pain, rapidity 42