34 EFFECTS OF IONIZING RADIATION ointment, with apparent success. When the epithelium was desquamating,all lesions were treated by daily washing with soap and water followed by the application of a water soluble vanishing type ointment which kept the injured skin soft and pliable. Raw areas, which became secondarily infected, were cleansed with soap and aureomycin ointment was applied. Bullous lesions of the feet were left intact as long as no symptoms were present. If painful, the fluid was aspirated with sterile technique and a pressure dressing applied. A single aspiration was adequate since the bullue did not refill. In one instance, an extensive, raw, weeping ulcer developed for which penicillin was given for two days. During this time the lesion developed healthy granulation tissue. Some of the lesions of the skin of the foot remained thickened and less pliable after desquamation. This was relieved by the use of vaseline or cocoa butter to soften the tis- ‘sues. The one persistent ear lesion did not heal after desquamation. This was treated daily with warm boric acid compresses and washing with surgical soap to remove the eschar. Slowly, regenerating epithelium grew in from the edges of the ulcer. Upon reexamination, 6 months after exposure, healing was complete with a depigmented scar remaining as evidence of the previous ulceration. 3.5 3.51 Factors Influencing Severity of ' the Lesions Character of the Fallout Material This material was composed mainly of cal- cium oxide from the incinerated coral, with adherent fission products. Fifty to eighty percent of the beta rays emanating from this ma- terial during the exposure period had an average energy of about 100 kev. Since 80 mi- crons of tissue produces 50 percent attenuation of such radiation (1), a greater portion of energy was dissipated in the epidermis which is roughly 40 to 70 microns in thickness. The remaining 20 to 50 percent of the beta rays had un average energy of approximately 600 kev. The latter would penetrate well into the derm since it takes 800 microns of tissue to produc 50 percent attenuation of this energy radiatic (1,2). In addition, a wide spectrum ¢ gamma energies irradiated the skin. Tl gamma contribution to the skin was sma compared to the beta dose and is discussed | Chapter I, 3.52 Dose to the Skin The skin lesions observed resulted primari from beta radiation from fallout material d posited on the skin. The gammadose to tl skin was small compared to the beta dose, ar thus relatively unimportant in producing t] lesions. The summation of gamma and be contributions to the skin is considered in Se tion 1.3. In general it is evident that skin i jury was largely produced by material in co tact with the skin. The total surface dose ca not be calculated with accuracy but minim and maximal values at various depthsin t! skin can be estimated biologically. Hair fc licles in the areas in which epilation occurr must have received 1 dose in excess of tl known minimal epilating dose of about 400 for 200 kvp X-ray. Since regrowthof hair c curred, the upper limit of dose at the depth | the hair follicle must not have exceeded the pe manentepilating dose of around 700 r of 2 kvp X-ray (3). From this a rough id of surface dose may be made. .A dose to t. hair follicles comparable to 400-700 r of | radiation must have been due almost entire to the more penetrating beta component (ave age energy, 600 kev). Therefore, the mini surface dose in rep from this componentalo was probably four to tive times the dose at t hair follicle, i. e., roughly 1,600-3,500 re The soft component (average energy, 100 ke contributed a considerably larger shure to t surface dose but with only slight penetratic 3.53 Protective Factors The following factors provided some prot: tion: