TREATMENT The treatment of the skin lesions was largely nonspecific. Most of the superficial lesions were treated with calamine lotion with one percent phenol, which in most cases relieved the itching and burning. A few of the hyperpigmented lesions not relieved by calamine with phenol were treated with pontocaine ointment, with apparent success. When the epithelium was desquamating, all lesions were treated by daily washing with soap and water followed by the appli- cation 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 dressings were applied. Bullous lesions of the feet were left intact as long as no symptoms were present. If painful, the bullous fluid was aspirated with sterile technique to remove the clear straw-colored fluid and a pressure dressing applied. A single aspiration was adequate since the bullae 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 tissues. 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 re—examination 6 months after exposure, healing was complete with a depigmented scar remaining as evi- dence of the previous ulceration. FACTORS INFLUENCING SEVERITY OF THE LESIONS 1, Character of the Fallout Material. This material was composed mainly of calcium oxide from coral, with adherent fission products. Fifty to eighty percent of the beta rays emanating from this material during the exposure period were soft with an average energy of about 100 kev. Since 80 microns of tissue produces 50 percent attenuation of such radiation (1), a greater portion of energy was dissi- pated in the epidermis which is roughly forty to seventy microns in thickness. The remaining 20 to 50 percent of the beta rays had an average energy of approximately 600 kev. The latter would penetrate well into the derm since it takes 800 microns of tissue to produce 50 percent attenuation of this energy radiation (1,2). In addition, a wide spectrum of gamma energies irradiated the skin. Approximately 10 percent of the total gamma spectrum was below 80 kev which would be absorbed largely in the superficial layers of the skin. The remainder of the gamma spectrum was distributed between 100 and 1,600 kev with a large proportion between 600 and 800 kev. 2. Dose to the skin. The skin lesions observed resulted primarily from beta radiation fran fallout material deposited on the skin, with minimal or no contribution fram chemical irritation. The gamma dose to the skin was small compared with the beta dose, and thus relatively unimportant in producing the lesions. The entire surface of the body of the people of Rongelap received approxi-— mately 175 r from gamma irradiation derived from fission products distributed on the ground, trees, and buildings. To this 175 r would have to be added the beta component from this source which might be large in view. of the high beta to gamm ratio in fission products. To these doses would have to be added the major contribution (beta) from the material in contact with the skin. The latter cannot be calculated, or estimated biologically with any degree of accuracy. A rough approximation of the dose received at the hair follicles can be made as follows: since epilation occurred, the hair follicles must have received a dose in excess of the known minimal epilating dose of about 400 r for 200 kvp X-rays. Since regrowth of hair occurred, the upper limit of dose at the depth of the hair follicle must not have exceeded the permanent epilating dose of around 700 r of 200 kvp X-ray (3). From this a rough idea of surface dose may be made. A dose to the hair follicles comparable to 400-700 r of X-radiation mst have been 432