EFFECTS OF FALLOUT RADIATION ON THE SKIN THE SHORTER-TERM BIOLOGICAL HAZARDS OF A FALLOUT FIELD Marshall Island experience, the extent and se- verity of the skin lesions were directly related to the amount of visible fallout and on Utirik, the least. contaminated island of the inhabited group no fallout was visible andno bets lesions of the skin developed. The particulate nature of the material produces spotty distribution on the body. The Marshallese claimed that the material adhered closely to the skin and was difficult to brush off. This was borne out by the difficulties of complete decontamination. Areas of the body where perspiration is greater such as the neck folds, axillae, antecubital fossae etc. caused the material to stick and lesions were more predominant in these areas. The hair tended to collect, the material also, particularly in view of the cocoanut oil hair dressing used by these people, which made decontamination extremely difficult. Clothing, even a single layer of cotton material, afforded almost complete protection as evidenced by the fact that alinost all of the skin lesions developed on exposed parts of the body. The loose clothing warn would not have accounted for more than about a 25 percent attenuation of the radiation so that the protection must have been due in part to the fact thattheloosely fitted clothing tended to hold the radioactive material away from the skin. It is also possible that the material did not stick to the clothing as well as to the skin. There are certain biological factors known to influence the sensitivity of the skin to radiation. In addition to species differences, it is known that the skin of certain parts of the body is more sensitive than that of others. In general the thinner-skinned flexor surfaces of the body are more sensitive than the thicker-skinned extensor surfaces [16]. This was found to be true in the Marshallese since lesions were more prevalent on the front and sides of the neck, axilla and antecubital fossae. Another factor is associated with pigmentation of the skin, to be less sensitive to radiation than blends or fallout is an exceedingly complicated problem people with ruddy complexions [17]. A factor which was pointed outearlier is that areas of the body where perspiration is more profuse cause the fallout to collect resulting in greater and I will leave the main discussion of the subject to other speakers. The degree of skin Sources of radiation ta the skin.- Damage to the skin results largely from the beta com- the energies of the beta particles of the componentisotopes. Thus soft radiation confined reaction and damage is more dependent on the skin effects. depth dose than on the surface dose of beta radiation and the depth dose is dependent on ponent of the fallout in view of the fact that the beta-gammaratio is quite high, All of the largely to the dead horny Jayer and upper epidermis would be relatively ineffective in energy of the beta particles entering the skin tion and particulate nature of the fallout in producing a reactionin the skin; more energetic radiation, penetrating through the epidermis, could result in transepidermal necrosis; and deeper penetration into the dermis could result, in more severe ulcerating Jesions. Each radioisotope has its own characteristic spectrum of energies with a maximum energy, but since relatively few particles are of this energy, the average energy, which is roughly one-third of the maximum energyand the 50 percent atten- sources on the skin, By far the greatest part of the skin dose comes from this source. mating skineffects. Figure 1 shows roughly the 50 percent atten- is absorbed in the skin. Soft gamma rays accounts for some of the radiation dose to the skin, and the harder gamma rays contribute least since they are more penetrating. The skin dose results from two sources of beta radiation, the fallout material in direct contact with the skin and the material on the ground. 1. Contact source.—The spotty distribu- 137 Estimation of beta doses to the skin from FepDermis POERMIS g the occurrenceof fallout would have to be visible to result. in such damage. Forexample, in the Darker-skinned people, brunettes, are known 3 It seems likely that 50% ATTENUATION IN SKIN (MICRONS) 186 sufficiently concentrated. 900 1060; L L Ot 02 1 1 1 as of os BETA ENERGY (ove) 4 J os Or Figure 1-40 percent attenuation in skin (microns), old reaction (erythema, epidermal atrophy) are fairly dependent on the energy of the beta particles of the various isotopes. Thus it takes uation in tissue are more micaningful in esti- 20,000-30,000 rep from S® (average energy 0.1 Mev.) to producea reaction while it only takes 1500-2000 rep of Sr®-Y" or Y" (average Radiation is largely from the skin surface. However, the possibility must be considered uation in skin of several isotopes. With the same surface dose the more energetic beta reaction. It is of interest that Moritz and Henriques found that the dose at 0.09 mm. tion into the dermal region via the hair greater damage to the skin. Table 1 is made up of data from animal studies from several investigators and shows the energy dependence of betas from various contact with skin results in multiple point that a certain amount of percutaneous absorption may take place and some penctrashafts, occur. sebaceous and sweat glands may The Castle fallout contained about 10 percent water soluble fission products, some of which might conceivebly have been absorbed percutaneously. Whitten et al. [18] have shown that thorium-x applied to the skin results in some percutaneous absorption and entry into the hair shafts and glands. Weintend to investigate this problem with fission products on the skin by means of autoradiography. 2. Ground source-—A certain amount of the skin dose mayresult from beta radiation from the fallout material on the ground. This contribution is likely to be far less than that from the contact source. The lower parts of the body will receive the greater part of this radiation since the beta particles are completely stopped in 2 meters of air. emmiting isotopes will naturally result in isotopes in producing recognizable skin reac- tions. Note that the surface doses for thresh- energy 0.5-0.6 Mev.) to produce the same depth of the pigskin (estimated to be the epidermal thickness) was constant within several hundred rep to produce transepidermal injury [15]. Wilhelmy has also noted thatit takes roughly the same dose of electrons and soft X-rays at the level of the subpapillary layer to produce erythema[19]. On this basis Taste 1—SURFACE DOSE REQUIRED TO PRODUCE RECOGNIZABLE EPIDERMAL INJURY Investigator Henshaw,et al_ow. 02 * Snider and Raper. Raper and Barnes... ...- . ee L - Lushbaugh. ...22-..200. 0.02. Moritz and Henriques . Antmsi eee Tsotope pe pa pa se se Co® Cg? Srve os ye Average en. eray (Mov) 0. 5 -5 -6 3 - 05 al 12 3 5 -7 Surface doso (rep) 1, 500-4, 2, 5, 2, 500-5, 20, 000-30, 4, 000-5, 2, 000-3, 1, 500-2, 1, 500-2, 1, 500-2, 000 500 000 000 060 000 000 000 000 000