LP. te EFFECTS OF FALLOUT RADIATION ON TILE SKIN Table Lis made up of data from animal studies from several investigators and stows the energy dependence of betas from various isotopes in producing recognizable skin reactions. Note that the surface doses for thresh- ai") T T T T | EPICERMIS oor 50% ATTENUATION IN SKIN (MICRONS) Estimation of beta doses to the skin from fallout is an exceedingly complicated problem and I will leave the main discussion of the subject to other speakers. The degree of skin reaction and damage is more dependent on the depth dose than on the surface dose of beta radiation and the depth dose is dependent on the energies of the beta particles of the component isotopes. Thus soft radiation confined largely to the dead horny layer and upper epidermis would be relatively ineffective in producing a reaction in the skins more energetic radtation, penetrating through the epidernis, 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 cnergy, which is roughly one-third of the maximum energy and the 50 percent attenuation in tissue are more meaningful in estimating skin effects, Figure 1 shows roughly the 50 percent attenuation in skin of several tsotopes. With the same surface dose the more energetic beta emmiting isotopes will naturally result in greater damage to the skin. 137 200 -300 ;-400 f500 f- > DERMIS 600 LTO... 600 g06r- 10007——LL at oO {yy to a2 a3 L L i l 0.4 O35 a6 0.7 BETA ENERGY (ove) Fiounrt 1.—60 percent attenuation tn ekin (microns). old reaction (erythema, epidermal atrophy) are fairly dependent on the energy of the beta particles of the various isotopes. Thus it takes 20,000-30,000 rep from S® (average energy 0.1 Mev.) to produco a reaction while it only takes 1500-2000 rep of Sr®-Y" or Y*' (average energy 0.5-0.6 Mev.) to produce the same reaction. It is of intercst that Moritz and Henriques found that the dose at 0.09 mm. 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 that it takes roughly the same dose of electrons and soft X-rays at the level of the subpapillary laver to produce erythema [19]. On this basis Taste 1.--SURFACHK DOSE REQUIRED TO PRODUCI RECOGNIZABLE EPIDERMAL INJURY Investigntor Henshaw, ct al... 0-2-2 2 eee. Snider and Raper... .....------.---- 2-2 -eRaper and Barnes... . 2222.22. eee Lushbaugh.-..-..-.....-----2---------------Moritz and Henriques .__.2 2222-2. eee _..-| Animal Rata. 2.2 ue leek Mice.....- 2-222 -2Rubbita._ 22222222. Sheep_.-.-...-----Pigs .-.----- 22. _ Do... 2 a ee eee eee eee eee eee wales ee do... .--- ee Do__o... 0. eee eee eee dee do.----2- 2 lee Do. 1-222 -----eeeeeee Lee ee eee ete ee do_. lee Do___..- we cee eee eee ee ee fee ee do__ 2 ee OT ~...-dO..--- 2 Lee Tsutope , Pr ps p32 §% S%5 Co Cs!" gre yu * "yoo Average ene emy (Mev.) | 0.5 .6 5 id .05 Jl 2 3 a) 47 Surface dose (req) 1, 500-4, 2, 5, 2, 500-5, 900 500 000 000 4, 2, 1, 1, 1, 000 000 000 600 GOO 20, 000-30, 000 000-5, 000-3, 500-2, 500-2, 500-2, :