to plaques containing different radioisotopes, Pertinent data are abstracted as follows: Surface Dose Required to Froduce | Injury(loectgen-equivalant= Zsstove Enerey beta) Yttrium? 1,53 1,800 Strontiza%™ 0.61/ Tttriua9 ; 3,500 2,20! Kstinated Anount of tratedGitato Dejth 1,200 1,400 The average maxima energy of the beta particles from fallout material varies with tine but will be assumed te be roughly comparable, in respect to depth dose, to Yttriua’! or sr”, _ Since the gamma dose at a depth of 7 ng/cw would not be significantly different fron the surface gamma dose, the ratio ef 130 te 1 for beta-ganza will be assured at the basal layer of the epidersis, Th net {One experiment with sheep, using 6r7=190 plaques, shoved that 2500 reps at the plaques’ surface produced ulesration in ons but not another of two sheep.® On the other hand, 1000 rads delivered to tissue depth of 7 wc/ea® fron a 392 one inch dtaneter distfiype of antes) vot stated) produced tanning, prolonged erythena and desquanstion.©#} Tt is to be remenbered that the above discussion was first based on Surface gamma dose rates whereas the gonitors vill be making their garma ®*Conparative Study of Experimentally Produced Beta Lesions and Skin Lesions in Utah Range Sheep", Lushbaugh, C.£E., Spalding, 3.¥, and Hale, DB. LASL Bovember 30, 1953 (UHCLASSIFIED). *#HW-33068 A status report. Sept. 15, 1954 (COKFIDENTIAL), ngs Al A\