Appendix 9 (continued) C. Data on Principle Isotopes of Iodine Contributing to Thyroid Dose (From "Inhalation of Radioiodine from Fallout: Hazards and Countermeasures" by R. Colel37) eax? Mev Relative abundance, % Range in tissue, um 50%-Dose radius,* um Iodine-131 Betas 0.246 0.332 0.606 0.807 2.2 10.6 86.4 0.8 1,000 2,100 150 310 2,500 3,900 5,400 8,400 11,900 375 625 920 1,500 2,400 6,800 1,200 8,100 15,800 1,460 3,300 Iodine-132 Betas 0.681 0.934 1.150 1.583 2.111 15 20 22 22 21 Iodine-133 Betas 0.49 1.34 ? 93 Todine-134 Betas 0.87 1.55 2.65 3.51 5 65 25 5 . Iodine~135 Betas 0.40 1.00 1.43 35 40 25 1,300 4,300 7,300 195 690 1,300 *The 502%-dose radius is defined, for a point source in tissue, as the distance within which 50% of the dose, for that energy, is distributed. **Since this isotope with 53-min half-life is important only for about 6 hr, it was not considered in the Marshallese thyroid dose calculations. -~ 117 -