the time integrals in fluids concentrated from extracellular fluid, and in the tissues from which these fluids are derived, so we have then for the time integral of the concentrations in the concentrated fluids, 10°5 x R, where R is the fluid-to-plasma ratio. 1.25 x Now R is a poor choice inasmuch as it also represents Roentgens, but, nonetheless, R is meant to béthe fluid-to-plasma ratio. Thedose factor then for extrathyroidal iodide concentrating tissues, is this 1.25 <fes R d/g x 0.2 MeV, corresponding to the energy from the disintegration-of7iodine-131 times the conversion factor of 51.2 rad per (uCi-d/g)-MeV, and!this is then the resulting expression for the dose factor for extrathytértdal iodide concentrating tissues. ee ia Next viewgraph, please: (LRA-16). We also made an attempt to estimate a dose factor for iodine-13i-to_the lactating breast by making note of the recoveries of, well, jodine-131> or of the dietary iodide in milk. Now 0.03 - 26.8% of I-131 administered to..women at the conclusion of the last breast feeding, resulted in the recovery of this range of values of the isotope in milk. In the case of dietary stable iodide, ten percent or less of the daily ingested iodide is secreted in milk. And this varies inversely with the dietary intake of iodine=So the transfer coefficient and time integral then of the concentrationin milk following a single intake of iodide, assuming a milk secretion rateof one liter per day, and 22 this seems to be a reasonable value for nursing mothers, leads to, well, a 23 transfer coefficient, or time integral of 0.1 of a dayper liter, and this 24 is equivalent to 10-4 d/ml. 25 time integrals in milk and lactating breast, so we have 10-4 d/g for the 26 time integral 27 times the 0.2 MeV times the conversion factor, and we get about 1.0 x 10-3 28 rad/uCci. Now again we assume the. equivalence of the in the lactating breast. 17 Dose factor then-is this number