dose to the pancreas and certainly less than two times the dose to the pancreas. Now we previously stated that we would evaluate the dose to the salivary glands and the lactating breast from the ingestion of lIodine-131. Both of these tissues can concentrate Stomach, lactating concentrating breast, mechanisms, and or iodine. certain an iodine Serous other tissues salivary glands, possess concentrating mechanism iodine that is comparable to that of the thyroid. Next viewgraph, please (LRA-14). We can summarize available data by examining the fluid-to-plasma ratio. 11 fluid-to-plasma 12 juice, 13 derived. 14 to a 15 rate. 16 inversely with the collection rate. 17 ratio and milk; and the range of values for the readily We list the average saliva, for gastric and these are the references from which the data were In the case of the salivary glands, the fluid-to-plasma ratio are large extent In the independent of the plasma concentration and secretion case of gastric juice, the fluid-to-plasma May I have the next viewgraph, please (LRA-15). ratio varies So we made attempts 18 to estimate dose factors to extrathyroidal fodide concentrating tissues for 19 jodine-131 as follows: 20 assumed to be the rapidly turning-over component of the iodine retention 21 function 22 effective turnover rate of about two per day. 23 concentration in extracellular fluid is then 0.7, assuming that 0.7 of the 24 ingested ‘iodine 25 corresponds to the iodide space, 26 that we just examined above. 27 28 This with leads a The half-life of iodine in extracellular fluid is half-life goes to of 0.35 the to a time days; extracellular this is equivalent to an Now the time integral of the fluid, and the 2.7 x 104 ml and the two per day is the turnover rate integral cellular fluid of 1.3 x 10-5 d/1. and then of the concentration in extra- Now we assume that the equivalence of