DISCUSSION ON TOPIC V Internal Emitters Col. Trum. I have material similar to that presented by Dr. Lindberg. if radioiodine is Lo becritical in fallout, it will I would like to not be in this typeof pickup but in a type which survey on cattle and humans are summarized. The data contained in Figures 1 and 2 were posium, and that is the pickup of the shorterlived isotopes. In my experience these may showa slide on which the results of an 1-131 taken fromvalues of I-131 measured since 1954 to present. The survey began shortly after Van Middlesworth made his initial report. The cattle samples were collected by veterinariens of the Armed Forces throughout the world. They are averaged in presentation, This survey was done in conjunction with Comar’s group at the Oak Ridge Institute of Nuclear Studies, where the survey of human thyroidal 1-131 was made from samples submitted from various points in the United States. In July 1955, a limited symposium on. this subject was held at the Medical Division, Oak Ridge Institute of Nuclear Studies. It was pointed out at that time that there was a . significant difference observed in the I-131 content of thyroids from pastured and stabled cattle. However,for the purpose of these data, only beef fed on the range or grown on the range and stabled for a short time furnished the samples. Dots, which are indistinguishable to me from this distance, represent nuclear detonations. If we were able to make the distinction you would note that some are labeled Russian, English, and United States shots. Contrary io the British, who have told me they can see a USA flag in every radionuclide they find, we find little difference. There is a peaking following each test. There is a delay in peaking which we would not expect with a short-lived nuclide such as I-131. 1 wish Dr. Comar were here to explain this moredefinitively. 448029 0-58 ~ 16 However, in my estimation, T had hoped would be discussed at this symchange the picture somewhat. I had hoped that there would be a program some place in which attention had been centered on these nuclides, where I think the relation between ingestion and inhalation or other factors may give us more variation. T should like to point out, unless Col. Rust whois present would like to speak on this, that it doos-not take a lethal dose of irradiation to varyiodine pickup in the animal thyroid. Col. Rust. You go ahead. Col. Traum. The first of the Col. Rust's slides is a micropathologysection of the normal animal (Figure 3). Figure 4 is the thyroid of the acutely irradiated animal. Note the microfollicular changes that distinguish the normal from the irradiated thyroid. Figure 5 showsthe results of iodine pickup inirradiated animals. The scatter of values reflects the physiological changes demonstrated in the histopathology of the previous figures. Although dose dependent, the variations are great. These variations are not due to techniques, but are reflections of the physiological condition of the animals. This phenomenon has been verified at the Radiobiology Division of the Army Medical Research Laboratory at Fort Knox. They have stated that under 900 r of whole bodyirradiation this phenomenon is a fairly good indication of dose. T point out these things because we happen to have these data. If anybody has more of such material we would like to know of it. Thank you. 223