POTASSIUM 40 AND CESIUM 137 IN HUMANS C.W. Mays, D.H. Taysum, and D.W. Glad Abstract: Whole-body gamma measurements have been made on 38 persons. of potassium in a person is approximately proportional tends to be greater in men than in women. in people living in Salt Lake City, to The amount body weight and The average Cesium content measured Utah, is greater than average values reported for people living in other parts of the United States. This differ- ence may be due to the proximity of Salt Lake City to the atomic bomb test Site in Nevada. About 70% of the people in the Radiobiology Laboratory have been measured. So far, there is no evidence of contamination with the radio- elements with which we work. INTRODUCTION: It has been estimated!) that during the winter of 1957-1958, over 95% of the gamma activity in people was due to the disintegration of Potassium 40 and Cesium 137. existed in Potassium 40 is a naturally occurring radioelement which has living systems for millions of years. Cesium 137 results from nuclear fission. It was first detected in humans by Miller and Marinelli in the spring of 1955. (2) These measurements have been pursued extensively at the Argonne National Laboratory using a large NaI(Tl) crystal detector and at the Los Alamos Scientific Laboratory using a large whole body liquid scintillation detector (3). Whole body measurements on personnel at the Radiobiology Laboratory were made to (a) monitor for possible contamination with the gamma emitting radioelements with which we work, and (b) to determine cst3/ burdens in persons from the Salt Lake City area. Positioning of Humans: Human measurements were made with our whole body gamma counter, K-9 Bark 11{4), Positioning was as shown on the following page.

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