Mean Concentration of Sr-90 in Human Bone United States ‘Age (years) 1958 O- & 5-19 2.0 1.0 over 19 pCi/gram of Calcium 1963 oe 3.0. 0.2 1.3 1968 © 3.2: ' 3.2 0.9 _ 1953 and 1963 Data from UNSCEAR Reports. 1968 Data from Health und Safety Laboratory Reports. The geographic variubility is upparently only a fuctor of two from the mean. This should be less than the variability in fallout deposition itself, due to the wide distribution of many food products. Cesium-137 (Man-made) Continuing measurements of the whole body cesiun-137- content of humans have been made in the states of California, Idaho, Illinois, Massachusetts, New Mexico, New York and Washington for many years. have also been made in other areas. Additional measurements Ces ium-137 can be measured in Living ' subjects with a whole-body counter, in contrast to the other radionuclides _which can only be measured in autopsy material. The following table shows _ the average adult whole body burdens as estimated for the United States.