UNCLASSIFIED BIOLOGY AND MEDICINE es a content, this trip is in part an effort to find the maximum concentration of strontium 90 in humans and thus estimate the high end of the distribution curve for strontium 90 in the world population. Soil Sampling Program Since 1953 the AEC has sponsored a program of world-wide soil sample collection and wna finde analysis under a cooperative agreement with the Department of Agriculture. The purpose of this program is to provide information on the amount of strontium 90 in soils as a result of weapons testing and on the ratio in which strontium and calcium enter the food chain and ultimately find their way into the skeleton. Arrangements were made for a Department of Agriculture representative to revisit the A similar program was to be conducted in the United States in the fall of 1957. Soils were to be resampled at locations visited in the past, and in addition, samples were to be taken from locations at different latitudes with similar rainfall patterns to determine the effect of latitude on the deposition of fallout material. Activities at the Health and Safety Laboratory, New York Operations Office Pasture survey. Strontium 90 and calcium determinations were being made on samples of vegetation, animal bone, and soil collected from five pasture sites* during the years 1953 to 1956, inclusive. Analyses of vegetation and animal bone were complete. The soil analyses were being repeated by extraction of the soil with hydrochloric acid for comparison with the results obtained by extraction with ammonium acetate and electrodialysis. Strontium 85 was being used as a tracer to permit more precise estimation of the analytical yield in the strontium 90 separation. Available calcium in soils, Thirty-soil samples from all over the world, including the United States, were being analyzed by the isotopic dilution method to determine the amount of calcium available to vegetation, in order to check the validity of other commonly accepted methods for the determination of available calcium. Improvement of cesium 137 determination in milk. The method of analyzing powdered milk for cesium 137 was being studied to prevent losses during the initial ashing. The procedure was being tested for reliability by recovery experiments and exchange of samples with other laboratories. Preparation and analysis of standard samples. Ten standard samples of ashed animal bone, simulated human bone ash, and ashed milk and vegetation were prepared for distribution through the United Nations to various countries. These samples will be used for inter-~ laboratory comparisons of analytical procedures, This will remove one of the chief obstacles in the evaluation of the analyses performed in various countries. BACKGROUND RADIATION STUDIES In August a team from the Health and Safety Laboratory of the New York Operations Office conducted a study of natural background radiation over a wide area of the United naa —_ * Ithaca, N. Y.; New Brunswick, N. J.; Raleigh, N. C.; Tifton, Ga.; and Logan, Utah. 4 L113241 | UNCLASSIFIED we tthe eam Se sites of earlier surveys to collect additional samples in Europe, Africa, South America, Asia, Australia, New Zealand, and the British Isles.