Foreign Food Collection The results of analysis for strontium and calcium of food samples collected in the Philippine Islands, Turkey, and Libya by teams of the Interdepartmental Commission on Nutrition for National Defense are given in table II. Values for foods in the United States also are given for comparison. TABLE II. SUMMARY OF FOREIGN FOOD ANALYSES 1 Strontium units correspond to the former terminology, "Sunshine Units." 2 Data inadequate to convert to strontium units. The minium range of values would be 5-29 strontium units (calcium content assumed to 0.10, the maximum value given); if the calcium content is lower, the range would be higher. 3 Taken from the manuscript, "Current Strontium 90 Level in United States Diet," J. L. Kulp. 4 Values for Perry, N. Y., Ithaca, N. Y., and Mandan, N. Dak., are determinations by the Health and Safety Laboratory, New York. Some Research Programs on Strontium 90 In addition to its sampling and monitoring program, the Commission describes in this report some of the research it supports into the effects of strontium 90 on man and his environment, on the distribution, uptake, accumulation and eventual deposition in bone of strontium 90, and on methods of removing it from biological materials and from the soil. The earlier section dealing with the Effects of Internal Radiation reports on other related research projects. Toxicity of strontium 90 in rats and monkeys. Investigators at the University of Rochester, conducting a systematic study of the effects of strontium 90 upon life span and incidence of bone cancers, give rats of varying ages radiostrontium in their drinking water. The concentrations are many times greater than those expected from fallout either from nuclear tests or from nuclear warfare. Experiments are incomplete, but findings thus far suggest that adult rats may carry a body burden of 1 microcurie of radiostrontium for as long as 21 months without marked shortening of life, or significant increase in occurrence of bone cancer. The 1 microcurie body burden of strontium 90 delivered approximately 1,200 rads 57 to the skeleton of the rat. A body burden of 1 microcurie of strontium 90 in the human being, the so-called Maximum Permissible Concentration, would deliver approximately 150 rads to the human skeleton in 50 years. Other experiments have shown that a body burden of 15 microcuries or more of strontium 90 in the rat is necessary to produce a significant incidence of bone cancers among the test animals in about 1 year. The radiation dose to the skeleton in these cases is on the order of 5,000 to 7,000 rads. Similar studies also are in progress with monkeys. Ecological Studies White Oak Lake bed. Ecological studies have been conducted at Oak Ridge National Laboratory in the contaminated White Oak Lake bed, for 12 years an area for impoundment of radiactive waste. Because of this history, it is a unique tract of land and contains more of the fission products strontium 90 and cesium 137 than any land now known. Average concentrations of radiostrontium are about 400 millicuries an acre; radiocesium ranges up to 20 curies an acre. In addition, there are significant concentrations of cobalt 60, ruthenium 106, cerium 144 and rare earths with a total average radiation level above 0.5 roentgen a day. Distribution and uptake of these fission products by both natural and cultivated vegetation can be studied in this environment, as can the long-term effects of low-level radiation on plant and animal populations. During the past year, the complex soil system has been further analyzed, the natural flora and fauna developing on the lake bed have been characterized and the concentrations determined for strontium 90 and cesium 137 in the soil, in the natural vegetation, and in corn. First results of the corn analyses indicated that concentrations of cesium 137 may differ between the various plant organs. The ratios of cesium 137 to potassium, an element employed similarly by the plant, indicated a considerable discrimination by the plant against taking up cesium 137. Preliminary analyses of strontium 90 and calcium concentrations indicated the plants discriminated less against Rad. One hundred ergs of absorbed energy per gram of absorbing material. strontium than against cesium. The evidence also indicated the highest concentrations were found in the leaves. Several species of mammals have been trapped on the lake bed. Since they undergo external exposure to radiation and also ingest contaminated food materials, the animals offer an opportunity to obtain information on long-term effects. Hanford. For ecological studies in the Hanford environs, a simulated natural pond was constructed as an initial experiment of a new research group. Cesium 137 was added to the pond, and its dissipation was studied. From work of this type it may be possible to determine types of organisms which will take up the greatest amounts of various isotopes and thus serve as indicators of contamination levels and as guides in evaluating potential hazards. Studies of Fallout Patterns The Atomic Energy Project at the University of California at Los Angeles conducted studies during Operation Plumbbob at the Nevada Test Site to (a) delineate fallout patterns of devices greater than 10 kilotons in yield with respect to radiation intensities and particle sizes, (b) characterize fallout material with respect to beta and gamma radiation characteristics and physical, chemical, and radiochemical properties, (c) determine the environmental persistence of fallout in selected areas, and the accumulation of radioisotopes by native animals collected from these selected contaminated areas, (d) measure the radioactivity level of Nevada and Utah agricultural areas and their produce by sampling before and after the Plumbbob series, and (e) train participating personnel in assessing environmental contamination. The groups who participated, totaling approximately 190, included university student employees, veterinarians from the United States Air Force and the United States Department of Agriculture, and technically trained staff of the United States Food and Drug Administration, the Federal Civil Defense Administration, the United States Geological Survey, and Atomic Energy Commission con tractors. Gamma radiation levels of fallout patterns were determined by aircraft using techniques of the United States Geological Survey and the Commission's raw materials exploration group, and by mobile ground teams. Cross checking of the aerial values corrected for height above the surface, and the ground monitor's readings, showed an agreement generally within plus or minus 15 percent. The fallout patterns of 7 tower-supported and 3-balloonsupported detonations were delineated to distances ranging from 100 to 600 miles from ground zero and, at the greater distances, fallout was timed for 12 hours after detonation. Up to 12 hours, balloonsupported shots appeared to produce at these distances less than 10 percent as much fallout as did tower-supported shots of equivalent yield and detonation height. It was estimated that 10 to 30 percent of the total radioactivity produced by tower-supported shots was accounted for by these measurements. Particle size analysis indicated that tower-supported shots produced much greater amounts of fallout than did balloon-supported shots in size ranges greater than 44 microns in diameter. In many locations most of the radioactive particles from balloon-supported shots were less than 5 microns in diameter. Biological availability of fallout was tested by solubility of fallout material in dilute hydrochloric acid and in water. Fallout material from tower-supported shots was soluble on the order of 7 percent in hydrochloric acid and 1 percent in water. The solubilities of fallout. material from balloon-supported shots were of the order of 70 percent in hydrochloric acid and 15 percent in water. Gamma measurements based upon both prelocated field monitoring instruments and laboratory analyses showed some deviations from the predicted rates of decay. In cases where variations occurred, the radiological decay occurred somewhat more rapidly for fallout that occurred at early times after a detonation, and more slowly for later fallout. Beta decay measurements more closely approximated the predicted rates. The accumulation of fission products by native rodents trapped in various locations within fallout patterns was documented for five detonations during Plumbbob to define the factors influencing biological accumulation of radioactive fallout. The data showed a marked similarity in the patterns of biological accumulation related to the time of arrival of fallout. Maximum mixed fission product accumulation in the animal tended to occur at places which fallout reached 2 to 3 hours after detonation, but concentrations in all tissues decreased at sites which fallout reached 3 to 12 hours after detonation. The rate of decrease was rapid for the 2- to 5-hour area. In the case of the several tower-supported detonations studied, fission product concentrations remained more or less uniform between 5- and 14hour areas. For the single balloon-supported detonation documented by radioactivity in native rodents, the rate of decrease was approximately constant between 2 and 12 hours. Nuclear Materials Management Standard Reference Materials On January 8, the Committee for Uranium Isotopic Standards was reconstituted as the Advisory Committee for Standard Reference Materials and Methods of Measurement to reflect the broadened scope of its activities (see app. 2). The committee reviews, evaluates and recommends means for providing standard reference materials (i. e., certified chemical and isotopic standards for uranium, plutonium, etc.) and approved methods of measurement for materials of special importance to atomic energy activities. Continuing plans to provide uranium isotopic standards through the joint efforts of the Commission and the National Bureau of Standards, the first nine of a series of 15 provisional uranium isotopic standards were shipped to the Bureau. This series, enriched in uranium 235 in a range from 0.5 weight percent to 93 weight percent will be evaluated by the Bureau before their distribution as provisional standards. Analytical facilities for handling plutonium were being prepared at the Commission's New Brunswick Laboratory. In addition to development of methods of measurement and general analytical work, the laboratory will study the characteristics of plutonium compounds for use as standard reference materials. Peaceful Uses of Atomic Energy Domestic. The annual meeting of Commission and contractor personnel concerned with materials management was held at Commission headquarters the week of May 19. Four panel discussions were held and some 20 papers presented. Approximately 200 attended. A symposium on "Reactor Fuel Measurements Techniques" was held at Michigan State University, East Lansing, Mich., on June 1820. The 25 papers presented covered such problems as sampling of fuel alloy melt, nondestructive analysis of fuel elements, and chemical analysis of fuel alloys and homogeneous slurries for major constituents. Both contractor personnel and access permit holders attended the meeting. Foreign. An information manual outlining the principles of source and special nuclear materials control followed by the Commission and its contractors has been prepared and is available for distribution to foreign nations which have entered into agreements for cooperation with the United States. |