APPENDIX 18 Cesium-137 and Strontium-90 Retention Following an Acute Ingestion of Ronzelap Food by Edward P. Hardy Jr. and Joseph Rivera (Health and Safety Laboratory, New York Operations Office, U.S. Atomic Energy Commission) and Robert A. (Brookhaven National Laboratory, Upton, New York). Conard Published in "Radioactive Fallout from Nuclear Weapons Tests, Proceedings from the Second Conference, Germantown, Md., November 3-6, 1964," Ed. A.W. Klement, Jr., AEC Conf. 765, Nov. 1965. SUMMARY The cesium-137 and strontium-90 body burdens of people living on Rongelap Island are high compared to most other populations of the world. The reason for this is that the natives consume foods which are contaminated with longlived fission product radioactivity resulting from an accidental fallout incursion in 1954. Their Cs-137° body burdens are comparable to those of people living in other limited areas such as Lapland and northern Alaska where unique ecological conditions are conducive to high concentrations of cesium-137 in indigenous foods. The metabolism of cesium-137 and strontium-90 has been studied in the Lapland and Alaskan groups but not in the Rongelap natives. Since facilities for a metabolic balance study were not available on Rongelap Island, one of us (R.A.C.) brought several native food items ‘y (pandanus fruit and coconut meat and milk) back to Brookhaven and consumed them under controlled conditions. Urinary and fecal specimens were collected and whole body counting measurements were made over a period of 180 days. The intake of strontium-90 over a seven day period was twenty times higher than normal and that of cesium-137, sixty times higher than normal. Fifty percent of the ingested cesium-137 in the Rongelap food was excreted in urine after 85 days while fourteen percent was eliminated via the feces at the same time. In contrast, most of the strontium-90 was unabsorbed. Fifty percent was excreted in feces at 10 days while only two and one-half percent was excreted in urine. The retention of cesium-137 as determined by both whole body counting and excretion measurements showed a biological half-life of 74 days. Strontium-90 retention as a function of time was best described as a series of exponentials, and approached a value of 25 percent after 140 days. These findings fall within the range of results of many other studies conducted under a wide variety of natural, @ wee conditions. accidental, and experimental Table I and Figures 1-4 summarize the above findings.