49 to that of the phantom, which was countedfor 30 min (Figure 52). In future whole-body counting of these people, it will be possible, by counting for longer periods and using an 8-in. Nal crystal, to improve the absolute measurementof trace amounts of other radionuclides that may be present. Since a total of 227 Marshallese persons were surveyed with the whole-body counter, in addition to numerouscontrols, the spectral analyses were performed with the aid of a 704 IBM computer. Radiochemical Procedures Twenty-four-hour urine specimens were collected in plastic bottles and sent to BNLfor radiochemical analysis. A modifica: »n of the method of Farabee*°® was used for the analysis of Sr®°. Sr was precipitated as the alkaline phosphate, ashed with HNO, and H.O,, and dissolved tn dilute HNO,,. After the solution was brought up toa volume of 800 cc, the alkaline earths were com- plexed with EDTA, and the pH was adjusted to 3.3. The solution was then passed through an ion exchange column (Dowex-50 in the Na form), and the column wasrinsed with 300 cc ofa solutron of 1% citric acid and 0.75% EDTAata pH of 3.0. The combined effluents contained >95% of the total Ca. The column wasthen rinsed with 6 .V HNO,to remove the Sr°°. Carrier Sr was added to the Sr*° fraction and precipitated with 70% fuming HNO, Yttrium-90 was milked and counted by the method of the AEC Health and Safety Laboratory.*' The supernatant from the alkaline phosphate precipitation was measured and divided into two portions. One portion was scavangedfor cesium with added carrier by means of a double precipitation of the aluminum sulfate and the chloroplatinate.*' The second portion was analyzedfor K by flame spectrophotometry. Food samples were weighed and dry-ashed in a muffle furnace at 800°C. The ash was weighed, and a small portion was counted for gross beta activity. The ash was dissolved in dilute HNO, and processed by the method described abovefor urine analysis. All counting was donein a low-level beta anticoincidencetype of counter, designed andbuilt at BNL. Samples were mounted on glass fiber filter discs with nylon rings and discs and Mylarfilm. Samples were counted against NBS standards processed and counted underidentical geometry.*' RESULTS AND DISCUSSION All three of the above methods were used for estimating the body burdens of gamma- andbetaemitting radionuclides in the Marshallese people. Individual values for all the people examined in 1959 may be found in Appendix 7 for gamma spectrographic analyses and in Appendix 8 for radiochemical analyses. Environmental Estimate One method used (the least quantitative) was the environmental estimate of body burden. The environmental estimate of internally-deposited Sr®° was madein two ways. In the first method, animals subsisting on diets similar to humandiets were sacrificed and their tissues were analyzed radiochemically. A numberof rats were collected on RongelapIsland at 2, 4, and 5 years after the 1954 accident. If the diet of these rats, primarily land plants, was sufficiently similar to the diet of humanbeings inhabitingthis area, the rat analyses might serve as indicators of the humaninternal radiation contamination. The Sr*°/Caratios of varioustissues of these rats were measured directly and comparedto theratios of the food andsoil on Rongelap collected at the same time; thatis, the environmental contamination was compared with the directly measured contamination in animal tissue. Extrapolation of the environmental data gives the equilibrium value which can be expected, whereasthe direct measurement gives the value at the time of measurement(and thusthe percentof the equilibrium value for the individual radionuclides). The Sr*°/Caratios for different plant foods on Rongelapvaried greatly, and the diet of the rats was too uncertain for an ‘‘average”’ diet to be assumed. Therefore, for a body burden estimateit was necessary to use the Sr°°/Ca valuesofthe soil itself. The “strontium-calcium observed ratio” (OR) of Comar‘** was used to denote the preferential utilization of calcium in the following manner: OR, mp: e-precursor — Sr/Ca of sample Sr/Ca of precursor The Sr®° discrimination ratio in the chain from soil (s) to bone (6) via plants ( #) can be expressed as follows: OR,.,=(OR,.,)(OR,.,) =(0.7)(0.25) =0.18 .