63 from its bremsstrahlung spectrum, but in practice the complications caused by the presence of gamma-ray emitters and by the size of the human Table 29 Cesium-137 Body Burdens body render this methodinfeasible.) Comparison of the excretion rates of °°Sr and '87Cs with the body burdens of '*’Cs measured by whole-body counting provides a clue to the “°Sr body burden status, A quantitative value cannot be deduced, however, because the factors relating the behavior ofthe two nuclidesare not sufficiently weil established. The study by Hardy, Rivera, and Conard** summarized in Appendix 18 is pertinent to this problem. '*’Cs and *°Sr retentions were followed for 190 days after ingestion of representative Rongelapfood items by one ofthe investigators. The '*’Cs ingested was almost quantitatively absorbed from the gastrointestinaltract, but 50% of the °°Sr was excreted via the feces in thefirst 10 days and maybe regarded as not having been absorbed. By the end ofthe study almostall of the '87Cs and about 75% of the *°Sr had been excreted in the urine andfeces. The exactfigure for retention is dependent on the correction used for activities ingested in the normal diet, and these were not measured. In this study the biological hailf- time for '*’Cs was estimated as 74 days. For both '87Cs and °°Sr the urinary excretion rates were markedly elevated during the ingestion period and for a few days afterward. This confirmsotherresults to the effect that the excretion rates found are strongly affected by the recent diet and, when there has been a recent intake of high activity food, the excretion rates do not provide accurate indices of the body burdens. Comparison of '37Cs Levels in Marshallese and Alaskan Eskimos It is of interest to compare the **’Cs body burden findings in the Rongelapese with those reported for certain Alaskan Eskimos. The findings in the Eskimo population in August 1965 are shown in Table 29.%* It may be noted that the results for adult Eskimos are equal, within statistical limits, to those for the adult male Rongelapese. For the Eskimo population the 1965 data run about 30% lower than the comparable 1964 data, and this trend parallels the findings in the local caribou, one of the principal componentsof their diet.*° The Federal Radtation Council Radtation Protection Guides** is cited as recommending a limit of 3000 nCi '*"Csin individual adults for this population, 9008344 for Residents of Anaktuvuk Pass, Alaska™* No, persons Body burden, nCi nCi per kg body wt. >21 23 920458 15.7£1.0 >21* 16 900+ 60 16.0413 Age, yr 15-20 3-14 5 22 490 +42 170417 9.51.0 6.2+0.3 *“Controls’” - members of a group who were first counted in 1963 and are re-examined periodically. and opinions are expressed to the effect that the current body burdens do notconstitute a radio- logical health hazard.** These opinions are consistent with those that have governedthe policies applicable to the Rongelapese. Radiochemical Analysis of Coconut Crabs A food item that has been of special interest throughout the Rongelap medical surveysis the coconut crab (Birgus datro), Because ofits high °°Sr content, it has been banned as a food. The follow- ing concentrations of °°Sr and '*’Cs were found in a crab taken from RongelapIsland in 1965 (radiochemical analysis by the Health and Safety Laboratory): *Sr, 66,600 pCi/kg original matter; 87s, 12,700 pCi/kg original matter; stable Ca, 92.1 g/kg original matter. Previous analyses of crabs taken from Rongelap Island have been reported in the 7, 8, and 9-10 year reports.*"'° For °°Sr the results have run: at 7 years 1140 pCi °°Sr/g Ca; 8 years 1317, 1086, 1113, and 1378 pCi °°Sr/g Ca; and 9-10 years 865, 628, and 780 pCi *°Sr/g Ca, and 39,292, 45,318, and 66,234 pCi '*"Cs/kg. The 1965 results for °°Sr are slightly below the average for the previoussurvey andfor ‘*’Cs are reduced to about '4 the previous results. All these results are markedly lower than those that have been obtained with crabs from the more heavily contaminated islets of Eniatok and Kabelle (Figure 71). The crab data may be compared withthe data on Rongelap subject No. 73, who had the highest 87Cs body burden (25,400 pCi/kg) and wasexcreting activity in concentrations of 78,000 pCi '*’Cs/g Ca and 50 pCi *°Sr/g Ca. It seems clear from this that becauseofits relatively high °°Sr content the