63 from its bremsstrahlung spectrum, but in prac- Tabie 29 tice the complications caused by the presence of gamma-ray emitters and bythe size of the human Cesium-137 Body Burdens body render this method infeasible.) Comparison ofthe excretion rates of °°Sr and 137Cs with the bady burdensof '*’Cs measured by whole-body counting provides a clue to the *°Sr body burdenstatus. A quantitative value cannot be deduced, however, because the factors relating the behavior ofthe two nuclides are not sufficiently well established. The study by Hardy, Rivera, and Conard** summarized in Appendix 18 is pertinent to this problem. '*’Cs and °°Sr retentions werefollowed for 190 daysafter ingestion of representative Rongelap food items by one of the investigators. The '°’Cs ingested was almost quantitatively absorbed from the gastrointestinal tract, but 50% of the *°Sr was excreted via the feces in the first 10 davs and may be regarded as not having been way absorbed. By the end ofthe study almostall of the Cs and about 75% of the *Sr had beensexcreted in the urine and feces. The exactfigure for reten- tion is dependenton the correction used for activities ingested in the normal diet, and these were not measured. In this study the biological halftimefor '*’Cs was estimated as 74 days. For both "Cs and %Sr the urinary excretion rates were markedly elevated during the ingestion period and for a few days afterward. This confirms otherre- sults 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 '?’Cs Levels in Marshallese and Alaskan Eskimos for Residents of Anaktuvuk Pass, Alaska®® Body nCi per Age, vr No. persons burden, nCi kg body wt. >2i 15-20 3-14 23 3 22 92058 490442 15.72=1.0 9.51.0 >21* 16 900 60 16.0+1.3 170+17 6.20.3 *“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 not constitute a radiological health hazard.*° These opinions are con- sistent with those that have governed the 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 (BSzrgus fatro). Because of its high °°Sr content, it has been bannedas a food. The follow- ing concentrations of °°Sr and '*’Cs were found in a crab taken from Rongelap Island in 1965 (radio- chemical analysis by the Health and Safety Laboratory): *°Sr, 66,600 pCi/kg original matter; 87Cs, 12,700 pCi/kg original matter; stable Ca, 92.1 g/kg original matter. Previous analyses of crabs taken from Rongelap Island have been reportedin 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, It is of interest to compare the ‘**Cs body burden findings in the Rongelapese with those reported 628, and 780 pCi *Sr/g Ca, and 39,292, 45,318, Eskimo population in August 1965 are shownin are slightly below the average for the previoussurvey andfor '*’Cs are reduced to about '4 the previous results. All these results are markedly lower for certain Alaskan Eskimos. The findings in the 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 findingsin the local caribou, one of the principal componentsoftheir diet.*° The Federal Radiation Council Radiation Protection Guides*” is cited as recommendinga limit of 3000 nCi '3’Cs in individual adults for this population, and 66,234 pCi '’Cs/kg. The 1965 results for °°Sr 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 with the data on Rongelap subject No. 73, who had the highest '37Cs 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 seemsclear from this that becauseofits relatively high °°Sr content the