69 induced activities (59Fe, 57-58.60Co, 54M{n, 144Cs143Pr, 99Zr-95Nb, and !°6Ru-296Rh). Radiological assessment has included surveys for gamma radia- tion fevels on the islands; radiochemical studies of soul profiles, lagoon bottoms, marinelife, plants, ant- mail life (e.g., rats. coconut crabs), food items, and urine samples; and gammaspectrographic analysis of internally deposited gamma emitters in personnel. The medica! team has been responsible since 1969 for monitoring the bodyburdens of the people returning to Bikini, as well as of the Marshallese exposed to fallout and their controls, and morere- cently also of the people returning to Eniwetok. The 1974 studies of environmental radiation on Rongelap, Uturik, and Bikini are being published separately.165 Until 1965 gamma spectroscopy was done in a 21-ton steel chamber built at BNL for shielding, with additional housing for the counting equipment (Figure 53). The subject to be counted took a soap and water shower, put on paper pajamas, and then stayed in the chamberfor about 15 min, during which soft music was piped in. Only a few small children were apprehensive during the procedure. More recently whole-body counting has been done with a smaller “shadow-shield”’ arrangement of lead bricks, a modification of the Hanford model!®(Figure 34). In 1974 spectroE r T T T T TT r 50,000 cF 3 :4 Activity (counis/ 15 min) 4 10,000 — = Rongelap male 5,000 ~ - ---- BNL medical team 7 male 4 L =f 1,000afL ‘\ ‘ ean l 00 - 44 \ [ . Ny iA \ F f { wi i —_— \ \ 50 F 1 0 4 0.4 a \ ™ i 0.8 Enerev (MeV) i 1 1.60 Figure 55. Gamma spectra obtained by whole-body counting, males, !974(——, Rongelap; -—-, BNL medical team). 137Cs; its levels are given for Rongelap, Utirik, and Bikini individuals in Appendix 12 and for groups in Table 41. Since the return to Rongelap, no differences have been seen between exposed and unexposed groups. Figures 56 and 57 show the estimated body burdens of gamma emitters and 9°Sr for the Rongelap people at various timesafter the initial exposure in 1954. After their return to Rongelapthe body burdens increased. §5Zn was present for a few years, apparently from fish in the diet; the reason for its rapid decrease was not immediately apparent but maybe related to movements of marine life in and out of the lagoon. Small amounts of Co wereidentified in personnel during the early years after the return (the highest concentration was in clams). 9°Sr body burdens reached their highest level during 1962 to 1965 at about 12 nCi *Weare indebted to Mr. Edward P. Hardy, Jr., Director, En- vironmental Studies Division, AEC Health and Safety Laboratory, New York, N.Y., for carrying out the radiochemical analyses. Table 40 Radionuclides in Coconut Crabs From Rongelap Year 1964 2| 4 4 1.20 marized in Tables 37 to 40; the results of indi- vidual urinalyses are given in Appendix 12.* By 1974 the only detectable gamma emitter was 4 —z iL. the low levels present in the people (see Figure 55).167-168 Annual collections of 24-hr urine sarnples from a numberof people have been madefor radiochemical analvsis. The results of radiochemical analyses of urine, water, and crabs over the past 5 years are sum- 7 1 fo\ 63Zn, but 5°Co was barely discernible, if at all, at 1961 1962 = in 100 1 10 =3 graphs showed a characteristic peak for 137Cs and 1963 1969 1972 1973 1974 137Cs, pCi/kg Sr, pCi/g Ca 1,140 1,224 (1,317; 1,086; 1,113; 1,378) 50,281 (39,292; 45,318; 758 (865; 628; 780) 66,234) 12,700 724 7,775 (8,540; 7,010) 705 (910; 500) 5,900 (5,600; 6,100; 353 (376; 419; 359; 6,800; 5,100) 259) 12,900" 933* 37,065 (64,700; 9,430)* 3,950 (6,639; 1,267)* 6,600 (5,000; 8,200) 448 (290; 606) 4,800* 290* *From northern istands of Rongelap Atoll, where radiation dose was muchhigher.