9 ~ pw °* ost &,| | $ §! ; oak of a | Z| o2t O1 i| ooo Cid! i ' : t ior, | 8 oS! .8 = t ‘54 ‘57 Fig. 1. 3 e i 3 3 “U 8 ' ' 1 al ” — RONGELAP aeuee ; BONE oa i = , oO 5; fi 3 ] ‘} \ =!1 ys! 8 2 77 “+69 71 73 75 “TAR - 2b yom 4 (tt ak UT UTIRIK | a) 1 ' \ GROUPS 4 OTHER B+ BIKINI £: EBEYE Zz, : \ : iw, ; TEAM}: 7, i | 4 MEMEDICAL | 2, Oi ' U=UTIRIK : ah i 0.3b —'Tes RONGELAP ----§37n, 8$7,, RONGELAP « '%Cs OTHER GROUPS - f ed OK he? ee _—_ 5457. 59 G1 63 65 67 69 71 73 7S 77 Body burdens of gamma emitters. +948 2 a3 YEAR Fig. 2. Body burdens of 90s; The body burdens of radionuclides tended to reach equilibrium with the environment in several years and then gradually to become lower. Figures 1 and 2 show estimated body burdens of gamma emitters and 90sr over the years. 90sr body burdens reached their highest level during 1962 to 1965 at about 12 nC. in adults and 22 nCi in children, about 6 and 11% respectively of the maximum permissible lifetime body burden levels for the population at large; i.e., 1/10 the ICRP value. Analyses of bone samples from several autopsies during the past 20 years gave estimated 90s, body burdens similar to those obtained from urinalysis (see Figure 2). 137cs body burdens also reached their peak in about 1965, at nearly 0.7 pCi (23% of the permissible level for the general population). The body burdens of the Utirik people were considerably below those of the Rongelapese. 2. Reevaluation This section, by E. Lessard and N. Greenhouse, summarizes their reevaluation of the doses accumulated to 1979 from residual radiation exposure by populations living on Rongelap and Utirik Islands since 1954. A dosimetric summary for the Rongelap and Utirik adult populations is given in Table 4. This information was obtained by methods outlined in BNL 51257, A Reconstruction of Chronic Dose Equivalents for Rongelap and Utirik Residents — 1954 to 1980. Briefly, a multicompartment model for declining continuous uptake was developed, based on the results of historic and contem— porary urine bioassay and whole-body counting data. Daily activity ingestion: rates were extracted from the model and input quantities and used in conjune— tion with current metabolic models for internal dosimetry. Tables 5 and 6 illustrate adult mean values for the body burdens on Rongelap and Utirik, respectively. These body burden histories are the result of direct body burden measurements or indirect body burden estimates based on urine bioassay measurements. Derived body burdens were calculated for Utirik during appropriate years when measured data were lacking. A mean ratio of 2.55 to 1.0 was observed in the Rongelap to Utirik budy burdens for 652n, - 115 -