164 Health Physics August 2010, Volume 99, Number 2 variation of the intake rates with time. Assuming implicitly that fallout from the Bravotest at Rongelap and Utrik was much more important than the fallout from all other tests, Lessard et al. (1984) used a single exponential relationship to model the decline of dietary activity intake during the entire period of time in which whole-body and intakes and are primarily related to the consumption of seafood and oflocally grownterrestrial foodstuffs internally contaminated with long-lived radionuclides as a result of root uptake, and, to a lesser degree, to the inadvertent consumption of soil (Simon 1998; NCRP 1999). The available whole-body counting and bioassay measurements were used as a basis to estimate the chronic intakes. Those whole-body and bioassay measurements were made on the Rongelap and Utrik evacuees for years after they returned to their respective home bioassay measurements were made, 1.e., from 1957 to 1981. The variation with time of the dietary intake rate, g, of radionuclide, Z, from test Bravo, at atoll, 7, with time, f, (assuming no additional fallout) can, thus, be expressedas: atolls (Lessard et al. 1984). Those two atolls had been q(Z, Bravo, j, t) = q(Z, Bravo,j, 7) evacuated within about two days following the detonation of the Castle Bravo test on 1 March 1954. Rongelap and Utrik inhabitants were returned to their homeatolls in June 1957 and June 1954, respectively (Simonetal. 2010, Table 3). During the first few weeksafter their return and until the 1980’s, a Brookhaven National Laboratory team regularly % I+EZAIXU-ME (5) where q(Z, Bravo, j, T) =the dietary intake rate (Bq d') of radionuclide Z from the conducted measurements of whole-body activity of '°’Cs, Co and ®Zn, as well as urinary concentrations of ”’Sr. Measurements of *Fe in blood were also performed but Bravo test on the day of return to the atoll /; T =is the time (d) elapsed between the Bravo test and the return to the atoll, and ¢ is greater than, or equalto, 7; A(Z) =the radioactive decay constant only once (Lessard et al. 1984). The steps used to estimate the chronic intakes of radionuclides were: (1) estimation of the chronic intakes by Rongelap and Utrik adult evacuees due to the Bravo test, (2) estimation of the chronic intakes (d') of radionuclide Z; and resulting from the Bravo test by adults of all other k(Z,j) =the dietary removal constant atolls, (3) estimation of the chronic intakes by adults resulting from tests other than Bravo, and (4) estima- (d_') of radionuclide Z at atoll j. The values of g(Z, Bravo, j, 7) and k(Z, 7) obtained by Lessard et al. (1984) are presented in Table 3. It is tion of the chronic intakes by children. worthwhile noting that the uncertainties are large and the Estimation of the chronic intakes by Rongelap and Utrik adult evacuees due to the Bravo test. Lessard et al. (1984) summarized the findings of the values of k for °Co and °Zn obtained for Rongelap were used for Utrik by Lessard et al. (1984), as well as in this work Brookhaven whole-body counting and bioassay program and estimated the ingestion rates of Fe, °°Co, ®Zn, °°Sr, because of the paucity of relevant measurements on the Utrik residents. In fact, because many more measurements were and '°’Cs for the adult populations monitored when they made on the Rongelap evacuees than on the Utrik evacuees, only the results obtained for the Rongelap evacuees were used returned to their atolls, and also provided data on the Table 3. Values used to estimate chronic intakes for the populations of Rongelap and Utrik. Uncertainties correspond to one standard deviation (based on Lessardet al. 1984). Ingestion rate on day Radionuclide, Z Atoll, j Fe Rongelap Sr Rongelap Co Zn BCs Fe Co Zn Sr BICs Rongelap Rongelap Rongelap Utrik Utrik Utrik Utrik Utrik of return to the atoll, q(Z, Bravo, j, T) (Bq d-') 1,700 + 930 95 + 32 1,300 + 940 21+ 1.1 390 + 130 1,300 130 21,000 0.40 210 + + + + + * Assumed value. > Assumed to be the same as in Rongelap. 710 44 16,000 0.30 110 Effective half-time of dietary removal, Radioactive decay Dietary removal rate, 7.1 x 104 0° constant, A(Z, j) (d7') K(Z, j) (d-') 3.6 X 107* 2.8 x 1073 2.0 x 1073 1.3 x 1073 6.3 X 107 2.0 x 107" 6.6 X 10° 7.1 3.6 2.8 6.6 6.3 xX x X X X 1074 10-4 107 10° 10° 1.7 x 10+ 2.0 1.3 1.6 1.8 0 x 107 xX 107% x 1074 x 1074 In 2/[A(Z, )+k(Z,/)] (d) 980 290 170 2,900 2,600 980 290 170 3,100 2,900