Table 5. Estimates of the daily intake of 137Cs from local foods by age group at Rongelap Atoll. Adult (2 18 y). The average daily intake of 137Cs for adults is obtained from our diet model. When imported foods are available, the intake is 1085 pCi/d (specific data are presented in Age Appendix A, Table A-1). 0 to 3 months 4 to 8 months A summary of the !37Cs intake by age group is given in Table5. 9 monthsto 1.4 y 15yto3y 4ytolly 12 y to17y 218 y 137Cs intake, pCi/d 424 556 773 517 594 761 1085 Retention of 137Cs and 99Sr represented by a two-compartment, exponential model, where for adults the short-term Cesium-137 compartment has a biological half-life (T!/?) for Fetus 137Cs of 2d for both males and females, and the long-term compartment a T!/? of 110d and 85 d The fetus is assumed to be in dynamic equilibrium with the mother. Experimental results indicate that in the first few months of pregnancy the ratio of the !37Cs concentration in mothers to that in the fetus is 3:1, changing to for males and females, respectively (ICRP, 1979; NCRP, 1977; Richmondet al., 1962). In some cases, the loss of !37Csis better represented by a three-compartment model (Leggett et al., 1984), but generally the short-term compartmentin the , two-compartment model represents an average of compartments with half-lives the order of a few hours, a few days, and 1 or 2 weeks. The about 1:1 in last months (linuma et al., 1969; Nagai, 1970). Consequently, the dose received by the fetus should be no more and perhapsless than that received by the adult mother (linuma fractional deposition of 137Cs in the model for et al., 1969; Nagai, 1970). In addition, the biological half-life of the short- and long-term compartments for 137Cs is shorter in pregnant women than in nonpregnant women, leading to lesser body adults is 0.10 and 0.90, respectively (ICRP, 1979; NCRP, 1977). These fractional depositions and half-lives represent a model for an average adult around which particular individuals will vary. The long-term compartment is the most burdens in pregnant women (Bengtsson et al., 1964; Zundel et al., 1969; Godfrey and Vennart, 1968). Consequently, the dose to pregnant women would be less than to nonpregnant women. Based on data presented by linumaet al. (1969), the dose to the fetus would be about half that calculated for an adult. significant compartment for dose assessment, and there is abundant evidence in the literature that showsthe long-term T!/? changes dramatically with age from birth to adulthood (Lloyd et al.,, Infants, Children, Adolescents, and Adults 1966, 1970; Wilson and Spiers, 1967; Boni, 1969; It is assumed that when !3/Cs_ is ingested, 100% of the 13’Cs crosses the gut and enters the blood, i.e., Fy = 1.0 (NCRP, 1977; ICRP, 1979). Theloss of 137Cs from the bodyis then generally T0001 bb linuma etal., 1969; Weng and Beckner, 1973; Lloyd, 1973; Cryer, 1972; Karcher et al., 1969; Richmondetal., 1962). The T'”? for 197Cs ranges from 10 to 12 d in infants (Wilson and Spiers, 12