Table 5. Estimates of the daily intake of 37Cs Adult (2 18 y). The average daily intake of from local foods by age group at Rongelap Atoll. 137Cs for adults is obtained from our diet model. When imported foods are available, the intake Age is 1085 pCi/d (specific data are presented in Appendix A, Table A-1). A summary of the !97Cs intake by age group is given in Table 5. 137Cs intake, pCi/d Q to 3 months 4 to 8 months 9 monthsto 1.4 y l5yto3y 424 556 773 517 4ytolly 594 12y toi7y 218y 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 85d The fetus is assumed to be in dynamic equilibrium with the mother. Experimental results indicate that in the first few monthsof pregnancy theratio of the 137Cs concentration in mothers to that in the fetus is 3:1, changing to about 1:1 in last months (linumaet al., 1969; Nagai, 1970). Consequently, the dose received by the fetus should be no more and perhapsless for males and females, respectively (ICRP, 1979; NCRP, 1977; Richmondet al., 1962). In some cases, the loss of 137Cs is 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 than that received by the adult mother (Jinuma fractional deposition of 137Cs in the model for et al., 1969; Nagai, 1970). In addition, the biological half-life of 137Cs the short- and long-term compartments for adults is 0.10 and 0.90, respectively (ICRP, 1979; NCRP, 1977). These fractional depositions and is shorter in pregnant women than in nonpregnant women, leading to lesser body burdens in pregnant women (Bengtsson etal., half-lives represent a model for an average adult around which particular individuals will vary. The long-term compartment is the most 1964; Zundelet al., 1969; Godfrey and Vennart, 1968). Consequently, the dose to pregnant women would be less than to nonpregnant women. Based on data presented by linuma etal. (1969), the significant compartment for dose assessment, and there is abundant evidence in the literature that dose to the fetus would be about half that calculated for an adult. showsthe long-term T!/? changes dramatically with age from birth to adulthood (Lloydetal.,, Infants, Children, Adolescents, and Adults 1966, 1970; Wilson and Spiers, 1967; Boni, 1969; "It ig assumed that when 137Csis ingested, linuma etal., 1969; Weng and Beckner, 1973; 100% of the 137Cs crosses the gut and enters the Lloyd, 1973; Cryer, 1972; Karcher et al., 1969; Richmondetal., 1962). The T'/? for 137Cs_ ranges blood, i.e., Fy = 1.0 (NCRP, 1977; ICRP, 1979). The loss of 137Cs from the bodyis then generally » a Crt JuuE ZOO from 10 to 12 d in infants (Wilson and Spiers, 12