30-, 50-, and 70-y dose equivalents are less when intake begins as an infant or child than when intake begins as an adult. Even if the ?9Sr intake for infants and children were significantly higher than what we have estimated, the total integral 30-, 50-, and 70-y effective dose equivalent from both initial intake is the same regardless of age, the integral 30-, 50-, and 70-y dose equivalents are slightly greater when intake begins as an adult than for intake beginning at any other age. This results from the combination of changing body weights, fractional deposits, and biological half-life for 137Cs with age and the reduced concentration of !37Cs in food with time. For example, when intake begins as an infant, the 137Cs concentration in food has declined by about 35% by the time the infant reaches 18 y of age, when the dietary intake is greater and the biological half-life of 137Cs longer. Consequently, if the intake of 137Cs for an infant or child were equal to that for the adult (which it is not based on available dietary information 137Cs and 9Sr would be greater for adults than for infants and children because !37Cs accounts for about 97% of the total estimated effective dose equivalent at the atolls via the ingestion pathway and %Sr for less than 3%. Doses from 137Cs and Srare insignificant through the inhalation pathway as compared to that via ingestion (Robison et al., 1987; ICRP, 1979; Cristy et al., 1984; Kendall, 1986). Consequently, the relative magnitude of the from the Marshall Islands), the estimated integral integral 30-, 50-, and 70-y dose equivalent would children, and adults can be determined by dose equivalent among infants, still be similar to that estimated for adults. In the case of 99Sr, the dose commitmentper unit intake is greater by about a factor of 5 for intake beginning at ages 0 to 5 y than for intake beginning as an adult. However, when agedependent differences in intake of 29Sr via the diet are accounted for, the estimated integral evaluating the ingestion pathway; that analysis indicates that the estimated effective integral dose equivalents for adults due to ingestion of 137Cs and 99Sr is a conservative estimate for intake beginning in infancy and. childhood. References Aarkrog, A. (1963), “Caesium-37 from Fall-out in Human Milk," Nature 197, 667-668. Abraham, S., M.D. Carroll, C.L. Johnson, and C.M.. Villa Dresser (1979), Caloric and Selected Nutrient Values for Persons 1-74 years of Age: First Health and Nutrition Examination Survey, United States 1971-1974, U.S. Department of Health, Education and Welfare, DHEW Publication No. (DHS) 79-1657,-Series 11, No. 209. Adams, N. (1981), "Dependence on Ageat Intake of Committed Dose Equivalents from Radionuclides,” Phys. Med. Biol. 26, 1019-1034. Bengtsson, L.G., Y. Naversten, and K.G. Svensson (1964), "Maternal and Infantile Metabolism of Caesium,” Assessment of Radioactivity in Man, Vol. H, International Atomic Energy Agency, Vienna, Austria, pp. 21-32. I0001 1b 22 steaeee radiological half-life of 137Cs and where the