Estimates of the Radiological Dose from Ingestion of 137Cs and 90Sr to Infants, Children, and Adults in the Marshall Islands Abstract In this report, we examine whether the radiological dose equivalent due to the intake of 137Cs and 90Sr at a contaminated atoll in the Marshall Islands would be greater when intake begins as an adult than when intake begins as an infant or child. We found that generally 137Cs contributes 97 to 98% of the dose and 90Sr contributes only 2 to 3%. We also found that the integral 30-, 50-, and 70-y effective dose equivalent estimated for intake beginning as adults is greater than that for intake beginning at any other age. There are two factors that cause the adult estimated dose to be greater than the dose to infants and children. The major factor is the consistently higher mtake of local foods, and consequently higher intake of 137Cs, for adults. The serond is a combination of changing body weights, fractional deposits, and biological half-life for 137Cs with age, and the reduced concentration of 137Cs in food with time. Consequently, the estimated effective integral dose | equivalents for adults due to ingestion of 137Cs and 99Sr can be used as a . conservative estimate for intake beginning in infancy and childhood. Introduction The purpose of this report is to determine whether the radiological dose equivalent due to the intake of 137Cs and Sr at a contaminated atoll in the Marshall Islands would be greater when intake begins as an adult than when intake begins as an infant or child. In previous publications, we have estimated the radiological doses to adults at several atolls in the northern Marshall Islands resulting from external gamma exposureandinternal ingestion of 137Cs5 , 90S , 239+240py and 244Am (Robison etal., 1982a, 1982b, 1987; Robison, 1983). We have mentioned in all of these reports that the Mah oT g se bh eS Y radiological dose from the ingestion of 137Cs and 9S; beginning in infancy or early childhood would lead to 30- and 50-y integral doses that are about the same or less than similar doses estimated for intake beginning as an adult. These statements were based on dietary data for the daily intake of 137Cs and 9%Sr at the Marshall Islands, differences in physiological parameters (such as biological half-life and deposition patterns for 137Cs and 9°Sr), body mass as a function of age, and dosimetry; we published a preliminary evaluation of the relative estimated radiological doses for