4.4 Infant Dosage The doses that have been under consideration are for adults. In the case of children and infants, the doses might be different owing to variations in (1) physical and physiological processes and (2) dust and diet. Physical and physiological factors. conversion factors in Tables 4.2 #1A & #1B. These variables affect the For example, the smaller size of children can diminish the fraction of gamma ray energy absorbed in the body; the residence time of the radionuclide in the body may be less than in adults; the fraction aWsorbed from the gut might be puch more. Furthermore, a long-lived radionuclide deposited in the body at age 6 months will be diluted by growth so that its “picocuries per gran of tissue", on which a dose depends, will fall significantly with time. Table 4.4 #1, based on the United Kingdom NRPB report (1987b), and consistent with the recommendations of the ICRP (International Commission on Radiological Protection), shows that the corrections for children are well on their way to disappearing by age 10 y, but are important in the first year or so of not more than transuranics, it for ingestion it that year. of life. The correction for cesium-137 is an increase 20%, but that for strontium is about 3.6-fold. For the is 2.4-fold for inhalation during the first year, but is 22-fold for months 0-6, and 2.1-fold thereafter in These factors are for committed doses which in the case of children aged 10 and less are calculated to age 70 years rather than for the standardized period of 50 years in adults. For radionuclides with short physiological half-lives such as cesium-137 (less than 110 days), this is of no consequence. But for the transuranics with half-lives in liver and bone marrow of 20 and 50 years, respectively, the extra residence time adds to the 50-year committed dose. In general it would be expected that the smaller intake of children and infants will compensate for the increased size of their dose-factors compared to the adult ones in Tables 4.2 #1A & #18. Since there are almost no directly pertinent Rongelap data on such inputs, we have approached the problem in two ways. First, we have made some calculations aized at setting upper bounds. Second, we have attempted to obtain inforpation fron the Marshall Islands on infant and small child diets. 3000b42