Acute and chromic mtakesof fallout radionuclides @ SL Simow er av intakerates of "Cs by children compared to adults were 167 3 to7 y, and 0 for other children We assumedthatthe thyroid does not occur until the end of the 11” week followmg conception when the fetal thyroid begms to function (ICRP 2001) This mmphesthat the thyroid dose to intakes of Sr, which are, as for '°’Cs, mamly dueto the fraction of the dose the fant would receive per umt intake 18 for children aged less than 3 y, 1 4 for children aged same age dependency was applicable for estrmating consumption of internally contammated terrestrial food- stuffs However, the mtakes of ®Zn, ™Fe, and “Co were due to the consumption offish and other seafood Using the consumption estimates for fish and other seafood provided by Robison and Phillips (1989) and the assumption that the activity mtake was proportional to the amounts of seafood consumed, the age-dependent rela- tive mtakes of Zn, “Fe, and “Co were | for adults, 0 9 for 15-y-old, 08 for 10-y-old, 06 for 5-y-old, 03 for 1-y-old, and 01 for newborn the fetus per umt mtake of “I by the mother 1s a small after bnth ~0 001% at 5 wk development, 0 03% at 10 wk, 2% at 15 wk, 6% at 25 wk, and about 10% at 35 wk In this work,the doses to the embryo and fetus are assumed to be very small and taken to be equal to zero Forall age groups andall radionuclides considered, with the exception of the "I mtakes by adults, the dose coefficients are based on the biokinetic models recommended by ICRP (1996, 2004) The only parameter values that have been changed are those of the alimentary tract absorption fractions (f,), which have been taken from the review by Ibrahim et al Dosecalculations Annual absorbed doses to RBM, thyroid, colon, and stomach wall have been estimated for the time period from 1948 through 1970 for representative mdividuals who were assumed to bealive in 1970 The methods used to estimate doses resultmg from acute mtakes and from chronic mtakes will be considered m turn Annual doses from acute intakes. The method for calculatmg annual doses from acute mtakes1s stmply the product of the acute average mtake, @ (Bq), of radionuchde z and the dose coefficient (Gy Bq"') for that radionuclide where the dose coefficient was specific to an imterval of time after mtake either the remainder of the calendar year m which the intake occurred,or the full year M successive years Dio, 1, y) = Olt) X DC(o, 1, age, y), (9) where (2010), that are specifically related to the mtakes of radionuclides in particulate fallout An established computer code (Eck- erman et al 2006) was usedto solve the ICRP biokmetic models and to provide annual dose coefficients for all organs and age groups Foranytest, the first year armual dose coefficient was the dose per umt intake received from the date of the mtake until the end of the calendar year (e g , 365 dif the date of intake was | January, 306d if the date of mtake was 1 March, and 61 dif the date of intake was | November) The annual dose coefficients for the subsequent years were the doses per umt mtake received durmg the full calendar years This deriva- tion, which mfluences the first year’s estrmated dose as well as estrmated doses m subsequent years for radionuchdes with long radioactive half-lives, 1s 1lus- trated m Fig 1, takmg °°Sr as an example The annual dose for the first year was highest for an mtake assumed to have taken place on | January, was 15% less 1f the mtake occurred on | March, and about 78% D(o,t, y) =the dose (Gy) for organ o from radionuchde zm a specific year, y, after mtake, OG) =the average acute mtake (Bq) of radionuchde 2, and DC(o, t, age, y) =the amual dose coefficient (mGy Bq"') for organ o from radionuchde 1, for age in a specific year, y, after mtake The armual dose coefficients, which are the absorbed doses per umt activity mtakes (mGy Bqu'), have been estimated for six age groups (<I y, 1-2 y, 3-7 y, 8-I2y, 13-17 y, 18+ y) Dosesto the embryo and fetus have not been calculated as they are expected to have been much smaller than those received during thefirst year oflife For example, m the case of 1odme, which has been relatively well studied, selective uptake of that element by the fetal less 1f the mtake occurred on I November For the subsequent years, m comparison, the armual dose coefficient for 1 January mtake was lower compared to the other dates (4% lower compared to 1 March and about 15% lower compared to 1 November) For intakes of ‘I by adults, the dose coefficients were derived based on the parameters of the biokmetic model presented m Fig Al for an average of the two preferred data sets of physiologic parameters (Table Al) The set of physiological parameters assigned as 2b (Table Al) assumed a fractional thyroid uptake about one-third greater than 1s usually assumed for populations with typical western diets (42% compared to 30%) In orderto correct the thyroid mass for a greater than typical thyroid uptake (Zvonova 1989), we assumed the thyroid massto be larger than the usual default assumptions by the same proportion Hence, for our purposes, we assumed the adult thyroid mass to be 26 g compared to the