Thyroidal burdens of 129I from various dietary sources

Thyroidal burdens of 129I were calculated for 1-, 4- and 14-yr-olds, and adults, using available dietary data. Milk and milk products contributed 63, 57, 54 and 33% of the total thyroidal 129I burden of the four respective age groups. As the contribution from dairy products decreased, that from meat increased from about 12% for 1-yr-olds to 35% for adults, while that from leafy vegetables remained relatively stable, from 17 to 21%. From ingested foods produced in air assumed to contain 1 pCi 129I per m3, daily dietary 129I intakes of 1.3, 1.2, 1.7 and 1.5 nCi were computed for the 1-, 4-, and 14-yr-old child and adult, respectively. For each nCi ingested daily, thyroidal dose rates for the respective age groups were calculated to be 4.9, 2.1, 1.7 and 2.6 rem/yr, with the altered dose rates reflecting age-related differences in thyroid gland size and iodine kinetics. (author)