FALLOUT I-131 IN CHILDREN--IN VIVO MEASUREMENTS.

Abstract

The relative importance of inhalation and ingestion as modes of entry of I/sup 131/ from fallout into the thyroids of children was investigated during the fall of 1962, using as subjects fifteen children ranging in age from 6 to 14 years. One group of children was maintained on a regular diet, and the second on a restricted diet containing no radioactive iodine. The levels found in the children on the testricted diet were either zero or very small, demonstrating that ingestion was the predominating mode of entry. in a second phase of the investigation, the effect of Nal in reducing the uptake of I/sup 131/ was studied by maintaining all the children on a regular diet and administering 0.5 mg NaI/ day to seven of the children. Administration of stable iodide resulted in a smaller thyroid content, but did not completely suppress the uptake of radioiodine. Measurements were made in a small shielded room, using two 6.3 x 3.8 cm NaI(Tl) crystals. The limit of detectability of the system, with a 30-min counting time, was 30 pC I/sup 131/ in the thyroid. (auth)