Food chain of tritium

Ceratopteris pteriodes, soy bean and aquatic rice were cultivated with HTO, and male rats were administered with the diet containing HTO and T. T metabolism and distribution were determined separately in the free water and the tissue-bound water. T in the free water of the plants showed hardly any changes according to the sites, and that in the dry tissue tended to show high values in the stage and portion of high anabolic activity. In the animal system, the T uptake by the organic components was high, and it was rapidly excreted in tissues with a high metabolic activity, but was low, accompanied by slow excretion, in tissues with a low activity. Therefore, T excreted slowly and remained in the adipose tissue and brain containing large amounts of lipids. As for the T distribution into the tissue components, T was first distributed into small molecules and then, to large molecules after metabolism, in the fraction of hepatic tissue. The in-vivo behaviors of T-labeled compounds were varied because of their in-vivo metabolism. (Chiba, N.)