Comparative metabolism of tritium in rat after single ingestion of some tritiated organic compounds versus tritiated water.

As part of a series of studies designed to evaluate the relative radiotoxicity of various tritiated compounds, tritiated water, leucine, glucose and thymidine were singly ingested to rat and the metabolic fate of tritium was studied in various tissues over more than 100 days. The distribution and retention of tritium varied widely, depending on the chemical form in which tritium was administered. Tritium introduced as tritiated water behaved essentially as body water and distributed uniformly among the tissues. However, tritium administered as organic compounds resulted in relatively high incorporation into organic tissue constituents and its distribution differed among the various tissues. Moreover, the excretion rate of tritium from tissues was slower for tritiated organic compounds than for tritiated water. Administration of tritiated organic compounds results in higher radiation doses to the tissues than does administration of tritiated water. Among the tritiated compounds examined, for equal radioactivity administered, leucine gave the highest radiation dose, followed in turn by tritiated thymidine, glucose, and water.