Biokinetics of radiotellurium in rats.

Radiotellurium is present in the environment primarily due to its release during nuclear reactor accidents. Little is known of tellurium metabolism in juveniles, although the element is relatively abundant and has a number of industrial uses. A biokinetic study of radiotellurium in rats was performed using gamma-ray counting. Wistar strain rats were used to determine the uptake of H2(123m)TeO3 by the whole-body retention of juvenile rats and the conceptus in relation to its gestational stages, by measurements in the placenta, fetal membranes, fetal fluid and fetus. The whole-body retention of 123mTe in juvenile rats was higher than that of adult rats. The relative concentration in the placenta and fetal membranes was higher than in the fetus. No activity was observed in the fetal fluid. These results indicate that the placenta and fetal membranes play significant roles as barriers to the transfer of 123mTe into the fetus. The ratio, relative concentration in fetus/relative concentration in mother (C(F)/C(M)), was calculated. The C(F)/C(M) ratio was dependent on the stage of gestation and ranged from 0.2 to 0.5. A little 123mTe was transferred to the suckling rats through the mother's milk when the isotope was administered intravenously to the mother.