Influence of iron on plutonium absorption by the adult and neonatal rat

To determine how iron affects plutonium absorption, adult rats were gavaged with 238Pu nitrate (pH 2) after they had been fed an iron-deficient diet or treated with iron supplements. Neonatal rats born to dams on an iron-deficient diet were also gavaged with 238Pu. An iron-deficient diet resulted in enhanced 238Pu absorption both in the adults and in neonates born to iron-deficient dams. Ferric iron increased 238Pu absorption 12-fold in adult rats; injected iron-dextran reduced that increase; gavaged ferrous iron reduced 238Pu absorption to one-third of the control value. Rat neonates absorbed 30 to 40 times as much 238Pu as adults; absorption was lowered in groups that received iron supplements: Iron-dextran caused a 50% reduction; ferric iron, 95%; and ferrous iron, greater than 95%. The results demonstrate an effect of the oxidation state of iron on plutonium absorption in adult rats different from that observed in suckling rats. The results suggest that the high rate of 238Pu absorption by neonatal animals is due not only to the permeability of their intestines but also to their high demand for iron.