The chemical forms of plutonium in the gastrointestinal tract

In order to study the chemical form in which plutonium, and other actinides may occur in the various parts of the human gastro-intestinal tract, a simple model system has been developed. This system consists of a ''mouth'', in which reactions with human saliva may be studied, a ''gastric'' system containing a simulated gastric juice and an alkaline ''duodenal'' compartment. Centrifugation and gelpermeation chromatography on Sephadex G-50 were used to separate ''insoluble/hydrolysed'', high molecular weight (protein-bound), and low molecular weight plutonium. Except when the plutonium was present as a complex with DTPA, the proportions of all three components were found to change markedly during the transition from ''mouth'' to ''duodenal'' conditions. In the presence of a tea infusion or potato juice over 70% of the plutonium was in insoluble form, but in the presence of orange juice about 70% of the plutonium remained as soluble low molecular weight complexes in the mouth and duodenum. It is concluded that the absorption of plutonium from the gastrointestinal tract is more likely to be influenced by the ligands present at the site of absorption than by the chemical form in which the plutonium enters the mouth