Simulation of the digestive process in the evaluation of radionuclide availability in pharmaceutical clays for internal use

The occurrence and mobility of natural radioactive elements such as polonium, uranium and thorium isotopes in six pharmaceutical clays for internal use (as found on the Italian market) were determined because the effects on human health must take into account the availability of these elements. The simulation of gastrointestinal digestion was divided into two stages and was accomplished using two different solutions: a synthetic stomach solution and a synthetic bile-pancreas solution. The same sample was treated in two different ways: (a) only gastric digestion and (b) gastrointestinal digestion (stomach solution + bile-pancreas solution). Very significant differences were found for uranium with respect to those found for thorium, and for polonium with regard to either gastric or gastrointestinal digestion. On the contrary, the differences between the polonium mobility and that of thorium are not very pronounced for either gastric or gastrointestinal digestion. Gastric digestions present no differences with respect to complete gastrointestinal digestion for uranium, thorium and polonium mobility.