A process for removing Pb2+ toxins from bodily fluids involves contacting the bodily fluid with an ion exchange composition to remove the metal toxins in the bodily fluid, including blood and gastrointestinal fluid. Alternatively, blood can be contacted with a dialysis solution which is then contacted with the ion exchange composition. The ion exchange compositions are represented by the following empirical formula:

AmTiaNb1-aSixOy

having either the pharmacosiderite, sitinakite, pharmacosiderite-sitinakite intergrowth topologies or mixtures thereof. There are also compositions comprising the above ion exchange compositions in combination with bodily fluids or dialysis solution. The ion exchange compositions may be supported by porous networks of biocompatible polymers such as carbohydrates or proteins.