[Thorium a radioactive element in current use: physical-chemical properties and biological processing]

The radioactive properties and physicochemistry of thorium were studied and correlations drawn between thorium and element sof the titanium group, lanthanides and plutonium. It appears that the behavior of Th4+ and Pu4+ are similar, particularly their distribution pattern on bone surfaces. Chelating agents are reviewed and the structure of metal chelates indicated.