Current and future radionuclide speciation studies in biological media

Radionuclides may be released into the environment accidentally or incidentally, which could raise health risks when ingested or inhaled by humans. In order to study the behaviour of radionuclides in the human organism (metabolism, retention, excretion), knowledge of radionuclide speciation is indispensable: speciation governs the transfer, bioavailability and toxicity of elements and is also of considerable interest for decorporation. In this context, the Commissariat a I'Energie Atomique has created a working group on speciation to share data both on thermodynamic constants and on speciation analysis methods of interest to chemists, environmentalists and biologists. The initial focus was on the 31 radionuclides described in different International Commission on Radiological Protection models (HRTM, HAT) and the National Council on Radiation Protection model (wound). Particular attention was devoted to selecting the inorganic and organic ligands, most representative of biological media. The base applied to speciation in solution and at interfaces and solubility (BASSIST) thermodynamic database was developed for this purpose. The aim of this paper is to present the state of the art on radionuclide speciation tools within biological media and to emphasise some missing data in order to orient future research.