Asia-Pacific Symposium on Radiochemistry, Napa, CA, Nov. 29 – Dec. 5, 2009

Sergei Tolmachev made a platform presentation at the Asia-Pacific Symposium on Radiochemistry (APSORC-09), Napa, CA, November 29 – December 5, 2009, titled “The U.S. Transuranium Registries: Forty Years’ Experience and New Directions in the Analysis of Actinides in Human Tissues.” This highlighted new research (in collaboration with Dr. Philip Doble, University of Technology, Sydney, Australia) to apply UTS’s techniques for elemental bio-imaging of actinides by Laser-Ablation ICP-MS to USTUR tissue samples. A manuscript is being submitted for peer-reviewed journal publication in the Conference Proceedings.

The U.S. Transuranium and Uranium Registries: Forty years’ experience and new directions in the analysis of actinides in human tissues
S.Y. Tolmachev (USTUR), A.C. James (USTUR)

September 2008 was the 40^th anniversary of the U.S. Atomic Energy Commission’s vision in establishing the National Plutonium Registry. Its successors, the U.S. Transuranium and Uranium Registries (USTUR), continue to follow individuals with documented accidental exposures to actinide elements, to study their uptake, translocation and retention (biokinetics), and tissue dosimetry. To date, 330 past-worker volunteers have donated their tissues for scientific research, including 36 whole body donors. This talk outlines the history, mission and research goals of the Registries, and the current status of the USTUR’s Radiochemistry Program. We present an overview of the analytical methods for plutonium (Pu), americium (Am) and uranium (U) isotopic determination in human tissues currently applied; including inductively coupled mass spectrometry (ICP-MS) based techniques. Recent developments in rapid radiochemical separation of the actinides from soft tissue and bone samples using vacuum-assisted extraction chromatography are also outlined. The results of inter-comparing ^239+240Pu, ²⁴¹Am and ^234,235,238U determinations by ICP-MS, α-spectrometry (AS) and kinetic phosphorescence analysis (KPA, for total U) are discussed. ICP-MS is a major advance over AS and KPA in enabling the measurement of the ²⁴⁰Pu/²³⁹Pu atom ratio, the short-lived β-emitter ²⁴¹Pu, and the anthropogenic ²³⁶U. For the first time ²⁴¹Am and ²⁴¹Pu were measured in human tissues using ICP-MS. The measured ²⁴⁰Pu/²³⁹Pu, ²³⁵U/²³⁸U and ²³⁶U/²³⁸U atom ratios clearly identify the origins of these actinides in human tissues. A new avenue of research with samples of USTUR human tissue is the application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to elemental bio-imaging (EBI) of the actinides (of both anthropogenic and natural origin). We present elemental distribution maps for ^235,238U and ²³²Th in lymph nodes measured for both non-exposed (chronic intake) and occupationally exposed (inhalation) subjects. The implications of these findings for dose assessment are discussed. [USTUR-0276-09]

Presentation Slides