65th Annual Meeting of the Radiation Research Society, San Diego, CA, November 3-6, 2019
Sergei Tolmachev gave an invited presentation at the 2019 Radiation Research Society Meeting, in San Diego, CA.
From autopsies to synchrotrons to Mars – Why the brain matters
Sergei Y. Tolmachev (USTUR), Tatjana Paunesku (Northwestern University), Gayle Woloschak (Northwestern University), John D. Boice (Vanderbilt University Cancer Center)
The possible health effects of cosmic rays in space (i.e., high energy heavy ions) are unknown. Animal experiments suggest that these exotic high-energy ions with high atomic numbers might result in cognition effects and perhaps early dementia. The National Aeronautics and Space Administration is particularly interested in such exposures to galactic cosmic rays and their possible consequences for long-term missions, such as to Mars.
The Million Person Study attempts to address these issues related to cognition and dementia by studying nuclear workers with intakes of alpha-emitting radionuclides. These workers with high-LET exposure to brain tissue are the only human analogue for exposure to space radiation. Postmortem radiochemical analyses of human tissues collected at autopsies have shown that intakes of plutonium, radium, americium, uranium, and polonium deposit in the brain. Studies at the US Transuranium and Uranium Registries have demonstrated that approximately 0.2% of systemic plutonium is deposited in the brain. Internally deposited radionuclides continually expose the brain to helium nuclei (alpha particles). The radiation dose to brain tissue is assumed to be uniform and can be estimated from bioassay data and tissue analyses using biokinetic and dosimetric models. To improve brain dose estimates for internally deposited radionuclides, explicit modelling of brain biokinetics is being investigated.
Actinide distribution within the brain is being examined at Argonne National Laboratory by synchrotron-based x-ray fluorescent microscopy using the Advanced Photon Source. [USTUR-0529-19A]