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U.S. Transuranium and Uranium Registries Conference Contributions

Health Effects of Incorporated Radionuclides, Berkeley, CA, October 13-17, 2013

Dr. Avtandilashvili gave a podium and a poster presentation at the HEIR meeting.

Dr. Maia Avtandilashvili attended the 11th International Conference on Health Effects of Incorporated Radionuclides (HEIR), held in Berkeley, CA on October 13-17, 2013. The HEIR conference had a program of lectures that were highly relevant to the work that is conducted at the USTUR, and the conference was attended by experts in fields such as internal dosimetry and radiation biology. Dr. Avtandilashvili gave both a podium and a poster presentation at this meeting. The podium presentation described the deposition and long-term retention of uranium hexaflouride (UF6) in a USTUR Registrant. The poster outlined a study that will use Bayesian analyses to determine equivalent lung doses for each of the USTUR’s deceased Registrants. Preliminary results for eight workers who had inhaled plutonium were presented.

USTUR case study on accidental exposure to uranium hexafluoride
M. Avtandilashvili (USTUR), S.L. McComish (USTUR), S.Y. Tolmachev (USTUR)

The International Commission on Radiological Protection (ICRP) Human Respiratory Tract Model1 was applied to the bioassay and autopsy data from the US Transuranium and Uranium Registries’ (USTUR) whole-body donor 1031 to evaluate the committed effective dose due to an accidental exposure to large quantities of airborne uranium hexafluoride (UF6)2. Bioassay data obtained for this case included eight urine samples analyzed shortly after the accident, and three follow-up urine measurements approximately four decades later. Recently, post-mortem analysis of tissue samples collected at autopsy was performed using inductively coupled plasma mass spectrometry (ICP-MS). Uranium (234,235,238U) concentrations and 235U/238U and 234U/238U isotopic ratios were determined for 31 samples including 7 bones, lungs, liver, brain, kidney, and other soft tissues. ICP-MS analysis of right lung including thoracic lymph nodes (LNTH) demonstrated a 235U/238U atomic ratio of 0.00856±0.00005 that indicated significant retention of inhaled uranium material (enriched uranium) in the respiratory tract several decades post-accident. This is not consistent with the ICRP default assumption of a rapid lung dissolution pattern (absorption type F) for this type of material1. Urinalysis data along with tissue analysis results were used to calculate the point estimates of intake and dose. Uranium activities in tissues were adjusted to account for chronic exposure to natural uranium due to dietary intake, as well as through inhalation of ambient air. Uranium deposition in tissues that would have resulted from chronic ingestion and inhalation exposure was estimated based on the reference intake rates for the general population3. In this evaluation, mixtures of uranium materials with different absorption types – F, M, and S1 were tested. It was demonstrated that, although the inhaled material consisted of mostly soluble fraction adequately described by absorption type F, approximately 13% of the mixture exhibited the slow dissolution pattern consistent with type S material. No deposition of type M material was confirmed in this evaluation. Total intake was estimated to be about 80 mg of uranium. This is about a factor of 2 higher than the intake reported by Kathren and Moore2 based on urine data only. Committed effective dose of 3 mSv was calculated based on the assumption that the isotopic composition measured in the thoracic region of the respiratory tract represents the inhaled material. Approximately 60% of the total effective dose was contributed by the lungs. [USTUR-0347-13A]


  1. International Commission on Radiological Protection. Human respiratory tract model for radiological protection. Oxford: Pergamon Press; ICRP Publication 66; Ann ICRP 24(1-3); 1994.
  2. Kathren RL, et al. Health Phys 51(5):609-619; 1986.
  3. United Nations Scientific Committee on the Effects of Atomic Radiation. USCEAR 2000 Report to the General Assembly, with scientific annexes. Sources and effects of ionizing radiation. Volume I: Sources. Annex B: Exposures from natural radiation sources; 2000. Available at

Presentation Slides

Uncertainty analysis on lung doses for US nuclear workers
M. Avtandilashvili (USTUR), S.L. McComish (USTUR), S.Y. Tolmachev (USTUR)

The United States Transuranium and Uranium Registries (USTUR) is a unique resource of data from US nuclear workers with known histories of internal actinide (mainly plutonium, uranium, and americium) contamination. Currently, extensive sets of data including radiation exposure records, bioassay measurements, medical histories, and post-mortem tissue analysis results are available in the Registries for 300+ deceased tissue donors1. These data are broadly used to refine internal dose assessment methods as the bases of credible standards for radiological protection. Inhalation is the most common pathway of internal contamination for nuclear workers. Hence, accurate assessment of absorbed doses to the radiosensitive tissues of the respiratory tract is important for better understanding of health effects caused by inhaled radionuclides. Recently published results of uncertainty analysis for European radiation workers using Bayesian analysis methods2 demonstrated that the uncertainties on lung absorption parameters had a dominant effect on the uncertainties on lung doses and indicated the need for further research for a better determination of parameter values for a sizable variety of potential inhalation scenarios. A similar approach was adapted in this study for the USTUR Registrants exposed to plutonium via inhalation. The Weighted Likelihood Monte-Carlo Sampling (WeLMoS) method, as implemented in IMBA Uncertainty Analyzer software tool3, was applied to the bioassay and autopsy data from the USTUR donors to evaluate the lung doses, calculate the associated uncertainties expressed by Bayesian posterior probability distributions, and derive the material-specific sets of lung absorption parameters for further use in epidemiologic studies. Objectives and design of this study along with the preliminary results are discussed. [USTUR-0348-13A]


  1. United States Transuranium and Uranium Registries. USTUR-0344-12. Annual Report for October 1, 2010 to March 31, 2012. Ed: Parker M., Tolmachev SY. 2013.
  2. Puncher M, Birchall A, Bull RK. Uncertainties on lung doses from inhaled plutonium. Radiat Res 176: 494-507; 2011.
  3. Puncher M, Birchall A. A Monte Carlo method for calculating Bayesian uncertainties in internal dosimetry. Radiat Prot Dosim 132(1): 1-12; 2008.