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U.S. Transuranium and Uranium Registries Conference Contributions

Health Physics Society Internal Dosimetry Workshop, Corvallis, OR, February 6-9, 2023

The Health Physics Society’s midyear meeting was devoted the topic of internal dosimetry. Presentations at the meeting covered a wide variety of subjects related to the topic of calculating dose from internally incorporated radionuclides. Among them was a session organized by the USTUR called, “U.S. Transuranium and Uranium Registries Research.” The presentations given during this session provided of glimpse of the wide variety of topics studied at the USTUR, and also how highly the resources available at the USTUR are valued by the scientific community.

55 years of the United States Transuranium and Uranium Registries: History, contributions, and impact on radiation protection

Sergei Y. Tolmachev (USTUR)

The United States Transuranium and Uranium Registries (USTUR) and the associated National Human Radiobiology Tissue Repository (NHRTR) is a federal-grant program funded by U.S. Department of Energy and operated by College of Pharmacy and Pharmaceutical Sciences at Washington State University in Richland, Washington, USA. The Registries was established in 1968 to study the biokinetics and internal dosimetry of actinides – such as uranium, thorium, plutonium, and americium – in occupationally exposed individuals who volunteer their bodies for scientific use posthumously (partially or entirely). A portion of the tissues received by the USTUR is radiochemically analyzed for actinides. The remaining portion is retained at the NHRTR in frozen or formalin-fixed state for future studies. Currently, the USTUR/NHRTR holds over 10,000 frozen and formalin-fixed tissue samples from 47 whole- and 118 partial-body USTUR donors, and about 10,000 acid-digested tissue samples (acid solutions). The NHRTR tissue materials are available to qualified scientists for their research upon request. The USTUR has published over 300 peer-reviewed papers and book chapters, and has contributed to five National Council on Radiation Protection and Measurements (NCRP) reports, one NCRP commentary, and eight International Commission on Radiological Protection publications. Since 1992, 20 graduate students, including eight PhDs, have used USTUR data to complete the research requirements of their studies. Presentation given by George Tabatadze. USTUR-0624-22A

Presentation Sides

Unique resources available through collaboration with the USTUR

Nicole E. Martinez (Clemson University, Oak Ridge National Laboratory)

The United States Transuranium and Uranium Registries (USTUR) is a long-standing research program in the United States that is currently operated by Washington State University and funded by the Department of Energy. USTUR facilities are uniquely and conveniently situated off campus in Richland, Washington, with independent laboratory, administration, and archival spaces. The focus of USTUR is actinide elements in the human body, and related research ranges from radiochemical methodology to biokinetics and dosimetry. Detailed records are maintained at USTUR for registrants dating back to the 1950s. Additionally, USTUR houses the National Human Radiobiology Tissue Repository (NHRTR) which boasts an incredible range of historical samples from USTUR registrants, radium workers, and a multi-decade study conducted at Los Alamos National Laboratory. Data produced and/or archived by the USTUR is used nationally and internationally by both individual researchers and scientific organizations. The unique resources at USTUR are available to researchers interested in related topics, often at little to no cost to them. This presentation discusses the resources available at USTUR with a few specific examples of recent collaborations. USTUR-0629-22A

Applicability of a unique USTUR dataset: Female nuclear worker treated with chelation therapy after plutonium exposure via inhalation

Sara Dumit (Los Alamos National Laboratory), Maia Avtandilashvili (USTUR), Stacey McComish (USTUR), Guthrie Miller (retired Los Alamos National Laboratory), Jasen Swanson (US Army), Sergei Y. Tolmachev (USTUR)

The purpose of this presentation is to describe and explore the applicability of a unique dataset of radiobioassay measurement results from a female former nuclear worker available at the United States Transuranium and Uranium Registries (USTUR). This individual was exposed to plutonium-americium mixture via acute inhalation and was medically treated with 1 gram of Ca-DTPA on day 0, 5 and 14 post-intake. A total of 13 fecal and 24 urine samples was collected and analyzed for plutonium and americium from day 0 until day 20. She was followed-up for 14 years for plutonium urine bioassay measurements. The uniqueness of this dataset is due to: (i) early and long-term data from a female with plutonium intake; (ii) bioassay data following chelation therapy for a female; (iii) fecal measurement results. This dataset can be used in chelation modeling studies, biokinetic modeling development, and internal dosimetry refinement. We intend to publish the radiobioassay measurements in the scientific literature. USTUR-0627-22A

Presentation Slides

Uncertainty in plutonium internal dose estimates for Rocky Flats workers

Martin Šefl (USTUR), Joey Y. Zhou (US Department of Energy), Maia Avtandilashvili (USTUR), Sergei Y. Tolmachev (USTUR)

Radiation epidemiology typically relies on dose predictions based on urine bioassay measurements and other worksite monitoring data. At the United States Transuranium and Uranium Registries (USTUR), bioassay data and post-mortem tissue radiochemical analyses are used for actinide biokinetic modeling and estimation of organ doses. To estimate uncertainties in internal radiation dose from plutonium, a group of 23 former nuclear workers from Rocky Flats Plant was selected from the USTUR health physics database. Selected workers had at least 5 positive urine samples (more than contemporary minimum detectable activity) and did not undergo a chelation treatment. The plutonium activity concentrations in the skeleton and liver were between 0.39 and 30.8 Bq kg-1, and 1.04 and 354 Bq kg-1, respectively. The plutonium concentration in the respiratory tract ranged from 4.43 to 7,230 Bq kg-1. Uncertainty was calculated as a bias between doses estimated using urine and post-mortem tissue analysis results. USTUR-0630-22A

Presentation Slides

Taurus Advanced – Internal dosimetry software for research

Anthony E Riddell (UKHSA), Tracy J Smith (UKHSA), Demetrio Gregoratto, Thomas Hyatt (UKHSA)

In order to meet a requirement for software to perform internal dose assessments using the methodology described in the International Commission on Radiological Protection’s ‘Occupational Intakes of Radionuclides’ series of publications, the UK Health Security Agency (UKHSA) has developed a new code called ‘Taurus’. Taurus is the successor to UKHSA’s earlier IMBA (Integrated Modules for Bioassay Analysis) code. The initial release ‘Base’, version of Taurus has been available for more than a year and is routinely used for operational protection and statutory dose assessment purposes within the UK. However, development has started on an ‘Advanced’ version of Taurus, which can be used to perform internal dose calculations for research purposes, while this work is not yet complete, it has already permitted Taurus to be used to meet some current research needs. Examples of this Include: The calculation of annual absorbed doses to organs and provision for intakes involving mixtures of isotopic and chemical forms, for an epidemiological study of uranium workers from the UK, Europe, USA and Canada; The implementation of the NCRP ‘Wound’ model within the code and the capability to use wound content, in addition to other in vivo and excreta measurements, as a bioassay quantity within data ‘fitting’, which will be used for collaborative research work with the United States Transuranium and Uranium Registries. Both existing and proposed future capabilities of Taurus are discussed, along with some examples of their application in the field of internal dosimetry research. USTUR-0631-22A

ICP-MS measurement of plutonium, uranium, and americium in the hair and nail samples of former nuclear workers

Dana Arbova (University of Missouri), Sergei Tolmachev (USTUR), John Brockman (University of Missouri)

The hair and nail samples from former nuclear workers with known history of exposure to actinides and donate their tissues to the United States Transuranium and Uranium Registries were used for this study. Using inductively-coupled plasma mass spectrometry (ICP-MS), the 239Pu, 238U, and 241Am concentrations and 239Pu/240Pu, 235U/238U, and 236U/238U atom ratios were measured. The concentration of 239Pu ranged from 0.22–15.8 ng/kg. The 240Pu/239Pu atom ratios ranged from 0.029 to 0.075. The concentration of uranium was between 1.84 µg/kg and 29.5 µg/kg and the 235U/238U ratios ranged from 4.8×10-3 to 7.6×10-3. Elevated 236U/238U atom ratios were measured in two cases and ranged from 5.0×10-6 – 2.4×10-5 indicating exposure to reprocessed uranium. The concentration of 241Am was measured in four cases and ranged from 0.02–0.21 ng/kg. This work demonstrates that ICP-MS is capable of measuring ultra-trace levels of actinides in hair and nail samples. In this group of occupationally exposed workers hair and nail samples collected post-mortem contained measurable actinide levels decades after the intake. Presenter. USTUR-0625-22A

Hematology profile of a radium dial painter cohort

Ronald E. Goans (MJW Corporation, REAC/TS), Richard E. Toohey (REAC/TS), Carol J. Iddins (REAC/TS), Mike Mumma (International Epidemiology Institute), Stacey L. McComish (USTUR), Sergei Tolmachev (USTUR)

In a collaborative effort with the US Transuranium and Uranium Registries (USTUR) and the Million Person Study, it has been possible to examine medical records and peripheral blood slides from a cohort of 166 former radium dial painters (RDP). The RDP are a well-described group of predominantly young women who incidentally ingested 226Ra and 228Ra as they painted luminescent watch dials in the first half of the twentieth century. Early papers describing disease processes in RDP often described an acute anemia. The purpose of this study was to evaluate any residual anemia in RDP survivors. The painters and ancillary personnel (mean age 64.4 y) were subsequently evaluated at Argonne National Laboratory (ANL) and at MIT in the 1960s-1970s. Our cohort contained 107 dial painters, 22 dial handlers, 19 radium chemists, and other personnel dealing with radium. Members of the cohort had ingestion of 226Ra and 228Ra at an early age (average age 20.6 ± 5.4 y; range 13-40 y) during the years 1914-1955. Exposure duration ranged from 1-1,820 weeks with red marrow dose 1.5-6,750 mGy. A subset of the RDP cohort has been derived: 7 patients with previously treated osteosarcoma (mean red marrow alpha dose 5.4 ± 1.2 Gy), 5 patients with > 1 Gy alpha dose to red marrow but who did not have osteosarcoma (mean marrow dose 2.8 ± 0.5 Gy), and a third set of 35 patients with zero dose as determined by whole body counting. Preliminary hematology findings from the complete blood count (CBC) are consistent with microcytic anemia and chronic inflammation in the osteosarcoma group. These initial conclusions suggest that an analysis of the entire sarcoma cohort would be valuable. USTUR-0633-22A

Is the autopsy report a “gold standard”?

Xirui Liu (USTUR), Stacey L. McComish (USTUR), Joey Y. Zhou (US Department of Energy), Sergei Y. Tolmachev (USTUR)

Compared to death certificates, autopsy reports generally provide a more detailed picture of the diseases present at the time of death, and they are frequently used as a “gold standard” to check the accuracy of death certificates. However, during our study of misclassification errors that occur on death certificates, we realized that autopsy reports are still an imperfect source of information. Among 312 individuals for which full autopsy reports were available, only 256 (82%) of them provided a summary of findings. The remaining 56 (18%) provided a list of findings and diagnoses without a summative conclusion about causes of death. This may be due to the differences in the pathologists’ personal reporting styles. It does appear that certain pathologists tended to provide summaries on their autopsy reports, while others provided only a list of diagnoses and pathological observations. Additionally, autopsy reports that included summaries typically did not lay out the progression from the underlying cause of death to the immediate cause of death using language that directly translated to the structure on the death certificates. This may render the process of inferring the underlying cause of death rather subjective. It was also found that when the pathologists had access to clinical information, the underlying cause of death on the death certificates was more likely to match the autopsy reports. Even when the certifying physicians did not use the autopsy findings to complete the death certificates, mention of what happened prior to death on the autopsy reports still improved the match rate by 15.8%. This highlights the importance of providing pathologists with relevant clinical information prior to the autopsy. USTUR-0628-22A

Presentation Slides

USTUR – A golden nugget among DOE resources

John D. Boice (NCRP, Vanderbilt University), Lawrence T. Dauer (Memorial Sloan Kettering Cancer Center)

For over 50 years, the USTUR has made substantial contributions to radiation understanding, radiation dosimetry, radiation protection, and radiation epidemiology. It is a shining light among DOE Resources that burns brightly but often it seems under a bushel, i.e., the contributions are often overlooked or underappreciated. The USTUR focus has been on intakes of radionuclides such as plutonium, uranium and radium, and the autopsy program has provided essential dosimetric information used extensively by ICRP in the development of biokinetic and anatomical models for radiation protection. Most recently the USTUR has contributed to enhancing the models for explicit brain dose following the uptake of alpha-particle emitting radionuclides, which are now being applied to epidemiologic studies in the Million Person Study (MPS) coordinated by NCRP and Vanderbilt University (NCRP Commentary 31, 2022).* A mission statement for USTUR includes assisting epidemiology and this goal has continually been achieved: from radium dial paints to workers at the Los Alamos National Laboratory! The exciting (to the radiation researcher) behind the scenes contributions also include active and essential collaborations on other worker studies such as Rocky Flats and Hanford, as well as the evaluation of radiation-induced biomarkers, all of which allow the epidemiologist to accurately incorporate organ doses from intakes of radionuclides and conduct dose-response analyses. Such evaluations are challenging and not often done because the detailed organ-specific data are not available. The USTUR is an essential component of the MPS, a truly golden nugget in the DOE system, that adds substantial value to our understanding of the late health effects following intakes of radioactive elements. *Financial support for the MPS was provided by the US Department of Energy (Grants DE-AU0000042 and DE-AU0000046) and the National Aeronautics and Space Administration (Grant 80NSSC17M0016). USTUR-0626-22A