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U.S. Transuranium and Uranium Registries Conference Contributions

2021 Health Physics Society Midyear Workshop, Clemson, SC, May 23-26, 2021

The Health Physics Society’s 2021 midyear meeting was held in a hybrid format, allowing participants to join in-person from Clemson University, or virtually. Martin Šefl, a post-doctoral researcher at the USTUR, presented his work to explore biases in organ activities and intakes associated with occupational exposures to plutonium. In addition, the USTUR’s director, Sergei Tolmachev, was a co-author on two presentations related to reanalysis of data from the radium dial painter studies.

Uncertainty analysis on organ activities and intakes from occupational exposure to plutonium

Martin Šefl (USTUR), Joey Y. Zhou (US Department of Energy), Maia Avtandilashvili (USTUR), Stacey L. McComish (USTUR), Daniel J. Strom (USTUR), George Tabatadze (USTUR), Sergey Y. Tolmachev (USTUR)

The United States Transuranium and Uranium Registries (USTUR) studies the actinide biokinetics and tissue dosimetry in accidentally exposed nuclear workers (volunteer tissue donors). Since 1968, the USTUR has received 313 partial- and 47 whole-body tissue donations. Post-mortem radiochemical analyses of tissues collected at autopsy provide information on long-term retention and distribution of actinides in the human body. These data are accompanied by workers’ detailed records on exposure incidents, bioassay monitoring, and medical history. These datasets provide a unique opportunity to evaluate uncertainties in the radiation dose assessment for radiation epidemiology. Among 349 cases with completed radiochemical analysis, 55 cases were selected based on the following criteria: a) at least, five Pu-239 urine measurements exceeding the contemporary detection limit; b) Pu-239 concentrations in the skeleton and liver greater than 0.1 Bq/kg and 1 Bq/kg, respectively, and c) no extensive decorporation therapy. The objectives of this study were to compare: 1) Pu-239 activities in the skeleton and liver predicted based upon urine bioassay with activities measured post-mortem; 2) intake estimates based on the urine data alone with those based on both urine data and post-mortem radiochemical analyses. IMBA Professional Plus® internal dosimetry software was used to fit the super complex intake regime and to predict organ activity using the ICRP 130 Human Respiratory Tract, ICRP 141 Plutonium Systemic, and ICRP 30 Gatro-Intestinal Tract models. Investigation of 11 individuals, who had worked at the same worksite revealed that the model predictions of Pu-239 activities in organs estimated from urine bioassay differed from the measured values, on average, by 16±36% for the skeleton, and 10±78% for the liver. Intakes calculated using urine data alone differed from those estimated by simultaneously fitting the urine and tissue radiochemical analysis data, on average, by 98±107%.

Presentation Slides

Radium dial painters: An overview

Nicole E. Martinez (Clemson University, Oak Ridge National Laboratory), Derek W. Jokish (Francis Marion University, Oak Ridge National Laboratory), Richard W. Leggett (Oak Ridge National Laboratory), Keith F. Eckerman (Oak Ridge National Laboratory, Easterly Scientific), Sergei Tolmachev (USTUR), Michael Mumma (Vanderbilt University), Lawrence T. Dauer (Memorial Sloan Kettering Cancer Center, National Council on Radiation Protection and Measurements), John D. Boice (Vanderbilt University, National Council on Radiation Protection and Measurements)

Many early discoveries involving radiation and radioactivity found medical or commercial use, with radium a prime example. Marie and Pierre Curie discovered radium in 1898 and soon after radium was being marketed as a medicinal cure-all. It was also quickly discovered that radium could be combined with phosphorescent material to make luminous paint, with related patents filed as early as 1903. The first radium dial watches were sold commercially in 1913, followed by a rapid increase in demand for similar radioluminous products through World War I. Thousands of workers, mainly women, painted dials and instruments with radium paint, using their lips to give the brush a fine point. Although such “tipping” was prohibited in 1926, thousands of women in the US, most of whom were teenagers when they started painting dials, had already spent years licking radium brushes. Being a dial painter was considered glamorous and patriotic, but many dial painters ultimately experienced painful consequences associated with their intakes of radium during work. This tragic experience had a significant historical impact on industrial safety standards, including protection measures taken during the Manhattan Project, and epidemiologic study of the dial painters has formed the basis for radiation protection standards for intakes of radionuclides by workers as well as the public. The study of 3,276 radium dial painters is being updated as part of the Million Person Study (MPS) of low-dose health effects that is designed to evaluate radiation risks among healthy American workers and veterans. This presentation summarizes the history of radium dial painters, presents broad scope information learned to date, and discusses the ongoing follow up work and dose reconstructions that seek to provide new information on the lifetime risk of cancer and other adverse effects of ionizing radiation among women following intakes of radionuclides. [USTUR-0583-21A]

Dosimetry for a radium dial painter cohort – Past approaches and improvements

Derek W. Jokisch (Francis Marion University), Nicole E. Martinez (Clemson University), Richard W. Leggett (Oak Ridge National Laboratory), Keith F. Eckerman (Easterly Scientific), Lawrence T. Dauer (Memorial Sloan Kettering Cancer Center), Sergei Y. Tolmachev (USTUR), Michael T. Mumma (Vanderbilt University), John D. Boice (Vanderbilt University)

As part of the Million Person Study, work has begun on revisiting and expanding a Radium Dial Painter cohort of 3,276 workers. In the first half of the 20th century, workers manually painted radio-fluorescent paint onto watch and gauge dials. The paint contained Ra-226 and Ra-228 with varying isotopic ratios depending on company, workplace, and year. Workplace practices also varied by individual worker, location, and year. The practice of pointing or ‘tipping’ the paintbrushes with one’s lips was widespread in the United States until the mid-1920s and resulted in significant ingestions of radium paint. Past comprehensive studies were conducted by Massachusetts Institute of Technology, Argonne National Laboratory and other organizations. The current approach builds upon past measurements and calculations of individual radium body burdens which are coupled to the latest biokinetic models to arrive at new estimates of radium intake in the workers. Most dial painters were teenagers or in their early twenties when they began painting. Our current work treats the intakes as chronic over the work period and in and models radium uptake and skeletal development in an age-dependent manner. The current work also explicitly models radioactive progeny in the body. The latest energy absorption models for alpha emitters in the skeleton represent another improvement to past dosimetry calculations. Further, the cohort eligible for dose-response analyses is being expanded by including individuals for whom there was no dosimetry information on record. We discuss methods for estimating doses to such individuals, including uncertainties, based on imputing exposure parameters from contemporary peers performing similar work at the same facilities. This presentation focuses on doses to the bone and bone marrow. Future work will address doses to other tissues of interest such as the paranasal sinuses, lung, breast, brain and heart. [USTUR-0584-21A]