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Papers by Maia Avtandilashvili

Kluwer Academic Publishers eBooks, Mar 1, 2006

National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in ... more National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in Georgia as independent expert institution since 1998, initiated studying of the radioecological condition in regions of Georgia and assessment of the risk for population from ionizing radiation. Analysis of results were obtained during 2001-2002 show soil polluted by anthropogenic radionuclides, committed annual individual effective dose due to external exposure for population come to 0.15-0.35 mSv; 137 Cs levels in agricultural products sometimes exceeds the recommended values.

Radiation Protection Dosimetry

The skeleton is a major plutonium retention site in the human body. Estimation of the total pluto... more The skeleton is a major plutonium retention site in the human body. Estimation of the total plutonium activity in the skeleton is a challenging problem. For most tissue donors at the United States Transuranium and Uranium Registries, a limited number of bone samples is available. The skeleton activity is calculated using plutonium activity concentration (Cskel) and skeleton weight. In this study, latent bone modelling was used to estimate Cskel from the limited number of analysed bone samples. Data from 13 non-osteoporotic whole-body donors were used to develop latent bone model (LBM) to estimate Cskel for seven cases with four to eight analysed bone samples. LBM predictions were compared to Cskel estimated using an arithmetic mean in terms of accuracy and precision. For the studied cases, LBM offered a significant reduction of uncertainty of Cskel estimate.

The United States Transuranium and Uranium Registries’ (USTUR) female whole body tissue donor was... more The United States Transuranium and Uranium Registries’ (USTUR) female whole body tissue donor was occupationally exposed to highly enriched uranium for 17 years. One hundred and twenty-nine tissue samples were collected at the time of death, 31 years post-exposure. These samples were radiochemically analyzed for uranium. The highest uranium concentration of 16.5 ± 2.0 µg kg− 1 was measured in the lungs, and the lowest concentration of 0.11 ± 0.01 µg kg− 1 in the liver. The thyroid had the highest concentration of 6.3 ± 2.9 µg kg− 1 among systemic tissues. Mass-weighted average concentration in the entire skeleton was estimated to be 1.60 ± 0.19 µg kg− 1. In the skeleton, uranium was non-uniformly distributed among different bones. Thirty-one years after the intake, approximately 40% of occupational uranium was still retained in the skeleton, followed by the kidneys (~ 30%), and the brain and liver (~ 10%). Systemic uranium was equally distributed between the skeleton and soft tissue...

Journal of Radiological Protection

Health Physics, 2008

Georgia has geological formations with high uranium content, and several buildings are built with... more Georgia has geological formations with high uranium content, and several buildings are built with local materials. This can create potentially high radon exposures. Consequently, studies to mitigate these exposures have been started. This study presents a preliminary investigation of radon in Tbilisi, the capital of Georgia. An independent radiological monitoring program in Georgia has been initiated by the Radiocarbon and Low-Level Counting Section of I. Javakhishvili Tbilisi State University with the cooperation of the Environmental Monitoring Laboratory of the Physics/ Health Physics Department at Idaho State University. At this initial stage the E-PERM systems and GammaTRACER were used for the measurement of gamma exposure and radon concentrations in air and water. Measurements in Sololaki, a densely populated historic district of Tbilisi, revealed indoor radon (222 Rn) concentrations of 1.5-2.5 times more than the U.S. Environmental Protection Agency action level of 148 Bq m ؊3 (4 pCi L ؊1). Moreover, radon-in-air concentrations of 440 Bq m ؊3 and 3,500 Bq m ؊3 were observed at surface borehole openings within the residential district. Measurements of water from various tap water supplies displayed radon concentrations of 3-5 Bq L ؊1 while radon concentrations in water from the hydrogeological and thermal water boreholes were 5-19 Bq L ؊1. In addition, the background gamma absorbed dose rate in air ranged of 70-115 nGy h ؊1 at the radon test locations throughout the Tbilisi urban environment.

Nato Science Series: IV: Earth and Environmental Sciences

National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in ... more National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in Georgia as independent expert institution since 1998, initiated studying of the radioecological condition in regions of Georgia and assessment of the risk for population from ionizing radiation. Analysis of results were obtained during 2001-2002 show soil polluted by anthropogenic radionuclides, committed annual individual effective dose due to external exposure for population come to 0.15-0.35 mSv; 137 Cs levels in agricultural products sometimes exceeds the recommended values.

Journal of Radiological Protection

The US National Council on Radiation Protection and Measurements (NCRP) convened Scientific Commi... more The US National Council on Radiation Protection and Measurements (NCRP) convened Scientific Committee 6–12 (SC 6–12) to examine methods for improving dose estimates for brain tissue for internally deposited radionuclides, with emphasis on alpha emitters. This Memorandum summarises the main findings of SC 6–12 described in the recently published NCRP Commentary No. 31, ‘Development of Kinetic and Anatomical Models for Brain Dosimetry for Internally Deposited Radionuclides’. The Commentary examines the extent to which dose estimates for the brain could be improved through increased realism in the biokinetic and dosimetric models currently used in radiation protection and epidemiology. A limitation of most of the current element-specific systemic biokinetic models is the absence of brain as an explicitly identified source region with its unique rate(s) of exchange of the element with blood. The brain is usually included in a large source region called Other that contains all tissues no...

Journal of Radiological Protection, 2021

Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and ra... more Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and radiation workers. They may result in significant doses to radiosensitive organs and tissues in an exposed individual’s body. The United States Transuranium and Uranium Registries’ whole-body donor (Case 0303) accidentally punctured his finger on equipment contaminated with plutonium nitrate. The wound was surgically excised and medically treated with intravenous injections of Ca-DTPA. A total of 16 g Ca-DTPA was administered in 18 treatments during the 2 months following the accident. Ninety-three urine samples were collected and analysed over 14 years following the accident. An estimated 239Pu activity of 73.7 Bq was excreted during Ca-DTPA treatment. Post-mortem radiochemical analysis of autopsy tissues indicated that 40 years post-accident 21.6 ± 0.2 Bq of 239Pu was retained in the skeleton, 12.2 ± 0.3 Bq in the liver, and 3.7 ± 0.1 Bq in other soft tissues; 1.35 ± 0.02 Bq of 239Pu was...

Health Physics, 2021

Abstract This whole-body tissue donor to the United States Transuranium and Uranium Registries wa... more Abstract This whole-body tissue donor to the United States Transuranium and Uranium Registries was occupationally exposed to plutonium nitrate-dioxide mixture via chronic inhalation. This individual was involved in the Manhattan Project operations and later participated in medical follow-up studies. Soft tissues and bones collected at autopsy were analyzed for 238Pu, 239+240Pu, and 241Am. Fifty-three years post-intake, 700±2 Bq of 239+240Pu were still retained in the skeleton, 661±11 Bq in the liver, and 282±3 Bq in the respiratory tract. Bioassay measurements and organ activities at the time of death were used to estimate the intake and radiation doses using the TAURUS internal dosimetry software. For this individual, an ICRP Publication 130 Human Respiratory Tract Model with case-specific particle size of 0.3 μm, ICRP Publication 100 Human Alimentary Tract Model, and ICRP Publication 141 Plutonium Systemic Model adequately described long-term plutonium retention and excretion. The total cumulative 239+240Pu intake of 31,716 Bq was estimated, of which 24,853 Bq (78.4%) were contributed by inhalation of plutonium nitrate and 6,863 Bq (21.6%) of plutonium dioxide. The committed equivalent doses to the red bone marrow, bone surface, liver, lungs, and brain were 0.71 Sv, 6.5 Sv, 8.3 Sv, 3.8 Sv, and 0.068 Sv, respectively. The committed effective dose was 1.22 Sv.

PLOS ONE, 2021

Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on ur... more Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results. Methods The comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries. Results Post-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of 239Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average...

Health Physics, 2020

Inhalation of plutonium is a significant contributor of occupational doses in plutonium productio... more Inhalation of plutonium is a significant contributor of occupational doses in plutonium production, nuclear fuel reprocessing, and cleanup operations. Accurate assessment of the residence time of plutonium in the lungs is important to properly characterize dose and, consequently, the risk from inhalation of plutonium aerosols. This paper discusses the long-term retention of plutonium in different parts of the respiratory tract of two workers who donated their bodies to the US Transuranium and Uranium Registries. The post-mortem tissue radiochemical analysis results, along with the urine bioassay data, were interpreted using Markov Chain Monte Carlo and the latest biokinetic models presented in the Occupational Intakes of Radionuclides series of ICRP publications. The materials inhaled by both workers were found to have solubility between that of plutonium nitrates and oxides. The long-term solubility was also confirmed by comparison of the activity concentration in the lungs and the thoracic lymph nodes. The data from the two individuals can be explained by assuming a bound fraction (fraction of plutonium deposited in the respiratory tract that becomes bound to lung tissue after dissolution) of 1% and 4%, respectively, without having to significantly alter the particle clearance parameters. Effects of different assumptions about the bound fraction on radiation doses to different target regions was also investigated. For inhalation of soluble materials, an assumption of fb of 1%, compared to the ICRP default of 0.2%, increases the dose to the most sensitive target region of the respiratory tract by 258% and that to the total lung by 116%. Some possible alternate methods of explaining higher-than-expected long-term retention of plutonium in the upper respiratory tract of these individuals-such as physical sequestration of material into the scar tissues and possible uptake by lungs-are also briefly discussed.

BIO Web of Conferences, 2019

BIO Web of Conferences, 2019

Since 1968, the U.S. Transuranium and Uranium Registries (USTUR) has followed up with occupationa... more Since 1968, the U.S. Transuranium and Uranium Registries (USTUR) has followed up with occupationally-exposed individuals (volunteer Registrants) by studying the biokinetics (deposition, translocation, retention, and excretion) and tissue dosimetry of actinide elements [1]. The USTUR holds data on work history, radiation exposure and bioassay measurements, as well as medical records from more than 400 former nuclear workers. These individuals had documented intakes of actinides at the levels higher than 74 Bq. Inhalation and wound are two major routes of intake and 239 Pu is a primary radionuclide (Fig. 1.)

Radiation Research, 2019

‘‘Improved Modeling of Plutonium-DTPA Decorporation,’’ (Radiat Res 2019; 191:201-10) by Gremy and... more ‘‘Improved Modeling of Plutonium-DTPA Decorporation,’’ (Radiat Res 2019; 191:201-10) by Gremy and Miccoli’ Sara Dumit, Bastian Breustedt, Maia Avtandilashvili, Stacey L. McComish, Daniel J. Strom, George Tabatadze and Sergei Y. Tolmachev a Los Alamos National Laboratory, Los Alamos, New Mexico; b Karlsruhe Institute of Technology, Safety and Environment (SUM), Hermann-vonHelmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; and c U.S. Transuranium and Uranium Registries, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Richland, WA 99354-4959

Health Physics, 2019

The skeleton is one of the major retention sites for internally deposited actinides. Thus, an acc... more The skeleton is one of the major retention sites for internally deposited actinides. Thus, an accurate estimation of the total skeleton content of these elements is important for biokinetic modeling and internal radiation dose assessment. Data from 18 whole-body donations to the US Transuranium and Uranium Registries with known plutonium intakes were used to develop a simple and reliable method for estimation of plutonium and 241 Am activity in the total skeleton from single-bone analysis. A coefficient of deposition K dep , defined as the ratio of actinide content in the patella to that in the skeleton, was calculated for 239 Pu, 238 Pu, and 241 Am. No statistical difference was found in K dep values among these radionuclides. Variability in K dep values was investigated with relation to skeleton pathology (osteoporosis). The average K dep of 0.0051 ± 0.0009 for the osteoporotic group was statistically different from K dep of 0.0032 ± 0.0010 for nonosteoporotic individuals. The use of K dep allows for rapid estimation of the total skeletal content of plutonium and 241 Am with up to 35% uncertainty. To improve accuracy and precision of total skeleton activity estimates, regression analysis with power function was applied to the data. Strong correlation (r 2 > 0.9) was found between 239 Pu, 238 Pu, and 241 Am activities measured in the patella bone and total skeleton activity. The results of this study are specifically important for the optimization of bone sample collection for US Transuranium and Uranium Registries partial-body donations.

Radiation and Environmental Biophysics, 2019

A recently proposed system of models for plutonium decorporation (SPD) was developed using data f... more A recently proposed system of models for plutonium decorporation (SPD) was developed using data from an individual occupationally exposed to plutonium via a wound [from United States Transuranium and Uranium Registries (USTUR) Case 0212]. The present study evaluated the SPD using chelation treatment data, urine measurements, and post-mortem plutonium activities in the skeleton and liver from USTUR Case 0269. This individual was occupationally exposed to moderately soluble plutonium via inhalation and extensively treated with chelating agents. The SPD was linked to the International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) and the ICRP Publication 30 Gastrointestinal Tract model to evaluate the goodness-of-fit to the urinary excretion data and the predictions of post-mortem plutonium retention in the skeleton and liver. The goodness-of-fit was also evaluated when the SPD was linked to the ICRP Publication 130 HRTM and the ICRP Publication 100 Human Alimentary Tract Model. The present study showed that the proposed SPD was useful for fitting the entire, chelation-affected and non-affected, urine bioassay data, and for predicting the post-mortem plutonium retention in the skeleton and liver at time of death, 38.5 years after the accident. The results of this work are consistent with the conclusion that Ca-EDTA is less effective than Ca-DTPA for enhancing urinary excretion of plutonium.

Radiation Research, 2018

Individuals with significant intakes of plutonium (Pu) are typically treated with chelating agent... more Individuals with significant intakes of plutonium (Pu) are typically treated with chelating agents, such as the trisodium salt form of calcium diethylenetriaminepentaacetate (CaNa 3-DTPA, referred to hereafter as Ca-DTPA). Currently, there is no recommended approach for simultaneously modeling plutonium biokinetics during and after chelation therapy. In this study, an improved modeling system for plutonium decorporation was developed. The system comprises three individual model structures describing, separately, the distinct biokinetic behaviors of systemic plutonium, intravenously injected Ca-DTPA and in vivo-formed Pu-DTPA chelate. The system was linked to ICRP Publication 100, ''Human Alimentary Tract Model for Radiological Protection'' and NCRP Report 156, Development of a Biokinetic Model for Radionuclide-Contaminated Wounds and Procedures for Their Assessment, Dosimetry and Treatment.'' Urine bioassay and chelation treatment data from an occupationally-exposed individual were used for model development. Chelation was assumed to occur in the blood, soft tissues, liver and skeleton. The coordinated network for radiation dosimetry approach to decorporation modeling was applied using a chelation constant describing the secondorder, time-dependent kinetics of the in vivo chelation reaction. When using the proposed system of models for plutonium decorporation, a significant improvement of the goodness-of-fit to the urinary excretion data was observed and more accurate predictions of postmortem plutonium retention in the skeleton, liver and wound site were achieved.

Health Physics, 2018

Abstract Decorporation therapy with salts of diethylenetriamine-pentaacetic acid binds actinides,... more Abstract Decorporation therapy with salts of diethylenetriamine-pentaacetic acid binds actinides, thereby limiting uptake to organs and enhancing the rate at which actinides are excreted in urine. International Commission on Radiological Protection reference biokinetic models cannot be used to fit this enhanced exertion simultaneously with the baseline actinide excretion rate that is observed prior to the start of therapy and/or after the effects of therapy have ceased. In this study, the Coordinated Network on Radiation Dosimetry approach, which was initially developed for modeling decorporation of plutonium, was applied to model decorporation of americium using data from a former radiation worker who agreed to donate his body to the US Transuranium and Uranium Registries for research. This individual was exposed to airborne 241Am, resulting in a total-body activity of 66.6 kBq. He was treated with calcium-diethylenetriamine-pentaacetic acid for 7 y. The time and duration of intakes are unknown as no incident reports are available. Modeling of different assumptions showed that an acute intake of 5‐μm activity median aerodynamic diameter type M aerosols provides the most reasonable description of the available pretherapeutic data; however, the observed 241Am activity in the lungs at the time of death was higher than the one predicted for type M material. The Coordinated Network on Radiation Dosimetry approach for decorporation modeling was used to model the in vivo chelation process directly. It was found that the Coordinated Network on Radiation Dosimetry approach, which only considered chelation in blood and extracellular fluids, underestimated the urinary excretion of 241Am during diethylenetriamine-pentaacetic acid treatment; therefore, the approach was extended to include chelation in the liver. Both urinary excretion and whole-body retention could be described when it was assumed that 25% of chelation occurred in the liver, 75% occurred in the blood and ST0 compartment, and the chelation rate constant was 1 × 10−10 pmol−1 d−1. It was observed that enhancement of urinary excretion of 241Am after injection of diethylenetriamine-pentaacetic acid exponentially decreased to the baseline level with an average half-time of 2.2 ± 0.7 d.

Kluwer Academic Publishers eBooks, Mar 1, 2006

National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in ... more National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in Georgia as independent expert institution since 1998, initiated studying of the radioecological condition in regions of Georgia and assessment of the risk for population from ionizing radiation. Analysis of results were obtained during 2001-2002 show soil polluted by anthropogenic radionuclides, committed annual individual effective dose due to external exposure for population come to 0.15-0.35 mSv; 137 Cs levels in agricultural products sometimes exceeds the recommended values.

Radiation Protection Dosimetry

The skeleton is a major plutonium retention site in the human body. Estimation of the total pluto... more The skeleton is a major plutonium retention site in the human body. Estimation of the total plutonium activity in the skeleton is a challenging problem. For most tissue donors at the United States Transuranium and Uranium Registries, a limited number of bone samples is available. The skeleton activity is calculated using plutonium activity concentration (Cskel) and skeleton weight. In this study, latent bone modelling was used to estimate Cskel from the limited number of analysed bone samples. Data from 13 non-osteoporotic whole-body donors were used to develop latent bone model (LBM) to estimate Cskel for seven cases with four to eight analysed bone samples. LBM predictions were compared to Cskel estimated using an arithmetic mean in terms of accuracy and precision. For the studied cases, LBM offered a significant reduction of uncertainty of Cskel estimate.

The United States Transuranium and Uranium Registries’ (USTUR) female whole body tissue donor was... more The United States Transuranium and Uranium Registries’ (USTUR) female whole body tissue donor was occupationally exposed to highly enriched uranium for 17 years. One hundred and twenty-nine tissue samples were collected at the time of death, 31 years post-exposure. These samples were radiochemically analyzed for uranium. The highest uranium concentration of 16.5 ± 2.0 µg kg− 1 was measured in the lungs, and the lowest concentration of 0.11 ± 0.01 µg kg− 1 in the liver. The thyroid had the highest concentration of 6.3 ± 2.9 µg kg− 1 among systemic tissues. Mass-weighted average concentration in the entire skeleton was estimated to be 1.60 ± 0.19 µg kg− 1. In the skeleton, uranium was non-uniformly distributed among different bones. Thirty-one years after the intake, approximately 40% of occupational uranium was still retained in the skeleton, followed by the kidneys (~ 30%), and the brain and liver (~ 10%). Systemic uranium was equally distributed between the skeleton and soft tissue...

Journal of Radiological Protection

Health Physics, 2008

Georgia has geological formations with high uranium content, and several buildings are built with... more Georgia has geological formations with high uranium content, and several buildings are built with local materials. This can create potentially high radon exposures. Consequently, studies to mitigate these exposures have been started. This study presents a preliminary investigation of radon in Tbilisi, the capital of Georgia. An independent radiological monitoring program in Georgia has been initiated by the Radiocarbon and Low-Level Counting Section of I. Javakhishvili Tbilisi State University with the cooperation of the Environmental Monitoring Laboratory of the Physics/ Health Physics Department at Idaho State University. At this initial stage the E-PERM systems and GammaTRACER were used for the measurement of gamma exposure and radon concentrations in air and water. Measurements in Sololaki, a densely populated historic district of Tbilisi, revealed indoor radon (222 Rn) concentrations of 1.5-2.5 times more than the U.S. Environmental Protection Agency action level of 148 Bq m ؊3 (4 pCi L ؊1). Moreover, radon-in-air concentrations of 440 Bq m ؊3 and 3,500 Bq m ؊3 were observed at surface borehole openings within the residential district. Measurements of water from various tap water supplies displayed radon concentrations of 3-5 Bq L ؊1 while radon concentrations in water from the hydrogeological and thermal water boreholes were 5-19 Bq L ؊1. In addition, the background gamma absorbed dose rate in air ranged of 70-115 nGy h ؊1 at the radon test locations throughout the Tbilisi urban environment.

Nato Science Series: IV: Earth and Environmental Sciences

National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in ... more National Research and Educational Collaboration for Radioecology (NRECR), successfully acting in Georgia as independent expert institution since 1998, initiated studying of the radioecological condition in regions of Georgia and assessment of the risk for population from ionizing radiation. Analysis of results were obtained during 2001-2002 show soil polluted by anthropogenic radionuclides, committed annual individual effective dose due to external exposure for population come to 0.15-0.35 mSv; 137 Cs levels in agricultural products sometimes exceeds the recommended values.

Journal of Radiological Protection

The US National Council on Radiation Protection and Measurements (NCRP) convened Scientific Commi... more The US National Council on Radiation Protection and Measurements (NCRP) convened Scientific Committee 6–12 (SC 6–12) to examine methods for improving dose estimates for brain tissue for internally deposited radionuclides, with emphasis on alpha emitters. This Memorandum summarises the main findings of SC 6–12 described in the recently published NCRP Commentary No. 31, ‘Development of Kinetic and Anatomical Models for Brain Dosimetry for Internally Deposited Radionuclides’. The Commentary examines the extent to which dose estimates for the brain could be improved through increased realism in the biokinetic and dosimetric models currently used in radiation protection and epidemiology. A limitation of most of the current element-specific systemic biokinetic models is the absence of brain as an explicitly identified source region with its unique rate(s) of exchange of the element with blood. The brain is usually included in a large source region called Other that contains all tissues no...

Journal of Radiological Protection, 2021

Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and ra... more Contaminated wounds are a common route of internal deposition of radionuclides for nuclear and radiation workers. They may result in significant doses to radiosensitive organs and tissues in an exposed individual’s body. The United States Transuranium and Uranium Registries’ whole-body donor (Case 0303) accidentally punctured his finger on equipment contaminated with plutonium nitrate. The wound was surgically excised and medically treated with intravenous injections of Ca-DTPA. A total of 16 g Ca-DTPA was administered in 18 treatments during the 2 months following the accident. Ninety-three urine samples were collected and analysed over 14 years following the accident. An estimated 239Pu activity of 73.7 Bq was excreted during Ca-DTPA treatment. Post-mortem radiochemical analysis of autopsy tissues indicated that 40 years post-accident 21.6 ± 0.2 Bq of 239Pu was retained in the skeleton, 12.2 ± 0.3 Bq in the liver, and 3.7 ± 0.1 Bq in other soft tissues; 1.35 ± 0.02 Bq of 239Pu was...

Health Physics, 2021

Abstract This whole-body tissue donor to the United States Transuranium and Uranium Registries wa... more Abstract This whole-body tissue donor to the United States Transuranium and Uranium Registries was occupationally exposed to plutonium nitrate-dioxide mixture via chronic inhalation. This individual was involved in the Manhattan Project operations and later participated in medical follow-up studies. Soft tissues and bones collected at autopsy were analyzed for 238Pu, 239+240Pu, and 241Am. Fifty-three years post-intake, 700±2 Bq of 239+240Pu were still retained in the skeleton, 661±11 Bq in the liver, and 282±3 Bq in the respiratory tract. Bioassay measurements and organ activities at the time of death were used to estimate the intake and radiation doses using the TAURUS internal dosimetry software. For this individual, an ICRP Publication 130 Human Respiratory Tract Model with case-specific particle size of 0.3 μm, ICRP Publication 100 Human Alimentary Tract Model, and ICRP Publication 141 Plutonium Systemic Model adequately described long-term plutonium retention and excretion. The total cumulative 239+240Pu intake of 31,716 Bq was estimated, of which 24,853 Bq (78.4%) were contributed by inhalation of plutonium nitrate and 6,863 Bq (21.6%) of plutonium dioxide. The committed equivalent doses to the red bone marrow, bone surface, liver, lungs, and brain were 0.71 Sv, 6.5 Sv, 8.3 Sv, 3.8 Sv, and 0.068 Sv, respectively. The committed effective dose was 1.22 Sv.

PLOS ONE, 2021

Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on ur... more Purpose Radiation dose estimates in epidemiology typically rely on intake predictions based on urine bioassay measurements. The purpose of this article is to compare the conventional dosimetric estimates for radiation epidemiology with the estimates based on additional post-mortem tissue radiochemical analysis results. Methods The comparison was performed on a unique group of 11 former Manhattan Project nuclear workers, who worked with plutonium in the 1940s, and voluntarily donated their bodies to the United States Transuranium and Uranium Registries. Results Post-mortem organ activities were predicted using different sets of urine data and compared to measured activities. Use of urinalysis data collected during the exposure periods overestimated the systemic (liver+skeleton) deposition of 239Pu by 155±134%, while the average bias from using post-exposure urinalyses was –4±50%. Committed effective doses estimated using early urine data differed from the best estimate by, on average...

Health Physics, 2020

Inhalation of plutonium is a significant contributor of occupational doses in plutonium productio... more Inhalation of plutonium is a significant contributor of occupational doses in plutonium production, nuclear fuel reprocessing, and cleanup operations. Accurate assessment of the residence time of plutonium in the lungs is important to properly characterize dose and, consequently, the risk from inhalation of plutonium aerosols. This paper discusses the long-term retention of plutonium in different parts of the respiratory tract of two workers who donated their bodies to the US Transuranium and Uranium Registries. The post-mortem tissue radiochemical analysis results, along with the urine bioassay data, were interpreted using Markov Chain Monte Carlo and the latest biokinetic models presented in the Occupational Intakes of Radionuclides series of ICRP publications. The materials inhaled by both workers were found to have solubility between that of plutonium nitrates and oxides. The long-term solubility was also confirmed by comparison of the activity concentration in the lungs and the thoracic lymph nodes. The data from the two individuals can be explained by assuming a bound fraction (fraction of plutonium deposited in the respiratory tract that becomes bound to lung tissue after dissolution) of 1% and 4%, respectively, without having to significantly alter the particle clearance parameters. Effects of different assumptions about the bound fraction on radiation doses to different target regions was also investigated. For inhalation of soluble materials, an assumption of fb of 1%, compared to the ICRP default of 0.2%, increases the dose to the most sensitive target region of the respiratory tract by 258% and that to the total lung by 116%. Some possible alternate methods of explaining higher-than-expected long-term retention of plutonium in the upper respiratory tract of these individuals-such as physical sequestration of material into the scar tissues and possible uptake by lungs-are also briefly discussed.

BIO Web of Conferences, 2019

BIO Web of Conferences, 2019

Since 1968, the U.S. Transuranium and Uranium Registries (USTUR) has followed up with occupationa... more Since 1968, the U.S. Transuranium and Uranium Registries (USTUR) has followed up with occupationally-exposed individuals (volunteer Registrants) by studying the biokinetics (deposition, translocation, retention, and excretion) and tissue dosimetry of actinide elements [1]. The USTUR holds data on work history, radiation exposure and bioassay measurements, as well as medical records from more than 400 former nuclear workers. These individuals had documented intakes of actinides at the levels higher than 74 Bq. Inhalation and wound are two major routes of intake and 239 Pu is a primary radionuclide (Fig. 1.)

Radiation Research, 2019

‘‘Improved Modeling of Plutonium-DTPA Decorporation,’’ (Radiat Res 2019; 191:201-10) by Gremy and... more ‘‘Improved Modeling of Plutonium-DTPA Decorporation,’’ (Radiat Res 2019; 191:201-10) by Gremy and Miccoli’ Sara Dumit, Bastian Breustedt, Maia Avtandilashvili, Stacey L. McComish, Daniel J. Strom, George Tabatadze and Sergei Y. Tolmachev a Los Alamos National Laboratory, Los Alamos, New Mexico; b Karlsruhe Institute of Technology, Safety and Environment (SUM), Hermann-vonHelmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany; and c U.S. Transuranium and Uranium Registries, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Richland, WA 99354-4959

Health Physics, 2019

The skeleton is one of the major retention sites for internally deposited actinides. Thus, an acc... more The skeleton is one of the major retention sites for internally deposited actinides. Thus, an accurate estimation of the total skeleton content of these elements is important for biokinetic modeling and internal radiation dose assessment. Data from 18 whole-body donations to the US Transuranium and Uranium Registries with known plutonium intakes were used to develop a simple and reliable method for estimation of plutonium and 241 Am activity in the total skeleton from single-bone analysis. A coefficient of deposition K dep , defined as the ratio of actinide content in the patella to that in the skeleton, was calculated for 239 Pu, 238 Pu, and 241 Am. No statistical difference was found in K dep values among these radionuclides. Variability in K dep values was investigated with relation to skeleton pathology (osteoporosis). The average K dep of 0.0051 ± 0.0009 for the osteoporotic group was statistically different from K dep of 0.0032 ± 0.0010 for nonosteoporotic individuals. The use of K dep allows for rapid estimation of the total skeletal content of plutonium and 241 Am with up to 35% uncertainty. To improve accuracy and precision of total skeleton activity estimates, regression analysis with power function was applied to the data. Strong correlation (r 2 > 0.9) was found between 239 Pu, 238 Pu, and 241 Am activities measured in the patella bone and total skeleton activity. The results of this study are specifically important for the optimization of bone sample collection for US Transuranium and Uranium Registries partial-body donations.

Radiation and Environmental Biophysics, 2019

A recently proposed system of models for plutonium decorporation (SPD) was developed using data f... more A recently proposed system of models for plutonium decorporation (SPD) was developed using data from an individual occupationally exposed to plutonium via a wound [from United States Transuranium and Uranium Registries (USTUR) Case 0212]. The present study evaluated the SPD using chelation treatment data, urine measurements, and post-mortem plutonium activities in the skeleton and liver from USTUR Case 0269. This individual was occupationally exposed to moderately soluble plutonium via inhalation and extensively treated with chelating agents. The SPD was linked to the International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) and the ICRP Publication 30 Gastrointestinal Tract model to evaluate the goodness-of-fit to the urinary excretion data and the predictions of post-mortem plutonium retention in the skeleton and liver. The goodness-of-fit was also evaluated when the SPD was linked to the ICRP Publication 130 HRTM and the ICRP Publication 100 Human Alimentary Tract Model. The present study showed that the proposed SPD was useful for fitting the entire, chelation-affected and non-affected, urine bioassay data, and for predicting the post-mortem plutonium retention in the skeleton and liver at time of death, 38.5 years after the accident. The results of this work are consistent with the conclusion that Ca-EDTA is less effective than Ca-DTPA for enhancing urinary excretion of plutonium.

Radiation Research, 2018

Individuals with significant intakes of plutonium (Pu) are typically treated with chelating agent... more Individuals with significant intakes of plutonium (Pu) are typically treated with chelating agents, such as the trisodium salt form of calcium diethylenetriaminepentaacetate (CaNa 3-DTPA, referred to hereafter as Ca-DTPA). Currently, there is no recommended approach for simultaneously modeling plutonium biokinetics during and after chelation therapy. In this study, an improved modeling system for plutonium decorporation was developed. The system comprises three individual model structures describing, separately, the distinct biokinetic behaviors of systemic plutonium, intravenously injected Ca-DTPA and in vivo-formed Pu-DTPA chelate. The system was linked to ICRP Publication 100, ''Human Alimentary Tract Model for Radiological Protection'' and NCRP Report 156, Development of a Biokinetic Model for Radionuclide-Contaminated Wounds and Procedures for Their Assessment, Dosimetry and Treatment.'' Urine bioassay and chelation treatment data from an occupationally-exposed individual were used for model development. Chelation was assumed to occur in the blood, soft tissues, liver and skeleton. The coordinated network for radiation dosimetry approach to decorporation modeling was applied using a chelation constant describing the secondorder, time-dependent kinetics of the in vivo chelation reaction. When using the proposed system of models for plutonium decorporation, a significant improvement of the goodness-of-fit to the urinary excretion data was observed and more accurate predictions of postmortem plutonium retention in the skeleton, liver and wound site were achieved.

Health Physics, 2018

Abstract Decorporation therapy with salts of diethylenetriamine-pentaacetic acid binds actinides,... more Abstract Decorporation therapy with salts of diethylenetriamine-pentaacetic acid binds actinides, thereby limiting uptake to organs and enhancing the rate at which actinides are excreted in urine. International Commission on Radiological Protection reference biokinetic models cannot be used to fit this enhanced exertion simultaneously with the baseline actinide excretion rate that is observed prior to the start of therapy and/or after the effects of therapy have ceased. In this study, the Coordinated Network on Radiation Dosimetry approach, which was initially developed for modeling decorporation of plutonium, was applied to model decorporation of americium using data from a former radiation worker who agreed to donate his body to the US Transuranium and Uranium Registries for research. This individual was exposed to airborne 241Am, resulting in a total-body activity of 66.6 kBq. He was treated with calcium-diethylenetriamine-pentaacetic acid for 7 y. The time and duration of intakes are unknown as no incident reports are available. Modeling of different assumptions showed that an acute intake of 5‐μm activity median aerodynamic diameter type M aerosols provides the most reasonable description of the available pretherapeutic data; however, the observed 241Am activity in the lungs at the time of death was higher than the one predicted for type M material. The Coordinated Network on Radiation Dosimetry approach for decorporation modeling was used to model the in vivo chelation process directly. It was found that the Coordinated Network on Radiation Dosimetry approach, which only considered chelation in blood and extracellular fluids, underestimated the urinary excretion of 241Am during diethylenetriamine-pentaacetic acid treatment; therefore, the approach was extended to include chelation in the liver. Both urinary excretion and whole-body retention could be described when it was assumed that 25% of chelation occurred in the liver, 75% occurred in the blood and ST0 compartment, and the chelation rate constant was 1 × 10−10 pmol−1 d−1. It was observed that enhancement of urinary excretion of 241Am after injection of diethylenetriamine-pentaacetic acid exponentially decreased to the baseline level with an average half-time of 2.2 ± 0.7 d.