Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLUTONIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed1987

Inhalation deposition and retention patterns of a U-Pu chain aggregate aerosol.

Chain aggregate aerosol particles are normally formed during many high-temperature combustion and vaporization processes. The shape of chain aggregate aerosol particles could have an effect on the pattern of inhalation deposition and retention of the particles in the respiratory tract. A chain aggregate aerosol of nuclear reactor fuel could be present as an inhalation hazard if it were released to the atmosphere after a meltdown, core-disruptive accident. Rats were exposed to a chain aggregate U-Pu aerosol made by laser vaporization of mixed-oxide, breeder reactor fuel (20% plutonium dioxide and 80% uranium dioxide), then sacrificed to measure the clearance and retention of the fuel aerosol particles. Deposition of the 0.7-micron (activity median aerodynamic equivalent diameter) aerosol particles resulted in an average initial lung burden of 4140 Bq alpha activity. The chain aggregate particle shape was not a major factor in the total deposition; however, it may have influenced the regional distribution of the activity deposited. Retention of the particles in the upper airways of the tracheobronchial tree was on the order of 1% of the concurrent lung burden, which is consistent with recent data of other investigations. This study indicates that insoluble chain aggregate particles are retained in the tracheobronchial airways to a degree similar to simple spherically shaped particles of equivalent volume diameter.

Aerosols↗
PubMed1989

The accuracy of some simple models for predicting particulate interception and retention in agricultural systems.

The accuracy of three radionuclide transfer models for predicting the interception and retention of airborne particles by agricultural crops was tested using Pu-bearing aerosols released to the atmosphere from nuclear fuel facilities on the U.S. Department of Energy's Savannah River Plant, near Aiken, SC. The models evaluated were: 1) NRC, the model defined in U.S. Nuclear Regulatory Guide 1.109; 2) FOOD, a model similar to the NRC model that also predicts concentrations in grains; and 3) AGNS, a model developed from the NRC model for the southeastern United States. Plutonium concentrations in vegetation and grain were predicted from measured deposition rates and compared to concentrations observed in the field. Crops included wheat, soybeans, corn and cabbage. Although predictions of the three models differed by less than a factor of 4, they showed different abilities to predict concentrations observed in the field. The NRC and FOOD models consistently underpredicted the observed Pu concentrations for vegetation. The AGNS model was a more accurate predictor of Pu concentrations for vegetation. Both the FOOD and AGNS models accurately predicted the Pu concentrations for grains.

Aerosols↗
PubMed1990

Biokinetics of 237Pu citrate and nitrate in the rat: implications for Pu studies in man.

Plutonium-237 decays mainly by electron capture with a half-life of 45 d. Alpha particles are emitted in only 5 x 10(-3)% of its disintegrations. This nuclide can now be produced with relatively small amounts of alpha-emitting contaminants so that, in principle, 237Pu can be used for studies of Pu biokinetics in man. However, because of its high specific activity, there was some doubt that its metabolism would be the same as that of the alpha- and beta-emitting isotopes of Pu normally encountered in the nuclear industry. In this study, the biokinetics of nearly "pure," high specific activity 237Pu are compared with those of lower specific activity, "impure" 237Pu containing significant amounts of alpha-emitting Pu, following administration to rats by intravenous injection as the citrate. Both the distribution and excretion of the "pure" and "impure" 237Pu used in the two studies were similar and also in good agreement with the results of previously reported studies using 239Pu and 241Pu citrate, thus validating the use of 237Pu for studies of Pu metabolism in man. Data on the biokinetics of 237Pu nitrate are also included.

Animals↗
PubMed1993

Liver cancer induction by 239Pu, 241Am, and thorotrast in the grasshopper mouse, Onychomys leukogaster.

Forty young adult grasshopper mice (Onychomys leukogaster) of both genders were injected with either 129 or 44 kBq kg-1 of monomeric 239Pu and were maintained for lifetime observation. Average liver doses to death (mean times +/- standard deviation (SD) from injection to death = 405 +/- 133 and 756 +/- 189 d) were calculated as approximately 16 and 9 Gy, respectively. These animals developed a total of 18 primary liver tumors (neoplasms, malignant, and benign). Comparison of these mice to a previously published study involving 49 control animals of the same species, 70 mice given 241Am, and 73 given Thorotrast, indicated that the liver cancer induction of Thorotrast can be attributed almost exclusively to the effects of the radioactivity and not to its nonradiation properties. This suggests that projected risks of liver cancer induction from 239Pu, 241Am, or other liver-seeking actinides in humans probably can be estimated from the liver cancer experience in Thorotrast patients using the calculated radiation doses to liver. For this species, the linear risk coefficient for induction of liver neoplasia (percent of mice with liver tumor) by 241Am or Thorotrast was estimated to be about 14.6 +/- 5.4 times the average liver dose (in Gy) for groups of animals with average liver doses of 5 Gy or less. The lowest average liver dose among groups of these mice given 239Pu was about 9 Gy, the dose was not in the linear range, and it was too high to yield reliable results for determining a risk coefficient for low dose irradiation. However, the estimates for a risk coefficient were similar for the plutonium and americium mice with liver doses of approximately 9 Gy or 16 Gy.

Americium↗
PubMed1994

Distribution of skeletal malignancies in beagles injected with 239Pu citrate.

The distribution of skeletal malignancies among our beagles injected with 239Pu as young adults roughly seems to follow the distribution of skeletal mass and skeletal 239Pu. These findings are similar to those we reported previously for a group of dogs given 26Ra. Although there were differences in tumor distribution between the animals given 226Ra and those given 239Pu, most of them were not statistically significant; however, the radium dogs seemed to show a greater sensitivity to bone tumor origin in the tibia, while there may have been a tendency among the plutonium dogs toward increased relative sensitivity in the scapula, lumbar vertebrae, sacrum, and ribs. In contrast, the most common site for the formation of naturally-occurring bone malignancy in the dog is the distal radius. Perhaps there were too few tumors and too few dogs to establish statistical significance. A correlation between tumor location and at least two anatomical-physiological factors in the skeleton indicated that these two factors (site-specific bone turnover rate and percent of red marrow at the site, which is correlated with vascularity) may influence the appearance of malignancies both individually and in combination. Except for the femur, there appeared to be no difference between the relative distribution of skeletal malignancies of low-level (30 Bq-2 Bq kg-1 injected) and high-level (3-122 kBq kg-1) dogs. Distribution of bone tumors between the axial and appendicular skeleton was 50% vs. 50% for 239Pu (42 and 42), but it was 39% axial vs. 61% appendicular (22 and 35, respectively) for dogs given 226Ra. This difference was not significant (p > 0.2).

Animals↗
PubMed1994

Effects of macromolecular chelating agents on the release of 239Pu and 59Fe from rat alveolar macrophages after phagocytic uptake of 239Pu-59Fe-iron hydroxide colloid.

The chelation-mediated mobilization of 239Pu and 59Fe from rat alveolar macrophages which had engulfed 239Pu-59Fe-hydroxide colloids was studied by exposing the macrophages to diethylenetriaminepentaacetic acid and macromolecular weight forms of diethylenetriaminepentaacetic acid. The release of 239Pu and 59Fe by these macromolecular weight chelating agents and diethylenetriaminepentaacetic acid was assessed in monolayer culture and shown to be dependent upon the nature of the engulfed colloids. Whereas calcium-diethylenetriaminepentaacetic acid, aminoethylcellulose-diethylenetriaminepentaacetic acid, and aminoethylcellulose-diethylenetriaminepentaacetic acid oxidized with periodic acid (aminoethylcellulose-diethylenetriaminepentaacetic acid(I2) exhibited some effectiveness at releasing 239Pu and 59Fe from macrophages which had engulfed the low aggregative colloid, they were less effective in the release of these radionuclides from the high aggregative colloid. The efficacy of these chelating agents on the removal of radionuclides from alveolar macrophages differed between iron and plutonium, suggesting the significant difference in the dissolution and subsequent metabolism of these radionuclides in alveolar macrophages. From the similarities of the percentage increases in 239Pu mobilized from the low aggregate colloid by aminoethylcellulose-diethylenetriaminepentaacetic acid (I2) and diethylenetriaminepentaacetic acid, it would appear that both forms of diethylenetriaminepentaacetic acid could be accessing the same deposits of 239Pu; however, for 59Fe the percentage increases are quite different for the two forms of diethylenetriaminepentaacetic acid. SiO2-diethylenetriaminepentaacetic acid, an insoluble macromolecular weight chelating agent, was ineffective at releases 239Pu but was slightly effective at releasing radioiron.

Animals↗
PubMed1995

Application of a canine 238Pu biokinetics/dosimetry model to human bioassay data.

Associated with the use of 238Pu in thermoelectric power sources for space probes is the potential for human exposure, primarily by inhalation and most likely as 238PuO2. Several models have been developed for assessing the level of intake and predicting the resulting radiation dose following human exposure to 239Pu. However, there are indications that existing models do not adequately describe the disposition and dosimetry of 238Pu following human exposure. In this study, a canine model that accounts for these differences has been adapted for use with human excretion data. The model is based on existing knowledge about organ retention of plutonium. An analysis of the sensitivity of the model to changes in aerosol-associated properties indicated that predictions of urinary excretion are most sensitive to changes in particle solubility and diameter and in the ratio of fragment:particle surface area. Application of the model to urinary excretion data from seven workers exposed to a 238Pu ceramic aerosol gave estimated intakes of 390-8,200 Bq and associated initial pulmonary burdens of 80-1,700 Bq. The resulting 50-y dose commitments to critical organs per Bq of 238Pu intake were estimated to be 0.5 mSv for the thoracic region, 0.2 mSv for the liver, and 1 mSv for the bone surfaces.

Animals↗
PubMed1995

A comparison of techniques used to estimate the amount of resuspended soil on plant surfaces.

The objectives of this study were to compare four common techniques used to estimate soil mass loadings on plant surfaces and to assess the need to account for particle-size distributions of both the soil tracer and contaminant of concern within the soil. Soil loadings (g soil kg-1 dried plant) from split samples collected in a pasture near Chernobyl were estimated using soil tracers of plutonium analyzed via alpha spectroscopy (mean +/- standard error; 1.0 +/- 0.2), titanium analyzed with an inductive coupled plasma spectrometer; (3.6 +/- 0.6), and neutron activation analysis for scandium (8.1 +/- 1.6), as well as simply washing the soil off the vegetation (34.1 +/- 5.6) Differences were significant at p < 0.001. We also found that soil loading estimates from any one technique varied by a factor of 10 depending on the soil particle size used in the calculations. This was because soil loadings decreased when smaller-sized soil fractions dominated the resuspension process. However, the percent of the plant's total contamination attributable to soil loading increased with smaller soil particles. Smaller soil particles apparently contribute less to the mass of soil loading (g soil kg-1 dry plant), but more to the total plant contamination (Bq) because of the higher concentration of contaminant found in the smaller-sized soil fractions. Differences in mass loading estimates due to the technique chosen (a factor of 10), or due to differences in elemental concentration as a result of the soil particle size used in the calculation (also a factor of 10), were greater than the natural variability observed in the field (2.5).

Alpha Particles↗
PubMed1996

Comparative distribution of 241 Am and 239,240 Pu in soils around the Rocky Flats Environmental Technology Site.

The distribution and behavior of 241 Am and 239,240 Pu in soils from the buffer zone of the Rocky Flats Environmental Technology Site have been investigated. Concentrations of both radionuclides decreased at similar rates with soil depth. More than 80% of the total inventory of both contaminants was found in the upper 9 cm of the soils with over 50% of the inventory residing in the top 3 cm. Comparison with earlier studies indicate that the plutonium depth profile has not changed significantly over the last 25 y. The inventories of 241 Am and 239,240 Pu decreased with distance from the 903 Pad (a former waste storage site) according to a power function, and the plume extended mainly toward the east. The lateral movement of the two contaminants away from the 903 Pad was not significantly different. The median activity ratio of 241 Am: 239,240 Pu ranged from 17 to 19% and was independent of sampling location and soil depth. This observation provided further evidence that the movement of both contaminants is indistinguishable in the study area. Because of the strong correlation between the two radionuclides, 241 Am concentrations can then be used to infer 239,240 Pu by counting the 241 Am via gamma spectroscopy.

Americium↗
PubMed1997

Data quality objectives for surface-soil cleanup operation using in situ gamma spectrometry for concentration measurements.

In situ gamma spectrometry is an efficient method for monitoring the progress of cleanup activities for radioactive contaminants in surface soil and for evaluating the attainment of cleanup standards. However, desired data precision and accuracy must be specified for such a detection system prior to the operation to ensure that the level of uncertainty associated with the concentration measurements is acceptable. A method for developing data quality objectives is described in this paper for in situ gamma spectrometry to achieve numerical goals for data precision and accuracy for cleanup operations. Concentration measurement for a radionuclide at its cleanup level must have a precision commensurate with the importance of cleanup decisions. The 95% lower limit of detection of the system is suggested to be about one tenth the expected system response at the cleanup level. The count time required to achieve the preferred 95% lower limit of detection, and hence the desired precision, can then be determined. The accuracy error arises from the overall calibration factor, which relates the detector responses (e.g., count rate) to physical quantities of interest (e.g., radionuclide soil concentration). The major source of error for the calibration factor using in situ gamma spectrometry is the misidentification of the type of the depth profile of radionuclide concentration in soil. If surrogate radionuclides are used, such as 241Am for plutonium, the variation in the concentration ratio would be another significant source of error. Soil sampling programs performed prior to a cleanup operation will greatly reduce the accuracy error for an in situ detection system, and the analysis of system errors may determine the degree of sampling required. The planning of such a program is discussed in the study. Uncertainty analysis using a Latin Hypercube sampling technique for the calibration factor is also demonstrated. The quantitative result of the uncertainty analysis is useful for determining a nuclide's maximum peak count rate using gamma spectrum that ensures the attainment of the cleanup standard for that nuclide with a pre-specified confidence level (e.g., 95%). The cleanup operation of 239,240Pu in surface soil in the safety shot areas at the Nevada Test Site serves as an example to illustrate the data quality objectives development.

Americium↗
PubMed1998

Microdistribution of 239Pu in the beagle skeleton.

The microdistribution of 239Pu was analyzed in the humerus, lumbar vertebra, and proximal ulna of young adult beagles using neutron induced autoradiography. The animals were sacrificed serially in groups of three at 4, 8, 16, 32, and 64 wk after a single injection of 3.5 kBq kg(-1) body weight. The kinetic behavior of surface concentrations was modeled using a simple concept of deposition and clearance in skeletal regions. Bones with high turnover showed a larger initial uptake and a faster clearance than bones with low turnover rates. Using a regression procedure, the surface deposition and clearance of plutonium was calculated as a function of the turnover rate. With time after injection the initial nonuniformity of trabecular surface labels tends to become more uniform. The trabecular:cortical affinity ratio is about 10. Trabecular activity is gradually translocated to cortical sites. The affinity ratio of forming to resting surfaces is about three. In some bones a continuous increase of marrow stars was observed, whereas in other bones no clear-cut tendency could be seen. The highest level of marrow labeling occurred in the lumbar vertebra and the humerus shaft.

Animals↗
PubMed1999

Is there a difference in radionuclide-induced bone tumor sensitivity between male and female beagles?

An analysis of bone tumor occurrences among male and female beagles given monomeric 239Pu or 226Ra was not able to establish a difference in sensitivity to induction of bone malignancy by radium or plutonium exposure. This is in contrast to the situation reported for mice. Female mice are substantially more sensitive to 239Pu irradiation than males, but this difference is obliterated by gonadectomy, females becoming less sensitive and males becoming more sensitive. Although there may be some nonuniformity between human males and females for radiation-induced bone sarcoma occurrence, analysis of data sets containing both men and women exposed to 224Ra, 226Ra, 228Ra, or 226+228Ra appears not to reveal substantial differences in sensitivity by gender, a situation similar to that reported herein for beagles.

Animals↗
PubMed2000

Fracture occurrence from radionuclides in the skeleton.

Because skeletal fractures were an important finding among persons contaminated with 226Ra, experience with fractures among dogs in our colony was summarized to determine the projected significance for persons contaminated with bone-seeking radionuclides. Comparison by Fisher's Exact Test of lifetime fracture occurrence in the skeletons of beagles injected as young adults suggested that for animals given 226Ra, 228Ra, 228Th, or 239Pu citrate, there was probably an excess over controls in fractures of the ribs, leg bones, spinous processes, and pelvis (os coxae) plus the mandible for dogs given 226Ra and the scapulae for dogs given 228Ra or 228Th. Regression analysis indicated that significantly elevated fracture occurrence was especially notable at the higher radiation doses, at about 50 Gy average skeletal dose for 239Pu, 140 Gy for 226Ra, about 40 Gy for 228Ra, and more than 15 Gy for 228Th. The average number of fractures per dog was significantly elevated over that noted in controls for the highest radiation doses of 239Pu and 226Ra and for the higher doses of 228Ra and 228Th. For those dogs given 90Sr citrate, there was virtually no important difference from control beagles not given radionuclides, even at group mean cumulative skeletal radiation doses up to 101 Gy. Because of a large proportion of dogs with fractures that died with bone malignancy (even at dosage levels lower than those exhibiting an excess average number of fractures per dog), we conclude that fracture would not be an important endpoint at lower levels of plutonium contamination in humans such as would be expected to occur from occupational or environmental exposure.

Animals↗
PubMed2000

Radioecological impacts of the Techa River contamination.

During the years 1949-1952, the Mayak Production Association (MAYAK), which was processing weapons-grade plutonium, was discharging radioactive wastes into the Techa River. As a result, all components of the river system (water, bottom soils, and flood plains) were exposed to massive radioactive contamination. The protective measures taken in the 1950's resulted in the improvement of the radioecological conditions in the Techa River. After 1952, the radioecological conditions in the area were mostly determined by the long-lived radionuclides 9OSr and 137Cs. This article focuses on the dependencies governing the migration of radionuclides along the vertical and horizontal planes in different components of the river system over a 40-y period. Until the 1990's, a decrease in 90Sr and 137Cs contents was noted in environmental samples and foodstuffs produced in riverside villages. In the subsequent years, the radioecological situation on the Techa stabilized. The sources of the current contamination of the river are represented by the runoffs from by-pass canals and swampy upper reaches.

Cesium Radioisotopes↗
PubMed2000

Deterministic effects from occupational radiation exposures in a cohort of Mayak PA workers: data base description.

Project 2.3 of the Joint Coordinating Committee on Radiation Effects Research (JCCRER) is a study of deterministic health effects among a cohort of Russia nuclear workers. The preliminary study population includes a stratified random sample of 221 radiation workers who were employed in a cohort of 8,055 workers at the Mayak PA facilities for at least one year during the period from 1948 to 1958. High annual doses, approaching 1 Gy per year from external and internal radiation sources, were reported for a significant proportion of the workers in this cohort. The present data set includes 96 cases of chronic radiation sickness (CRS), 14 cases of acute radiation syndrome (ARS) and 13 cases of plutonium pneumosclerosis (PPn). The remainder of the sample consists of "uninjured workers" who had no known history of radiation illness or injury; however, the uninjured workers are not "controls" for radiation exposure. The data base is currently being expanded to 600 individuals sampled from the cohort of workers from 1948 to 1958 to allow a more complete analysis of the deterministic health effects and comparisons with existing health effect models. The final data base will be used with state-of-the-art modeling techniques to determine threshold doses and dose-response relationships for key clinical diagnostic variables.

Acute Disease↗
PubMed2000

Development of an improved dosimetry system for the workers at the Mayak Production Association.

Databases are being created that contain verified and updated dosimetry and worker history information for workers at the Mayak Production Association. Many workers had significant external and internal exposures, particularly during the early years (1948-1952) of operation. These dosimetric and worker history data are to be used in companion epidemiology studies of stochastic and deterministic effects. The database contains both external and internal dose information and is being constructed from other databases that include radiochemical analyses of tissues, bioassay data, air sampling data, whole body counting data, and occupational and worker histories. The procedures, models, methods, and operational uncertainties will be documented and included in the database, technical reports, and publications. The cohort of the stochastic epidemiological study is expected to include about 19,000 persons while the cohort for the deterministic epidemiological study is expected to include about 600 persons. For external dosimetry, workplace gamma, beta, and neutron doses are being reconstructed. The models used for this incorporate issues such as known isotopes, composition, shielding, further analysis of film badge sensitivities, and records of direct measurements. Organ doses from external exposures are also being calculated. Methods for calculating dose uncertainties are being developed. For internal dosimetry, the organ doses have been calculated using the established FIB-1 biokinetic model. A new biokinetic model is being developed that includes more information of the solubility and biokinetics of the different chemical forms and particulate sizes of plutonium that were in the workplace. In addition, updated worker histories will be used to estimate doses to some workers where direct measurements were not made. A rigorous quality control procedure is being implemented to ensure that the correct dosimetry data is entering the various databases being used by the epidemiologists.

Beta Particles↗
PubMed2000

Chest wall thickness measurements of the LLNL phantom for small area germanium detector counting.

The Lawrence Livermore National Laboratory (LLNL) phantom was developed to calibrate lung counting systems that are used to estimate plutonium and other low energy photon emitting radionuclides deposited in the lung. Originally, low energy photon counting systems consisted of sodium iodide or phoswich detectors, but they have been largely replaced by smaller germanium detector arrays. The average chest wall thicknesses of the LLNL phantom's torso plate and its overlay plates provided by the manufacturer refer to the regions covered by phoswich detectors; however, germanium detectors are of a different size and are placed in different locations on the phantom's torso plate. Previous work has shown that the manufacturer's data were not applicable for large area germanium detectors. The lung counting system at the Korea Atomic Energy Institute (KAERI) is a small area germanium detector array. Although the detectors are placed within the phoswich circles, only about 25% of the area is covered by the detectors. The LLNL phantom at KAERI has been examined to determine if the manufacturer's data are valid or if new chest wall thickness values must be determined. This paper presents chest wall thickness data for the LLNL phantom with and without its B-series overlay plates at 17 keV, 60 keV, 200 keV, and 1,500 keV and shows that these values are different from the manufacturer's values.

Calibration↗
PubMed2001

Preliminary uncertainty analysis for the doses estimated using the Techa River dosimetry system--2000.

The Mayak Production Association (MPA) was the first facility in the former Soviet Union for the production of plutonium. As a result of failures in the technological processes in the late 1940's and early 1950's, members of the public were exposed via discharge of about 10(17) Bq of liquid wastes into the Techa River (1949-1956). Residents of many villages downstream on the Techa River were exposed via a variety of pathways; the more significant included drinking of water from the river and external gamma exposure due to proximity to sediments and shoreline. The specific aim of this project is to enhance the reconstruction of external and internal radiation doses for individuals in the Extended Techa River Cohort. The purpose of this paper is to present the approaches being used to evaluate the uncertainty in the calculated individual doses and to provide example and representative results of the uncertainty analyses. The magnitude of the uncertainties varies depending on location and time of individual exposure, but the results from reference-individual calculations indicate that for external doses, the range of uncertainty is about a factor of four to five. For internal doses, the range of uncertainty depends on village of residence, which is actually a surrogate for source of drinking water. For villages with single sources of drinking water (river or well), the ratio of the 97.5th percentile-to 2.5th percentile estimates can be a factor of 20 to 30. For villages with mixed sources of drinking water (river and well), the ratio of the range can be over two orders of magnitude.

Databases, Factual↗