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No evidence for chromosomal instability in radiation workers with in vivo exposure to plutonium.

The availability of cultured lymphocyte preparations from radiation workers with internal deposits of plutonium provided the opportunity to examine whether irradiation of bone marrow cells had induced a transmissible genomic instability manifesting as an increase in de novo chromosome aberrations in descendant cells in the peripheral blood. The men were originally classified as having more than 20% of the maximum permissible body burdens of plutonium, and recent red bone marrow dose calculations provided individual cumulative estimates at the time of sampling ranging up to 1.8 Sv. The initial sampling occurred approximately 10 years after the main major intake, and samples were subsequently taken during three further periods over the following 20 years. Control samples were available from three of the four sampling times. Chromosome analysis of solid Giemsa-stained material revealed no significant differences either in comparisons between the total group of plutonium workers and controls for comparable periods or when the comparisons were restricted to a group of plutonium workers with initial red bone marrow plutonium doses greater than 0.25 Sv. However, the frequencies of cells containing chromatid exchanges, chromatid breaks, and chromosome and chromatid gaps decreased significantly over the study period for both the plutonium workers as a whole and the controls, and a similar fluctuating pattern was seen when sequential samples from groups of the same individuals were examined. Cells with dicentrics, centric rings and excess acentric fragments remained at similar frequencies throughout the study period. There was therefore no evidence from the study of blood lymphocytes for the induction of persistent transmissible genomic instability in the bone marrow of radiation workers with internal deposits of plutonium. The work has, however, confirmed the need for appropriate controls when conducting studies of cytogenetic end points of instability.

Adult↗

Comparisons of the skeletal locations of putative plutonium-induced osteosarcomas in humans with those in beagle dogs and with naturally occurring tumors in both species.

Osteosarcomas occur from exposures to bone-seeking, alpha-particle-emitting isotopes, particularly plutonium. The skeletal distribution of putative 239Pu-induced osteosarcomas reported in Mayak Metallurgical and Radiochemical Plutonium Plant workers is compared with those observed in canine studies, and these are compared with distributions of naturally occurring osteosarcomas in both species. In the Mayak workers, 29% and 71% of the osteosarcomas were in the peripheral and central skeleton, respectively, with the spine having the most tumors (36%). An almost identical distribution of plutonium-induced osteosarcomas was reported for dogs injected with 239Pu as young adults. This distribution of osteosarcomas is quite different from the distributions of naturally occurring osteosarcomas for both species. In the Cooperative Osteosarcoma Study Group in humans (1,736 osteosarcomas from all ages), over 91% of the tumors occurred in the peripheral skeleton. In the Mayo Clinic group of older individuals (>40 years old), over 60% of the osteosarcomas appeared in the peripheral skeleton. The distribution of naturally occurring osteosarcomas in the canine is similar to that in the adult human. The similarities of the distributions of plutonium-associated osteosarcomas in the Mayak workers with those found in experimental studies suggest that many of the reported osteosarcomas may have been associated with plutonium exposures. These results also support the experimental paradigm that plutonium osteosarcomas have a preference for well vascularized cancellous bone sites. These sites have a greater initial deposition of plutonium, but also greater turnover due to elevated bone remodeling rates.

Adolescent↗

Lung fibrosis in plutonium workers.

There have been few systematic studies of the non-malignant health effects of alpha-particle radiation in humans. Animal studies and a report on plutonium-exposed workers from Russia suggest an association between high doses to the lung from plutonium exposure and the development of fibrotic lung disease. Prompted by a case of lung fibrosis in a retired plutonium worker, we tested the hypothesis that plutonium inhalation increases the risk for developing chest radiograph abnormalities consistent with pulmonary fibrosis. We conducted a retrospective study of nuclear weapons workers that included estimating absorbed doses to the lung with an internal dosimetry model. Our study population consisted of 326 plutonium-exposed workers with absorbed lung doses from 0 to 28 Sv and 194 unexposed workers. We compared the severity of chest radiograph interstitial abnormalities between the two groups using the International Labour Organization profusion scoring system. There was a significantly higher proportion of abnormal profusion scores among plutonium-exposed workers (17.5%) than among unexposed workers (7.2%), P < 0.01. Lung doses of 10 Sv or greater conferred a 5.3-fold risk (95% CI 1.2-23.4) of having an abnormal chest X ray consistent with pulmonary fibrosis when compared with unexposed individuals after controlling for the effects of age, smoking and asbestos exposure. This study shows that plutonium may cause lung fibrosis in humans at absorbed lung doses above 10 Sv.

Adult↗

Uptake and loss of plutonium from osteoclasts and macrophages in the mandibular condyle of the rat.

Female rats were used to study the kinetics of plutonium transfer from the bone surfaces of the mandibular condyle to osteoclasts and macrophages. This study was made using autoradiographs prepared from plastic sections of the mineralized bones of animals which had been injected with 241 Pu citrate. Measurements of the concentration of plutonium in the osteoclasts and macrophages at different times after the injection of plutonium showed that plutonium was concentrated by osteoclasts from bone surfaces and was retained with a half-time of approximately 70 h. Subsequently, plutonium appeared to be transferred to macrophages. The results showed that plutonium was unlikely to be accumulated by macrophages as a result of their participation in bone resorption.

Animals↗

Threat to the New York City water supply--plutonium.

The mayor of the City of New York received an anonymous letter on April 1st 1985 threatening to contaminate the water supply with plutonium unless all criminal charges against Mr Bernhard Goetz, the suspect in a dramatic subway shooting incident, were dismissed by April 11th 1985. Local and Federal authorities were called upon to evaluate the credibility of the threat and to institute a "round the clock" monitoring program by New York City personnel. The Environmental Measurements Laboratory, EML, was requested by the City to analyse a composite, large volume (approximately 175 litres) drinking water sample collected by City personnel on April 16th 1985. The concentration measured was 21 fCi/l which was a factor of 100 greater than previously observed results in our data base, and the mass isotopic content of the plutonium was very unusual. Additional samples were collected one to three months later at various distribution points in the water supply system. The plutonium concentrations were much lower and comparable to EML's earlier data. Mass isotopic analysis of these samples provided more reasonable compositions but with high uncertainties due to very low plutonium concentration. Recent measurements of large volume samples, approximately 1000 litres, collected in the Fall of 1985 from the New York City and New Jersey water supplies showed identical plutonium concentrations of 0.05 fCi/l. Mass isotopic analyses indicated similar 240Pu/239Pu ratios which were slightly lower than global fallout estimates. Due to our inability to confirm the elevated plutonium concentration value for the composite sample of April 16th 1985, it is impossible to conclude whether the threat to contaminate the New York City water supply was actually carried out or whether the sample was contaminated prior to receipt at EML.

Crime↗

Plutonium isotope ratios in the Yenisey and Ob estuaries.

Over the past 50 years, nuclear weapons' tests and releases from the nuclear industry have introduced anthropogenic plutonium into the environment. In the Arctic environment, the main source of plutonium is from the atmospheric weapons testing, but previous studies of plutonium in the Kara Sea have shown that, at certain sites, other releases can give rise to enhanced local concentrations. The present paper presents results from determination of plutonium concentrations and isotope ratios in the sediment samples collected during various expeditions to the Kara Sea, the Ob and Yenisey estuaries and their river systems. The data indicated a clear influence from a low 240Pu:239Pu source in surface sediments collected from the Yenisey estuary, whereas plutonium in Ob estuary sediments is dominated by global fallout. The results also show an increase in plutonium concentration (from 0.003 to 11Bq/kg) and a decrease in 240Pu:239Pu isotope ratio (from 0.16 to 0.05) going upstream from the Yenisey estuary towards the nuclear installation at Krashnoyarsk.

Arctic Regions↗

Conclusions on plutonium separation from atmospheric krypton-85 measured at various distances from the Karlsruhe reprocessing plant.

For wide-area atmospheric monitoring, krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80-90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km. At distances up to 40 km, the false alarm rate is less than 3.5%. On average, the fuel released 28 TBq krypton-85 per kg plutonium. For weapons-grade plutonium, the krypton signal would be lower by a factor of 2. Hence, the given percentages correspond to the detection probabilities for the separation of a significant quantity (8 kg) of plutonium per weekly sample under the specific meteorological conditions of the WAK. The minimum separation rates that could have been detected are 2 gram of weapons-grade plutonium per week at a distance of less than 1 km, 40 g/week at 5 km, 200 g/week at 39 km, and 1000 g/week at 130 km.

Air Pollutants, Radioactive↗

The binding of plutonium to transferrin in the presence of tri-n-butyl phosphate or nitrate and its release by diethylenetriaminepenta-acetate and the tetrameric catechoylamide ligand LICAMC(C).

The binding of plutonium to human apo-transferrin and to rat serum was investigated following delivery of the metal to the protein either as the plutonium-tri-n-butyl phosphate (Pu-TBP) complex in n-dodecane or as plutonium nitrate. Chromatographic behaviour, the failure to bind to iron-saturated transferrin and the release of plutonium by the chelating agents CaNa3DTPA and 3,4,3-LICAM(C) suggest that the transferrin complexes formed from the two plutonium compounds are similar. The tetracatechoylamide ligand LICAM(C) was found to be about 500 times more effective than DTPA, on a molar basis, for the release of plutonium from transferrin in rat serum.

Animals↗

Plutonium contamination from accidental release or simply fallout: study of soils at Palomares (Spain).

The activity concentration of plutonium in an environmental sample does not usually constitute sufficient information to determine if it is due only to fallout. Alpha and gamma spectrometry are used here conjointly in the study of environmental soil samples to distinguish between samples showing plutonium contamination due to fallout exclusively, and samples contaminated with plutonium from another source. The method was applied to soil samples collected in Palomares (Spain), where an accidental release of aerosols contaminated with plutonium occurred. The two contributions (fallout and accidentally released plutonium) were separated by means of the activity ratios between various radionuclides present in the samples analyzed. The fallout level was estimated from the 239 + 240Pu/137Cs activity ratio. For samples showing contamination due to the accident, the 238Pu/239 + 240Pu and 239Pu/240Pu activity ratios were also calculated to determine the grade of plutonium of this contamination.

Americium↗

The reactions of 1.0 nanometre diameter plutonium-238 dioxide particles with rat lung fluid.

The reactions of 1.0 nm particles of plutonium-238 dioxide with rat lung fluid have been studied both in vivo and in vitro. In both cases two products have been identified, (i) plutonium-labelled pulmonary surfactant and (ii) a heterogeneous plutonium-labelled material isolated by column chromatography. The formation of plutonium-labelled pulmonary surfactant results in the rapid translocation of plutonium from lungs to blood and in a high urinary excretion relative to administered plutonium citrate.

Animals↗

The plutonium problem: the Royal Society sits on the fence.

A recent Royal Society report, Management of Separated Plutonium, considers the production and disposal of plutonium from the spent fuel from civil and nuclear power reactors. It accepts the need for dealing with plutonium stocks because of the toxicity of the element and as it can be used to fabricate nuclear weapons, and expresses concern that it might be illicitly acquired by terrorists. It recommends an independent Government commission on the management of plutonium, and considers the various options for this. However, it does not analyse the arguments against plutonium as a reactor fuel, and underestimates the risks of diversion to nuclear weapons and nuclear terrorism. This paper reviews the options, and concludes that separated plutonium should be added to high-level waste, vitrified, and eventually buried in a deep geological repository.

Facility Regulation and Control↗

Experience with a routine fecal sampling program for plutonium workers.

A quarterly fecal sampling program was conducted at the U. S. Department of Energy's Hanford site for congruent to 100 workers at risk for an intake of plutonium oxide and other forms of plutonium. To our surprise, we discovered that essentially all of the workers were excreting detectable activities of plutonium. Further investigation showed that the source was frequent, intermittent intakes at levels below detectability by normal workplace monitoring, indicating the extraordinary sensitivity of fecal sampling. However, the experience of this study also indicated that the increased sensitivity of routine fecal sampling relative to more common bioassay methods is offset by many problems. These include poor worker cooperation; difficulty in distinguishing low-level chronic intakes from a more significant, acute intake; difficulty in eliminating interference from ingested plutonium; and difficulty in interpreting what a single void means in terms of 24-h excretion. Recommendations for a routine fecal program include providing good communication to workers and management about reasons and logistics of fecal sampling prior to starting, using annual (instead of quarterly) fecal sampling for class Y plutonium, collecting samples after workers have been away from plutonium exposure for a least 3 d, and giving serious consideration to improving urinalysis sensitivity rather than going to routine fecal sampling.

Feces↗

Assessment of plutonium exposure in the Enewetak population by urinalysis.

Since 1980, the inhabitants of Enewetak Atoll have been monitored periodically by scientists from Brookhaven National Laboratory for internally deposited radioactive material. In 1989, the establishment of fission track analysis and of a protocol for shipboard collection of 24-h urine samples significantly improved our ability to assess the internal uptake of plutonium. The purpose of this report is to show the distribution of plutonium concentrations in urine collected in 1989 and 1991, and to assess the associated committed effective doses for the Enewetak population based on a long-term chronic uptake of low-level plutonium. To estimate dose, we derived the plutonium dose-per-unit-uptake coefficients based on the dosimetric system of the International Commission on Radiological Protection. Assuming a continuous uptake, an integrated Jones's plutonium urine excretion function was developed to interpret the Enewetak urine data. The Appendix shows how these values were derived. The committed effective doses were 0.2 mSv, calculated from the 1991 average plutonium content in 69 urine samples.

Adolescent↗

A case study of selected medical findings among plutonium injectees.

Available medical records of plutonium injectees exposed in experimental studies of plutonium biokinetics under Manhattan Engineer District auspices have been reviewed for subsequent medical findings potentially related to the plutonium exposures. Five subjects who had been injected with approximately 11 kBq 239Pu, and one injected with 3.5 kBq 238Pu, had useful follow-up medical data. Bone lesions dominated the findings: none of six subjects with follow-up for bone conditions lacked bone lesions clearly or potentially caused, or worsened, by plutonium. Roentgenograms of three subjects, read by a radiologist experienced reading films of radium cases, demonstrated possible to likely plutonium effects. Two cases of osteoporosis or non-specific degenerative changes were seen, associated with a hip fracture and vertebral fractures. Areas of increased bone density were seen, as well as numerous dystopic calcifications and one unusual case of widespread pathologic calcification on bone surfaces probably due to a plutonium-related calciphylactic reaction. Non-skeletal findings include labyrinthitis with inflammatory mastoid changes, conduction deafness, and a benign neurofibroma directly adjacent to bone. The radium literature contains similar observed findings, but interpretation of these limited clinical observations is hampered by lack of quantitative data on humans exposed to radium with respect to prevalence of non-specific ear, mastoid, and skeletal symptomatologies or x-ray findings, or cumulative incidence rates of bone fractures or of other physical disabilities related to ear, mastoid, or bone damage. Disability and invalidism late in life can be risk factors for earlier mortality.

Adolescent↗

Plutonium in Colorado residents: results of autopsy bone samples collected during 1975-1979.

Concentrations of (239,240)Pu and the 240Pu/239Pu atom ratios were measured in rib samples from 55 non-occupationally exposed Colorado residents. Samples were collected at autopsy during 1975-1979 under an earlier study intended to compare plutonium levels in liver and lung of people who lived at various proximities to the Rocky Flats Environmental Technology Site (RFETS) near Denver. Overall, median (239,240)Pu concentrations from rib samples were 100, 80, and 57 microBq g(-1) ash weight for area locations A, B, and C, respectively. Area A encompassed subjects who lived within 25 km of RFETS, area B was between 25 and 50 km from RFETS, and area C included all of Colorado outside 50 km from the site and east of the continental divide. The corresponding median plutonium skeletal burdens estimated for these area locations were 146, 93, and 71 mBq, respectively. A statistically significant difference was noted only between plutonium concentrations in male rib samples and their skeletal burdens from area A compared to area C. However, based on a regression analysis of all study subjects, distance from RFETS was not statistically correlated to plutonium rib concentrations or skeletal burdens in this sample. Overall, median 240Pu/239Pu atom ratios were 0.20, 0.18, and 0.17 for areas A, B, and C, respectively. Although higher (239,240)Pu concentrations and skeletal burdens were indicated in area A males than area C males, we cannot conclude that RFETS releases may have caused this difference. The decreasing trends in the 240Pu/239Pu ratios with distance from RFETS are contrary with such a conclusion and strongly indicate that the material was primarily global fallout rather than weapons-grade plutonium that was processed at RFETS. Furthermore, there are other plausible explanations for the differences observed between area A and C residents. These include a decreasing trend in global fallout from the Rocky Mountain foothills eastward, smoking history differences, sample selection criteria, and possibly other unidentified factors. Nevertheless, estimated levels of total plutonium in this sample of Colorado residents were low and within the range of reported literature values for general, world-wide populations.

Autopsy↗

Chelating agents used for plutonium and uranium removal in radiation emergency medicine.

The prospects of using chelating agents for increasing the excretion of actinides are reviewed. The removal of plutonium by chelating agents is of great importance because plutonium is extremely dangerous and induces cancer due to radiation toxicity. Similarly, uranium is a radionuclide, which causes severe renal dysfunction within a short time period due to chemical toxicity. It may also induce cancers such as leukemia and osteosarcoma in cases of long-term internal radiation exposure. Investigations on chelating agents for the removal of plutonium were initiated in the 1960's and 1970's. Diethylenetriaminepentaacetic acid (DTPA) is recognized as a chelating agent that accelerates the excretion of plutonium in early treatment after an accident. Thereafter, there has long been an interest in finding new chelating agents with radionuclide removal properties for use in therapy, and many chelating agents such as 3,4,3-LIHOPO and CBMIDA have been studied for their ability to remove plutonium and uranium. Recently, the focus has turned to drugs that have been used successfully in the treatment of a variety of other diseases, for example the iron chelating drug deferiprone or 1,2-dimethyl-3-hydroxypyrid-4-one (L1), which is used in thalassaemia and ethane-1-hydroxy-1,1-bisphosphonate (EHBP), which is used in osteoporosis. Within this context, it is important to examine the clinical use of these two drugs as well as the properties of the experimental chelators 3,4,3-LIHOPO and CBMIDA in order to identify possible uses in the treatment of radiation workers contaminated with plutonium and uranium.

Animals↗

Effects of duration of fast and animal age on the gastrointestinal absorption of plutonium.

The fraction of plutonium absorbed after oral administration of Pu(VI) to 24-h-fasted mice was 19 X 10(-4), 13-fold higher than in fed mice, 1.4 X 10(-4). We have investigated the relevance of the high gastrointestinal (GI) absorption value for the 24-h-fasted animals in setting drinking water standards for humans. When fasting was initiated at the beginning of the active phase of the mouse's daily activity cycle (when they would normally eat), plutonium GI absorption rose from 2.8 X 10(-4) at zero-time to a level typical of the 24-h-fasted mouse after only 2 h of fasting. In contrast, in mice allowed to eat for 4 h into their active phase prior to initiation of the fast (meal-fed mice), 8 h of fasting were required before GI absorption rose to a level similar to that of the 24-h-fasted mouse. The fraction of plutonium retained after gavage administration of Pu(VI) to 1-day-old rats was 74 X 10(-4), 70-fold higher than the value for fed adults. Retention after GI absorption in neonates remained 30- to 70-fold higher than in adults until weaning. One week after weaning, the fraction absorbed and retained by fed weanling rats was the same as that for fed adults, 1 X 10(-4). Drinking water standards for plutonium have been set based on GI absorption values for fed adult animals. The 10- to 100-fold increases in plutonium absorption in young and fasted animals reported by ourselves and others, and the rapid rise to fasted levels of absorption at the start of the animal's active phase, indicate that consideration should be given to elevated levels of plutonium absorption in young and fasted individuals.

Aging↗

Plutonium-based superconductivity with a transition temperature above 18 K.

Plutonium is a metal of both technological relevance and fundamental scientific interest. Nevertheless, the electronic structure of plutonium, which directly influences its metallurgical properties, is poorly understood. For example, plutonium's 5f electrons are poised on the border between localized and itinerant, and their theoretical treatment pushes the limits of current electronic structure calculations. Here we extend the range of complexity exhibited by plutonium with the discovery of superconductivity in PuCoGa5. We argue that the observed superconductivity results directly from plutonium's anomalous electronic properties and as such serves as a bridge between two classes of spin-fluctuation-mediated superconductors: the known heavy-fermion superconductors and the high-T(c) copper oxides. We suggest that the mechanism of superconductivity is unconventional; seen in that context, the fact that the transition temperature, T(c) approximately 18.5 K, is an order of magnitude greater than the maximum seen in the U- and Ce-based heavy-fermion systems may be natural. The large critical current displayed by PuCoGa5, which comes from radiation-induced self damage that creates pinning centres, would be of technological importance for applied superconductivity if the hazardous material plutonium were not a constituent.

Journal Article↗