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Intruder states and the onset of deformation in the neutron-deficient even-even polonium isotopes.
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Journal Article↗
An experimental study on carcinogenesis related to localized fibrosis in the lung.
The present series of experiments was carried out in order to see what role pre-existing localized fibrosis plays in carcinogenesis of the lung. Hemorrhagic infarction was produced in the lung of 180 male Wistar rats by injecting 0.05 ml of hexachlorotetrafluorobutane into the tail vein. This resulted in localized fibrosis in the lung 3 months later. One hundred and fiften rats were alive 3 months after administration of the chemical. Of these animals, 30 were given no further treatment (control). The remaining 85 rats were given intratracheal instillation of 0.2 microCi of polonium-210 once a week, a total of 15 times. It was subsequently found that lung carcinoma was induced in close proximity to the localized pulmonary fibrosis in 3 of 26 rats (11.5%) during the period from completion of the 15 weekly administrations of polonium-210 until the end of this experiment (21 months after the 1st instillation of polonium-210). Polonium-210 was found to be deposited in the fibrous thickening of the alveolus around the subpleural fibrotic lesion, bronchial epithelium, and peribronchial lymph apparati at the initial period of administration of polonium-210, but during the period of pulmonary carcinogenesis, it was deposited in the localized fibrotic lesion in the lung and in a few cancer cells. This suggests that polonium-210 deposited in the pulmonary fibrotic lesion remains there over a long period of time, indicating a reduced clearance ability at this site.
Adenocarcinoma↗
Measurement of natural radionuclides in U.K. diet.
The levels of radium-226, lead-210 and polonium-210 in the U.K. diet have been determined. The important food groups contributing to the intake of these radionuclides have been identified. Seventy-five percent of the daily intake of radium-226 is derived from beverages, cereals, other vegetables, bread, sugars and preserves. Seventy-five percent of the intake of lead-210 and polonium-210 is derived from bread, milk, cereals, beverages, other vegetables, sugars and preserves, and meat products. The average daily intakes of these radionuclides are tentatively calculated to be 30 mBq for radium-226 and 82 mBq for both lead-210 and polonium-210. These levels are compared with data from other countries. The annual effective dose equivalents resulting from the intakes are approximately 3 muSv for radium-226 and 54 muSv from lead-210 and polonium-210 together. The differences between these doses and other current estimates are discussed.
Diet↗
Carcinogenic agents in snuff.
The oral use of snuff has been associated with an increased-risk for cancer of the oral cavity and pharynx. The five most popular U.S. snuff brands were analyzed for alkaloids, volatile and tobacco-specific N-nitrosamines (TSNA), benzo[a]pyrene (CAS: 50-32-8), and polonium-210. The carcinogenic TSNA in the five snuff brands ranged from 9,600 to 289,000 ppb. These concentrations exceed the nitrosamine concentrations of other consumer products by at least 2 orders of magnitude. Polonium amounted to 0.16-1.22 pCi/g dry snuff. Trace amounts of benzo[a]pyrene (0.1-63 ppb) were indicative of contamination of the tobacco with thermal degradation products, probably due to fire curing or flue curing. The findings from this study, the biologic activity of snuff in animal models, and the epidemiologic studies on snuff use and oral cancer strongly suggest the need for reduction of carcinogens and especially of nitrosamines and polonium-210 in snuff.
Benzo(a)pyrene↗
Pioneers of nuclear medicine, Madame Curie.
Among those who have made important discoveries in the field of radioactivity and thus helped in the development of nuclear medicine as an identical entity are: Heinrich Hertz who in 1886 demonstrated the existence of radiowaves. In 1895 Wilhelm Röntgen discovered the X-rays. In 1896 H. Becquerel described the phenomenon of radioactivity. He showed that a radioactive uranium salt was emitting radioactivity which passing through a metal foil darkened a photographic plate. An analogous experiment performed by S.Thomson in London was announced to the president of the Royal Society of London before the time H.Becquerel announced his discovery but Thomson never claimed priority for his discovery. Muarie Sklodowska Curie (1867-1934) was undoubtedly the most important person to attribute to the discovery of radioactivity. In 1898 she discovered radium as a natural radioactive element. This is how she describes the hard time she had, working with her husband Pierre Curie (1859-1906) for the discovery of radium and polonium: "During the first year we did not go to the theater or to a concert or visited friends. I miss my relatives, my father and my daughter that I see every morning and only for a little while. But I do not complain...". In presenting her discovery of radium, Madame Curie said: " ...in the hands of a criminal, radium is very dangerous. So we must often ask ourselves: will humanity earn or lose from this discovery? I, myself belong to those who believe the former...". The notebooks that Madame Curie had when she was working with radium and other radioactive elements like polonium, thorium and uranium are now kept in Paris. They are contaminated with radioactive materials having very long half-lives and for this reason anyone who wishes to have access to these notes should sign that he takes full responsibility. There are some more interesting points in Madame Curie's life which may not be widely known like: Although her full name is Maria Sklodowska-Curie, she is not known neither by that full name nor as Maria Sklodowska but as Marie Curie. Madame Curie was the second of five children. At the age of 24 she went to Sorbonne-Paris after being invited by her sister Bronja to study for about 2-3 years; instead she stayed in Paris for her whole life. Her doctorate was on the subject: "Research on radioactive substances" which she completed in six years under the supervision of H. Becquerel. Pierre Curie was Director of the Physics Laboratory of the Ecole Municipale of Physics and Industrial Chemistry when he married M. Curie in 1895. Pierre Curie left his other research projects and worked full time with his wife. In this laboratory M. Curie and her husband Pierre discovered radium and polonium. In 1901 Pierre Curie induced a radiation burn on his forearm by applying on his skin radiferous barium chloride for 10 hours. During World War I, M.Curie organized for the Red Cross a fleet of radiological ambulances each with X-ray apparates which were called "Little Curies". The X-ray tubes of these apparates were unshielded and so M.Curie was exposed to high doses of radiation. Once an ambulance fell into a ditch and M.Curie who was inside the ambulance was badly bruised and stayed at home for 3 days. M. Curie with her daughters, Irene and Eve, was invited and visited America in 1921. She led a successful campaign to collect radium for her experiments. Before leaving America, President Harding donated through her to the Radium Institute of Paris 1 g of radium for research purposes. At that time the process to obtain 0.5 g of pure radium bromide required 1 ton of ore and 5 tons of chemicals. No measures of radiation protection were taken back then. In 1929 Madame Curie visited the United States for a second time. She met with President Hoover and with the help of the Polish women's association in America collected funds for another gram of radium. Madame Curie died of leukemia on July 4, 1934. Sixty years after her death her remnants were laid to rest under the dome of the Pantheon. Thus she became the first woman under her own merit, to rest in the Pantheon. In 1934 at the Institute of Radiology in Paris, Frederique Joliot and Irene Curie-Joliot discovered artificial radiation. They studied alpha particles and beta;-radiation.
Editorial↗
Determination of 210Pb and 210Po in sediment and soil leachates and in biological materials using a Sr-resin column and evaluation of column reuse.
In this work we present a suitable way to release lead and polonium from sediments and other samples. Results obtained by hot-acid dissolution and cold leaching showed that while good recoveries of 210Pb were obtained in both the cases, 210Po recovery in hot dissolution was poor due to volatility of polonium, and might lead to erroneous results due to non-equilibration of added 208Po tracer and 210Po in the matrix. A Sr-resin column was used for separation of Pb and Po. We also studied the possibility of reusing columns used earlier. The most significant problem in reuse is the reduction in column capacity, resulting in a reduction to half of its initial capacity. Other natural radionuclides do not interfere in the determination of 210Pb and 210Po and we found no measurable contamination of the column on repeated usage.
Alpha Particles↗
Determination of 210Po in environmental materials: a review of analytical methodology.
Polonium-210 ((210)Po) is analysed for a variety of purposes, including for radiological impact assessment, as a tracer of environmental processes, and as an indirect measure of its progenitor lead-210 ((210)Pb). Losses of polonium may occur at temperatures above 100 degrees C, depending on conditions, requiring particular care in sample preparation and treatment. In spite of this problem, the analysis of (210)Po is relatively straightforward, due to the ease of source preparation through spontaneous auto-deposition onto metal surfaces and the uncomplicated alpha spectrum. Although several optimisation studies have been carried out, published source preparation methods remain remarkably diverse. Some areas where further study would be useful are identified.
Air Pollutants, Radioactive↗
Removal of radionuclides at a waterworks.
A waterworks with an average production rate of 1.3 m3 s(-1), providing several large cities in the province of Scania with drinking water has been studied regarding its capacity to remove several natural and anthropogenic radionuclides. The raw water is surface water from lake Bolmen which is transported through an 80 km long tunnel in the bedrock before it enters the waterworks. The method used for purification is a combination of coagulation-flocculation and filtration in sand filters. Two different purification lines are currently in use, one using Al2(SO4)3 as a coagulant and one using FeCl3. After coagulation and flocculation the precipitate is removed and the water is passed through two different sand filters (rapid filtration and slow filtration). Water samples were collected at the lake, the inlet to the waterworks, after each of the flocculation basins (Al2(SO4)3 and FeCl3), after rapid filtration and from the municipal distribution network. The samples were analysed with respect to their content of uranium, thorium, polonium, radium, plutonium and caesium. The results show a high removal capacity for uranium (about 85%), thorium (>90%), plutonium (>95%) and polonium (>90% in the coagulation-flocculation process) while caesium, strontium and radium pass through the purification process with almost unchanged activity concentrations. During transportation of the water in the tunnel it was also observed that infiltration of groundwater leads to a change in isotopic ratios and/or activity concentrations for the naturally occurring radionuclides and plutonium.
Cesium↗
Intercomparison of retrospective radon detectors.
We performed both a laboratory and a field intercomparison of two novel glass-based retrospective radon detectors previously used in major radon case-control studies performed in Missouri and Iowa. The new detectors estimate retrospective residential radon exposure from the accumulation of a long-lived radon decay product, (210)Pb, in glass. The detectors use track registration material in direct contact with glass surfaces to measure the alpha-emission of a (210)Pb-decay product, (210)Po. The detector's track density generation rate (tracks per square centimeter per hour) is proportional to the surface alpha-activity. In the absence of other strong sources of alpha-emission in the glass, the implanted surface alpha-activity should be proportional to the accumulated (210)Po, and hence to the cumulative radon gas exposure. The goals of the intercomparison were to a) perform collocated measurements using two different glass-based retrospective radon detectors in a controlled laboratory environment to compare their relative response to implanted polonium in the absence of environmental variation, b) perform collocated measurements using two different retrospective radon progeny detectors in a variety of residential settings to compare their detection of glass-implanted polonium activities, and c) examine the correlation between track density rates and contemporary radon gas concentrations. The laboratory results suggested that the materials and methods used by the studies produced similar track densities in detectors exposed to the same implanted (210)Po activity. The field phase of the intercomparison found excellent agreement between the track density rates for the two types of retrospective detectors. The correlation between the track density rates and direct contemporary radon concentration measurements was relatively high, considering that no adjustments were performed to account for either the residential depositional environment or glass surface type. Preliminary comparisons of the models used to translate track rate densities to average long-term radon concentrations differ between the two studies. Further calibration of the retrospective detectors' models for interpretation of track rate density may allow the pooling of studies that use glass-based retrospective radon detectors to determine historic residential radon exposures.
Carcinogens, Environmental↗
Toxic and carcinogenic agents in dry and moist snuff.
The oral use of snuff is causatively associated with cancer of the oral cavity. Since most epidemiologic studies to date relate to the long-term use of dry snuff, which has dominated the U.S. smokeless tobacco market in the past, the concentrations of several toxic and carcinogenic agents in the three most popular dry snuff brands have been compared with those in the five most popular moist snuff brands sold in the United States. All eight samples were analyzed for nitrate, alkaloids, polyphenols, volatile carbonyl compounds, lead, cadmium, selenium, and the carcinogenic compounds benzo[a]pyrene (CAS: 50-32-8), polonium-210 (CAS: 13981-52-7), volatile N-nitrosamines (VNAs), N-nitrosodiethanolamine (CAS: 1116-54-7), and the tobacco-specific N-nitrosamines (TSNAs). Most of the snuff brands were rich in nitrate (greater than or equal to 1.5%), total polyphenols (greater than 2%), and in nicotine (greater than or equal to 1.5%), which is the habituating factor in tobacco use. Concentrations of the VNAs were significantly above the permissible limits set for some food products; the concentrations of the TSNAs in both snuff types exceeded the levels of nitrosamines in other consumer products by at least two to three orders of magnitude. The extremely high levels of the TSNAs in snuff have remained unchanged during the last decade and present the major carcinogenic risk factor for the oral use of snuff. Polonium-210 contributes further to the carcinogenic risk associated with snuff. The chemical-analytical data presented in this study do not indicate marked differences in the carcinogenic potential of moist snuff compared to dry snuff.
Acetone↗
Determination of 210Pb and 210Po in soil or rock samples containing refractory matrices.
A new method has been developed for determination of (210)Pb and (210)Po in soil or rock samples containing refractory matrices. The samples were first fused with Na(2)CO(3) and Na(2)O(2) at 600 degrees C for pre-treatment and then (210)Pb and (210)Po were sequentially leached out at 200-250 degrees C with HNO(3)+HF, HClO(4) and HCl. About 10% of the leaching solution was used for (210)Po determination, carried out by spontaneous deposition of polonium on a silver disc from a weakly acidic solution that contained hydroxylamine hydrochloride, sodium citrate and (209)Po tracer, measurement being made by alpha-spectrometry. The remains of the leaching solution were used for determination of (210)Pb, conducted by precipitation as sulphate, purification with Na(2)S as PbS in 6M ammonium acetate, separation from alpha-emitters by an anion-exchange resin column, source preparation as PbSO(4), and measurement with a beta-counter. The procedure has been checked with two certified IAEA reference materials, showing good agreement with the recommended values. The lower limits of detection for 1g of analysed soil or rock samples were found to be 0.75 Bqkg(-1) for (210)Po and 2.2 Bqkg(-1) for (210)Pb. A variety of solid sample species analysed through use of the procedure gave average yields of 90.0+/-9.8% for (210)Po and 88.4+/-7.1% for (210)Pb.
Chemical Fractionation↗
Concentration levels of 210Pb and 210Po in dry tobacco leaves in Greece.
Tobacco leaves are large and have sticky exudates that retain the radon decay products once they deposit on the leaves. The study of 210Po in tobacco is required, because of the cumulative alpha-radiation dose delivered to humans from inhaled 210Po in cigarette smoke. 210Pb is the other element of interest since it is the 210Po precursor in the radioactive decay chain. In the present study, the concentrations of these two radionuclides were determined in tobacco samples from seven regions in Greece. 210Po was determined by alpha spectrometry using a surface barrier detector after radiochemical separation and spontaneous deposition of polonium on a nickel disk. The 210Pb activity in the samples was determined via the 210Po resulting from the decay of 210Pb. The results of the present study indicate that 210Po concentrations ranged from 3.6 to 17.0 mBqg(-1) (average 13.1 mBqg(-1)) of dry tobacco, while 210Pb concentrations ranged from 7.3 to 18.0 mBqg(-1) (average 13.4 mBqg(-1)). The mean value of the annual committed effective dose for smokers (20 cigarettes per day) of Greek tobacco was estimated to be 287 microSv (124 microSv from 210Po and 163 microSv from 210Pb). The inhalation dose for smokers is on average about 12 times higher than for non-smokers living in the mid-latitudes of the northern hemisphere.
Greece↗
Speciation of 210Po and 210Pb in air particulates determined by sequential extraction.
Speciation of (210)Po and (210)Pb in air particulates of two Syrian phosphate sites with different climate conditions has been studied. The sites are the mines and Tartous port at the Mediterranean Sea. Air filters were collected during September 2000 until February 2002 and extracted chemically using different selective fluids in an attempt to identify the different forms of these two radionuclides. The results have shown that the inorganic and insoluble (210)Po and (210)Pb (attached to silica and soluble in mineral acids) portion was found to be high in both sites and reached a maximum value of 94% and 77% in the mine site and Tartous port site, respectively. In addition, only 24% of (210)Pb in air particulates was found to be associated with organic materials probably produced from the incomplete burning of fuel vehicle and similar activities. Moreover, the (210)Po/(210)Pb activity ratio in air particulates was higher than that in all samples at both sites and varied between 3.85 in November 2000 at Tartous port site and 20 in April 2001 at the mine area. These activity ratios were also higher than the natural levels. The (210)Po/(210)Pb activity ratio was also determined in each portion resulting from the selective extraction and found to be higher than that in most samples. The sources of (210)Po excess in these portions are discussed. Soil suspension, which is common in the dry climate dominant in the area, sea water spray and heating of phosphate ores were considered; polonium is more volatile than the lead compounds at even moderate temperature. Furthermore, variations in the chemical forms of (210)Po and (210)Pb during the year were also investigated. However, the results of this study can also be utilized for dose assessment to phosphate industry workers.
Air Pollutants, Radioactive↗
Concentration and distribution of 210Po in the tissues of the scallop Chlamys varia and the mussel Mytilus edulis from the coasts of Charente-Maritime (France).
Polonium-210 (210Po) has been analysed in the soft parts of two bivalves species, the scallop Chlamys varia and the common mussel Mytilus edulis, from the Bay of La Rochelle and Ré Island, on the French Atlantic coast. Between those sites, the highest 210Po concentrations have been found in whole scallop soft parts from La Rochelle, reaching 1,181 +/- 29 Bq kg(-1) dry weight (dwt), a size effect being related to the highest 210Po concentration in the smallest scallops. The results show a significant difference in concentrations for similar size individuals between species in each site (C. varia > M. edulis) and between sites for each species (Ré Island > Bay of La Rochelle). Very high 210Po concentrations have been found in the digestive gland of C varia, ranging 3,150-4,637 Bq kg(-1) dwt. Thus, the digestive gland contains up to 60% of the radionuclide. Subcellular investigations have shown that approximately 40% of the 210Po contained in the digestive gland is in the cytosolic fraction, suggesting a high bioavailability of the 210Po from this fraction to the trophic upper level. Calculations will show that approximately 4 kg of scallops flesh intake would be necessary to reach the annual incorporation limit of 1 mSv.
Animals↗
Temporal changes of 210Po in temperate coastal waters.
The temporal variation of Polonium-210 (210Po) was examined in coastal sea water, the mussel Mytilus edulis, the winkle Littorina littorea and green alga Ulva lactuca in order to investigate the entry of 210Po into the marine food chain. More than 99% of 210Po in the water column occurred in the particulate phase. Dissolved 210Po concentrations peaked during the spring phytoplankton bloom and it is suggested this is related to preferential scavenging of 210Po by the increased numbers of bacteria, viruses and small dissolved particulates. Changes in L. littorea 210Po specific activity are thought not to be related to food, but to a drop in body weight following spawning. Much of the 210Po accumulated by M. edulis was located in the digestive gland. The specific activity of 210Po in the digestive gland of M. edulis was shown to be strongly correlated with changes in sea water suspended particulate specific activity. Examination of other trace metal (Ag, Al, As, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Sb, Se, Sn and Zn) variations in the digestive gland revealed that class B and borderline metals had a strong positive correlation with 210Po. On-going work is investigating whether the accumulation and loss of 210Po is affected by the presence of metallothioneins.
Animals↗
Inhalation of 210Po and 210Pb from cigarette smoking in Poland.
The carcinogenic etfect of 210Po and 210Pb with respect to lung cancer is an important problem in many countries with very high cigarette consumption. Poland has one of the highest consumptions of cigarettes in the world. The results of 210Po determination on the 14 most frequently smoked brands of cigarettes which constitute over 70% of the total cigarette consumption in Poland are presented and discussed. Moreover, the polonium content in cigarette smoke was estimated on the basis of its activity in fresh tobaccos, ash, fresh filters and post-smoking filters. The annual effective doses were calculated on the basis of 210Po and 210Pb inhalation with the cigarette smoke. The results of this work indicate that Polish smokers who smoke one pack (20 cigarettes) per day inhale from 20 to 215 mBq of 210Po and 210Pb each. The mean values of the annual effective dose for smokers were estimated to be 35 and 70 microSv from 210Po and 210Pb, respectively. For persons who smoke two packs of cigarettes with higher radionuclide concentrations, the effective dose is much higher (471 microSv yr(-1)) in comparison with the intake in diet. Therefore, cigarettes and the absorption through the respiratory system are the main sources and the principal pathway of 210Po and 210Pb intake of smokers in Poland.
Absorption↗
210Po bioaccumulation by mushrooms from Poland.
The paper presents results on 210Po activity concentration measured in mushroom samples collected in northern Poland (Białogard and Elblag areas). Among 20 species of wild mushrooms, King Bolete (Boletus edulis), accumulated 210Po in the highest degree. Therefore this species of higher mushrooms is an excellent bioindicator for 210Po radioactivity in the land environment. Finally, the effective dose of polonium emission was calculated for a consumer of King Bolete. Wild mushroom consumption contributed up to 37 microSv to the effective dose in an individual consuming about 5 kg (fresh weight) of heavily contaminated Boletus edulis species per year.
Agaricales↗