Studying of <Superscript>210</Superscript>Po and <Superscript>210</Superscript>Pb Deposition in Some Lichen Species in Manisa,Turkey

Lichens are very useful for monitoring of the radionuclide deposition because having a high efficiency capturing the radionuclides from the atmospheric fallout. In the present work, ²¹⁰Po and ²¹⁰Pb deposition in some lichen species were determined using an alpha spectrometer. Different lichens were collected around Demirci-Manisa and investigated their uses as biomonitor for ²¹⁰Po and ²¹⁰Pb deposition. The highest activity concentrations for ²¹⁰Po and ²¹⁰Pb were detected in Neofuscelia pulla (898 Bq kg^?1 and 1207 Bq kg^?1, respectively). The mean activities in the lichen species ranged from 164 to 584 Bq kg^?1 for ²¹⁰Po and from 175 to 671 Bq kg^?1 for ²¹⁰Pb. The activity ratios for ²¹⁰Po/²¹⁰Pb ranged from 0.75 to 1.57.     

210Po and 210Pb inhalation by cigarette smoking in Italy

210Po and its precursor 210Pb in cigarette smoke contribute a significant radiation dose to the lungs of smokers. In this work, the concentration of 210Po was determined in 17 of the most frequently smoked cigarette brands in Italy. Samples of tobacco, fresh filters, ash, and post-smoking filters were analyzed; 210Po was determined by alpha spectrometry after its spontaneous deposition on a silver disk. To verify the radioactive equilibrium between 210Po and 210Pb, lead was determined in one tobacco sample by counting the beta activity of its decay product 210Bi with a gas flow proportional detector after separation. The results of the present study show 210Po concentrations ranged from 6.84 to 17.49 mBq per cigarette. Based on these results, smokers who smoke 20 cigarettes per day inhale, on average, 79.53 +/- 28.65 mBq d(-1) of 210Po and 210Pb each. The mean value of the annual committed effective dose for Italian smokers, calculated by applying the dose conversion factor for adults of 4.3 microSv Bq(-1) for 210Po and 5.6 microSv Bq(-1) for 210Pb, was estimated to be 124.8 and 162.6 microSv y(-1) for 210Po and 210Pb, respectively. The lung dose from inhalation of cigarette smoke is much higher than the lung dose from inhalation of atmospheric 210Po and 210Pb.     

Dietary intake of 210Po and 210Pb in the environment of Goa of south-west Coast of India

This paper deals with the distribution and activity intake of 210Po and 210Pb in food, diet, and potable water samples of the Goa region and the estimated committed effective dose due to ingestion of these radionuclides. The activity concentrations of 210Po and 210Pb were determined in about 30 food and diet samples from different places of Goa in order to know the distribution and intake of these radionuclides. The activity concentration of 210Po in fish and prawn samples were significantly higher than concentrations found in vegetable and rice samples. Higher concentrations of 210Po and 210Pb were observed in leafy vegetables than in non-leafy vegetables. Among the diet samples the activity concentrations of 210Po and 210Pb in non-vegetarian meal samples were relatively higher than in vegetarian meal and breakfast samples. The committed effective dose due to annual intake of 210Po was found to be 94.6 microSv, 49.1 microSv, 10.5 microSv, and 2.2 microSv and that of 210Pb found to be 81.6 microSv, 59.9 microSv, 14.6 microSv, and 2.0 microSv for the ingestion of non-vegetarian meal, vegetarian meal, breakfast, and potable water, respectively.     

Levels of 226Ra, 210Pb and total U in fish near a Saskatchewan uranium mine and mill

Radionuclide levels in fish from the Beaverlodge Lake area, Saskatchewan, Canada, varied significantly among lakes, species and tissues, but did not vary with fish sex or age. Fish from lakes affected by an operating uranium mine and mill had radionuclide levels one to two orders of magnitude above levels in fish from an uncontaminated control lake. Concentrations were greatest in white suckers, intermediate in lake whitefish, and low in lake trout. Skin and bone contained the highest radionuclide levels; levels in flesh were much lower. The mean ash-weight concentration of 226Ra in non-control, eviscerated, whole fish was 9.3, 1.8 and 0.8 pCi X g-1 in white suckers, lake whitefish and lake trout respectively. Mean 210Pb levels for those species were 4.0, 1.4 and 0.5 pCi X g-1, while U content was 96.8, 28.2 and 5.8 micrograms X g-1, respectively. Radium-226 content in forage fish ranged from 9.7-70 pCi X g-1. Lead-210 levels ranged from 3.9-55.0 pCi X g-1, while U levels ranged from 15-119 micrograms X g-1. Bioconcentration factors varied among sites, species and tissues. The primary radionuclide transfer pathway appears to be via sediments, either through direct contact or through food organisms. Bottom-feeding species had the highest radionuclide levels while piscivorous fish had the lowest levels. The internal dose rate to non-control fish are comparatively low; any effects are likely to occur at the genetic level.     

An experimental analysis of the contribution of 210Po and of 210Po produced by 210Pb decay to the gross alpha-particle activity of water samples

The contribution of 210Po and of 210Po produced by 210Pb decay to the gross alpha-particle activity of water samples by U.S. Environmental Protection Agency Method 900.0 is investigated as a function of residue mass and geometry and time between sample collection and analysis. It is shown that these factors can cause the contribution to gross alpha-particle activity of 210Po to be up to 2.0 and 1.1 times the initial 210Po activity for grab and quarterly composite samples, respectively, and can cause the contribution to gross alpha-particle activity of 210Po from 210Pb decay to be up to 1.1 times and 1.5 times the 210Pb activity for grab and quarterly composite samples, respectively. It is also shown qualitatively that at least for some residues, there is a loss of polonium due to volatilization when the sample is heated over a flame.     

210Pb in Forage Consumed by Dairy Cows

The aim of this research was to determine ²¹⁰Pb concentrations in forage from farms located in the municipalities of Pedra and Venturosa, in the Brazilian state of Pernambuco, where rolled blocks of mafic rock with a high percentage of U₃O₈ were found. The concentrations of ²¹⁰Pb varied from 2 to 503 Bq kg⁻¹ in the forage dry matter samples evaluated. Due to the elevated levels of ²¹⁰Pb in the forage samples, it is concluded that this radionuclide is highly available to be ingested by dairy cows and this could represent a hazard to the human population due to possible milk contamination.     

Assessment and significance of the skeletal doses due to 210Po in radioactive spa workers.

The high exposure due to radon and daughter products found in many Italian radioactive spas, suggested a research program designed to assess the lung and skeletal doses accumulated by the subjects working in those spas. The assessment of such doses will permit the evaluation of the significance of a follow-up of the exposed subjects with epidemiological studies. In this paper some preliminary results will be discussed, mainly related to the estimation of the²¹⁰Po skeletal doses in a few subjects. The²¹⁰Pb²¹⁰Po skeletal burdens in the subjects have been evaluated on the basis of their²¹⁰Pb²¹⁰Po urinary excretion collected at various intervals during a period of 1 year. The experimental results on the most exposed subjects have shown skeletal doses of the order of 20–40 rem/year and lung exposures higher than 100 WLM (Working Level Month).     

Occurrence of 210Po and Biological Effects of Low-Level Exposure: The Need for Research

Background: Polonium-210 (210Po) concentrations that exceed 1 Bq/L in drinking-water supplies have been reported from four widely separated U.S. states where exposure to it went unnoticed for decades. The radionuclide grandparents of 210Po are common in sediments, and segments of the public may be chronically exposed to low levels of 210Po in drinking water or in food products from animals raised in contaminated areas.Objectives: We summarized information on the environmental behavior, biokinetics, and toxicology of 210Po and identified the need for future research.Methods: Potential linkages between environmental exposure to 210Po and human health effects were identified in a literature review.Discussion: 210Po accumulates in the ovaries where it kills primary oocytes at low doses. Because of its radiosensitivity and tendency to concentrate 210Po, the ovary may be the critical organ in determining the lowest injurious dose for 210Po. 210Po also accumulates in the yolk sac of the embryo and in the fetal and placental tissues. Low-level exposure to 210Po may have subtle, long-term biological effects because of its tropism towards reproductive and embryonic and fetal tissues where exposure to a single alpha particle may kill or damage critical cells. 210Po is present in cigarettes and maternal smoking has several effects that appear consistent with the toxicology of 210Po.Conclusions: Much of the important biological and toxicological research on 210Po is more than four decades old. New research is needed to evaluate environmental exposure to 210Po and the biological effects of low-dose exposure to it so that public health officials can develop appropriate mitigation measures where necessary.     

香烟中钋——210含量及其对人体肺组织所致剂量的研究

本文报告了１６种国产香烟和４种外烟中的＾２１０ｐｏ含师时还报告了吸烟过程中＾２１０Ｐｏ在烟蒂、烟灰和吸入烟雾等部分的分配情况,本实验采用的是＾２１０Ｐｏ自沉积法,使用了低温灰化装置和标准模拟吸烟装置,本文给出了我国整支香烟中＾２１０Ｐｏ含量范围,其值为１３．７－４３．４ｍＢｑ／支或１８．０－６７．３ｍＢｑ／克。平均值为２６．５ｍＢｑ／支或３３．７ｍＢｑ／克。国产香烟＾２１０Ｐｏ含量一般高于国外水平     

Measurement of 210Pb atmospheric flux in the Pacific Northwest

Monthly atmospheric flux of 210Pb in Seattle, WA, has been measured over a period of 7 yr. Direct correlation exists between monthly rainfall and the 210Pb deposition; however, for the same amount of rainfall the 210Pb deposition varies from year to year. The mean annual input of 210Pb is 0.44 dpm/cm2 and the standard error of the mean is +/- 0.24 dpm/cm2. A 4.4-fold fluctuation in the 210Pb annual flux was observed during this investigation.     

Biliary excretion of 203Hg, 64Cu, 52Mn, and 210Pb in the rat

Cikrt, M. (1972).Brit. J. industr. Med.,29, 74-80. Biliary excretion of ²⁰³Hg, ⁶⁴Cu, ⁵²Mn, and ²¹⁰Pb in the rat. The biliary excretion of ⁵²Mn, ⁶⁴Cu, ²⁰³Hg, and ²¹⁰Pb after intravenous adminstration of ⁵²MnCl₂, ⁶⁴CuCl₂, ²⁰³HgCl₂, and ²¹⁰Pb (NO₃)₂ in non-toxic doses was studied in rats. Cumulative biliary excretion reached by 24 hours after administration in the case of ⁶⁴Cu 31·06%, of ⁵²Mn 26·7%, of ²⁰³Hg 3·8%, and of ²¹⁰Pb 6·7% of the administered dose. The excretion curve for ²⁰³Hg differed significantly from those of the other three metals. The maximum rate of excretion was reached at different periods after administration for each metal. The excretion of the metals via the wall of the gastrointestinal tract during 24 hours after administration was also studied. The excretion into faeces occurred mainly via the bile; to a lesser extent there was excretion through the wall, probably chiefly of the upper segments of the digestive tract.     

Estimation of Dose Due to Ingestion of 210Pb in Milk from Dairy Cattle in the Semi-Arid Region of Pernambuco, Brazil

²¹⁰Pb is widely distributed in the environment. In this context, the aim of this research has been: (1) to determine ²¹⁰Pb concentrations in milk and dairy products from farms located in the cities of Pedra and Venturosa in Pernambuco, Brazil; and (2) to calculate the dose due to the ingestion of ²¹⁰Pb in these products. The ion exchange resin method was used and the concentration of ²¹⁰Pb varied from 62 to 650 mBq l⁻¹ in fresh milk, from 202 to 1,494 mBq kg⁻¹ in curdled cheese and from 11 to 253 mBq l⁻¹ in milk whey. The estimated dose due to ingestion of milk and dairy products in this region was 0.2 Sv, which is at least two orders of magnitude above the maximum recommended levels.     

Pb-210 in Rock and Soils of the Semi-Arid Agreste Region of Pernambuco,Brazil

The aim of this research was to determine ²¹⁰Pb concentrations in rocks and soils of farms located in the municipalities of Pedra and Venturosa. In these farms, rolled blocks of mafic rock with a high percentage of U₃O₈ were found. The concentrations of ²¹⁰Pb varied from 3.2 to 201 kBq kg⁻¹ in rock samples and from 195 to 86,400 Bq kg⁻¹ in soil samples. The high levels of radioactivity found in the samples, indicate the need to conduct more detailed studies to evaluate the risk of radionuclide ingestion due to milk consumption by the population in the state of Pernambuco.     

Movement of dissolved radionuclides from submerged uranium Mine tailings into the surface water of Langley Bay,Saskatchewan, Canada

The Gunnar mine operated in northern Saskatchewan, Canada from 1955 to 1964, extracting uranium from approximately 5 × 10⁶ tonnes of ore by the sulphuric acid leach process. Large quantities of the acidic tailings were discharged, covering the entire bottom of Langiey Bay and forming a delta. Measurements ofin situ sediments showed release rates of up to 14.8 pCi²¹⁰Pb and 155.6 pCi²²⁶Ra per m²/hr along with traces of²²⁸Th and uranium into the surface water of the bay. It was calculated that, at this rate, it would take 5.5 days for the²²⁶Ra concentrations to reach the ambient concentrations of 4.8 pCi/L found in Langley Bay surface water. Comparing this with the reported 14-day hydraulic retention time for the bay, the flux of radionuclides from the sediments can account for the entire concentration measured in the surface water.     

Accumulation of 137Cs in Finnish Lapps

It is already widely known that the Lapps have received or will receive high extra doses from nuclear tests performed thus far. However, the most spectacular source of irradiation is the natural radionuclide²¹⁰ Po (3 rem/30 yr). The second in importance is the natural external radiation (1.65 rem/ 30 yr)., while the third (for the present generation) is the fallout nuclide ¹³⁷Cs (1 rem/ 30 yr). The arctic food chains described exist not only in Lapland but in all the arctic and subarctic regions of the northern hemisphere.     

Polonium-210 as a poison.

The death of Alexander Litvinenko on 23 November 2006 has brought into focus scientific judgements concerning the radiotoxicity of polonium-210 ((210)Po). This paper does not consider the specific radiological circumstances surrounding the tragic death of Mr Litvinenko; rather, it provides an evaluation of published human and animal data and models developed for the estimation of alpha radiation doses from (210)Po and the induction of potentially fatal damage to different organs and tissues. Although uncertainties have not been addressed comprehensively, the reliability of key assumptions is considered. Concentrating on the possibility of intake by ingestion, the use of biokinetic and dosimetric models to estimate organ and tissue doses from (210)Po is examined and model predictions of the time-course of dose delivery are illustrated. Estimates are made of doses required to cause fatal damage, taking account of the possible effects of dose protraction and the relative biological effectiveness (RBE) of alpha particles compared to gamma and x-rays. Comparison of LD(50) values (dose to cause death for 50% of people) for different tissues with the possible accumulation of dose to these tissues suggests that bone marrow failure is likely to be an important component of multiple contributory causes of death occurring within a few weeks of an intake by ingestion. Animal data on the effects of (210)Po provide good confirmatory evidence of intakes and doses required to cause death within about 3 weeks. The conclusion is reached that 0.1-0.3 GBq or more absorbed to blood of an adult male is likely to be fatal within 1 month. This corresponds to ingestion of 1-3 GBq or more, assuming 10% absorption to blood. Well-characterised reductions in white cell counts would be observed. Bone marrow failure is likely to be compounded by damage caused by higher doses to other organs, including kidneys and liver. Even if the bone marrow could be rescued, damage to other organs can be expected to prove fatal.     

Radionuclides and trace metals in Canadian moose near uranium mines: comparison of radiation doses and food chain transfer with cattle and caribou

Tissues from 45 moose and 4 cattle were collected to assess the health of country foods near uranium mines in northern Saskatchewan. Bone, liver, kidney, muscle and rumen contents were analyzed for uranium, radium-226 (226Ra), lead-210 (210Pb), and polonium-210 (210Po). Cesium-137 (137Cs), potassium-40 (40K), and 27 trace metals were also measured in some tissues. Within the most active mining area, Po in liver and muscle declined significantly with distance from tailings, possibly influenced by nearby natural uranium outcrops. Moose from this area had significantly higher 226Ra, 210Pb, 210Po, and 137Cs in some edible soft tissues vs. one control area. However, soil type and diet may influence concentrations as much as uranium mining activities, given that a) liver levels of uranium, 226Ra, and 210Po were similar to a second positive control area with mineral-rich shale hills and b) 210Po was higher in cattle kidneys than in all moose. Enhanced food chain transfer from rumen contents to liver was found for selenium in the main mining area and for copper, molybdenum and cadmium in moose vs. cattle. Although radiological doses to moose in the main mining area were 2.6 times higher than doses to control moose or cattle, low moose intakes yielded low human doses (0.0068 mSv y(-1)), a mere 0.3% of the dose from intake of caribou (2.4 mSv y(-1)), the dietary staple in the area.     

Radon progeny as sources of gross-alpha radioactivity anomalies in ground water

Gross-alpha radiation data from ground water samples are subject to variability introduced as a result of analytical procedure. For example, ground water in the surficial aquifer of central Florida commonly has gross-alpha radioactivity in excess of 555 Bq m-3 (15 pCi L-1). This activity, commonly unsupported by Ra, often results from the 222Rn progeny. The relatively short-lived daughters of 222Rn can give rise to variations in gross-alpha measurements of up to 2 orders of magnitude in replicate samples. Polonium-210, a longer-lived Rn daughter, is also found in concentrations greater than predicted by the Ra content. As a consequence, it is suggested that gross-alpha measurements include Po analyses with Ra and U when standards are exceeded. It should be recognized that, depending on the activity of 210Pb, 210Po activity may vary significantly with holding time. Variations of measured Po activity in replicate samples collected and prepared by present methods indicate that Po analyses may be inconsistent and frequently underestimate total Po activity. Sample preparation methods and measurement techniques are discussed which greatly improve the overall accuracy and consistency of gross-alpha and Po analyses.     

The human alimentary tract transfer and body retention of environmental polonium-210.

This paper presents the results of a 4 year study to investigate the human alimentary tract transfer factor (f(A) value) and body retention of 210 Po in shellfish. In the first 3 years, mussels (Mytilus edulis L.), cockles (Cerastoderma edule L.) and brown meat from crab (Cancer pagurus L.) were successively studied. In each year five volunteers (from a pool of seven) ate a suitable portion of the shellfish and provided 24 h samples of excreta usually for 3 days before and for at least 7 days during and after eating. Subsamples of shellfish were analysed to determine the intakes of 210 Po. Faeces were analysed and the data used to assess apparent fA values. Urine samples were analysed in the mussel and crab studies to provide urinary excretion parameters. Pb-210 was also analysed during the mussel study; the levels were low, leading to large uncertainties, but confirming the negligible effect of radioactive decay to its granddaughter 210 Po in the main study. In the fourth year, larger samples of brown crab meat were eaten by five volunteers and faecal samples were taken at suitable times over periods of up to 43 days to study body retention of 210 Po. The first approximately 7 days provided additional data on fA values. Pooled results for the apparent fA for the whole study lay in the range 0.15-0.65 with a mean of 0.46; corrections for endogenous excretion suggest a true fA value of approximately 0.51, supporting the value of 0.5 currently used by the International Commission on Radiological Protection (ICRP). The retention data suggest a biological half-time of about 40 days, in broad consistency with the 50 days currently used by the ICRP. Thus there is no strong evidence from this study suggesting a change in dose coefficient for 210 Po. Full experimental data are provided to allow independent further interpretation.     

Source areas of airborne 7Be and 210Pb measured in Northern Finland

Daily aerosol samples were collected at Sodankyl?, Northern Finland, from July 1995 to June 1997. The filter samples were analyzed for 7Be by semiconductor gamma spectrometry and for 210Pb by alpha counting of the in-grown 210Po. The concentrations were lognormally distributed with median concentrations of 2,500 and 160 muBq m(-3) for 7Be and 210Pb, respectively. The trajectory analysis performed showed that the highest 210Pb activity concentrations were associated with continental air masses originating in Central Russia. High 7Be activity concentrations were found in air masses from Central Russia and, during springtime, also in air masses coming from southwest. The latter cases were attributed to the transfer of stratospheric air masses into the troposphere along the polar front. Slightly elevated 7Be and 210Pb concentrations were found in air masses coming to Sodankyla from northwest between 70th and 80th latitudes. This was attributed to the long-range transport from continental North America.