Polonium

bismuth ← polonium → astatine
Te
↑
Po
↓
Uuh
Appearance
silvery
General properties
Name, symbol, number polonium, Po, 84
Pronunciation play /pɵˈloʊniəm/ po-LOH-nee-əm
Element category metalloid
Group, period, block 16, 6, p
Standard atomic weight (209)g·mol−1
Electron configuration [Xe] 6s2 4f14 5d10 6p4
Electrons per shell 2, 8, 18, 32, 18, 6 (Image)
Physical properties
Phase solid
Density (near r.t.) (alpha) 9.196 g·cm−3
Density (near r.t.) (beta) 9.398 g·cm−3
Melting point 527 K, 254 °C, 489 °F
Boiling point 1235 K, 962 °C, 1764 °F
Heat of fusion ca. 13 kJ·mol−1
Heat of vaporization 102.91 kJ·mol−1
Specific heat capacity (25 °C) 26.4 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K)       (846) 1003 1236
Atomic properties
Oxidation states 6, 4, 2, -2
(amphoteric oxide)
Electronegativity 2.0 (Pauling scale)
Ionization energies 1st: 812.1 kJ·mol−1
Atomic radius 168 pm
Covalent radius 140±4 pm
Van der Waals radius 197 pm
Miscellanea
Crystal structure cubic
Magnetic ordering nonmagnetic
Electrical resistivity (0 °C) (α) 0.40 µΩ·m
Thermal conductivity (300 K) ? 20 W·m−1·K−1
Thermal expansion (25 °C) 23.5 µm·m−1·K−1
CAS registry number 7440-08-6
Most stable isotopes
Main article: Isotopes of polonium
iso NA half-life DM DE (MeV) DP
208Po syn 2.898 y α 5.215 204Pb
ε, β+ 1.401 208Bi
209Po syn 103 y α 4.979 205Pb
ε, β+ 1.893 209Bi
210Po trace 138.376 d α 5.307 206Pb

Polonium (pronounced /pɵˈloʊniəm/, po-LOH-nee-əm) is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive metalloid,[1] polonium is chemically similar to bismuth[2] and tellurium, and it occurs in uranium ores. Polonium has been studied for possible use in heating spacecraft. It is unstable; all isotopes of polonium are radioactive.

Contents

Characteristics

Isotopes

Polonium has 33 known isotopes, all of which are radioactive. They have atomic masses that range from 188 to 220 u. 210Po (half-life 138.376 days) is the most widely available. 209Po (half-life 103 years) and 208Po (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron.

210Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to its stable daughter isotope, 206Pb. A milligram of 210Po emits about as many alpha particles per second as 4.5 grams of 226Ra. A few curies (1 curie equals 37 gigabecquerels, 1 Ci = 37 GBq) of 210Po emit a blue glow which is caused by excitation of surrounding air. A single gram of 210Po generates 140 watts of power.[3] Because it emits many alpha particles, which are stopped within a very short distance in dense media and release their energy, 210Po has been used as a lightweight heat source to power thermoelectric cells in artificial satellites; for instance, 210Po heat source was also used in each of the Lunokhod rovers deployed on the surface of the Moon, to keep their internal components warm during the lunar nights.[4] Some anti-static brushes contain up to 500 microcuries (20 MBq) of 210Po as a source of charged particles for neutralizing static electricity in materials like photographic film.[5]

About one in 100,000 alpha emissions causes an excitation in the nucleus which then results in the emission of a gamma ray.[6] Because of its relatively high rate of alpha emissions, only about 1 in 100,000 result in releasing a gamma ray. But it is the alpha particles, not the side effect of an occasional gamma ray, that results in sup>210Po decay. Low gamma output renders gamma detection nearly impossible. Background gamma radiation is higher. Alpha particles are not high energy particles so are absorbed easily. Even the outer layer of human skin is sufficient to trap them. Nevertheless, alpha radiation is much higher than gamma radiation, leaving alpha detection as the best method of quantifying this isotope in a laboratory.

Solid state form

The alpha form of solid polonium.

Polonium is a radioactive element that exists in two metallic allotropes. The alpha form has a simple cubic crystal structure with an edge length of 335.2 picometres; the beta form is rhombohedral.[7][8] The structure of polonium has been characterized by X-ray diffraction [9][10] and electron diffraction.[11]

210Po (in common with 238Pu) has the ability to become airborne with ease: if a sample is heated in air to 55 °C (131 °F), 50% of it is vaporized in 45 hours, even though the melting point of polonium is 254 °C (489 °F) and its boiling point is 962 °C (1763 °F).[12][13] More than one hypothesis exists for how polonium does this; one suggestion is that small clusters of polonium atoms are spalled off by the alpha decay.

Chemistry

The chemistry of polonium is similar to that of tellurium and bismuth. Polonium dissolves readily in dilute acids, but is only slightly soluble in alkalis. The hydrogen compound PoH2 is liquid at room temperature (melting point −36.1°C, boiling point 35.3°C). Halides of the structure PoX2, PoX4 and PoX6 are known. The two oxides PoO2 and PoO3 are the products of oxidation of polonium.[14]

It has been reported that some microbes can methylate polonium by the action of methylcobalamin.[15][16] This is similar to the way in which mercury, selenium and tellurium are methylated in living things to create organometallic compounds. As a result when considering the biochemistry of polonium one should consider the possibility that the polonium will follow the same biochemical pathways as selenium and tellurium.

Compounds

Polonium has no common compounds, only synthetically created ones.

Oxides

  • PoO2
  • PoO3

Hydrides

  • PoH2

Halogen Compounds

  • PoX2, e.g. polonium dichloride, PoCl2
  • PoX4
  • PoX6

History

Also tentatively called "Radium F", polonium was discovered by Marie Skłodowska-Curie and her husband Pierre Curie in 1898[17] and was later named after Marie Curie's native land of Poland (Latin: Polonia)[18][19] Poland at the time was under Russian, Prussian, and Austrian partition, and did not exist as an independent country. It was Curie's hope that naming the element after her native land would publicize its lack of independence. Polonium may be the first element named to highlight a political controversy.[20]

This element was the first one discovered by the Curies while they were investigating the cause of pitchblende radioactivity. The pitchblende, after removal of the radioactive elements uranium and thorium, was more radioactive than both the uranium and thorium put together. This spurred the Curies on to find additional radioactive elements. The Curies first separated out polonium from the pitchblende, and then within a few years, also isolated radium.

Detection

Intensity against photon energy for three isotopes.

Gamma counting

By means of radiometric methods such as gamma spectroscopy (or a method using a chemical separation followed by an activity measurement with a non-energy-dispersive counter), it is possible to measure the concentrations of radioisotopes and to distinguish one from another. In practice, background noise would be present and depending on the detector, the line width would be larger which would make it harder to identify and measure the isotope. In biological/medical work it is common to use the natural 40K present in all tissues/body fluids as a check of the equipment and as an internal standard.

Intensity against alpha energy for four isotopes, note that the line width is narrow and the fine details can be seen.
Intensity against alpha energy for four isotopes, note that the line width is wide and some of the fine details can not be seen. This is for liquid scintillation counting where random effects cause a variation in the number of visible photons generated per alpha decay.

Alpha counting

The best way to test for (and measure) many alpha emitters is to use alpha-particle spectroscopy as it is common to place a drop of the test solution on a metal disk which is then dried out to give a uniform coating on the disk. This is then used as the test sample. If the thickness of the layer formed on the disk is too thick then the lines of the spectrum are broadened, this is because some of the energy of the alpha particles is lost during their movement through the layer of active material. An alternative method is to use internal liquid scintillation where the sample is mixed with a scintillation cocktail. When the light emitted is then counted, some machines will record the amount of light energy per radioactive decay event. Due to the imperfections of the liquid scintillation method (such as a failure for all the photons to be detected, cloudy or coloured samples can be difficult to count) and the fact that random quenching can reduce the number of photons generated per radioactive decay it is possible to get a broadening of the alpha spectra obtained through liquid scintillation. It is likely that these liquid scintillation spectra will be subject to a Gaussian broadening rather than the distortion exhibited when the layer of active material on a disk is too thick.

A third energy dispersive method for counting alpha particles is to use a semiconductor detector.

From left to right the peaks are due to 209Po, 210Po, 239Pu and 241Am. The fact that isotopes such as 239Pu and 241Am have more than one alpha line indicates that the nucleus has the ability to be in different discrete energy levels (like a molecule can).

Occurrence and production

Polonium is a very rare element in nature because of the short half-life of all its isotopes. It is found in uranium ores at about 100 micrograms per metric ton (1 part in 1010), which is approximately 0.2% of the abundance of radium. The amounts in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers.[21][22][23]

Neutron capture

Synthesis by (n,γ) reaction

In 1934 an experiment showed that when natural 209Bi is bombarded with neutrons, 210Bi is created, which then decays to 210Po via β decay. The final purification is done pyrochemically followed by liquid-liquid extraction techniques.[24] Polonium may now be made in milligram amounts in this procedure which uses high neutron fluxes found in nuclear reactors. Only about 100 grams are produced each year, practically all of it in Russia, making polonium exceedingly rare.[25][26]

Proton capture

Synthesis by (p,n) and (p,2n) reactions

It has been found that the longer-lived isotopes of polonium can be formed by proton bombardment of bismuth using a cyclotron. Other more neutron rich isotopes can be formed by the irradiation of platinum with carbon nuclei.[27]

Applications

When it is mixed or alloyed with beryllium, polonium can be a neutron source: beryllium releases a neutron upon absorption of an alpha particle that is supplied by 210Po. It has been used in this capacity as a neutron trigger or initiator for nuclear weapons. However, a license is needed to own and operate this form of neutron source.[28] Other uses include the following.

Toxicity

Overview

By mass, polonium-210 is around 250,000 times more toxic than hydrogen cyanide (the actual LD50 for 210Po is about 1 microgram for an 80 kg person (see below) compared with about 250 milligrams for hydrogen cyanide[33]). The main hazard is its intense radioactivity (as an alpha emitter), which makes it very difficult to handle safely: one gram of Po will self-heat to a temperature of around 500 °C (932 °F).[3] Even in microgram amounts, handling 210Po is extremely dangerous, requiring specialized equipment and strict handling procedures. Alpha particles emitted by polonium will damage organic tissue easily if polonium is ingested, inhaled, or absorbed, although they do not penetrate the epidermis and hence are not hazardous if the polonium is outside the body.

Acute effects

The median lethal dose (LD50) for acute radiation exposure is generally about 4.5 Sv.[34] The committed effective dose equivalent 210Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled.[35] Since 210Po has an activity of 166 TBq per gram (4,500 Ci/g)[35] (1 gram produces 166×1012 decays per second), a fatal 4.5 Sv (J/kg) dose can be caused by ingesting 8.8 MBq (238 microcuries, µCi), about 50 nanograms (ng), or inhaling 1.8 MBq (48 µCi), about 10 ng. One gram of 210Po could thus in theory poison 20 million people of whom 10 million would die. The actual toxicity of 210Po is lower than these estimates, because radiation exposure that is spread out over several weeks (the biological half-life of polonium in humans is 30 to 50 days[36]) is somewhat less damaging than an instantaneous dose. It has been estimated that a median lethal dose of 210Po is 0.015 GBq (0.4 mCi), or 0.089 micrograms, still an extremely small amount.[37][38]

Long term (chronic) effects

In addition to the acute effects, radiation exposure (both internal and external) carries a long-term risk of death from cancer of 5–10% per Sv.[34] The general population is exposed to small amounts of polonium as a radon daughter in indoor air; the isotopes 214Po and 218Po are thought to cause the majority[39] of the estimated 15,000-22,000 lung cancer deaths in the US every year that have been attributed to indoor radon.[40] Tobacco smoking causes additional exposure to polonium.[41]

Regulatory exposure limits

The maximum allowable body burden for ingested 210Po is only 1.1 kBq (30 nCi), which is equivalent to a particle massing only 6.8 picograms. The maximum permissible workplace concentration of airborne 210Po is about 10 Bq/m3 (3 × 10−10 µCi/cm³).[42] The target organs for polonium in humans are the spleen and liver.[43] As the spleen (150 g) and the liver (1.3 to 3 kg) are much smaller than the rest of the body, if the polonium is concentrated in these vital organs, it is a greater threat to life than the dose which would be suffered (on average) by the whole body if it were spread evenly throughout the body, in the same way as caesium or tritium (as T2O).

210Po is widely used in industry, and readily available with little regulation or restriction. In the US, a tracking system run by the Nuclear Regulatory Commission will be implemented in 2007 to register purchases of more than 16 curies (590 GBq) of polonium 210 (enough to make up 5,000 lethal doses). The IAEA "is said to be considering tighter regulations... There is talk that it might tighten the polonium reporting requirement by a factor of 10, to 1.6 curies (59 GBq)."[44]

Famous poisoning cases

Notably, the murder of Alexander Litvinenko, a Russian dissident, in 2006 was announced as due to 210Po poisoning[45][46] (see Alexander Litvinenko poisoning). According to Prof. Nick Priest of Middlesex University, an environmental toxicologist and radiation expert, speaking on Sky News on December 2, Litvinenko was probably the first person ever to die of the acute α-radiation effects of 210Po.[47]

It has also been suggested that Irène Joliot-Curie was the first person ever to die from the radiation effects of polonium (due to a single intake) in 1956.[48] She was accidentally exposed to polonium in 1946 when a sealed capsule of the element exploded on her laboratory bench. A decade later, on 17 March 1956, she died in Paris from leukemia which may have been caused by that exposure.

According to the book The Bomb in the Basement, several death cases in Israel during 1957-1969 were caused by 210Po.[49] A leak was discovered at a Weizmann Institute laboratory in 1957. Traces of 210Po were found on the hands of professor Dror Sadeh, a physicist who researched radioactive materials. Medical tests indicated no harm, but the tests did not include bone marrow. Sadeh died from cancer. One of his students died of leukemia, and two colleagues died after a few years, both from cancer. The issue was investigated secretly, and there was never any formal admission that a connection between the leak and the deaths had existed.[50]

Treatment

It has been suggested that chelation agents such as British Anti-Lewisite (dimercaprol) can be used to decontaminate humans.[51] In one experiment, rats were given a fatal dose of 1.45 MBq/kg (8.7 ng/kg) of 210Po; all untreated rats were dead after 44 days, but 90% of the rats treated with the chelation agent HOEtTTC remained alive after 5 months.[52]

Commercial products containing polonium

No nuclear authority has asserted that a commercial product was a likely source for the poisoning of Litvinenko. However, as Prof. Peter D. Zimmerman says, "Polonium 210 is surprisingly common. ...Polonium sources with about 10 percent of a lethal dose are readily available—even in a product sold on Amazon.com."[53]

Potentially lethal amounts of polonium are present in anti-static brushes sold to photographers.[54] Many of the devices are available by mail order. General Electric markets a static eliminator module with 500 µCi (20 MBq), roughly 2.5 times the lethal dose of 210Po if 100%-ingested, for US$79;[55] Staticmaster sells replacement units with the same amount (500 µCi) of 210Po for US$36.[56] In USA, the devices with no more than 500 µCi of (sealed) 210Po per unit can be bought in any amount under a "general license"[57] which means that a buyer need not be registered by any authorities: the general license "is effective without the filing of an application with the Commission or the issuance of a licensing document to a particular person."

If these sources were used to collect the amount of polonium likely used in the poisoning—and one could devise a method of separating the polonium from its protective casing—it would take 10–100 modules for price of US$360 to US$7,100. That such a thing could be done is extremely difficult according to the manufacturers and would be highly dangerous to anyone attempting to do so without some special equipment like a glovebox.

Sometimes sources of polonium used in industry are stolen or lost. According to the Nuclear Regulatory Commission (NRC), there were registered at least 8 cases of loss of control of potentially lethal polonium sources in the USA during 2006.

Tiny amounts of such radioisotopes are sometimes used in the laboratory and for teaching purposes—typically of the order of 4–40 kBq (0.1–1.0 µCi), in the form of sealed sources, with the polonium deposited on a substrate or in a resin or polymer matrix—are often exempt from licensing by the NRC and similar authorities as they are not considered hazardous. Small amounts of 210Po are manufactured for sale to the public in the United States by a company called Spectrum Techniques as 'needle sources' for laboratory experimentation, and are retailed by scientific supply companies such as United Nuclear. It would require about 15,000 of these 210Po sources, at a total cost of about $1 million, to obtain a toxic quantity of polonium. It would also require substantial processing to extract the polonium; the actual polonium is a layer of plating which in turn is plated with a material such as gold. This allows the alpha radiation (used in experiments such as cloud chambers) while preventing the polonium from being released and presenting a toxic hazard. According to United Nuclear, they typically sell between four and eight sources per year.[58][59]

According to some estimates,[60] the cost of the quantity of pure polonium-210 used to kill Litvinenko would be around £20 million (US$39 million).[61] However, this estimation is based on retail prices of commercially available demonstration radiation sources with very small activities and cannot be considered as reasonable.

Tobacco

The presence of polonium in tobacco smoke has been known since the early 1960s.[62][63] Some of the world's biggest tobacco firms researched ways to remove the substance—to no avail—over a 40-year period but never published the results.[23]

Radioactive polonium-210 contained in phosphate fertilizers is absorbed by the roots of plants (such as tobacco) and stored in its tissues.[64][65][66] Tobacco plants fertilized by rock phosphates contain polonium-210, which emits alpha radiation estimated to cause about 11,700 lung cancer deaths annually worldwide.[23][67][68]

See also

Notes

  1. ↑ "Chemical Elements.com - Metalloids". http://www.chemicalelements.com/groups/metalloids.html. Retrieved 2009-05-05. 
  2. ↑ "Polonium". http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/Po.html. Retrieved 2009-05-05. 
  3. ↑ 3.0 3.1 "Polonium". Argonne National Laboratory. http://www.ead.anl.gov/pub/doc/polonium.pdf. Retrieved 2009-05-05. 
  4. ↑ Andrew Wilson (1987). Solar System Log. London: Jane's Publishing Company Ltd. p. 64. ISBN 0710604440. 
  5. ↑ "Staticmaster Ionizing Brushes". AMSTAT Industries. http://www.amstat.com/solutions/staticmaster.html. Retrieved 2009-05-05. 
  6. ↑ "210PO a decay". http://atom.kaeri.re.kr/cgi-bin/decay?Po-210%20A. Retrieved 2009-05-05. 
  7. ↑ Gary L. Miessler; Donald A. Tarr (2004). Inorganic Chemistry (3 ed.). Upper Saddle River, N.J.: Pearson Prentice Hall. pp. 285. ISBN 0-13-120198-0. 
  8. ↑ "The beta Po (A_i) Structure". http://cst-www.nrl.navy.mil/lattice/struk/a_i.html. Retrieved 2009-05-05. 
  9. ↑ Desando, R. J.; Lange, R. C. (1966). "The structures of polonium and its compounds—I α and β polonium metal". Journal of Inorganic and Nuclear Chemistry 28: 1837. doi:10.1016/0022-1902(66)80270-1. 
  10. ↑ Beamer, W. H.; Maxwell, C. R. (1946). "The Crystal Structure of Polonium". Journal of Chemical Physics 14: 569. doi:10.1063/1.1724201. 
  11. ↑ Rollier, M. A.; Hendricks, S. B.; Maxwell, L. R. (1936). "The Crystal Structure of Polonium by Electron Diffraction". Journal of Chemical Physics 4: 648. doi:10.1063/1.1749762. 
  12. ↑ Bogdan Wąs, Ryszard Misiak, Mirosław Bartyzel, Barbara Petelenz (2006). "Thermochromatographic Separation of 206,208Po from a Bismuth Target Bombardet with Protons". Nukleonica 51 (Suppl. 2): s3-s5. http://www.ichtj.waw.pl/ichtj/nukleon/back/full/vol51_2006/v51s2p03f.pdf. 
  13. ↑ Lide, D. R., ed. (2005), CRC Handbook of Chemistry and Physics (86th ed.), Boca Raton (FL): CRC Press, ISBN 0-8493-0486-5 
  14. ↑ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5. 
  15. ↑ Momoshima N., Song L.X., Osaki S.,Maeda Y., (2001). "Formation and emission of volatile polonium compound by microbial activity and polonium methylation with methylcobalamin". Environ Sci Technol 35 (15): 2956–2960. doi:10.1021/es001730. http://www.medscape.com/medline/abstract/11478248?prt=true. 
  16. ↑ Momoshima N., Song L.X., Osaki S.,Maeda Y., (2002). "Biologically induced Po emission from fresh water". J Environ Radioact. 63: 187. doi:10.1016/S0265-931X(02)00028-0. 
  17. ↑ Curie P., Curie M. (1898). "Radiations from Compounds of Uranium and of Thorium". Comptes Rendus 126: 1101. 
  18. ↑ Pfützner M. (1999). "Borders of the Nuclear World --- 100 Years After Discovery of Polonium". Acta Physica Polonica B 30: 1197. http://adsabs.harvard.edu/abs/1999AcPPB..30.1197P. 
  19. ↑ Adloff J. P. (2003). "The centennial of the 1903 Nobel Prize for physics". Radichimica Acta 91: 681. doi:10.1524/ract.91.12.681.23428. 
  20. ↑ Kabzinska K. (1998). "Chemical and Polish aspects of polonium and radium discovery". Przemysl Chemiczny 77 (3): 104–107. 
  21. ↑ Kilthau, Gustave F (1996). "Cancer risk in relation to radioactivity in tobacco". Radiologic Technology 67 (3): 217–222. PMID 8850254. 
  22. ↑ "Alpha Radioactivity (210 Polonium) and Tobacco Smoke". http://kidslink.bo.cnr.it/besta/fumo/epolonio.html. Retrieved 2009-05-05. 
  23. ↑ 23.0 23.1 23.2 Monique E. Muggli et al. (2008). "Waking a Sleeping Giant: The Tobacco Industry’s Response to the Polonium-210 Issue". American Journal of Public Health 98 (9): 1643. doi:10.2105/AJPH.2007.130963. PMID 18633078. 
  24. ↑ Schulz, Wallace W.; Schiefelbein, Gary F.; Bruns, Lester E. (1969). "Pyrochemical Extraction of Polonium from Irradiated Bismuth Metal". Ind. Eng. Chem. Process Des. Dev. 8 (4): 508. doi:10.1021/i260032a013. 
  25. ↑ "Q&A: Polonium-210". RSC Chemistry World. 2006-11-27. http://www.rsc.org/chemistryworld/News/2006/November/27110601.asp. Retrieved 2009-01-12. 
  26. ↑ "Most Polonium Made Near the Volga River". The St. Petersburg Times - News. 2001-01-23. http://www.sptimesrussia.com/index.php?action_id=2&story_id=20100. 
  27. ↑ Atterling, H., Forsling, W. (1959). "Light Polonium Isotopes from Carbon Ion Bombardments of Platinum". Arkiv for Fysik 15 (1): 81–88. http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=4238755. 
  28. ↑ Rhodes, Richard (2002). Dark Sun: The Making of the Hydrogen Bomb. New York: Walker & Company. pp. 187–188. ISBN 068480400X. 
  29. ↑ "BBC News : College breaches radioactive regulations". 2002-03-12. http://news.bbc.co.uk/1/hi/england/1868414.stm. Retrieved 2009-05-05. 
  30. ↑ "Static Control for Electronic Balance Systems". http://www.thermo.com/eThermo/CMA/PDFs/Articles/articlesFile_16929.pdf. Retrieved 2009-05-05. 
  31. ↑ Hanslmeier, Arnold (2002). The sun and space weather. Springer. p. 183. ISBN 1402006845. http://books.google.com/?id=07TEK_w3A4AC&pg=PA183. 
  32. ↑ Emsley, John (2001). Nature's Building Blocks. New York: Oxford University Press. p. 331. ISBN 0198503415. 
  33. ↑ "Hydrogen cyanide msds". http://www.physchem.ox.ac.uk/MSDS/HY/hydrogen_cyanide.html. 
  34. ↑ 34.0 34.1 "Health Impacts from Acute Radiation Exposure". http://www.pnl.gov/main/publications/external/technical_reports/PNNL-14424.pdf. Retrieved 2009-05-05. 
  35. ↑ 35.0 35.1 "Nuclide Safety Data Sheet: Polonium–210". http://hpschapters.org/northcarolina/NSDS/210PoPDF.pdf. Retrieved 2009-05-05. 
  36. ↑ "Effective half-life of polonium in the human". http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=7162390. Retrieved 2009-05-05. 
  37. ↑ "Polonium Poisoning". http://nuclearweaponarchive.org/News/PoloniumPoison.html. Retrieved 2009-05-05. 
  38. ↑ Harrison J et al. (2007). "Polonium-210 as a poison". J. Radiol. Prot. 27 (1): 17. doi:10.1088/0952-4746/27/1/001. PMID 17341802. "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". 
  39. ↑ "National Academy of Sciences 1988 report: Health Risks of Radon and Other Internally Deposited Alpha-Emitters: BEIR IV, page 5". http://fermat.nap.edu/openbook.php?record_id=1026&page=5. Retrieved 2009-05-05. 
  40. ↑ "National Academy of Sciences 1999 report: Health Effects Of Exposure To Indoor Radon". http://newton.nap.edu/html/beir6/. Retrieved 2009-05-05. 
  41. ↑ "The Straight Dope: Does smoking organically grown tobacco lower the chance of lung cancer?". http://www.straightdope.com/columns/070928.html. Retrieved 2009-05-05. 
  42. ↑ "Nuclear Regulatory Commission limits for 210Po". U.S. NRC. 2008-12-12. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/appb/Polonium-210.html. Retrieved 2009-01-12. 
  43. ↑ "PilgrimWatch - Pilgrim Nuclear - Health Impact". http://www.pilgrimwatch.org/health1.html. Retrieved 2009-05-05. 
  44. ↑ Peter D. Zimmerman (2006-12-19). "The Smoky Bomb Threat". The New York Times. http://www.nytimes.com/2006/12/19/opinion/19zimmerman.html. Retrieved 2006-12-19. 
  45. ↑ "The mystery of Litvinenko's death". BBC News. 24 November 2006. http://news.bbc.co.uk/1/hi/uk/6180432.stm. 
  46. ↑ "UK requests Lugovoi extradition". BBC News. 2007-05-28. http://news.bbc.co.uk/1/hi/uk/6698545.stm. Retrieved 2009-05-05. 
  47. ↑ "Focus: Cracking the code of the nuclear assassin". The Times (London). http://www.timesonline.co.uk/article/0,,2087-2484295_1,00.html. Retrieved 2010-05-22. 
  48. ↑ Manier, Jeremy (December 4, 2006). "Innocent chemical a killer". The Daily Telegraph (Australia). http://www.news.com.au/dailytelegraph/story/0,22049,20863878-5001031,00.html. Retrieved 2009-05-05. 
  49. ↑ Karpin, Michael (2006). The bomb in the basement: How Israel went nuclear and what that means for the world. Simon and Schuster. ISBN 0743265947. 
  50. ↑ Maugh, Thomas; Karen Kaplan (2007-01-01). "A restless killer radiates intrigue". Los Angeles Times. http://articles.latimes.com/2007/jan/01/science/sci-polonium1. Retrieved 2008-09-17. 
  51. ↑ "Guidance for Industry. Internal Radioactive Contamination — Development of Decorporation Agents" (PDF). http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/ucm071944.pdf. Retrieved 2009-07-07. 
  52. ↑ Rencováa J., Svoboda V., Holuša R., Volf V., Jones M. M., Singh P. K. (1997). "Reduction of subacute lethal radiotoxicity of polonium-210 in rats by chelating agents". International Journal of Radiation Biology 72: 247. doi:10.1080/095530097143338. 
  53. ↑ "The smoky bomb threat - Opinion - International Herald Tribune". http://www.iht.com/articles/2006/12/19/opinion/edzimmer.php. Retrieved 2009-05-05. 
  54. ↑ "Solutions to Static Problems". Amstat Industries. http://www.amstat.com/solutions/staticmaster.html. Retrieved 2006-12-01. 
  55. ↑ "Static Eliminator". GE Osmonics' Labstore. http://www.osmolabstore.com/OsmoLabPage.dll?BuildPage&1&1&1005. Retrieved 2010-05-15. 
  56. ↑ "Staticmaster Antistatic Products". SPI Supplies. http://www.2spi.com/catalog/photo/statmaster.shtml. Retrieved 2007-08-29. 
  57. ↑ "General domestic licenses for byproduct material". http://www.nrc.gov/reading-rm/doc-collections/cfr/part031/full-text.html. Retrieved 2009-05-05. 
  58. ↑ Singleton, Don (November 28, 2006). "The Availability of polonium-210". http://donsingleton.blogspot.com/2006/11/polonium-210.html. Retrieved 2006-11-29. 
  59. ↑ "UnitedNuclear Isotopes for sale over the Internet". http://www.unitednuclear.com/isotopes.htm. Retrieved 2007-03-19. 
  60. ↑ Cobain, Ian (2006-12-02). "Litvinenko affair: now the man who warned him poisoned too". The Guardian (London). http://www.guardian.co.uk/russia/article/0,,1962354,00.html. Retrieved 2009-05-05. 
  61. ↑ Hooper, Rowan (13 December 2006). "Natural selections: Murder in the genes? Polonium, peacocks—and a dead spy". The Japan Times Online. http://search.japantimes.co.jp/cgi-bin/fe20061213rh.html. Retrieved 2006-12-13. 
  62. ↑ Radford EP Jr, Hunt VR (1964). "Polonium 210: a volatile radioelement in cigarettes". Science 143: 247. doi:10.1126/science.143.3603.247. 
  63. ↑ Kelley TF (1965). "Polonium 210 content of mainstream cigarette smoke". Science 149: 537. doi:10.1126/science.149.3683.537. 
  64. ↑ Hussein EM (1994). "Radioactivity of phosphate ore, superphosphate, and phosphogypsum in Abu-zaabal phosphate". Health Physics 67: 280. doi:10.1097/00004032-199409000-00010. 
  65. ↑ Barisic D, Lulic S, Miletic P (1992). "Radium and uranium in phosphate fertilizers and their impact on the radioactivity of waters". Water Research 26: 607. doi:10.1016/0043-1354(92)90234-U. .
  66. ↑ Scholten LC, Timmermans CWM (1992). "Natural radioactivity in phosphate fertilizers". Nutrient cycling in agroecosystems 43: 103. doi:10.1007/BF00747688. 
  67. ↑ Tidd J (2008). "The big idea: polonium, radon and cigarettes". Journal of the Royal Society of Medicine 101 (3): 156. doi:10.1258/jrsm.2007.070021. PMID 18344474. 
  68. ↑ William Birnbauer (September 7, 2008). "Big Tobacco covered up radiation danger". The Age, Melbourne, Australia. http://www.theage.com.au/national/big-tobacco-covered-up-radiation-danger-20080906-4b54.html?page=-1. 

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