Polonium

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Polonium
84Po
Te

Po

Lv
bismuthpoloniumastatine
Appearance
silvery
General properties
Name, symbol, numberpolonium, Po, 84
Pronunciation/pɵˈlniəm/ po-LOH-nee-əm
Metallic categorypost-transition metal
post-transition metal status is disputed (see article text)
Group, period, block16 (chalcogens), 6, p
Standard atomic weight(209)
Electron configuration[Xe] 6s2 4f14 5d10 6p4
2, 8, 18, 32, 18, 6
Electron shells of polonium (2, 8, 18, 32, 18, 6)
History
DiscoveryPierre Curie and Marie Curie (1898)
First isolationWilly Marckwald (1902)
Physical properties
Phasesolid
Density (near r.t.)(alpha) 9.196 g·cm−3
Density (near r.t.)(beta) 9.398 g·cm−3
Melting point527 K, 254 °C, 489 °F
Boiling point1235 K, 962 °C, 1764 °F
Heat of fusionca. 13 kJ·mol−1
Heat of vaporization102.91 kJ·mol−1
Molar heat capacity26.4 J·mol−1·K−1
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)   (846)10031236
Atomic properties
Oxidation states6, 4, 2, −2
(amphoteric oxide)
Electronegativity2.0 (Pauling scale)
Ionization energies1st: 812.1 kJ·mol−1
Atomic radius168 pm
Covalent radius140±4 pm
Van der Waals radius197 pm
Miscellanea
Crystal structurecubic
Polonium has a cubic crystal structure
Magnetic orderingnonmagnetic
Electrical resistivity(0 °C) (α) 0.40 µΩ·m
Thermal conductivity ? 20 W·m−1·K−1
Thermal expansion(25 °C) 23.5 µm·m−1·K−1
CAS registry number7440-08-6
Most stable isotopes
Main article: Isotopes of polonium
isoNAhalf-lifeDMDE (MeV)DP
208Posyn2.898 yα5.215204Pb
β+1.401208Bi
209Posyn103 yα4.979205Pb
β+1.893209Bi
210Potrace138.376 dα5.307206Pb
· r
 
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Polonium
84Po
Te

Po

Lv
bismuthpoloniumastatine
Appearance
silvery
General properties
Name, symbol, numberpolonium, Po, 84
Pronunciation/pɵˈlniəm/ po-LOH-nee-əm
Metallic categorypost-transition metal
post-transition metal status is disputed (see article text)
Group, period, block16 (chalcogens), 6, p
Standard atomic weight(209)
Electron configuration[Xe] 6s2 4f14 5d10 6p4
2, 8, 18, 32, 18, 6
Electron shells of polonium (2, 8, 18, 32, 18, 6)
History
DiscoveryPierre Curie and Marie Curie (1898)
First isolationWilly Marckwald (1902)
Physical properties
Phasesolid
Density (near r.t.)(alpha) 9.196 g·cm−3
Density (near r.t.)(beta) 9.398 g·cm−3
Melting point527 K, 254 °C, 489 °F
Boiling point1235 K, 962 °C, 1764 °F
Heat of fusionca. 13 kJ·mol−1
Heat of vaporization102.91 kJ·mol−1
Molar heat capacity26.4 J·mol−1·K−1
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)   (846)10031236
Atomic properties
Oxidation states6, 4, 2, −2
(amphoteric oxide)
Electronegativity2.0 (Pauling scale)
Ionization energies1st: 812.1 kJ·mol−1
Atomic radius168 pm
Covalent radius140±4 pm
Van der Waals radius197 pm
Miscellanea
Crystal structurecubic
Polonium has a cubic crystal structure
Magnetic orderingnonmagnetic
Electrical resistivity(0 °C) (α) 0.40 µΩ·m
Thermal conductivity ? 20 W·m−1·K−1
Thermal expansion(25 °C) 23.5 µm·m−1·K−1
CAS registry number7440-08-6
Most stable isotopes
Main article: Isotopes of polonium
isoNAhalf-lifeDMDE (MeV)DP
208Posyn2.898 yα5.215204Pb
β+1.401208Bi
209Posyn103 yα4.979205Pb
β+1.893209Bi
210Potrace138.376 dα5.307206Pb
· r

Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie and Pierre Curie. A rare and highly radioactive element with no stable isotopes, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Applications of polonium are few, and include heaters in space probes, antistatic devices, and sources of neutrons and alpha particles. Because of its position in the periodic table, polonium is sometimes referred to as a metalloid,[1] however others note that on the basis of its properties and behavior it is "unambiguously a metal".[2]

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 138.4 days; it decays directly to its stable daughter isotope, 206Pb. A milligram of 210Po emits about as many alpha particles per second as 5 grams of 226Ra.[3] 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.

About one in 100,000 alpha emissions causes an excitation in the nucleus which then results in the emission of a gamma ray with a maximum energy of 803 keV.[4][5] However, it is the alpha particles, not the side effect of an occasional gamma ray, that results in 210Po decay. The gamma radiation level from polonium is below the normal background.

Solid state form

The alpha form of solid polonium.

Polonium is a radioactive element that exists in two metallic allotropes. The alpha form is the only known example of a simple cubic crystal structure in a single atom basis, with an edge length of 335.2 picometers; the beta form is rhombohedral.[6][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. Polonium solutions are first colored in pink by the Po2+ ions, but then rapidly become yellow because alpha radiation from polonium ionizes the solvent and converts Po2+ into Po4+. This process is accompanied by bubbling and emission of heat and light by glassware due to the absorbed alpha particles; as a result, polonium solutions are volatile and will evaporate within days unless sealed.[14][15]

It has been reported that some microbes can methylate polonium by the action of methylcobalamin.[16][17] 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 polonium will follow the same biochemical pathways as selenium and tellurium.

Compounds

Polonium has no common compounds, only synthetically created ones, and more than 50 of those are known.[18] The most stable class of polonium compounds are polonides, which are prepared by direct reaction of two elements. Na2Po has the antifluorite structure, the polonides of Ca, Ba, Hg, Pb and lanthanides form a NaCl lattice, BePo and CdPo have the wurtzite and MgPo the nickel arsenide structure. Most polonides decompose upon heating to about 600 °C, except for HgPo that decomposes at ~300 °C and the lanthanide polonides, which do not decompose but melt at temperatures above 1000 °C. For example PrPo melts at 1250 °C and TmPo at 2200 °C.[19]

Polonium hydride (PoH2) is a volatile liquid at room temperature prone to dissociation.[19] The two oxides PoO2 and PoO3 are the products of oxidation of polonium.[20]

Halides of the structure PoX2, PoX4 and PoX6 are known. They are soluble in the corresponding hydrogen halides, i.e., PoClX in HCl, PoBrX in HBr and PoI4 in HI.[21] Polonium dihalides are formed by direct reaction of the elements or by reduction of PoCl4 with SO2 and with PoBr4 with H2S at room temperature. Tetrahalides can be obtained by reacting polonium dioxide with HCl, HBr or HI.[22]

Other polonium compounds include acetate, bromate, carbonate, citrate, chromate, cyanide, formate, hydroxide, nitrate, selenate, monosulfide, sulfate and disulfate.[21][23]

Polonium compounds[22][24]
FormulaColorm.p. (°C)Sublimation
temp. (°C)
SymmetryPearson symbolSpace groupNoa (pm)b(pm)c(pm)Zρ (g/cm3)ref
PoO2pale yellow500 (dec.)885fccFm3mcF12225563.7563.7563.748.94[25]
PoCl2dark red355130orthorhombicoP3Pmmm4736743545016.47[26]
PoBr2purple-brown270 (dec.)[27]
PoCl4yellow300200monoclinic[26]
PoBr4red330 (dec.)fccFm3mcF1002255605605604[27]
PoI4black[28]

Oxides

Hydrides

Halogen compounds

History

Also tentatively called "Radium F", polonium was discovered by Marie and Pierre Curie in 1898[29] and was named after Marie Curie's native land of Poland (Latin: Polonia)[30][31] 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.[32]

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 in July 1898, and five months later, also isolated radium.[14][33][34]

In the United States, Polonium was produced as part of the Manhattan Project during World War II. It was a critical part of the implosion-type nuclear weapon design used in the Fat Man bomb on Nagasaki in 1945. Polonium and Beryllium were the key ingredients of the 'Urchin' detonator at the center of the bomb's spherical Plutonium pit. The Urchin ignited the nuclear chain reaction at the moment of prompt-criticality to ensure the bomb did not fizzle.

Much of the basic physics of Polonium was classified until after the war. The fact that it was used as an initiator was classifed until the 1960s.[35]

The Atomic Energy Commission and the Manhattan Project funded human experiments using polonium on 5 people at the University of Rochester between 1943 and 1947. The people were administered between 9 and 22 microcuries of Polonium to study its excretion.[36][37][38]

Detection

Emission intensity vs. photon energy for three polonium 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.

Emission intensity vs. alpha energy for four isotopes, note that the line width is narrow and the fine details can be seen.
Emission intensity vs. 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 of 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 0.1 mg per metric ton (1 part in 1010),[39][40] 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.[41][42][43]

Because of the small abundance, isolation of polonium from natural sources is a very tedious process. The largest batch was extracted in the first half of the 20th century by processing 37 tonnes of residues from radium production. It contained only 40 Ci (9 mg) of polonium-210.[44] Nowadays, polonium is obtained by irradiating bismuth with high-energy neutrons or protons.[14][45]

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.[46] Polonium may now be made in milligram amounts in this procedure which uses high neutron fluxes found in nuclear reactors.[45] Only about 100 grams are produced each year, practically all of it in Russia, making polonium exceedingly rare.[47][48]

This process can cause problems in lead-bismuth based liquid metal cooled nuclear reactors such as those used in the Soviet Navy's K-27. Measures must be taken in these reactors to deal with the unwanted possibility of 210Po being released from the coolant.[49][50]

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.[51]

Applications

Polonium-based sources of alpha particles were produced in the former Soviet Union.[52] Such sources were applied for measuring the thickness of industrial coatings via attenuation of alpha radiation.[53] Because of intense alpha radiation, a one-gram sample of 210Po will spontaneously heat up to above 500 °C (932 °F) generating about 140 watts of energy. Therefore, 210Po is used as an atomic heat source to power radioisotope thermoelectric generators via thermoelectric materials.[3][14][54][55] For instance, 210Po heat sources were used in the Lunokhod 1 (1970) and Lunokhod 2 (1973) Moon rovers to keep their internal components warm during the lunar nights, as well as the Kosmos 84 and 90 satellites (1965).[52][56]

The alpha particles emitted by polonium can be converted to neutrons using beryllium oxide, at a rate of 93 neutrons per million alpha particles.[54] Thus Po-BeO mixtures or alloys are used as a neutron source, for example in a neutron trigger or initiator for nuclear weapons[14][57] and for inspections of oil wells. About 1500 of such sources with an individual activity of 1850 Ci have been used annually in the Soviet Union.[58]

Polonium was also part of brushes or more complex tools that eliminate static charges in photographic plates, textile mills, paper rolls, sheet plastics, and on substrates prior to the application of coatings (such as automotive). Alpha particles emitted by polonium ionize air molecules that neutralize charges on the nearby surfaces.[59][60] However, polonium needs to be replaced in these devices nearly every year because of its short half-life; it is also highly radioactive and therefore has been mostly replaced by less dangerous beta particle sources.[3]

Toxicity

Overview

Polonium is highly dangerous and has no biological role.[14] By mass, polonium-210 is around 250,000 times more toxic than hydrogen cyanide (the actual LD50 for 210Po is less than 1 microgram for an average adult (see below) compared with about 250 milligrams for hydrogen cyanide[61]). The main hazard is its intense radioactivity (as an alpha emitter), which makes it very difficult to handle safely. Even in microgram amounts, handling 210Po is extremely dangerous, requiring specialized equipment (a negative pressure alpha glove box equipped with high performance filters), adequate monitoring, and strict handling procedures to avoid any contamination. 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 as long as the alpha particles remain outside of the body. Meanwhile, wearing chemically resistant and "intact" gloves is a mandatory precaution to avoid transcutaneous diffusion of polonium directly through the skin. Polonium delivered in concentrated nitric acid can easily diffuse through inadequate gloves (e.g., latex gloves) or the acid may damage the gloves.[citation needed]

Acute effects

The median lethal dose (LD50) for acute radiation exposure is generally about 4.5 Sv.[62] The committed effective dose equivalent 210Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled.[63] Since 210Po has an activity of 166 TBq per gram (4,500 Ci/g)[63] (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[64]) 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.[65][66]

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.[62] 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[67] of the estimated 15,000–22,000 lung cancer deaths in the US every year that have been attributed to indoor radon.[68] Tobacco smoking causes additional exposure to polonium.[69]

Regulatory exposure limits and handling

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).[70] The target organs for polonium in humans are the spleen and liver.[71] 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)."[72]

Polonium and its compounds must be handled in a glove box, which is further enclosed in another box, maintained at a slightly lower pressure than the glove box to prevent the radioactive materials from leaking out. Gloves made of natural rubber do not provide sufficient protection against the radiation from polonium; surgical gloves are necessary. Neoprene gloves shield radiation from polonium better than natural rubber.[73]

Well-known poisoning cases

Notably, the murder of Alexander Litvinenko, a Russian dissident, in 2006 was announced as due to 210Po poisoning[74][75] (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.[76] However, according to William Dunkerley, a senior fellow at the American University in Moscow, the London coroner has yet to rule that polonium was actually the cause of Litvinenko's death, or that he was even a victim of homicide.[77]

It has also been suggested that Irène Joliot-Curie was the first person to die from the radiation effects of polonium. She was accidentally exposed to polonium in 1946 when a sealed capsule of the element exploded on her laboratory bench. In 1956 she died from leukemia.[78]

According to the book The Bomb in the Basement, several death cases in Israel during 1957–1969 were caused by 210Po.[79] 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.[80]

Abnormally high concentrations of 210Po have been detected in July 2012 in clothes and personal belongings of the Palestinian leader Yasser Arafat, who died in 2004 of uncertain causes. However, the spokesman for the Institut de Radiophysique in Lausanne, Switzerland, where those items were analyzed, stressed that the "clinical symptoms described in Arafat's medical reports were not consistent with polonium-210 and that conclusions could not be drawn as to whether the Palestinian leader was poisoned or not", and that "the only way to confirm the findings would be to exhume Arafat's body to test it for polonium-210."[81] On 27 November 2012 Arafat's body was exhumed and samples were taken for separate analysis by experts from France, Switzerland and Russia. Results are expected by April 2013.

Treatment

It has been suggested that chelation agents such as British Anti-Lewisite (dimercaprol) can be used to decontaminate humans.[82] 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.[83]

Detection in biological specimens

Polonium-210 may be quantitated in biological specimens by alpha particle spectrometry to confirm a diagnosis of poisoning in hospitalized patients or to provide evidence in a medicolegal death investigation. The baseline urinary excretion of polonium-210 in healthy persons due to routine exposure to environmental sources is normally in a range of 5-15 mBq/day. Levels in excess of 30 mBq/day are suggestive of excessive exposure to the radionuclide.[84]

Commercial products containing polonium

Some anti-static brushes contain up to 500 microcuries (20 MBq) of 210Po as a source of charged particles for neutralizing static electricity.[85] 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",[86] which means that a buyer need not be registered by any authorities.

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 as 'needle sources' for laboratory experimentation, and are retailed by scientific supply companies. 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.[87][88]

Occurrence in humans and the biosphere

Polonium-210 is widespread in the biosphere, including in human tissues, because of its position in the uranium-238 decay chain. Natural uranium-238 in the Earth's crust decays through a series of solid radioactive intermediates including radium-226 to the radioactive gas radon-222, some of which, during its 3.6-day half-life, diffuses into the atmosphere. There it decays through several more steps to polonium-210, much of which, during its 138-day half-life, is washed back down to the Earth's surface, thus entering the biosphere, before finally decaying to stable lead-206.[89][90][91]

As early as the 1920s Lacassagne, using polonium provided by his colleague Marie Curie, showed that the element has a very specific pattern of uptake in rabbit tissues, with high concentrations particularly in liver, kidney and testes.[92] More recent evidence suggests that this behavior results from polonium substituting for sulfur in sulfur-containing amino-acids or related molecules[93] and that similar patterns of distribution occur in human tissues.[94] Polonium is indeed an element naturally present in all humans, contributing appreciably to natural background dose, with wide geographical and cultural variations, and particularly high levels in arctic residents, for example.[95]

Tobacco

The presence of polonium in tobacco smoke has been known since the early 1960s.[96][97] 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.[43]

Radioactive polonium-210 contained in phosphate fertilizers is absorbed by the roots of plants (such as tobacco) and stored in its tissues.[98][99][100] Tobacco plants fertilized by rock phosphates contain polonium-210, which emits alpha radiation estimated to cause about 11,700 lung cancer deaths annually worldwide.[43][101][102]

Food

Polonium is also found in the food chain, especially in seafood.[103][104]

See also

References

  1. ^ "Chemical Elements.com – Metalloids". http://www.chemicalelements.com/groups/metalloids.html. Retrieved 2009-05-05.
  2. ^ Hawkes, Stephen J. (2010). "Polonium and Astatine Are Not Semimetals". Journal of Chemical Education 87 (8): 783. Bibcode 2010JChEd..87..783H. doi:10.1021/ed100308w.
  3. ^ a b c "Polonium". Argonne National Laboratory. http://www.ead.anl.gov/pub/doc/polonium.pdf. Retrieved 2009-05-05.
  4. ^ Greenwood, p. 250
  5. ^ "210PO a decay". http://atom.kaeri.re.kr/cgi-bin/decay?Po-210%20A. Retrieved 2009-05-05.
  6. ^ Greenwood, p. 753
  7. ^ Miessler, Gary L.; Tarr, Donald A. (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 (9): 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 (9): 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 (10): 648. Bibcode 1936JChPh...4..648R. doi:10.1063/1.1749762.
  12. ^ Wąs, Bogdan; Misiak, Ryszard; Bartyzel, Mirosław; Petelenz, Barbara (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. ^ a b c d e f Emsley, John (2001). Nature's Building Blocks. New York: Oxford University Press. pp. 330–332. ISBN 0-19-850341-5.
  15. ^ Bagnall, p. 206
  16. ^ 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.
  17. ^ Momoshima, N.; Song, L.X.; Osaki, S.; Maeda, Y. (2002). "Biologically induced Po emission from fresh water". J Environ Radioact. 63 (2): 187. doi:10.1016/S0265-931X(02)00028-0.
  18. ^ Bagnall, p. 199
  19. ^ a b Greenwood, p. 766
  20. ^ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
  21. ^ a b Figgins, P. E. (1961) The Radiochemistry of Polonium, National Academy of Sciences, US Atomic Energy Commission, pp. 13–14 Google Books
  22. ^ a b Greenwood, p. 765, 771, 775
  23. ^ Bagnall, pp. 212–226
  24. ^ Wiberg, Egon; Holleman, A. F. and Wiberg, Nils Inorganic Chemistry, Academic Press, 2001, p. 594 ISBN 0123526515.
  25. ^ Bagnall, K. W.; D'Eye, R. W. M. (1954). "The Preparation of Polonium Metal and Polonium Dioxide". J. Chem. Soc: 4295–4299. doi:10.1039/JR9540004295.
  26. ^ a b Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1955). "The polonium halides. Part I. Polonium chlorides". Journal of the Chemical Society (Resumed): 2320. doi:10.1039/JR9550002320.
  27. ^ a b Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1955). "The polonium halides. Part II. Bromides". Journal of the Chemical Society (Resumed): 3959. doi:10.1039/JR9550003959.
  28. ^ Bagnall, K. W.; d'Eye, R. W. M.; Freeman, J. H. (1956). "657. The polonium halides. Part III. Polonium tetraiodide". Journal of the Chemical Society (Resumed): 3385. doi:10.1039/JR9560003385.
  29. ^ P. Curie and S. Curie (1898) "Sur une substance nouvelle radio-active, contenue dans la pechblende" (On a new radioactive substance contained in pitchblende), Comptes rendus, vol. 127, pp. 175–178. English translation.
  30. ^ Pfützner, M. (1999). "Borders of the Nuclear World --- 100 Years After Discovery of Polonium". Acta Physica Polonica B 30: 1197. Bibcode 1999AcPPB..30.1197P.
  31. ^ Adloff, J. P. (2003). "The centennial of the 1903 Nobel Prize for physics". Radichimica Acta 91 (12–2003): 681. doi:10.1524/ract.91.12.681.23428.
  32. ^ Kabzinska, K. (1998). "Chemical and Polish aspects of polonium and radium discovery". Przemysl Chemiczny 77 (3): 104–107.
  33. ^ Académie des Sciences (French) Link OK 30 DEC 12
  34. ^ Académie des Sciences (French) Link OK 30 DEC 12
  35. ^ RESTRICTED DATA DECLASSIFICATION DECISIONS, 1946 TO THE PRESENT (RDD-7), January 1, 2001, U.S. Department of Energy Office of Declassification, via fas.org
  36. ^ American nuclear guinea pigs : three decades of radiation experiments on U.S. citizens. United States. Congress. House. of the Committee on Energy and Commerce. Subcommittee on Energy Conservation and Power, published by U.S. Government Printing Office, 1986, Identifier Y 4.En 2/3:99-NN, Electronic Publication Date 2010, at the University of Nevada, Reno, unr.edu
  37. ^ Studies of polonium metabolism in human subjects, Chapter 3 of Biological Studies with Polonium, Radium, and Plutonium, National, Nuclear Energy Series, Volume VI-3, McGraw-Hill, New York, 1950., cited in "American Nuclear Guinea Pigs...", 1986 House Energy and Commerce committee report
  38. ^ “The Human Plutonium Injection Experiments” (pdf) by William Moss and Roger Eckhardt, Los Alamos Science, Number 23, 1995. retrieved from fas.org on 2012 9 30
  39. ^ Greenwood, p. 746
  40. ^ Bagnall, p. 198
  41. ^ Kilthau, Gustave F (1996). "Cancer risk in relation to radioactivity in tobacco". Radiologic Technology 67 (3): 217–222. PMID 8850254.
  42. ^ "Alpha Radioactivity (210 Polonium) and Tobacco Smoke". http://kidslink.bo.cnr.it/besta/fumo/epolonio.html. Retrieved 2009-05-05.
  43. ^ a b c Monique, E. Muggli; Ebbert, Jon O.; Robertson, Channing; Hurt, Richard D. (2008). "Waking a Sleeping Giant: The Tobacco Industry's Response to the Polonium-210 Issue". American Journal of Public Health 98 (9): 1643–50. doi:10.2105/AJPH.2007.130963. PMC 2509609. PMID 18633078. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2509609/.
  44. ^ Adloff, J. P. and MacCordick, H. J. (1995). "The Dawn of Radiochemistry". Radiochimica Acta 70/71: 13–22. http://www.nucleonica.com/wiki/Articles/Article03/Article3.htm., reprinted in Adloff, J.P (1996). One hundred years after the discovery of radioactivity. p. 17. ISBN 978-3-486-64252-0. http://books.google.com/?id=whGiCQywLi8C&pg=PA17.
  45. ^ a b Greenwood, p. 249
  46. ^ 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.
  47. ^ "Q&A: Polonium-210". RSC Chemistry World. 2006-11-27. http://www.rsc.org/chemistryworld/News/2006/November/27110601.asp. Retrieved 2009-01-12.
  48. ^ "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.
  49. ^ Long-lived radionuclides of sodium, lead-bismuth, and lead coolants in fast-neutron reactors, Atomic Energy, Volume 87, Number 3 (1999), 658-662, DOI: 10.1007/BF02673579, V. I. Usanov, D. V. Pankratov, É. P. Popov, P. I. Markelov, L. D. Ryabaya and S. V. Zabrodskaya
  50. ^ Тамара Девятова За какими корабельными реакторами будущее? В. В. Наумов, контр-адмирал в отставке, Атомная стратегия : Журнал. — ноябрь 2006. — В. 26. retr 2012 9 29
  51. ^ Atterling, H., Forsling, W. (1959). "Light Polonium Isotopes from Carbon Ion Bombardments of Platinum". Arkiv for Fysik 15 (1): 81–88. OSTI 4238755.
  52. ^ a b Радиоизотопные источники тепла (in Russian). npc.sarov.ru
  53. ^ Bagnall, p. 225
  54. ^ a b Greenwood, p. 251
  55. ^ Hanslmeier, Arnold (2002). The sun and space weather. Springer. p. 183. ISBN 1-4020-0684-5. http://books.google.com/?id=07TEK_w3A4AC&pg=PA183.
  56. ^ Wilson, Andrew (1987). Solar System Log. London: Jane's Publishing Company Ltd. p. 64. ISBN 0-7106-0444-0.
  57. ^ Rhodes, Richard (2002). Dark Sun: The Making of the Hydrogen Bomb. New York: Walker & Company. pp. 187–188. ISBN 0-684-80400-X.
  58. ^ Красивая версия "самоубийства" Литвиненко вследствие криворукости (in Russian). stringer.ru (2006-11-26).
  59. ^ "Static Control for Electronic Balance Systems". http://www.thermo.com/eThermo/CMA/PDFs/Articles/articlesFile_16929.pdf. Retrieved 2009-05-05.
  60. ^ "BBC News : College breaches radioactive regulations". 2002-03-12. http://news.bbc.co.uk/1/hi/england/1868414.stm. Retrieved 2009-05-05.
  61. ^ "Hydrogen cyanide msds". http://www.physchem.ox.ac.uk/MSDS/HY/hydrogen_cyanide.html.
  62. ^ a b "Health Impacts from Acute Radiation Exposure". http://www.pnl.gov/main/publications/external/technical_reports/PNNL-14424.pdf. Retrieved 2009-05-05.
  63. ^ a b "Nuclide Safety Data Sheet: Polonium–210". http://hpschapters.org/northcarolina/NSDS/210PoPDF.pdf. Retrieved 2009-05-05.
  64. ^ "Effective half-life of polonium in the human". OSTI 7162390.
  65. ^ "Polonium Poisoning". http://nuclearweaponarchive.org/News/PoloniumPoison.html. Retrieved 2009-05-05.
  66. ^ Harrison, J.; Leggett, Rich; Lloyd, David; Phipps, Alan; Scott, Bobby (2007). "Polonium-210 as a poison". J. Radiol. Prot. 27 (1): 17–40. Bibcode 2007JRP....27...17H. 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"
  67. ^ "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.
  68. ^ "National Academy of Sciences 1999 report: Health Effects Of Exposure To Indoor Radon". http://newton.nap.edu/html/beir6/. Retrieved 2009-05-05.
  69. ^ "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.
  70. ^ "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.
  71. ^ "PilgrimWatch – Pilgrim Nuclear – Health Impact". http://www.pilgrimwatch.org/health1.html. Retrieved 2009-05-05.
  72. ^ Zimmerman, Peter D. (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.
  73. ^ Bagnall, p. 204
  74. ^ Geoghegan, Tom (2006-11-24). "The mystery of Litvinenko's death". BBC News. http://news.bbc.co.uk/1/hi/uk/6180432.stm.
  75. ^ "UK requests Lugovoi extradition". BBC News. 2007-05-28. http://news.bbc.co.uk/1/hi/uk/6698545.stm. Retrieved 2009-05-05.
  76. ^ Watson, Roland (2006-12-03). "Focus: Cracking the code of the nuclear assassin". The Sunday Times (London). http://web.archive.org/web/20080210081034/http://www.timesonline.co.uk/article/0,,2087-2484295_1,00.html. Retrieved 2010-05-22.
  77. ^ Dunkerley, William. "The Phony Litvinenko Murder". http://www.omnicompress.com/plm.
  78. ^ Manier, Jeremy (2006-12-04). "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.
  79. ^ Karpin, Michael (2006). The bomb in the basement: How Israel went nuclear and what that means for the world. Simon and Schuster. ISBN 0-7432-6594-7.
  80. ^ 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.
  81. ^ Bart, Katharina (2012-07-03). Swiss institute finds polonium in Arafat's effects. Reuters.
  82. ^ "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.
  83. ^ 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 (3): 247. doi:10.1080/095530097143338.
  84. ^ R. Baselt, Disposition of Toxic Drugs and Chemicals in Man, 10th edition, Biomedical Publications, Seal Beach, CA, in preparation. http://www.biomedicalpublications.com/dt10.pdf
  85. ^ "Staticmaster Ionizing Brushes". AMSTAT Industries. http://www.amstat.com/solutions/staticmaster.html. Retrieved 2009-05-05.
  86. ^ "General domestic licenses for byproduct material". http://www.nrc.gov/reading-rm/doc-collections/cfr/part031/full-text.html. Retrieved 2009-05-05.
  87. ^ Singleton, Don (2006-11-28). "The Availability of polonium-210". http://donsingleton.blogspot.com/2006/11/polonium-210.html. Retrieved 2006-11-29.
  88. ^ "UnitedNuclear Isotopes for sale over the Internet". http://www.unitednuclear.com/isotopes.htm. Retrieved 2007-03-19.
  89. ^ Hill, C. R. (1960). "Lead-210 and Polonium-210 in Grass". Nature 187 (4733): 211. Bibcode 1960Natur.187..211H. doi:10.1038/187211a0.
  90. ^ Hill, C.R. (1963). "Natural occurrence of unsupported radium-F (Po-210) in tissue". Health Physics (9): 952–953.
  91. ^ Heyraud, M.; Cherry, R. D. (1979). "Polonium-210 and lead-210 in marine food chains". Marine Biology 52 (3): 227. doi:10.1007/BF00398136.
  92. ^ Lacassagne, A. & Lattes, J. (1924) Bulletin d'Histologie Appliquée à la Physiologie et à la Pathologie, 1, 279.
  93. ^ Vasken Aposhian, H.; Bruce, D. C. (1991). "Binding of Polonium-210 to Liver Metallothionein". Radiation Research 126 (3): 379–382. doi:10.2307/3577929. JSTOR 3577929. PMID 2034794.
  94. ^ Hill, CR (1965). "Polonium-210 in man". Nature 208 (5009): 423–8. Bibcode 1965Natur.208..423H. doi:10.1038/208423a0. PMID 5867584.
  95. ^ Hill, C. R. (1966). "Polonium-210 Content of Human Tissues in Relation to Dietary Habit". Science 152 (3726): 1261–2. Bibcode 1966Sci...152.1261H. doi:10.1126/science.152.3726.1261. PMID 5949242.
  96. ^ Radford EP Jr, Hunt VR (1964). "Polonium 210: a volatile radioelement in cigarettes". Science 143 (3603): 247–9. Bibcode 1964Sci...143..247R. doi:10.1126/science.143.3603.247. PMID 14078362.
  97. ^ Kelley TF (1965). "Polonium 210 content of mainstream cigarette smoke". Science 149 (3683): 537. Bibcode 1965Sci...149..537K. doi:10.1126/science.149.3683.537.
  98. ^ Hussein EM (1994). "Radioactivity of phosphate ore, superphosphate, and phosphogypsum in Abu-zaabal phosphate". Health Physics 67 (3): 280–2. doi:10.1097/00004032-199409000-00010. PMID 8056596.
  99. ^ Barisic D, Lulic S, Miletic P (1992). "Radium and uranium in phosphate fertilizers and their impact on the radioactivity of waters". Water Research 26 (5): 607. doi:10.1016/0043-1354(92)90234-U..
  100. ^ Scholten LC, Timmermans CWM (1992). "Natural radioactivity in phosphate fertilizers". Nutrient cycling in agroecosystems 43 (1–3): 103. doi:10.1007/BF00747688.
  101. ^ Tidd J (2008). "The big idea: polonium, radon and cigarettes". Journal of the Royal Society of Medicine 101 (3): 156–7. doi:10.1258/jrsm.2007.070021. PMC 2270238. PMID 18344474. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2270238/.
  102. ^ Birnbauer, William (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.
  103. ^ Ota, Tomoko; Sanada, Tetsuya; Kashiwara, Yoko; Morimoto, Takao and Sato, Kaneaki (2009). "Evaluation for Committed Effective Dose Due to Dietary Foods by the Intake for Japanese Adults". Japanese Journal of Health Physics 44. http://ci.nii.ac.jp/naid/110007226760.
  104. ^ Smith-Briggs, JL; Bradley, EJ (1984). "Measurement of natural radionuclides in U.K. diet". Science of the Total Environment 35 (3): 431–40. doi:10.1016/0048-9697(84)90015-9. PMID 6729447.

Bibliography

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