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Polonium-210, historically called “radium F,” is the predominant naturally occurring isotope of polonium and the one most widely used. Polonium-210 is a radioactive decay product in the natural uranium-238 decay series; along with lead-210 it is one of two relatively long-lived decay products of radon-222. Polonium-210 has a half-life of 138 days, and it decays to stable lead-206 by emitting an alpha

Polonium-210, historically called “radium F,” is the predominant naturally occurring isotope of polonium and the one most widely used. Polonium-210 is a radioactive decay product in the natural uranium-238 decay series; along with lead-210 it is one of two relatively long-lived decay products of radon-222. Polonium-210 has a half-life of 138 days, and it decays to stable lead-206 by emitting an alpha

particle. One-thousandth of a gram (1 mg) of polonium-210 emits as many alpha particles as 5 g of radium-226. The energy released by

particle. One-thousandth of a gram (1 mg) of polonium-210 emits as many alpha particles as 5 g of radium-226. The energy released by

its decay is so large (140 watts/g) that a capsule containing about half a gram reaches a temperature above 500ºC.

its decay is so large (140 watts/g) that a capsule containing about half a gram reaches a temperature above 500 °C.

== Sources of Polonium ==  

== Sources of Polonium ==

Because it is produced during the decay of naturally ubiquitous uranium-238, polonium-210 is widely distributed in small amounts in the earth’s crust. Although it can be produced by the chemical processing of uranium ores or minerals, uranium ores contain less than 0.1 mg polonium-210 per ton. Originally, polonium-210 was obtained from the rich pitchblende ore found in Bohemia, but it can also be obtained from aged radium salts that contain about 0.2 mg per gram of radium. Although a number of other polonium isotopes are present in the natural decay series, their short half-lives preclude any appreciable concentrations.

Because it is produced during the decay of naturally ubiquitous uranium-238, polonium-210 is widely distributed in small amounts in the earth’s crust. Although it can be produced by the chemical processing of uranium ores or minerals, uranium ores contain less than 0.1 mg polonium-210 per ton. Originally, polonium-210 was obtained from the rich pitchblende ore found in Bohemia, but it can also be obtained from aged radium salts that contain about 0.2 mg per gram of radium. Although a number of other polonium isotopes are present in the natural decay series, their short half-lives preclude any appreciable concentrations.

Due to its scarcity, polonium-210 is usually produced artificially in a nuclear reactor by bombarding bismuth-209 (a stable isotope) with neutrons. This forms radioactive bismuth-210, which has a half-life of 5 days. Bismuth-210 decays to polonium-210 through beta decay. Milligram amounts of polonium-210 have been produced by this method. The longer-lived isotopes polonium-209 (half-life 103 years) and polonium-208 (half-life 2.9 years) are also produced in reactors or particle accelerators, but these are very expensive.

Due to its scarcity, polonium-210 is usually produced artificially in a nuclear reactor by bombarding bismuth-209 (a stable isotope) with neutrons. This forms radioactive bismuth-210, which has a half-life of 5 days. Bismuth-210 decays to polonium-210 through beta decay. Milligram amounts of polonium-210 have been produced by this method. The longer-lived isotopes polonium-209 (half-life 103 years) and polonium-208 (half-life 2.9 years) are also produced in reactors or particle accelerators, but these are very expensive.

== Uses of Polonium ==

== Uses of Polonium ==

Polonium-210 is used mainly in static eliminators, which are devices designed to eliminate static electricity in machinery where it can be caused by processes such as paper rolling, manufacturing sheet plastics, and spinning synthetic fibers. The polonium-210 is generally electroplated onto a backing foil and inserted into a brush, tube, or other holder. Alpha particles from the polonium ionize adjacent air, and the air ions then neutralize static electricity on the surfaces in contact with the air. These devices generally need to be replaced every year because of the short half-life of this [[radioisotope]]. Polonium-210 is also used in brushes to remove dust from photographic films and camera lenses. Static eliminators typically contain from tens to hundreds of mCi (thousandth of a [[Curie|curie]]) of radioactivity. Polonium-210 can also be combined with beryllium to produce neutron sources, and in fact it was used as neutron-producing initiators of at least the first generation of atomic weapons. In addition, polonium-210 has been investigated as a heat source for thermoelectric power devices for space applications.

Polonium-210 is used mainly in static eliminators, which are devices designed to eliminate static electricity in machinery where it can be caused by processes such as paper rolling, manufacturing sheet plastics, and spinning synthetic fibers. The polonium-210 is generally electroplated onto a backing foil and inserted into a brush, tube, or other holder. Alpha particles from the polonium ionize adjacent air, and the air ions then neutralize static electricity on the surfaces in contact with the air. These devices generally need to be replaced every year because of the short half-life of this [[radioisotope]]. Polonium-210 is also used in brushes to remove dust from photographic films and camera lenses. Static eliminators typically contain from tens to hundreds of mCi (thousandth of a [[curie]]) of radioactivity. Polonium-210 can also be combined with beryllium to produce neutron sources, and in fact it was used as neutron-producing initiators of at least the first generation of atomic weapons. In addition, polonium-210 has been investigated as a heat source for thermoelectric power devices for space applications.

== Presence in environment ==

== Presence in environment ==

Lifetime cancer mortality risk coefficients have been calculated for nearly all radionuclides, including polonium-210 . Risk coefficients for inhalation are about 6 times higher than for dietary ingestion. Similar to other radionuclides, the risk coefficients for ingestion of tap water containing polonium-210 are about 75% of those shown for dietary ingestion. Polonium-210 poses no external risk when outside the body.

Lifetime cancer mortality risk coefficients have been calculated for nearly all radionuclides, including polonium-210 . Risk coefficients for inhalation are about 6 times higher than for dietary ingestion. Similar to other radionuclides, the risk coefficients for ingestion of tap water containing polonium-210 are about 75% of those shown for dietary ingestion. Polonium-210 poses no external risk when outside the body.

== External Links ==

== External links ==

*[http://www.ead.anl.gov/pub/doc/polonium.pdf/ Polonium: Human Health Fact Sheet, August, 2005]

*[http://www.ead.anl.gov/pub/doc/polonium.pdf/ Polonium: Human Health Fact Sheet, August, 2005]

*[http://www.bt.cdc.gov/radiation/isotopes/polonium/qa.asp/ Information about Public Health Issues Related to Polonium-210]

*[http://www.bt.cdc.gov/radiation/isotopes/polonium/qa.asp/ Information about Public Health Issues Related to Polonium-210]

[[Category:Elements]]

[[Category:Elements]]

[[Category:Health]]

[[Category:Health]]

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