zubedayo_mchuzi
JF-Expert Member
- Sep 2, 2011
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Toxicity
Po-210 is highly radioactive and chemically toxic element. Direct damage occurs from energy absorption into tissues from alpha particles. As an alpha-emitter Po-210 represents a radiation hazard only if taken into the body. It´s important to note that alpha particles do not travel very far - no more than a few centimetres in air. They are stopped by a sheet of paper or by the dead layer of outer skin on our bodies. Therefore, external exposure from Po-210 is not a concern and Po-210 does not represent a risk to human health as long as Po-210 remains outside the body. Most traces of it on a person can be eliminated through careful hand-washing and showering.
Po-210 can enter the body through eating and drinking of contaminated food, breathing contaminated air or through a wound. The biological half-time (the time for the level of Po-210 in the body to fall by half) is approximately 50 days. If taken into the body, Po-210 is subsequently excreted, mostly through faeces but some is excreted through urine and other pathways. People who come into contact with a person contaminated by Po-210 will not be at risk unless they ingest or inhale bodily fluids of the contaminated person.
About Illicit Ttrafficking Incidents Involving Po-210 Of the approximately 520 incidents reported by States to the IAEA´s Illicit Trafficking Data Base since 2004, 14 incidents have involved industrial Po-210 sources. Three of these incidents occurred in 2006. The incidents involved the theft, loss, or disposal of static eliminators and air ionizers containing sealed Po-210 sources. Po-210 used in these sealed sources is bound with other materials and extraction of the Po-210 would require some chemical treatment in a laboratory.
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. 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).[4] Even in microgram amounts, handling 210Po is extremely dangerous, requiring specialized equipment (a.o., alpha glove box under depression and 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.
Acute effects
The median lethal dose (LD50) for acute radiation exposure is generally about 4.5 Sv.The committed effective dose equivalent 210Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled.[37] Since 210Po has an activity of 166 TBq per gram (4,500 Ci/g)[37] (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[38]) 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.
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 510% per Sv. 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[41] of the estimated 15,000-22,000 lung cancer deaths in the US every year that have been attributed to indoor radon.Tobacco smoking causes additional exposure to polonium.
Po-210 is highly radioactive and chemically toxic element. Direct damage occurs from energy absorption into tissues from alpha particles. As an alpha-emitter Po-210 represents a radiation hazard only if taken into the body. It´s important to note that alpha particles do not travel very far - no more than a few centimetres in air. They are stopped by a sheet of paper or by the dead layer of outer skin on our bodies. Therefore, external exposure from Po-210 is not a concern and Po-210 does not represent a risk to human health as long as Po-210 remains outside the body. Most traces of it on a person can be eliminated through careful hand-washing and showering.
Po-210 can enter the body through eating and drinking of contaminated food, breathing contaminated air or through a wound. The biological half-time (the time for the level of Po-210 in the body to fall by half) is approximately 50 days. If taken into the body, Po-210 is subsequently excreted, mostly through faeces but some is excreted through urine and other pathways. People who come into contact with a person contaminated by Po-210 will not be at risk unless they ingest or inhale bodily fluids of the contaminated person.
About Illicit Ttrafficking Incidents Involving Po-210 Of the approximately 520 incidents reported by States to the IAEA´s Illicit Trafficking Data Base since 2004, 14 incidents have involved industrial Po-210 sources. Three of these incidents occurred in 2006. The incidents involved the theft, loss, or disposal of static eliminators and air ionizers containing sealed Po-210 sources. Po-210 used in these sealed sources is bound with other materials and extraction of the Po-210 would require some chemical treatment in a laboratory.
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. 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).[4] Even in microgram amounts, handling 210Po is extremely dangerous, requiring specialized equipment (a.o., alpha glove box under depression and 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.
Acute effects
The median lethal dose (LD50) for acute radiation exposure is generally about 4.5 Sv.The committed effective dose equivalent 210Po is 0.51 µSv/Bq if ingested, and 2.5 µSv/Bq if inhaled.[37] Since 210Po has an activity of 166 TBq per gram (4,500 Ci/g)[37] (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[38]) 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.
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 510% per Sv. 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[41] of the estimated 15,000-22,000 lung cancer deaths in the US every year that have been attributed to indoor radon.Tobacco smoking causes additional exposure to polonium.
