Polonium-210 is the deadly poison that was used to kill the former Russian spy, Alexander Litvinenko, in London in 2006. He died of radiation sickness.
Litvinenko is alleged to have swallowed a fatal dose of Po-210 by drinking tea at a business meeting with two other Russians. Both were charged with his murder.
This incident is thought to have exposed 700 people to radiation, although none became seriously ill. Some locations in London, including a restaurant and nightclub, were temporarily closed as a safety measure.
The autopsy involved complex safety measures.
Polonium-210 is abbreviated to Po-210, (210)Po, or 210 Po.
Fast facts on polonium-210
Here are some key points about polonium-210. More detail is in the body of this article.
Polonium-210 is a rare radioactive metal discovered by Marie Curie in the late 19th century.
While radioactive, it emits a high-energy form of radiation, but the particles do not travel far and it decays relatively quickly.
If polonium-210 enters the body, through inhalation, swallowing, broken skin, the results can be fatal.
By mass, polonium-210 is one of the deadliest toxins, around 250 billion times more toxic than hydrogen cyanide.
What is Po-210?
Polonium-210 is highly radioactive substance and a lethal poison.
Polonium is a radioactive chemical element (atomic number 84) that was discovered in 1898 by Marie Curie, who named the element after her country, Poland.
In its natural state, at room temperature, polonium is a solid metal with a silver color. Polonium-210 is one of 25 known radioactive isotopes of polonium.
Purified polonium is very volatile, and polonium isotopes are radioactive. The most common and best-known polonium isotope is polonium-210.
This material is highly dangerous, but it has a relatively short half-life. As a result, it ceases to be dangerous relatively quickly. It decays into a new, stable metal: lead.
Its physical half life is 140 days. This means that half its radioactivity dies away in this time.
Its biological half life is 40 days, so it takes 40 days for biological processes to eliminate half of the Polonium-210 in the body.
Where do you find it
Polonium-210 is present in small amounts in the human body, due to low levels in the normal environment and the food chain, especially in seafood. Tobacco smokers have more polonium-210 because smoking causes it to accumulates in the lungs.
Polonium-210 is used in industry to make devices that remove static. This is useful for making tape, rolling paper, and spinning synthetic fibers, for example. It is also used to keep environments dust free, such as in the production of computer chips.
Natural polonium is very rare. As little as about 100 micrograms (0.0001 grams) of polonium occurs in one ton of uranium ore.
Effects on the body
Polonium-210 is one of the most toxic substances known to man, yet it is all around us.
There are very low levels of polonium-210 in the environment, and it enters our bodies through the food chain, for example, when eating seafood.
These environmental levels are normally harmless to human health, except in smokers, who have higher levels.
However, in sufficient amounts, it can be lethal within days or weeks.
How dangerous is it?
Polonium does not have toxic chemical properties. The danger comes when it emits radiation.
Toxicologists estimate that one gram of polonium-210 could be enough to:
kill 50 million people
make another 50 million people ill
Litvinenko could have died after consuming less than one millionth of that amount.
As a weapon, it would be lethal. But it is also extremely difficult to obtain. When used in commercial devices, this is done in such a way that the polonium could not be separated for use as a poison.
Even if someone did manage to acquire some polonium, it is not particularly dangerous to carry around, because its high-energy radiation can be blocked by a relatively thin barrier, such as a piece of paper.
Polonium-210 cannot penetrate the skin, and the particles usually lose all their energy after traveling through a few centimeters of air.
However, this also makes it safe to transport and hard to detect, for a would-be poisoner.
To poison someone, however, it must then be introduced to the body.