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.
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.
This can be done through:
- Entry through skin abrasions or wounds.
A person cannot be contaminated by another, contaminated person unless they swallow or inhale bodily fluids from that person.
How it causes damage
Polonium radiation destroys DNA and can lead to cell death and cancer.
Polonium-210 is a known carcinogen. When inhaled, it causes lung cancer.
When swallowed, it becomes concentrated in red blood cells, before spreading to the liver, kidneys, bone marrow, gastrointestinal tract, and the testicles or ovaries.
As polonium spreads around the body, it leaves a trail of reactive radicals, because it takes electrons from any molecule in its path.
Damage to DNA from the alpha particle radiation can cause apoptosis, or "cell suicide." Even low-level DNA damage can cause genetic changes that affect the cells' ability to reproduce.
Different organs and tissues vary in their sensitivity to the alpha radiation damage. Bone marrow tissue is particularly susceptible, because it creates the blood cells, and also the lining of the gut.
The main difficulty with diagnosing polonium-210 poisoning is that it is so rare. No one would expect it. Some laboratories in the U.S. can carry out urine tests to assess for it.
Symptoms would depend on the strength of polonium used.
They would likely include:
- nausea and vomiting
- hair loss
- lowered white blood cell count, or lymphopenia
- damage to bone marrow
The higher the dose, the faster the effect will be.
After these acute symptoms, the patient may appear to recover, but bone marrow damage will continue, resulting in lower white blood cell and platelet counts.
Next, depending on the dose, various body organs will be affected, including the bone marrow, the gastrointestinal system, and the cardiovascular and central nervous system (CNS).
If the CNS is affected, this is irreversible and leads to death. At high doses, this can lead to confusion, convulsion, and coma within minutes of the poisoning.
Finally, the person will either die or recover. If they do not recover, they will die within weeks or months. Anyone who survives may take months to recover.
If polonium poisoning is reversible, and if the person knows they have been exposed, an early diagnosis can lead to successful treatment. However, success will depend on the size of the dose received.
Supportive care will include:
- Symptom control
- Prevention or treatment of infections, more likely because of a lower WBC count
- Blood and platelet transfusions when needed
If a person knows they have very recently swallowed the poison, gastric aspiration or lavage may help remove the source of radiation.
The use of certain drugs may reduce the effects of radiation poisoning.
Chelating agents such as dimercaprol and penicillamine have been used in animal research and some human subjects. Chelation is used to treat poisoning with heavy metals as the chelating agent can bind to the metal and prevent its absorption, leading to its elimination from the body.
Dimercaprol has been used to treat poisoning with the heavy metals mercury, gold, bismuth, antimony, thallium, and lead. It has been used with some success to chelate polonium.
In 2007, concerns were raised in the United States (U.S.), about Polonium-210 levels in ground water in Fallon, in the Lahontan Valley, NV.
The Centers for Disease Control and Prevention (CDC) say that those using public water are not at risk. They advise people who are using well water, and whose water tests high for polonium-201, to process their water with a properly functioning reverse osmosis system before drinking it or using it for cooking or for animals.
In 2007, the Food and Drug Administration (FDA) found that levels of the substance in milk were not enough to worry about.
Now, however, there is concern that new methods of oil and gas production, including "fracking" may lead to higher levels of Polonium-210 and other potentially hazardous products. The Environmental Protection Agency (EPA) is monitoring this.