Was Russian spy taken down by VX?Just 10 milligrams of the nerve agent is enough to kill in minutes

Military scientists are desperately trying to identify what was used to strike down Russian spy Sergei Skripal.

Poison has typically been Russia's weapon of choice when 'dealing with' perceived traitors.

From poison-tipped umbrellas to radioactive tea, a number of deadly toxins have been used in Russia-linked deaths in the UK.

VX

VX is one of the deadliest chemical weapons created by man. Experts say just 10 milligrams of the nerve agent or a single drop is enough to kill in minutes.

With the texture and feel of engine oil, it can cause convulsions, loss of consciousness, paralysis and respiratory failure in minutes.

It has the texture and feel of engine oil, but its only known use is as a chemical warfare agent.

VX - classified as a weapon of mass destruction by the United Nations - was used in the murder of Kim Jong Nam, the estranged half-brother of North Korean leader Kim Jong UN, at Kuala Lumpur airport on February 13. 

SARIN

Sarin – a volatile nerve agent that was initially developed in Germany as a pesticide – is a liquid that is clear, colourless, tasteless and odourless.

People can be exposed to sarin through skin contact, eye contact or by breathing it in through the air or it can be mixed with water or food.

Symptoms of severe exposure to sarin include loss of consciousness, convulsions, paralysis and respiratory failure leading to death.

Other possible poisons: 

THALLIUM

 Dubbed the 'poisoner's poison', Thallium is highly toxic but is tasteless, colourless and odourless and any contact with skin is dangerous.

Thallium (pictured) is highly toxic but is tasteless, colourless and odourless and any contact with skin is dangerous

Thallium, once known as 'Inheritance Powder' because it could easily kill people, is typically found in electronics and was used by Saddam Hussein on dissidents.

It is slow-acting and painful and symptoms include vomiting, diarrhea and hair loss. However, it is hard to trace and experts at Porton Down science park in Salisbury may never find out what was used.   

RICIN

Ricin is a poison found naturally in castor beans, the same substance used to make castor oil.

If castor beans are chewed and swallowed, the released ricin can cause injury.

It can be found as a powder, mist or pellet or it can be dissolved in water or weak acid. It is very difficult to trace.

Ricin works by getting inside the body's cells and preventing them from making the proteins they need – and without them, cells die.

Eventually this is harmful to the whole body and can cause death. But the effects of ricin poisoning depend on whether it was inhaled, ingested or injected.

Cold War dissident Georgi Markov was assassinated on the streets of London in 1978 by a Bulgarian secret service agent, who used an umbrella that fired a pellet of ricin into his leg. 

Ricin is a poison found naturally in castor beans (pictured), the same substance used to make castor oil

When inhaled, symptoms include difficulty in breathing, fever, cough, nausea, sweating and tightness in the chest. Death occurs after blood pressure plummets and breathing stops.

When swallowed, ricin causes vomiting, diarrhea, dehydration, low blood pressure, seizures, and blood in the urine.

There is no known antidote but treatment includes use of respirators, fluids, flushing the stomach and treating low blood pressure.

POLONIUM-210

The toxin is considered an ideal poison because it is harmless until swallowed with a miniscule amount sufficient to cause a slow, painful and very public death.

However, it is almost impossible to acquire without a nuclear reactor - and then decays within a few months.

The radioactive substance was used to kill former Russian spy Alexander Litvinenko in London in 2006, perhaps the most high-profile case of fatal poisoning.

Thallium was the deadly poison that investigators originally thought had killed Alexander Litvinenko (pictured) 

It was slipped into a cup of green tea at the Millennium Hotel in Mayfair.

Polonium-210 also leaves a radioactive trace, which in the Litvinenko case led investigators to Andrei Lugovoy.

In 2016 a public inquiry concluded that the killing of Mr Litvinenko had 'probably' been carried out with the approval of Russian president Vladimir Putin.

THALLIUM

Thallium was the deadly poison that investigators originally thought had killed Alexander Litvinenko.

Thallium sulphate is colourless, odourless and tasteless salt that is soluble in water, making it an almost ideal poison to use to kill.

Known as the 'poisoner's poison', if ingested, it attacks the nervous system and internal organs and even a dose as small as a gram can cause death.

Other symptoms include hair loss, vomiting, and diarrhoea. Within three days, victims can suffer headaches, convulsions, coma, delirium, dementia and even psychosis.

It's believed Russian businessman Alexander Perepilichnyy was poisoned after Gelsemium was slipped into his sorrel soup

GELSEMIUM

Gelsemium is a rare and deadly plant poison which initially causes dizziness, nausea, blurred vision and convulsions.

At larger doses, it causes paralysis of the spinal cord leading to an almost loss of muscle power and ultimately asphyxia.

It's believed Russian businessman Alexander Perepilichnyy was poisoned after the substance was slipped into his sorrel soup.

Police initially thought his death was not suspicious because there was no signs of toxins after he was found dead near his luxury home in Surrey in 2012.

But scientists later found chemical traces of gelsemium in his stomach. An inquest into his death has been adjourned pending further inquiries.

Former Ukranian President Victor Yushchenko suffered facial disfigurement after being given TCDD

CURARE

Curare is a plant extract initially used for poison arrows by South American tribes.

It causes the respiratory muscles to contract, asphyxiating the victim.

Scientists in Russia used curare under Joseph Stalin and American-born Communist spy Isaiah Oggins was executed in 1947 using this drug.

TCDD

This type of dioxin, an ingredient of Agent Orange, was used in the attempted assassination of Ukrainian opposition leader Viktor Yushchenko in 2004. 

He survived the attack to become his country’s president, but suffered major facial disfigurements.