Russian spy: What is a nerve agent and how was it used in the attempted murder of Sergei Skripal?

Police are trying to figure out where the toxic substance was made and the effects it has had

Sergei Skripal, a Russian former double agent, was found slumped on a bench alongside his daughter in Salisbury on Sunday. We now know they had been exposed to a nerve agent.

Such toxic substances have been used to deadly effect in assassinations and conflicts of the past.

They disrupts signals in the nervous system, causing debilitating side effects which can be fatal.

Here is everything you need to know about nerve agents

What are nerve agents?

They are anything that affects the nervous system. There are various different types of nerve agents and they can take many different forms.

Usually they come in liquid form as opposed to a gas and can seep through the skin and are incredibly toxic.

Russia came across such chemical agents for the first time when they swept into East Germany following World War Two and took control of the plants where they were made.

How do they work?

The toxins in nerve agents interfere with the central nervous system, causing the body to become overstimulated.

There are several different forms including Sarin, VX and Tabun, all of which have very similar structures and appear to work in the same way.

Dr Simon Cotton from the University of Birmingham said: “They interfere with the transmitting of nerve impulses.

“Our bodies use a molecule called acetylcholine that migrates the gaps between cells – it goes from one cell and slots into the second and triggers a nerve impulse.

“The body has to get rid of acetylcholine that is docked in the receptor because it builds up and you keep getting nerve impulses and become overstimulated.

“Our bodies have got an enzyme that breaks up acetylcholine called acetylcholinesterase – what a nerve agent does is bind to the acetylcholinesterase and stops it from working.”

What are the symptoms?

Twitching, spasms, heart failure and respiratory arrest are among the more common side effects.

Dr Cotton added: “It is basically overstimulated to death because of the build-up of acetylcholine.”

How much is needed to make an impact and how long does it take?

Only time amounts of nerve agent is required for it to take effect.

It is so toxic that it would usually be transported in something tightly sealed and those who apply it will need protective clothing.

“A drop would be needed, that is all, it is that sort of scale – a tiny scale,” Dr Cotton said.

People would start feeling funny within a few seconds, but it would depend on the dose.”

How is it applied?

This can vary and doses can be turned into an aerosol can spray or be used on a cloth.

When Kim Jong Nam, North Korea leader Kim Jong Un’s half-brother, was killed in Malaysia in 2017, a cloth doused with VX was smeared on his face.

Can victims be treated?

There are antidotes including a medication called atropine but they must be administered soon after exposure for them to work properly.