Deadly nerve agent sarin

Last updated at 16:42 17 May 2004


Sarin is a man-made colourless, odourless substance which is 25 times more dangerous than cyanide.

A pinprick-sized drop - a lethal dose of just 0.5mg for an adult human - can kill.

It is a member of the organophosphate family of chemicals which were widely used as pesticides before their effects were fully known.

Organophosphates have also been developed as "nerve agents", which have been the dominant form of chemical weapons since the Second World War.

They are easily dispersed and highly toxic. Agents such as sarin have rapid effects when absorbed through the skin and inhaled.

It can be used in liquid form or as a gas, which is heavier than air and floats above the ground.

As a liquid it can be used to poison foods or water or applied to clothing.

Reactions to the vapour form occur within seconds, reaction to applications to clothing can occur up to 18 hours later.

Mild exposure can lead to a wide range of symptoms from nausea and vomiting to paralysis and convulsions in more severe cases. Long-term neurological damage can also be caused.

Exposure can be treated with antidotes if applied quickly.

Because agents like sarin are stable and easy to produce from cheap, available products, they can be made by anyone with a basic laboratory - and an irresponsible mind.

Sarin was first developed by German scientists in 1938 as a pesticide but it was not used during the Second World War.

It is believed to have been used among other nerve agents between 1983 and 1988 in the Iran-Iraq war.

And it was dropped on the Kurdish town of Halabja in March 1988 by Saddam Hussein's forces, killing hundreds of civilians said to be Iran sympathisers.

Sarin was also used by the Aum Supreme Truth doomsday cult to kill seven people and injure 300 in Matsumoto, Japan, in 1994 and again to kill 12 people and injure 5,500 on the Tokyo underground in a 1995 attack.

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