By JEREMY LAURANCE in London
The mysterious assassination of Georgi Markov, a Bulgarian dissident, on Waterloo bridge in 1978 is lodged in the collective memory.
It was the day an ordinary domestic umbrella was turned into a lethal weapon by secret agents of a foreign power who committed murder on London's streets.
Markov,
an author and broadcaster who had defected to Britain nine years earlier, was stabbed in the thigh by unknown assailants, believed to be from the Bulgarian secret service. He died an agonising death three days later as doctors struggled to discover what was wrong with him. At the post-mortem examination a tiny pellet the size of a pinhead was discovered and ricin poisoning was identified as the cause of death.
Ricin is a plant toxin, which is easily extracted from the beans of the castor oil plant. The fatal dose by injection, the most lethal way of administering it, is thought to be around one microgram per kilogram of body weight. For a 63kg adult that would be equivalent to the material in a pinch of salt.
The toxin is potentially widely available. Ricin is a byproduct when castor beans are processed to make castor oil, and can be produced in liquid or crystalline form or as a dry powder. Although it is not particularly volatile it could be sprayed as an aerosol, but its use as a weapon of mass destruction is limited by the difficulty of distributing it in sufficient doses.
Dr Pat Troop, Britain's Deputy Chief Medical Officer, said yesterday that an aerosol would have to be sprayed directly into a victim's face to be an effective weapon.
It would probably not be lethal if pumped into the London Underground or an office air-conditioning system.
But there is no vaccine or antidote. Victims would be offered nursing care only to deal with their symptoms and make them as comfortable as possible.
Today it is banned under the International Chemical Weapons Convention. As a naturally occurring compound it is also classed as a biological weapon.
The real threat of an attack involving ricin is the terror it could provoke. The Government adviser on chemical weapons said yesterday : "A terror group could create a ricin aerosol. I suspect it would kill a few people but not many. But it would cause panic. That is the worry."
- INDEPENDENT
