Ricin, a derivative of the castor bean, is relatively easy to produce and stockpile. The toxin can be ground up and sprayed as an aerosol, added to food or drinks, or spread on surfaces.

The ease with which the toxin can be produced has made Ricin a weapon of choice for terrorist groups interesting in using non-conventional weapons. However, it would not be particularly suited to a mass casualty attack, and has mostly been used as a tool of assassination.

In the late 1970’s, agents of the former Soviet Union developed a variety of assassination weapons using Ricin; the best-known case is that of Bulgarian dissident Georgi Markov, who was fatally injected with Ricin inserted into the hollow tip of an umbrella as he waited for a bus on Waterloo Bridge in London in September 1978. He died four days later.

A number of terrorist organizations are known to have experimented with Ricin, including al-Qaida. A training manual used by the organization described how to manufacture the toxin, and al-Qaida members are known to have trained with Ricin in Afghanistan. U.S. troops also found traces of the toxin at suspected al-Qaida biological weapons sites in Afghanistan.

Ricin also is among the biological weapons listed by United Nations weapons inspectors as having been produced by Iraqi President Saddam Hussein’s regime.

A group affiliated with al-Qaida, which operates in the Kurdish areas of northern Iraq is also believed to have tested Ricin, along with other non-conventional agents. The group, Ansar al-Islam, is seen by some as a link between al-Qaida and Saddam Hussein.

London group may be part of international network

The raids in London are believed to be linked with similar anti-terrorism sweeps in France, where police have disrupted an Algerian-dominated network linked to Al-Qaida.

In November British police, acting partly on a tip from French intelligence arrested three suspects, one of whom was a leader of the Abu Doha network, a London-based group implicated in plots to bomb Los Angeles International Airport and the cathedral in Strasbourg, France.

The arrests sparked a wave of press reports that al-Qaida activists were plotting an attack with cyanide gas on the London underground. The government denied that such an attack was planned. However, French officials later said that intelligence had indicated a danger of chemical attack in Britain.

Last month, French police arrested three Algerians and a Moroccan, and discovered bomb-making materials, formulas for cyanide, and a protective suit in a Paris apartment. Some of the suspects were believed to be linked with those arrested the previous month in London. 

The arrests in Paris and London have caused a flurry of rumors that terrorists have been planning to carry out a non-conventional attack somewhere in Europe. However, until now, there has been no hard evidence that terrorists had actually acquired the materials needed for such an attack. The discovery of traces of Ricin in London marks the first time police have had enough evidence to issue a public warning.