Online Encyclopedia Search Tool

Your Online Encyclopedia


Online Encylopedia and Dictionary Research Site

Online Encyclopedia Free Search Online Encyclopedia Search    Online Encyclopedia Browse    welcome to our free dictionary for your research of every kind

Online Encyclopedia


Castor beans
Castor beans

The protein ricin (pronounced rye-sin) is a poison manufactured from the castor bean (Ricinus communis). Ricin can be extracted from castor beans and is known to have an average lethal dose of 0.2 milligrams (1/5,000th of a gram). It is considered to be twice as deadly as cobra venom.


Toxicity and manufacture

Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. There is no known antidote; only symptomatic and supportive treatment is available. Long term organ damage is likely in survivors. In small doses, such as the typical dose contained in a measure of castor oil, ricin causes digestive tract cramps. Ingested in larger doses, ricin causes severe diarrhea and victims can die of shock. (See abrin).

Although the castor bean plant has long been noted for its toxicity, ricin was first isolated and named in 1888 by H. Stillmark. Modern feed-making techniques break down the ricin in castor beans by heating at 140 degrees Celsius for 20 minutes, although some studies suggest that residual toxic effects may linger [1].

Ricin consists of two distinct protein chains (ricin A and B) that are linked to each other. Ricin A is toxic to the cell by interfering with RNA function, and thus protein synthesis, whereas ricin B is important for assisting ricin A into a cell by binding with a cell surface component. Inducing ricin B antibodies in humans may have been done.

Many plants such as barley have the A chain but not the B chain. Since people do not get sick from eating large amounts of such products, ricin A is of extremely low toxicity if and only if the B chain is not present.

Ricin is easily purified from castor-oil manufacturing waste. The seed-pulp left over from pressing for castor oil contains on average about 5% by weight of ricin. Since 0.2 mg of purified Ricin constitutes a fatal dose, this is a considerable amount of ricin.

As few as one Castor Bean, about 3 grams, may be fatal in a child.

Ricin production process

Use as a chemical/biological warfare agent

The best-known documented use of ricin as an agent of biological warfare was by the Soviet Union's KGB during the Cold War. In 1978, the Bulgarian dissident Georgi Markov was assassinated by Bulgarian secret police who surreptitiously 'shot' him on a London street with a modified umbrella using compressed gas to fire a tiny pellet contaminated with ricin into his leg. He died in hospital a few days later; the pellet was discovered entirely by happenstance.

Despite ricin's extreme toxicity and utility as an agent of chemical/biological warfare, it is extremely difficult to limit the production of the toxin. Under both the 1972 Biological Weapons Convention and the 1997 Chemical Weapons Convention, ricin is defined as a "schedule one" controlled substance. Despite this, more than 1 million metric tons of castor beans are processed each year, and approximately 5% of the total is rendered into a waste containing high concentrations of ricin toxin [2].

In August of 2002, US officials asserted that the Islamic militant group Ansar al-Islam tested ricin, along with other chemical and biological agents, in northern Iraq.

To put ricin as weapon into perspective, it is worth noting that as a biological/chemical weapon, ricin may be considered as not very powerful, if only in comparison with other poisons such as botulinum or anthrax. Hence, a military willing to use biological weapons and having advanced resources would rather use either of the latter than ricin. That is, though easy to produce, it is not as practical nor likely to cause as high casualities as other agents. Ricin degrades (ie, the protein changes structure and becomes less dangerous) much more readily than, for example, anthrax spores. (Jan van Aken, an expert on biological weapons explained in an interview with the German magazin Der Spiegel that he judges it rather reassuring that Al Qaeda experimented with ricin as it suggests their inability to produce botulin or anthrax.)

Pure ricin could be dispersed through the air, however it would tend to be oxidized and rendered harmless by ozone, nitrogen oxides, and other pollutants in a matter of minutes. Since it acts as an enzyme, catalyzing destruction of ribosomes, even a single oxidation is likely to render the ricin molecule harmless. Presumably it could be sealed inside some sort of dust particle that would dissolve in water, but this would be difficult.

The major reason it is dangerous is that there is no specific antidote, and that it is very easy to obtain (the castor bean plant is a common ornamental, and can be grown at home without any special care). Ricin is actually several orders of magnitude less toxic than botulinum or tetanus toxins, but those are more difficult to obtain.

Ricin-related arrests in Britain in 2003

Traces of ricin were detected by British police in a flat in Wood Green, North London after a raid on a suspected ring of terrorists in January 2003. The group was suspected of intending to use the poison in an attack on the London subways. A little later several arrests were made in France and a bottle of something that tested positive for ricin was found. Further analysis identified the material as ground wheat germ. The analytic confusion was caused by the similarity of many plant proteins to one of the ricin components, which suggests that higher quality (better specificity and sensitivity) analytic tests for ricin are needed.

Six more suspects have been arrested in Bournemouth in England in connection with the investigation into ricin found in London.

Three more suspects have been arrested in Manchester in England in connection with the investigation into ricin found in London, although it now appears as though the raid was initially carried out pursuant to an investigation into immigration issues. A Special Branch policeman, Stephen Oake , was fatally stabbed during the arrests, and three other officers were also injured, one seriously.

On January 20, 2003 Finsbury Park mosque was raided by police, apparently as part of the investigation into the discovery of ricin in Wood Green. A number of men who were apparently living at the mosque were arrested.

Ricin in Washington, D.C.

Ricin was detected in the mail at the White House in Washington, D.C. in November of 2003. The letter containing it was intercepted at a mail handling facility off the grounds of the White House, and it never reached its intended destination. The letter contained a fine powdery substance that later tested positive for ricin. Investigators said it was low potency and was not considered a health risk. This information was not made public until February 3, 2004, when preliminary tests showed the presence of ricin in an office mailroom of U.S. Senate Majority Leader Bill Frist's office. There were no signs that anyone who was near the contaminated area developed any medical problems. Several Senate office buildings were closed as a precaution.

Ricin in Popular Culture

Ricin was used as the poison of choice of the murderer in the 1962 comedy film Kill or Cure.

See also

External links

Last updated: 11-10-2004 23:33:57