Ricin 

Symptoms: 

Weakness, fever, cough and pulmonary edema occur 18-24 hours after inhalation exposure, followed by severe respiratory distress and death from hypoxemia in 36-72 hours.

Signs and symptoms noted above in large numbers of geographically clustered patients could suggest an exposure to aerosolized ricin. The rapid time course to severe symptoms and death would be unusual for infectious agents. Laboratory findings are nonspecific but similar to other pulmonary irritants which cause pulmonary edema. Specific serum ELISA is available. Acute and convalescent sera should be collected.

Treatment: 

Management is supportive and should include treatment for pulmonary edema. Gastric decontamination measures should be used if ingested.

Prophylaxis:

There is currently no vaccine or prophylactic antitoxin available for human use, although immunization appears promising in animal models. Use of the protective mask is currently the best protection against inhalation.

Isolation and Decontamination: 

Standard Precautions for healthcare workers. Secondary aerosols should generally not be a danger to health care providers. Weak hypochlorite solutions (0.1% sodium hypochlorite) and/or soap and water can decontaminate skin surfaces.

Background

A large protein chain, ricin is the toxin found in the castor bean that grows from the plant Ricinis communis. Once the oils have been removed, ricin can be readily precipitated from the remnants of the castor bean mash. Ricin in its toxic form consists of an "A" and "B" chain. The latter part attaches itself to the cell, and the A segment secretes itself into the ribosome, inhibiting protein synthesis. This results in the death of the cell. Victims of ricin poisoning may experience varying symptoms, including nausea, vomiting, headache, and shock that can lead to death. In cases where ricin has been injected, ricin poisoning may also produce a high fever. When inhaled in sufficient doses, ricin causes the death of tissue in the lungs and airways, leading to severe inflammation and edema. Death from ricin poisoning often occurs many hours after exposure.

Ricin presents a threat not just because of its highly toxic effects in humans, but also because of the wide availability of its source material, the castor plant. Furthermore, the techniques for manufacturing ricin are reasonably well known, and have often been described in the open literature.

Castor beans, and particularly the oil that can be extracted from them, have been used throughout the centuries. In the fourth century B.C.E., Herodotus described how the Egyptians used the oil of the versatile castor plant, and its beans have been found in the tombs of the pharaohs. In addition to its excellent lubricating properties in high-performance engines, traditional applications for castor oil include its use in laxatives. The oil lubricant firm Castrol™ has utilized castor beans for engines and other functions since 1909. The worldwide market for castor oil is currently valued at about US$400 million, with the annual demand averaging around 500,000 tons. In addition to its use in lubricating oils, castor oil is found in various products such as plastics, paints, shampoo, and cosmetics. Major national producers of castor beans include India, China, and Brazil. Castor beans are no longer grown in the United States, mostly due to low profit margins but also to liability concerns, since the toxin is still present in castor beans following oil extraction. The potent allergens produced by the beans during processing can also be hazardous to workers.

Near the end of World War I, the United States Chemical Warfare Service (CWS) extracted ricin from castor beans to produce a weapon. In a cooperative effort with British military scientists during World War II, a so-called "W bomb" was developed and tested. There is no evidence that it was ever used in actual combat.

Ricin and Bioterrorism

Generating a large scale aerosol is achieved best with a dry powder consisting of very small particles. Laboratory tests performed in the United States found that about 40 micrograms per kilogram of animal weight (rhesus monkeys) were sufficient to cause death through the inhaled route. Extrapolated in human terms, this would be equivalent to an (accumulated) lethal dose of about 3 milligrams for the average adult. This is clearly a potent toxin, although it is not much more toxic than the chemical VX nerve agent (which is lethal at about 10-15 milligrams) and is far less toxic than botulinum toxin, the world's most toxic substance.

Injected into the bloodstream, ricin has been estimated to be lethal at 70 micrograms for a person weighing about 160 pounds. Ricin could also potentially be used to contaminate shrapnel. Being heat stable, enough ricin might survive the blast of an improvised explosive device (IED).

For ingested amounts, low absorbability factors and hostile conditions in the gut make oral lethal doses for ricin significantly higher. In studies using laboratory mice, it required 20 milligrams per kilogram of weight to administer a lethal oral dose of ricin.

Using ricin to cause mass casualties would require either its aerosolization by means of a dispersal device or its addition to food and beverages as a contaminant. Both of these methods would require extensive prior research, development, operational planning, and testing, and are thus probably beyond the means of most terrorists.

The investigation into possible links between the North Africans recently arrested in London and the Al Qaeda terrorist network is still underway, but there are already strong indications that such a connection exists. The leadership of Al Qaeda has previously disseminated information to its militants about the production and employment of ricin, and various components of 'Usama bin Ladin's group apparently already possess the dangerous toxin.

Instructions about how to produce ricin have appeared in materials that were prepared and used to train Al Qaeda terrorists. For example, in a chapter on assassinations from an undated Al Qaeda military manual, 'I'alan al-Jihad 'ala al-Tawaghit al-Bilad [Declaration of Jihad Against the Country's Tyrants], a copy of which was seized in 2002 by the Manchester police, a number of recipes for making poisons are provided, including a method for manufacturing ricin. The manual instructs the reader to "soak...castor-oil plant seeds in about 10 ounces of water, adding two teaspoons of [lye]...." etc. Curiously enough, the recipe described in this particular Al Qaeda manual appears to have been translated nearly word-for-word from The Poisoner's Handbook (1988), an underground pamphlet that was originally published and distributed in the United States.

It was reported in March 2002 that trace amounts of both Bacillus anthracis (anthrax) spores and ricin were found at five or six of the approximately 110 sites searched by coalition forces in Afghanistan, but the trace evidence turned out to be insufficient to permit an accurate determination.

On 10 July 2002,U.S. forces detained a suspected BW smuggler in the Afghan village of Hesarak. A preliminary examination of the materials in his possession revealed trace amounts of ricin, but additional testing in the United States did not confirm this result.

In August 2002, it was reported that the Kurdish Islamist group Ansar al-Islam (Supporters of Islam), which has apparent ties to both Al Qaeda and Iran, tested ricin on barnyard animals and possibly also on an unwitting human who later died. This particular extremist group currently operates in the northeastern region of Iraq that lies outside of Saddam Husayn's direct control, numbers several hundred guerrillas--including 150 "Afghan Arabs" (i.e., Arab volunteers who fought against the Soviets in Afghanistan)--and has apparently already seized control over a dozen or more villages. As yet, the reports about its testing of ricin have not been confirmed. The United States is now investigating reports that some of the men arrested in Britain had links to this group.

On 13 January 2003, Russian presidential aide Sergei Yaztrzhembsky claimed that his country's special forces units operating in Chechnya had found instructions for making poisons, including ricin, in the possession of a guerrilla fighter they had killed. This discovery may have added significance, in that several members of a French Islamist cell arrested in December 2002 by the Direction de la Surveillance du Territoire (DST: Directorate for Territorial Security, the French domestic intelligence agency) had previously received training together with Chechens in Georgia's Pankisi Gorge area. These particular individuals, who apparently formed part of the very same network as those later arrested in London, were originally suspected of plotting to carry out a terrorist attack with chemical weapons. After conducting a thorough forensic examination, however, French authorities concluded that they were instead planning to manufacture conventional explosives.

Recently, U.S. officials have stated that four of the Islamists originally arrested in their north London flat were "associates" of a fugitive Al Qaeda leader whose nom de guerre is Abu Mus`ab al-Zarqawi. Al-Zarqawi is a chemical warfare specialist who has been accused by Jordanian authorities of organizing both the foiled January 2000 "Millenium" plot to bomb luxury hotels and bridges in Amman and the October 2002 assassination of American diplomat Lawrence Foley in the same city. It may also be highly significant that on 4 December 2002 al-Zarqawi's chief deputy, Al Qaeda operative Abu `Abd Allah al-Shami, was killed in northern Iraq while participating in a surprise Ansar al-Islam attack on Patriotic Union of Kurdistan (PUK) forces.

Assassination Poison

The current wisdom among biological defense experts is that ricin is more likely to be used as a tool in assassinations than as a weapon of mass destruction. This has certainly been true in the past. In 1978, Bulgarian dissident Georgii Markov was assassinated with ricin toxin by an operative of the Bulgarian secret service. In 1994 and 1995, four members of an American anti-government militia group, the Minnesota Patriots Council, were convicted under theU.S. 1989 Biological Weapons Anti-Terrorism Act for conspiring to kill law enforcement officials using ricin. Earlier, these men had responded to a March 1991 advertisement in the right-wing CBA Bulletin, which proffered a "Silent Tool of Justice...Castor Beans...Silent Death...Including instructions for extracting the deadly poison 'Ricin' from Castor Beans." In this case, ricin was manufactured by these individuals despite their lack of education and expertise. An FBI analysis of the group's recovered stockpile revealed the existence of 0.7 grams of powdered ricin of five percent strength, which was estimated by theU.S. Army Research Institute of Infectious Diseases (USAMRIID) to be sufficient for 129 lethal doses.