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Medical Definition of Ricin

Ricin: A potent protein toxin made from the waste left over from processing castor beans. The castor plant, which is called Ricinus communis, is found throughout the world. Ricin is fairly easy to extract. Worldwide a million tons of castor beans are processed annually in the production of castor oil. The waste mash from this process is 5% ricin by weight.

The toxin (ricin) can be in the form of a powder, mist, pellet, or it can be dissolved in water or weak acid. Ricin is quite stable and is not affected much by extreme conditions such as very hot or very cold temperatures.

Ricin is extremely toxic by several routes of exposure. When inhaled as a small particle aerosol, this toxin can produce pathologic changes within 8 hours and severe respiratory symptoms followed by acute hypoxic (low oxygen) respiratory failure within 36-72 hours. When ingested, ricin causes severe gastrointestinal symptoms followed by vascular collapse and death.

Signs and symptoms of ricin inhalation include the acute onset of fever, chest tightness, cough, dyspnea, nausea, and arthralgia (joint pain) occurs 4 to 8 hours after inhalational exposure. Airway necrosis and pulmonary capillary leak resulting in pulmonary edema are likely to occur within 18-24 hours, followed by severe respiratory distress and death from hypoxemia in 36-72 hours.

Diagnosis is by antigen detection (ELISA) in blood serum and respiratory secretions. Acute and convalescent sera provide confirmation.

Treatment is supportive. Gastric lavage and cathartics are indicated for ingestion. Charcoal is of little value for large molecules such as ricin.

There is no vaccine or prophylactic antitoxin. Use of a protective mask is currently the best protection against inhalation. Ricin is not volatile. Decontamination should be done with soap and water. Hypochlorite solutions also can inactivate ricin.

Ricin's significance as a potential biological warfare toxin relates in part to its wide availability. Ricin was apparently used in the assassination of Bulgarian exile Georgi Markov in London in 1978. Markov was attacked with a specially engineered weapon disguised as an umbrella, which implanted a ricin-containing pellet into his body. This technique was used in at least six other assassination attempts in the late 1970's and early 1980's. In 1994 and 1995, four men from a tax-protest group known as the "Minnesota Patriots Council," were convicted of possessing ricin and conspiring to use it (by mixing it with the solvent DMSO) to murder law enforcement officials. In 1995, a Kansas City oncologist, Deborah Green, attempted to murder her husband by contaminating his food with ricin. In 1997, a Wisconsin resident, Thomas Leahy, was arrested and charged with possession with intent to use ricin as a weapon.

Ricin is feared to have a high terrorist potential due to its ready availability, relative ease of extraction, and notoriety via the media. Some reports have indicated that ricin may have been used in the Iran-Iraq war during the 1980s and that quantities of ricin were found in Al Qaeda caves in Afghanistan. On February 2, 2004 a suspicious substance was found in the mail room of the US Senate office of the majority leader, Sen. Bill Frist, and repeated tests reportedly indicated the presence of the poison ricin.

Source: MedTerms™ Medical Dictionary
Last Editorial Review: 6/9/2016

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