Ricin Fact Sheet - Nasty Stuff
What it is:
Ricin is a potent toxin that has the potential to be used as an agent of biological warfare. Ricin is widely available, easily produced, and derived from the beans of the castor plant (Ricinus communis). It is of marginal toxicity in terms of its LD50 (the amount of toxin that is lethal 50% of the time) in comparison to toxins such as botulinum and Anthrax. There are no treatments or vaccines for Ricin.
How it is produced: Worldwide, one million tons of castor beans are processed annually in the production of castor oil; the waste mash from this process is 5-10% ricin by weight. Ricin can be produced relatively easily and inexpensively in large quantities in a fairly low technology setting. Ricin can be prepared in liquid or crystalline form, however, for it to be delivered in an aerosol it would need to be lyophilized (the process by which a liquid substance is dried by freezing in a high vacuum). While not overly difficult to aerosolize Ricin, it presents a technical challenge.
Historical significance: Ricin is said to have been 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.
How it is delivered: Ricin can be disseminated as an aerosol, by injection, or as a food and water contaminant. When inhaled as a small particle aerosol, this toxin may produce pathologic changes within 8 hours and severe respiratory symptoms followed by acute hypoxic respiratory failure in 36-72 hours. When ingested, ricin causes severe gastrointestinal symptoms followed by vascular collapse and death. Dermal exposure of ricin is of little concern because the absorption amount is insignificant.
What it does: Ricin blocks protein synthesis in the body, which can cause widespread organ damage as well as pulmonary, liver, renal and immunological failure.
Signs and Symptoms: Fever, coughing and gastrointestinal problems are likely to be the first symptoms. If eaten, the toxin causes stomach irritation, gastroenteritis, bloody diarrhea and vomiting. Inhalation causes severe lung damage, including pulmonary edema. It can also cause seizures and central nervous system depression.
After aerosol exposure, signs and symptoms would depend on the dose inhaled. Furthermore, lethal human aerosol exposures have not been described. Time to death in experimental animals is dose dependent, occurring 36-72 hours post inhalation exposure. Humans would be expected to develop severe lung inflammation with progressive cough, dyspnea, cyanosis and pulmonary edema.
Ingestion causes gastrointestinal hemorrhage with hepatic, splenic, and renal necrosis. Intramuscular administration causes severe local necrosis of muscle and regional lymph nodes with moderate visceral organ involvement.
Conclusions: Ricin's significance as a potential biological warfare toxin relates in part to its wide availability. Although ricin is not the ideal biological warfare agent, it remains a threat. It is widely available and easily produced. It is not the ideal agent of choice for an aerosol attack, but it is more a concern as a food and water contaminant.
Timeline of February 2004 Ricin incident: February 2, 2004
3 PM- Unknown powder found on an automatic mail opener in Senator Frist's (R-TN) personal office in the Dirksen Senate Office Building. Of the eight tests conducted on the powder, six were positive for Ricin.
9:30 PM- The confirmatory test corroborated that the powder was Ricin.
No other powder had been found elsewhere in the Senate complex. All air sampling and all environmental studies were negative, with the exception of what was found in that single office at that site.
February 3, 2004- The Senate office buildings (Dirksen, Hart, and Russell) are closed to staff and visitors. Tours of the Capitol Building were cancelled, although the Congress remained in session.