Ricin: the next biological terror agent?

Ricin is a toxin found in the beans of the castor plant, Ricinus communis. It is one of the residuals from the processing of castor beans to castor oil and can be found or made in several forms, including powder, pellet, mist, or a solution in water or a weak acid. Because of the worldwide availability of the plant, the level of toxicity involved, and the ease with which the toxin can be extracted, ricin is considered to be an easily accessible biological weapon. With the recent discovery of ricin in a mailroom of a Senate office building, it appears that this agent is back in the news. The toxin also has been found recently in other mail-related incidents, as in a letter to the Department of Transportation regarding changes in truckers' work schedules.

Ricin is occasionally used for medicinal purposes, including bone marrow transplants and the killing of cancer cells. Accidental exposure to ricin is rare.

When injected, as little as 500 micrograms can kill an adult; however, if the exposure route is through inhalation or swallowing, the amount required would be greater. When ricin enters the body, it prevents cells from creating necessary proteins, which causes the cells to die. Symptoms of poisoning usually occur within hours, although onset times vary according to the method and dose of exposure. Symptoms from inhalation may include

* fever,

* cough,

* nausea, and

* respiratory distress.

Symptoms from ingestion may include

* severe bloody diarrhea,

* vomiting,

* severe dehydration,

* low blood pressure,

* seizures,

* hallucinations,

* blood in urine, and

* organ failure.

Currently, no antidote is available for ricin poisoning. Ricin poisoning cannot be transmitted from person to person.

The most famous case of ricin poisoning is that of Bulgarian dissident, Georgi Markov, in 1978. While waiting at a bus stop in London, Markov experienced a piercing pain in his right leg. It is thought that a man behind him had jabbed him with an umbrella. Markov continued on to work, but later that night developed a high fever. He was hospitalized the next day for an unknown form of blood poisoning and shortly after went into shock. He died three days later. It was not until an autopsy was performed that a small pellet was found in his right leg and it was discovered he had been poisoned by ricin.

For more information on ricin, visit www.bt.cdc.gov/agent/ricin/index.asp.

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