Ricin, << RY sihn or RIHS ihn, >> is a naturally occurring poison obtained from the beanlike seeds of the castor-oil plant. It ranks as one of the most toxic biological substances known. An injected dose of 500 micrograms (0.000018 ounce) of ricin can kill an adult human being. Ricin makes up about 1 to 5 percent by weight of the castor-oil seed. People throughout the world grow these seeds for their oil, which can be used in manufacturing or taken as a laxative. Ricin can be isolated from the waste material of castor-oil production and converted into a solid, liquid, or aerosol. It dissolves in water, has no detectable odor, and is relatively stable when heated. Ricin’s ready availability has led some experts to worry about its use as a biological weapon. However, ricin may also have medicinal uses.
Ricin consists of a protein, known as a toxalbumin, that kills cells by permanently deactivating ribosomes, protein-making structures needed for cells to function. As the cells die, tissues and organs in the body stop functioning, possibly resulting in death. No antidote exists for ricin, but immediate medical care can increase the chance of survival.
The symptoms associated with ricin poisoning depend on the dose, the method of exposure, and the individual’s health. When injected, ricin destroys lymph nodes and muscles near the injection site. Lymph nodes are small masses of tissue that filter harmful particles and bacteria from the body. Severe internal bleeding, multiple organ failure, and death usually follow within several days. When inhaled, ricin produces such symptoms as coughing, difficulty breathing, fever, nausea, and tightness in the chest. These symptoms are followed by pulmonary edema (the build-up of fluid in the lungs), respiratory failure, and death.
Ingesting ricin does not usually result in poisoning because the compound is poorly absorbed by the digestive system. When poisoning does occur, it causes abdominal pain, vomiting, and diarrhea that may become bloody. Severe dehydration can develop within days, accompanied by low blood pressure, possible hallucinations or seizures, liver, spleen and kidney failure, and perhaps death. Contact with ricin can cause pain and redness of the skin and eyes. However, the skin does not absorb ricin readily enough to result in poisoning. Ricin cannot be spread from person to person through casual contact.
Criminals, terrorists, and military groups have explored the use of ricin as a weapon. In 1978, an assassin in London stabbed the Bulgarian journalist and writer Georgi Markov with an umbrella engineered to inject a tiny, ricin-containing pellet. Markov died several days later of symptoms consistent with ricin poisoning. Some reports have suggested that ricin was used in the Iran-Iraq War (1980-1988). In 2002, the United States military reported finding traces of ricin in caves in Afghanistan used by the terrorist organization al-Qa`ida.
See also Castor oil ; Terrorism (Terrorist methods.) .
