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Ricin is a naturally occurring toxin found in minute quantities in the castor bean (Ricinus communis). It can cause toxicity if castor beans are thoroughly chewed or blenderized, although the quantity of ricin is small and it is poorly absorbed from the gastrointestinal tract, so symptoms following castor bean ingestion are usually limited to diarrhea and abdominal pain. Less commonly, severe gastroenteritis can lead to volume depletion and advanced chronic kidney disease. On the other hand, purified ricin is extremely toxic if administered parenterally: the LD50 for injected ricin in animals is as low as 0.1 mcg/kg. A fatal case of suspected ricin poisoning by homicidal injection of an estimated 0.28 mg of ricin was associated with diffuse organ damage and death from cardiac failure after 2 days. Inhalation of ricin powder has not been reported in humans, but animal studies suggest it could cause hemorrhagic tracheobronchitis and pneumonia.


A. Emergency and Supportive Measures

After suspected ricin inhalation or exposure to powdered ricin, remove clothing and wash skin with water. Personnel caring for such patients should wear protective respiratory gear, clothing, and gloves.

B. Specific Treatment

There is no known antidote or other specific treatment. A vaccine (RiVax®) has been developed and has been granted an Orphan Drug designation by the FDA. Provide supportive care for volume loss due to gastroenteritis and cardiac and respiratory support as needed.

Centers for Disease Control and Prevention. Ricin: Diagnosis & Laboratory Guidance for Clinicians. April 4, 2018.
Lopez  Nunez OF  et al. Ricin poisoning after oral ingestion of castor beans: a case report and review of the literature and laboratory testing. J Emerg Med. 2017;53:e67.
[PubMed: 28987302]  

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