Toxicity
Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis. It is resistant, but not impervious, to digestion by peptidases. By ingestion, the pathology of ricin is largely restricted to the gastrointestinal tract where it may cause mucosal injuries; with appropriate treatment, most patients will make a full recovery. Because the symptoms are caused by failure to make protein, they emerge only after a variable delay from a few hours to a full day after exposure. An antidote not yet tested on humans has been developed by the UK military, and a vaccine has been developed by the US military which has so far shown to be safe and effective when lab mice were injected with antibody-rich blood mixed with ricin, and has had some human testing. Symptomatic and supportive treatment is available. Long term organ damage is likely in survivors. Ricin causes severe diarrhea and victims can die of shock. Death typically occurs within 3–5 days of the initial exposure. Abrin is a similar toxin, found in the highly ornamental rosary pea.
Deaths caused by ingestion of castor plant seeds are rare, partly because of the indigestible capsule, and partly because ricin can be digested (although it is resistant). The pulp from eight beans is considered toxic for an adult. A solution of saline and glucose has been used to treat ricin overdose. Rauber and Heard have written that close examination of early 20th century case reports indicates that public and professional perceptions of ricin toxicity "do not accurately reflect the capabilities of modern medical management."
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