The protein ricin is a toxin from the castor bean.
It is considered to be twice as deadly as cobra venom.
Ricin is poisonous if inhaled, injected, or ingested, acting as a toxin by the inhibition of protein synthesis.
While there is no known antidote, the US military has developed a vaccine.
Symptomatic and supportive treatment is available.
Long term organ damage is likely in survivors.
In small doses, such as the typical dose contained in a measure of castor oil, ricin causes digestive tract cramps.
Ingested in larger doses, ricin causes severe diarrhea and victims can die of shock.