Ricin

Ricin
Ricin is one of the most toxic naturally occurring substances.It is derived from seeds of the castor bean plants. These seeds are also used to make castor oil. Accidental exposure to ricin is highly unlikely, except through the ingestion of castor beans.Castor beans are processed throughout the world to make castor oil. Ricin is part of the waste “mash” produced when castor oil is made.It can be in the form of a powder, a mist, or a pellet, or it can be dissolved in water. It is a stable substance under normal conditions, but can be inactivated by heat above 80 degrees Centigrade.
Symptoms of ricin poisoning by inhalation may occur within 8 hours of exposure. It would cause pulmonary edema and respiratory distress.If someone swallows a significant amount of ricin, he or she would develop vomiting and diarrhea that may become bloody.Ricin is unlikely to be absorbed through normal skin. Contact with ricin powders or products may cause redness and pain of the skin and the eyes.
In 1978, Bulgaruian dissident Georgi Markow  was killed in London using this poison. The poison was injected into him from the tip of an umbrella as Markow was waiting for a bus.

In the 1940s the U.S. military experimented with using ricin as a possible warfare agent. In some reports ricin has possibly been used as a warfare agent in the 1980s in Iraq and more recently by terrorist organizations.