Ricin

Ricin is a poison. It is a highly toxic, naturally occurring protein. It is produced in the seeds of the castor oil plant Ricinus communis. 

A dose of ricin the size of a few grains of table salt can kill an adult human. The median lethal dose (LD50) of ricin is around 22 micrograms per kilogram (1.78 mg for an average adult, around  of a standard aspirin tablet/0.4 g gross) in humans if injected or inhaled. Oral exposure to ricin is far less toxic and a lethal dose can be up to 30–40 milligrams per kilogram.

Ricin prevents cells from assembling various amino acids into proteins. Death can occur within a few hours or up to a day later. 

Ricin has been used as a terrorist weapon, including the assassination of Georgi Markov in 1978, supposedly by the KGB.

 References 

Category:Poisons
Category:Proteins