Ricin : threat, effects and protection


  • Lundberg Susanne
  • Melin Lena
  • Nilsson Calle
  • von Schoenberg Pontus

Publish date: 2003-01-01

Report number: FOI-R--0752--SE

Pages: 26

Written in: Swedish


Ricin is a protein toxin, which although it is derived from plants does not itself constitute a living material. It is therefore by definition a chemical weapon. Since ricin is a protein, its properties are in many aspects different from the classical chemical weapons (i.e. nerve agents, mustard gas) which are all small organic molecules. It is a toxin of "average" toxicity - it is roughly 1000 times less toxic than botulinum toxin, and as toxic as some of the nerve agents. Its potential as a chemical weapon was first illustrated in 1978, when ricin was used to assassinate the Bulgarian defector Georgi Markov. The actual usage of ricin is limited to this and one additional case, despite the growing medial interest in ricin the last decade. On several occasions, though, individuals have been convicted of possessing ricin. The last finding of ricin was in January 2003 when traces of ricin was found in an apartment in London. Ricin has several of the properties which are demanded on a toxin for it to be considered a potential threat. The seeds, from which ricin is derived, are easily obtained since the plant has been naturalized in several tropical and warm regions throughout the world, and is also commonly cultivated because of its beautiful appearance. The active substance is readily obtained to a relatively low cost and with low demands on technical skills or apparatus. The toxicity is relatively high, but with minimum risk of causing harm to users during handling. It is stable for a long time at room temperature, which indicates that the protein is relatively heat-stable. Post-exposure antidotes are not available, and the vaccines that have so far passed the clinical tests have showed negative side effects. A few states have earlier included ricin in their offensive BC-weapon programs, but on all known occasions it has been excluded due to a too low effectiveness compared to other agents. The risk that ricin is going to be used by states is therefore considered to be low. The properties of ricin might make it an attractive tool for terrorists and criminals though, and descriptions on how to purify and use ricin are circulating among such groups of individuals. The usage is in this context considered to be limited to a low-scale level. The knowledge of effective techniques during dispersal and spreading as well as decontamination is limited, making the assessment of the use of ricin as an average-scale chemical weapon difficult (i.e. spreading within closed areas). The psychological effect of average-scale usage is considered to be high because of the large attention ricin has been given lately.