Ricin as a Chemical Weapon

derived from the beans of the castor plant (Ricinus communis) is one of the most potent and easily produced toxins known. Early recognition of these characteristics led the United States to develop ricin as a chemical weapon during World 

War I (35). Although the entire castor plant is poisonous, the seeds contain the highest concentration of ricin (36). For hundreds of years, countries all over the world have cultivated the plant for its oil, specifically for use as a laxative and for lubrication. Castor oil has many industrial and commercial uses, having served as a lubricant for racing engines (Castrol-R racing motor oil) and as an additive in paints and varnishes. One of its derivatives, sebacic acid, is a component in the production of nylon and aUcyd resins, and contributes to the manufacture of plasticizers, lubricants, diffusion pump oils, cosmetics, and candles (35). India is currently the world leader in production, followed by China and Brazil (35). 

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The discovery of ricin in the Senate in Washington in 2004, at a Paris railway station in 2003 plus the finding in Afghanistan by a journalist, of a description of ricin purification, demonstrate the reality of its perceived potential as a chemical weapon. The suitability of ricin for this purpose derives from its extreme toxicity to mammalian cells, the fact that the source is naturally... 

At least theoretically, the similarity of abrin to ricin gives it a similar potential as a chemical weapon, although the relative low-scale cultivation of jequirity plants compared with castor oil plants make it less likely that abrin would be used in a large-scale attack. 

Ricin as a potential biological threat agent has received much popular press. In 2003, suspects were arrested in London for making ricin from castor seed in their apartment (Risen and van Natta 2003). The popular press has speculated that if ricin were made, it could be used to contaminate food in military mess halls. All of these instances indicate that biological and chemical materials may be a potential terrorist weapon to compromise the safety of the military and civilian food supply or other vulnerable areas. Given the extreme toxicity of ricin, the relative ease with which it can be obtained, and the fact that references to its use have been discovered in terrorist haunts, the ability to accurately and precisely detect ricin is a critical need. 

Several aspects of ricin, including its significant toxicity, past association with chemical warfare, and wide availability in ton quantities from castor seed meal, have contributed to the international regulation of the toxin as a potential weapon of mass destniction. Ricin is currently monitored as a Schedule 1 toxic chemical under the Convention on the Prohibition of the... 

TOXIN. A poisonous substance that occurs naturally in animals, bacteria, or plants. Examples include botulinum toxin, ricin, and tbe tri-chothecene mycotoxins. Some toxins can be produced artificially through chemical synthesis. The military relevance of toxins was recognized during World War I, when the U. S. Army Chemical Warfare Service (CWS) conducted research and production of selected toxins at the Catholic University of America. Weapons having toxins as their primary payload are controlled as both chemical weapons (CW) (under the Chemical Weapons Convention [CWC]) and biological weapons (BW) (under the Biological and Toxin Weapons Convention [BTWC]). Toxins have also seen use as assassination weapons. See also JUGLONE SAXITOXIN. 

During World War I, the US War Department investigated ricin for chemical warfare use (Audi et al, 2005). At that time it was being considered for use either as a toxic dust or as a coating for bullets and shrapnel. However, the toxic dust concept could not be adequately developed, and the coated bullet/shrapnel concept would violate the Hague Convention of 1899. The war ended before it was weaponized. 

Fig. 30-1. Toxicity, in mouse LD50 (see Table 30-2), plotted against the quantity of toxin required to provide a theoretically effective open-air aerosol exposure, under ideal meteorological conditions, to an area of 100 km2. Although the toxicity is based on direct studies with mice, it is believed to be very similar in humans. The mathematical model corrects for human parameters such as respiration. Ricin, saxitoxin, and botulinum, and trichothecene mycotoxins (T-2) kill at the concentrations depicted. Adapted from Spertzel RO, Wannemacher RW, Patrick WC, Linden CD, Franz DR. Technical Ramifications of Inclusion of Toxins in the Chemical Weapons Convention (CWC). Alexandria, Va Defense Nuclear Agency 1992 18. DNA Technical Report 92-116.

Toxins are natural substances that are poisonous. Animals (snake venom), plants (ricin from castor beans), bacteria (botulism toxin), and fungi (trichothecene mycotoxin T2) produce toxins. A man-made chemical substance that is poisonous is called a poison, not a toxin. To be useful as a weapon, a toxin has to be stable enough to be stored and must be producible in sufficient quantities. Some very potent toxins do not lend themselves to weapons use because they cannot be produced in more than minute quantities. 

The CWC has a wide scope, defining chemical weapons as munitions or other devices, specifically designed to cause death, temporary incapacitation or permanent harm to humans or animals (but not plants). It thereby encompasses past, known and possible chemical warfare agents, including toxins such as ricin and saxitoxin, and refers, in its preamble, to the principles of international law which prohibit the use of herbicides as a method of warfare. It divides these chemicals and many of their precursors into three categories known as schedules. In Schedule 1, it effectively bans 12 groups of chemicals from manufacturing industry and commerce,... 

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