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Ricin: Background Information for Clinicians

  • Ricin is a potent biological toxin (toxic protein) derived from part of the “waste” mash when beans from the castor plant (Ricinus communis) are processed during manufacture of castor oil.
  • Ricin is a stable substance, affected very little by extreme conditions, such as very hot or very cold temperatures.
  • Ricin can be in the form of a powder, a mist, a pellet, or it can be dissolved in water or weak acid.
  • It is water-soluble, odorless, tasteless, and stable under ambient conditions.
  • If the route of exposure is injection or inhalation, as little as 500 µg of ricin could be enough to kill an adult. A greater amount would be needed to cause death if ricin were ingested.
  • The extent of manifestations of ricin poisoning in humans depends on the amount of ricin to which a person was exposed, route of exposure, and extent of organ involvement.
  • Significant exposure to ricin would result in a relatively rapid, progressive worsening of symptoms over approximately 4 to 36 hours.
  • Death may occur within 36-72 hours of exposure.
  • It takes a deliberate act to manufacture ricin to poison people.
  • There have been several instances of ricin procurement for use as a terrorist or criminal weapon.
  • As a chemical weapon, ricin may be dispersed as a mist or powder, used to poison water or to contaminate food, or injected as a liquid into a person’s body.
  • No antidote exists for ricin.
  • The most important factor is to avoid exposure.
  • If exposure cannot be avoided, then the most important factors are to get ricin off or out of the body as quickly as possible, and to provide supportive medical care.
  • Ricin poisoning represents a potential public health emergency and should be reported to public health agencies and the regional poison control center.

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