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A maximum credible event is one that could cause a large loss of life in addition to disruption, panic and overwhelming use of civilian healthcare resources. This possibility brings about an attempt to evaluate and discuss substances that could be used as agents of biological warfare or as weapons of mass destruction (WMD).
An agent considered capable of causing a maximum credible event is highly lethal, inexpensively and easily produced in large quantities, stable in aerosol form and can be dispersed. The ideal agent is also communicable from person to person and has no treatment or vaccine.
Ricin is a potent toxin that could be used as an agent of biological warfare or as a WMD. Derived from the beans of the castor plant (Ricinus communis), ricin is native to Africa and common in warm climates worldwide. More than 1 million tons of castor beans are processed every year worldwide. It is easily and inexpensively produced, is highly toxic and is stable in aerosolized form. Ricin has no treatment or vaccine, but it is not communicable from person to person.
Although a large amount of ricin would be necessary to produce many casualties, it would be highly effective within a closed environment. Ricin can be disseminated as an aerosol, by injection or as a food and water contaminant. Its use as a food and water contaminant is a major concern. If ricin were used in that fashion, resultant deaths could overwhelm local healthcare resources.
Even use without casualties can be disruptive. Three U.S. Senate office buildings closed on February 3, 2004, after ricin was found in the mailroom that served Senate Majority Leader Bill Frist's office. No injuries were reported.
- On February 4, 2004, as part of the ongoing investigation as to the source of the most recent ricin attack, the Secret Service acknowledged that ricin had also been found at a White House mail-processing center in early November 2003.
- A vial containing ricin was also found at a post office in Greenville, South Carolina, in October 2003. The envelope, addressed to the U.S. Department of Transportation, was labeled "caution RICIN POISON." The letter, protesting a proposed federal limit on the number of truckers' hours behind the wheel to go into effect in January 2004, was signed "Fallen Angel."
- Officials suspect that the attacks in October 2003 and November 2003 are related because both letters were signed "Fallen Angel" and contained ricin of poor quality. The FBI is currently investigating whether these two earlier attacks are at all related to the ricin found in the Senate mailroom.
From 1991-1997, 3 cases involving ricin were reported in the United States.
- In Minnesota, 4 members of the Patriots Council, an extremist group that held antigovernment and antitax ideals and advocated the overthrow of the U.S. government, were arrested in 1991 for plotting to kill a U.S. marshal with ricin. The ricin was produced in a home laboratory. They planned to mix the ricin with the solvent dimethyl sulfoxide (DMSO) and then smear it on the door handles of the marshal's vehicle. The plan was discovered, and the men were convicted.
- In 1995, a man entered Canada from Alaska on his way to North Carolina. Canadian custom officials stopped the man and found him in possession of several guns, $98,000 and a container of white powder, which was identified as ricin.
- In 1997, a man shot his stepson in the face. Investigators discovered a makeshift laboratory in his basement and found agents such as ricin and nicotine sulfate.
The use of ricin is not limited in the United States.
- In December 2002, 6 terrorist suspects were arrested in Manchester, England. Their apartment was serving as a "ricin laboratory." Among them was a 27-year-old chemist who was producing the toxin.
- On January 5, 2003, British police raided 2 residences around London and found traces of ricin, which led to an investigation of a possible Chechen separatist plan to attack the Russian embassy with the toxin. Several arrests were made.
Ricin is a protein from the beans of the castor plant (R. communis). Castor beans are used in the production of castor oil, a brake and hydraulic fluid consituent. Ricin makes up 3%-5% of the "waste mash" that is produced during this process. Separating out this protein is not difficult; it only requires chromatography, a common undergraduate chemistry skill.
Symptoms for exposure to ricin depend on the route of exposure and the amount of absorption. Routes of exposure are respiratory (inhaled aerosol), gastrointestinal (GI [ingested]) and percutaneous (injected).
- If exposed to ricin through inhaled aerosol, it will most likely affect numerous individuals simultaneously. In this case, a cluster of people would develop similar symptoms over a brief period, typically within 8 hours following inhalation. Such an occurrence would point to the possibility of an intentional act. People exposed to the ricin may experience symptoms such as fever, nausea and vomiting, a progressively severe cough and congestion in the nose and throat. Other symptoms associated with inhalation of ricin include difficulty breathing and tightness in the chest. With significant exposure to ricin, breathing difficulties occur within 12-24 hours. A chest x-ray may reveal excess fluid in the lungs.
- If exposed to ricin by ingesting contaminated foods or beverages, symptoms may initially mimic food poisoning, usually within 6 hours after ingestion. People who ingested ricin may feel abdominal pain, often accompanied by vomiting and diarrhea. Because of this, they may also become dehydrated. Although ingesting ricin is usually less toxic than exposure through inhalation, with significant amounts of the poison, resulting symptoms may become more severe and possibly result in death.
- People injected with ricin, either in pellet form or with it dissolved in a liquid, may experience pain and swelling at the injection site. They may experience other flu-like symptoms as well, such as nausea, vomiting and body aches. More severe symptoms will occur later, and a critical life-threatening syndrome will develop.
When to Seek Medical Care
A person exposed to ricin should seek medical attention as soon as possible.
- If an area where ricin has been released, and people may have been exposed to it, they must immediately leave that area and move to an area with fresh air.
- If near an area where ricin has been released, people must wait for emergency personnel to advise them regarding appropriate evauation procedures.
- In an aerosol attack, people should use protective masks that are effective in preventing toxicity.
- To avoid possible contamination, people exposed to ricin must remove and dispose of any clothing and thoroughly wash their skin with copious amounts of soap and water. If their eyes are irritated, people must wash them out with water.
Exams and Tests
Diagnosing an aerosolized attack or a food and water contaminant with ricin primarily depends on symptoms and the likelihood of such an exposure. In cases of an isolated ricin injection, diagnosis is extremely difficult. In addition, diagnostic testing is of limited value, because no test is currently available to confirm exposure to ricin definitively. Nonetheless, in the case of possible exposure to ricin, a person would most likely undergo a complete physical examination by a doctor. Sophisticated diagnostic tests (not widely available) can identify ricin in the body up to 24 hours after exposure.
- If exposure is from an inhaled aerosol, the presentation is similar to a sudden, rapidly worsening lung injury. The most common findings include labored breathing or difficulty in breathing, tightness in the chest and rapid heart rate. A chest x-ray film shows excess fluid in the lungs.
- If exposure is through ingestion, the physical findings are usually confined to the GI tract. Symptoms include abdominal pain, vomiting and diarrhea. Dehydration is common. If the dose was sufficient and the disease has progressed, vomiting blood or passing bloody diarrhea or dark-colored tarry stools may occur.
- If exposure is from an injection, the skin at the injection site is examined for swelling or redness. The affected area may feel painful. The skin is also examined for the possibility of a retained foreign object. The physical findings on the skin from injected ricin may occur prior to or at the time of other flu-like symptoms.
Self-Care at Home
If exposure to ricin is a possibility, the people exposed must seek medical attention immediately.
No antidote or vaccine is available for ricin. Regardless of the route of exposure, treatment remains mainly supportive.
If exposure is from inhaled aerosol, the person may need assistance with breathing. If particularly severe, the person who was exposed may require intubation and use of a ventilator.
If ricin was ingested, the stomach may need to be pumped (called gastric decontamination). Superactivated charcoal may also be given to help soak up the poison. To treat dehydration, intravenous fluids may be given.
Antibiotics serve no role in the treatment of ricin poisoning.
- Medications may be given to treat seizures and low blood pressure that are sometimes associated with exposure to ricin.
- In the case of ricin exposure by infection, antibiotics may serve to prevent infection. A tetanus immunization may also be given as a precautionary measure.
Surgical care is not necessary for exposure to ricin, unless the ricin was injected. In this instance, the injection site should be treated to assess whether a foreign object is present. If so, the object should be surgically removed.
- Follow-up: Depending on the severity of the symptoms, a person exposed to ricin may be admitted to the hospital for monitoring.
The only effective prevention against a biologicial attack with ricin is avoidance; unfortunately, no antidote or vaccine exists. Currently, investigations are ongoing for possible vaccines and ricin inhibitors. Protective masks have been shown to be effective in preventing toxicity during an aerosol attack.
Although ricin is not the ideal biological warfare agent, it remains a threat, primarily as a food and water contaminant. Ricin is widely available and easily produced. With the increasing number of biological threats, hoaxes and "how" Internet resources available, this threat has the potential to become reality. Therefore, being familiar with ricin's characteristics is important.
Depending on the dose and the route, death can occur within 36-72 hours following the time of exposure. If death has not occurred within 3-5 days from the time of exposure, recovery is likely.
Support Groups and Counseling
Local or regional poison control centers may be able to provide more information about ricin. The Centers for Disease Control and Prevention (CDC) and the Agency for Toxic Substances and Disease Registry (ATSDR) are additional resources for informational material about ricin and its toxic effects.
For More Information
Regional Poison Control Center
Centers for Disease Control and Prevention (CDC)
Public Inquiry c/o Bioterrorism Preparedness and Response Planning
1600 Clifton Road
Atlanta, GA 30333
Agency for Toxic Substances and Disease Registry (ATSDR)
Division of Toxicology
1600 Clifton Road
Atlanta, GA 30333