(RNN) - Ricin is a poison that is present in castor beans, according the New York State Department of Health. It is part of the waste that is produced during the production of castor oil and as such, is one of the most easily produced plant toxins.
The chemical is extremely deadly, and an amount as small as a pinhead, about 500 micrograms, can be enough to kill, according to OSHA.gov.
Ricin kills by getting inside a person's cells and preventing them from making proteins. Eventually, the cells die, causing the person to die. But the process takes a long time.
How ricin kills depends on how the person was exposed to it. As a terrorism agent, ricin can be made into a powder, pellet, mist, or can be dissolved in water.
If ricin is inhaled, the first symptoms are usually difficulty breathing, fever, cough, nausea, and tightness in the chest, according to the CDC. Death happens as the result of low blood pressure and respiratory failure.
Ingestion of ricin causes the person to develop vomiting, diarrhea, and severe dehydration. Seizures may also develop. And within days, the victim's liver, spleen, or kidneys may stop working, causing death.
Symptoms can occur as soon as four hours and as late as 24 hours after exposure. But typically, they occur in less than 10 hours. Death can occur within 36 to 72 hours of exposure.
There is no known antidote for ricin poisoning.
In 1978, ricin was used to assassinate Georgi Markov, a Bulgarian dissident writer, who was stabbed with a ricin-poisoned umbrella, in what became known as the "Umbrella Murder."
The KGB is rumored to have conducted the assassination.
More recently, members of a militia from Georgia were arrested for and later pleaded guilty to planning ricin attacks in cities across the country.
Viewers of the television show Breaking Bad might recognize ricin, which was used by the main character, Walter White, to kill a rival drug dealer.
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