How deadly is ricin?

Castor beans, from which ricin is synthesized (Wikimedia Commons)

Made from ordinary castor beans, ricin can be incredibly dangerous and even deadly -- if milled or processed right. The substance is called “very toxic” by the U.S. Centers for Disease Control and Prevention.

Indeed, a few grains of ricin are harmful enough to kill; data from tests in monkeys suggest that just 3 milligrams of inhaled ricin can kill an adult human.

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Yet the substance is very challenging to create in its deadliest, ultrapure form, requiring special, technically difficult processes that are not readily available, the CDC says. In addition to the complexities involved in producing highly purified ricin, it is also very difficult to produce a form of the toxic substance that can be inhaled.

That’s why the minute amount of the poison that 41-year-old James Everett Dutschke is accused of mailing to various political figures was unlikely to cause mass casualties, experts said.

“I can’t imagine that ricin in an envelope is going to hurt anybody,” Raymond Zilinskas, director of chemical and biological weapons non-proliferation at the Monterey Institute of International Studies in California, told Nature. “It’s more likely remnants of a paste, intended to scare people.”

Ricin is very difficult to process from the beans in which it is naturally found. It is a part of the waste “mash” produced when castor oil is made, according to the CDC, and if the beans themselves are chewed and swallowed, the released ricin can cause injury.

Ricin is a stable substance under normal conditions, but can be rendered inactivate by extremes of heat, greater than 176 degrees Fahrenheit. It works its way inside the cells of a person’s body and prevents them from making the proteins they need, the CDC says. Without these proteins, cells die. Eventually this is harmful to the whole body, and death may occur.

Initial signs of poisoning by the quick-acting toxin can appear as early as four hours after exposure, the agency says, and vary based on type of exposure. They include difficulty breathing, fever and nausea, and even respiratory failure if inhaled. If ingested, it may cause vomiting and diarrhea.

Death from ricin poisoning can come within 36 to 72 hours of exposure, the CDC says.