In the News: What is Ricin?

By Eric Toner, M.D., and Amesh Adalja, M.D., F.A.C.P.

Just days after explosions rocked the finish of the Boston Marathon, a letter sent to President Obama this week has tested positive for ricin, a toxin historically used as a biological weapon in some parts of the world. Law enforcement officials don’t know if there is any connection to the marathon bombings, but the packages have renewed interest in this biological terror agent.

Experts at the Center for Biosecurity of UPMC answer questions here about what ricin is and how it affects the body.

Q. What is ricin?

A. Ricin is a protein that that can be extracted from the beans of the castor plant, which grows throughout the world including the southwestern United States. Ricin is a byproduct of castor oil production: When castor beans are crushed, they form a pulp from which castor oil is extracted, and ricin is what remains.

The Centers for Disease Control and Prevention (CDC) classifies ricin as a Category B threat agent, the second highest priority agents. The CDC says these Category B agents are moderately easy to disseminate, result in moderate morbidity rates and low mortality rates, and require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance.

Q. How does ricin affect the human body?

A. Ricin has the ability to inhibit protein synthesis. It can be ingested, injected or inhaled, the latter being the most lethal form. It is not contagious and cannot be spread from person to person.

Q. What are the symptoms of ricin poisoning?

A. If significant amounts are inhaled, ricin can cause respiratory distress, fever, cough, nausea, and tightness in the chest. Patients may experience heavy sweating and fluid in the lungs, resulting in a blue or purple discoloration of the skin. Low blood pressure and respiratory failure may occur, leading to death. Patients experiencing symptoms after exposure to ricin should seek medical attention.

For media seeking more information about ricin, please call Molly Bowen at the Center for Biosecurity of UPMC at 443-573-3304. Experts at the center include Eric Toner, M.D., an internist and emergency physician whose primary areas of interest are healthcare preparedness for catastrophic events, pandemic influenza response and medical response to bioterrorism. Amesh Adalja, M.D., F.A.C.P., is board certified in internal medicine, emergency medicine, infectious diseases and critical care medicine and also has extensive experience in terrorism and disaster preparedness.