Some basic facts about ricin
Castor beans (shown on top) are used to produce ricin, a deadly poison, as pictured in this handout photo from the National Counter Terrorism Centre. They are similar in colour and size to pinto beans (shown on bottom), but have a small pointed protrusion on the end.
There are reports coming out of the United States that suspicious letters containing a poison called ricin have been mailed to President Barack Obama and U.S. senator Roger Wicker.
The U.S. Centers for Disease Control and Prevention categorize ricin as a "Class B" threat, which is their second highest threat level. The tiniest amount of ricin -- just enough to fit on a pin head -- is also capable of killing an adult if properly prepared, according to an Associated Press report by Seth Borenstein.
But University of Maryland bioterrorism expert Milt Leitenberg tells AP that ricin is probably one of the "least significant" biological and chemical terror agents. AP also interviewed Dr. Patricia Quinlisk, medical director of the Iowa Public Health Department, who said that using ricin as a biological weapon is tougher than people think.
"Making ricin into something that can be released from an envelope into the air, be the right size to be inhaled and stick in the lungs is a lot to get right, especially if you are not a bioterrorism specialist and know how to do that," she said. "It's not something you can do in your garage."
But what is ricin exactly? Here are some basic facts about the dangerous poison, courtesy of the U.S. Centers for Disease Control and Prevention.
What is ricin?
Ricin is a poison naturally found in castor beans. It can come in powder, mist or pellet form and can also be dissolved in water or weak acid.
People can be poisoned by ricin if they chew and swallow castor beans. It can be inactivated by heat above 80 degrees Celsius.
Where is ricin found and how is it used?
Castor beans are processed worldwide in the production of castor oil and ricin can be made from the leftover waste material, which looks like a white mash. Some scientists have also experimented with using ricin to kill cancer cells.
How does ricin work?
Ricin penetrates human cells and prevents them from making proteins, thus killing the cells. The severity of the poisoning will depend on whether ricin has been inhaled, ingested or injected.
How can people be exposed to ricin?
According to the CDC: "It would take a deliberate act to make ricin and use it to poison people. Unintentional exposure to ricin is highly unlikely, except through the ingestion of castor beans."
Ricin poisoning is not contagious and cannot be spread through casual contact. The CDC says ricin can be refined into a terrorist or warfare agent and exposed to people through air, food or water.
Signs and symptoms of ricin poisoning:
Symptoms will differ, depending on how someone is exposed. If inhaled, symptoms can emerge as early as four to eight hours after the poisoning or as late as 24 hours after. If the ricin is ingested, symptoms usually occur in less than 10 hours.
Inhalation symptoms include: difficulty breathing, fever, cough, nausea, chest tightness, skin turning blue. Low blood pressure and respiratory failure could also occur, perhaps resulting in death.
Ingestion symptoms include: vomiting, diarrhea, bloody stool, severe dehydration, low blood pressure. Some people could have seizures or blood in their urine. Within several days, the person could suffer from multiorgan failure and die.
Exposure through the skin or eyes: contact with ricin powder could cause redness and pain but it is unlikely to be absorbed through the skin.
Death from ricin poisoning could occur within 36 and 72 hours of exposure.
Treatments for ricin poisoning:
There is no antidote for ricin. Doctors will support the victim in different ways, depending on how they were exposed. This could include: giving them intravenous fluids, medications to control seizures and low blood pressure, flushing out their stomachs and washing out their eyes.
Ricin's history as a biological weapon:
According to this explainer from Nature:
"Ricin has a long history as an agent of biological warfare. The US War Department first considered using ricin in 1918 and worked with British scientists to develop a ricin bomb that appears never to have been used in combat. The US military experimented with inhalable ricin powders in the 1940s and the Iraqi military packed it into artillery shells in the 1980s. Ricin was most likely used to kill Bulgarian journalist Georgi Markov in Great Britain in 1978. Ricin was also detected in 2003 and 2004 in a South Carolina postal facility, in a mailroom serving the office of the US Senate's then-majority leader Bill Frist, and in a letter sent to the White House, though it did not cause any illnesses or deaths in those cases. In the mid-1990s, members of a militia group, the Minnesota Patriots Council, were convicted of conspiring to kill law enforcement officials using ricin. It has also been found in the possession of suspected terrorist groups such as al Qaeda."
Ricin on television:
Anyone familiar with Walter White's antics on the hit series Breaking Bad will know that ricin is the cancer-patient-cum-meth-cooker's poison of choice.
Jennifer Yang is the Star’s global health reporter. She previously worked as a general assignment reporter and won a NNA in 2011 for her explanatory piece on the Chilean mining disaster. Follow her on Twitter: @jyangstar