Things You Should Know About Ricin Before Watching the “Breaking Bad” Finale

A tiny vial of powdered ricin could play a powerful part in the final episode of Breaking Bad, the cable-TV saga of cancer-stricken chemistry teacher turned meth kingpin Walter White.

At two points in the series White has created a powdered form of ricin. His attempt to use the first batch was foiled because his intended victim, a drug dealer named Tuco, never ingested the ricin-laced meth nor the ricin-laced dinner Walt tried to slip him. So far he hasn’t tried to use the second batch of poison, but thanks to a flash-forward scene the audience already knows that Walt will have his hands on the ricin at some point during the final episode.

His intended victim, whoever it may be, has reason to be scared. Ricin is a naturally occurring, extremely potent toxin that is derived from castor beans, the seeds of Ricinus communis. The tropical plant is also the source of castor oil (used in manufacturing and cosmetics) and is a popular ornamental plant. Swallowing the beans themselves can be dangerous, especially for children. In adults a fairly high dose (about 20 beans) is required to cause harm since the human digestive system can destroy much of the toxic protein in the bean. But once ricin is turned into a powder form, it is far more dangerous because it is easier for the body to absorb.

Ricin, meanwhile, is not just a TV prop. Earlier this year letters laced with ricin were mailed to President Obama and other government officials. The toxin was quickly identified and no one was hurt. The most famous case of ricin poisoning occurred in London in 1978 when an assassin jabbed Bulgarian dissident Georgi Markov with an umbrella that contained a ricin pellet. Markov died three days later.

If you’d like to know a little more about ricin in advance of Sunday’s Breaking Bad (AMC, 9 p.m.), here’s a primer prepared by National Geographic editor-at-large Cathy Newman, adapted from information on the CDC website.

How toxic is ricin? How do people get sick from it?

Ricin works by preventing cells from making the proteins they need. Without the proteins, cells die. Eventually this is harmful to the whole body and may cause death. As with most chemicals, whether a person becomes ill after exposure to ricin depends on how much ricin the person was exposed to, how long the exposure lasted, and what the exposure method was (inhalation, ingestion, or injection).

How is one exposed to ricin?

Exposure to ricin comes about by ingesting or inhaling material containing ricin. In a few rare cases, injections of ricin have led to poisoning.

What are the signs and symptoms of ricin poisoning?

If ricin is ingested, initial symptoms typically occur in less than 6-12 hours. These are most likely to affect the gastrointestinal system and include nausea, vomiting, and abdominal pain. The symptoms of ricin poisoning can rapidly progress to include severe dehydration and kidney and liver problems. If ricin is inhaled, initial symptoms may occur as early as 4-6 hours after exposure, but serious symptoms could also occur as late as 24 hours after exposure. The initial symptoms are likely to affect the respiratory system and can include difficulty breathing, shortness of breath, chest tightness, and cough. Death from ricin poisoning can take place within 36-72 hours of exposure, depending on the route of exposure and the dose.

Is there an antidote for ricin?

There is none. Because of that, the most important factor is avoiding exposure in the first place.

Have many people died after being exposed to ricin?

Several deaths have resulted after a victim was injected with ricin. People have been poisoned with ricin from eating castor beans, but most cases of eating castor beans do not result in poisoning because it is difficult for the digestive system to release the ricin from the beans. Also, ricin is not as well absorbed through the gastrointestinal tract, compared with injection or inhalation.

What tests are used to detect ricin?

There are several, including tests on environmental samples of suspicious materials and tests on human body fluids. Public health laboratories that are part of the CDC’s Laboratory Response Network (LRN) use rapid-detection tests for environmental samples. Some LRN laboratories can test clinical urine samples for the presence of ricinine, an indicator of exposure.

What do the results of these tests tell us?

The rapid tests indicate whether components of the castor bean are present in the environmental sample and whether ricin toxin is present. If both yield a “positive” result, then the presence of ricin can be confirmed.

What is the difference between a preliminary test and a confirmatory test?

A preliminary test result—such as a positive finding for ricin components—must be confirmed by a second LRN test, which detects ricin toxin. The ricin toxin test is considered the best test for determining the presence of ricin. A positive result for ricin components can be used in public health decisionmaking while officials wait for confirmatory results from the toxin test.