TORONTO -- A Canadian was arrested Sunday evening at the New York-Canada border, according to U.S. law enforcement officials, under suspicion that they had sent an envelope containing poison to the White House — the latest development in a long history of attempted poisonings using a deadly toxin called ricin.

The incident, although dramatic, is far from the first time that an attempted ricin poisoning has made headlines. And it’s not even the first time that someone has tried to mail the poison to the President of the United States.

The RCMP said in a statement this week that they were working with U.S. agencies after a letter that contained the poison ricin was believed to have been mailed from somewhere in Canada, as it was stamped with a partial postal code from a suburb of Montreal. 

The letter, addressed to U.S. President Donald Trump, was intercepted at an off-site screening facility before it could reach the White House.

The FBI said in a statement Sunday that “an arrest was made of an individual allegedly responsible for sending a suspicious letter. The investigation is ongoing.”

But what exactly is ricin, and how dangerous is it?

THE POISON

Like cyanide, ricin is a naturally occurring poison. It is found in castor beans, and can cause injury to anyone who chews or swallows those beans, according to the U.S. Centers for Disease Control and Prevention (CDC).

Castor beans can be safely turned into castor oil, leaving ricin behind as one of the waste products.

It is very difficult to accidentally be exposed to ricin. It takes a “deliberate act to make ricin and use it to poison people,” the CDC says on their website. It can take the form of a powder, pellet, mist or can be dissolved into water, making it dangerously versatile.

While ricin has been used experimentally in medicine to help kill cancer cells, it is most widely known for its deadly properties. Enough exposure to ricin can lead to death within 36 to 72 hours, depending on how it got into the body.

Although it is not an instantaneous poison, it is a gruesome one.

If ricin is inhaled, symptoms can begin as early as four hours. It would begin with signs such as respiratory distress, nausea and heavy sweating. This is followed by fluid filling up the lungs, and then respiratory failure.

When the poison is ingested instead, it results in vomiting, diarrhea, and ultimately could cause liver, spleen and kidney failure within a matter of days.

There is no antidote for ricin poisoning.

Dr. Amesh Adalia, a senior scholar at the Johns Hopkins Center for Health Security, told CTV News that this lack of an antidote is “why certain people committing bioterrorism […] go to it.”

A substance that was “easily neutralizable wouldn’t be attractive to people who are trying to do harm with it,” she added.

THE HISTORY

Attempting to mail poison to a president may sound like a plot from a movie, but it’s happened before. In 2013, there were two incidents involving ricin-laced letters being sent to then-U.S. President Barack Obama, occurring within months of each other.

In April of 2013, two envelopes were intercepted on their way to U.S. officials, and were found to have ricin in them. One was addressed to Obama, and the other was addressed to the office of Mississippi Republican Senator Roger Wicker.

A third letter was sent to a Mississippi judge, who, although receiving the letter, was unharmed.

After a strange investigation, in which an Elvis impersonator was originally charged with the crime, James Everett Dutschke was ultimately arrested and was sentenced with 25 years in prison.

In May of 2013, a woman went to police and claimed her husband had sent letters containing ricin to Obama and also to then-New York City mayor Michael Bloomberg.

The Texas actress, Shannon Guess Richardson, later admitted to purchasing the castor beans online, but claimed she hadn’t wanted to hurt anyone. Authorities said she had tried to implicate her estranged husband in the crime, who had filed for divorce.

In 2014, she was sentenced to 18 years behind bars.

Outside of attempted presidential poisonings, ricin has been in the history books, headlines or fiction numerous times.

One of the most dramatic assassinations of the Cold War featured the poison, delivered through the tip of an umbrella. Georgi Markov, a journalist and harsh critic of Bulgaria’s communist regime, was jabbed in the thigh at a bus stop by an assassin, who used the umbrella to inject a tiny pellet of ricin into Markov’s body. No one has ever been charged in his death.

Schemes involving ricin were featured in the award-winning show ‘Breaking Bad,’ which followed the downward spiral of a science teacher who started cooking meth. A British man was sentenced to eight years in prison in 2015 for trying to buy ricin over the internet, which he claimed was due to simple curiosity provoked by the show.

In 2015, a P.E.I university student was taken into custody by the RCMP after enough castor beans were discovered at his home to convince authorities that he was capable of producing a “substantial amount” of ricin.

In 2017, an Oklahoma woman was arrested after allegedly trying to hire someone on Craigslist to kill her ex-husband by giving him ricin-laced coffee.