Following a tradition of high-octane action movies like John Wick and Kill Bill, the Netflix revenge flick Kate is a roller-coaster ride of thrills. Mary Elizabeth Winstead stars as the тιтular Kate, an ᴀssᴀssin racing against the clock to find the conspirators who poisoned her with a highly radioactive substance known as Polonium-204. Winstead is joined by Woody Harrelson as Varrick, Kate’s handler, and Tadanobu Asano (Shōgun) as a yakuza boss named Renji.

Now, I’m no chemistry expert (I may or may not have skipped a few classes), but even I know that polonium is some serious stuff — although before watching Kate, I had never heard of Polonium-204. As it turns out, Polonium-204 is indeed a real element, and it is highly toxic. However, the way that Kate portrays how the substance affects Winstead’s character isn’t exactly scientifically accurate.

What Polonium-204 Is In Netflix’s Kate

A Stranger Poisons Kate With Polonium 204 At A H๏τel

After a previous ᴀssᴀssination has left her shaken, Kate is about to take on her final mission before retiring from the game. She meets a stranger at a H๏τel bar, and the two share a bottle of wine before sleeping together. The next day, Kate is about to take out her newest target when she is overcome with dizziness and fails to hit her mark.

She then crashes her car and ends up in a hospital, where the doctor reveals that she has radiation poisoning from ingesting Polonium-204 and has only one day to live. Realizing that it was the man from the H๏τel who poisoned her, Kate goes searching for answers.

Fighting off one gangster after the next, Kate tries to track down the person responsible even as the polonium breaks down her system. She meets and befriends a young girl named Ani, an obnoxious teen who is, nevertheless, one of the best characters of Kate. Kate treats the poisoning by injecting regular doses of a stimulant so that she can keep going, but her symptoms worsen as the film goes on, from nosebleeds and dizziness to vomiting and excruciating pain. By the time she finally gets her revenge, Kate accepts her inevitable death at the movie’s end.

Yes, Polonium-204 Is A Real Poison — What It Is, Explained

Polonium-204 Can’t Be Used To Poison Someone

Polonium-204 is, indeed, a real element — but it’s a bit complicated. Polonium was discovered by the famous physicist, Marie Curie, and her husband, Pierre, in 1898. It is a chalcogen with an atomic number of 84, and an atomic weight of 209. Its most common form is Polonium-210, which can be used as a ᴅᴇᴀᴅly poison, such as in the case of Alexander Litvinenko. A Russian spy who defected to the UK, Litvinenko was deliberately poisoned by 210 in 2006.

Symptoms of Polonium-210 poisoning include nausea and vomiting, hair loss, and bone marrow damage. In high doses, it can affect the central nervous system, resulting in convulsions, confusion, and putting the victim into a coma within minutes (via Medical News Today). In Kate, we do see moments where Kate suffers similar symptoms, such as vomiting, but her nosebleeds, dizziness, and other physical effects are invented for the movie.

However, unlike 210, Polonium-204 would not be a reliable method of poisoning someone in real life. Professor Ron B. Davis, the creator and host of the YouTube channel “ChemSurvival,” listed three reasons why: Firstly, 204 has a half-life of 3 ½ hours, which means that after a day, it decays and becomes ineffective. Second, 204 has too much radiation to transfer from one person to the next without the transporter being affected. Finally, to make Polonium-204, the neutrons needed to bombard the element have much too short a half-life to create a significant amount.

To date, there are no cases of Polonium-204 poisoning to determine whether the symptoms Kate experiences in the movie are accurate or not — probably because effectively using 204 to poison someone is nearly impossible. It’s tough to say why the writers of Kate chose Polonium-204 as their poison of choice. Perhaps because they weren’t counting on chemistry experts to debunk the method, or, more likely, they just wanted to create a fun action movie.