The World’s Most Dangerous Substances

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Podcast Transcript

There are a great many chemicals that are dangerous to work with. Things that you wouldn’t want to get on your skin or somehow ingest. 

However, there is a category beyond that of substances that are so dangerous that many chemists wouldn’t want to work with them under any circumstances. 

Things are so dangerous that even the smallest error could result in a disaster in the laboratory.

Learn more about the most dangerous substances in the world on this episode of Everything Everywhere Daily.


The list of dangerous substances is a long one. It includes everything from the most toxic nerve gases to things you might encounter in a walk in the woods.  

It would be impossible to have a comprehensive list of such substances, so in this episode, I want to focus on the worst of the worst. Not just things that are deadly but also things that are notorious to work with. 

I’ll start with the substance which has the distinction of being the strongest acid known to science: Fluoroantimonic Acid.

Fluoroantimonic Acid is considered a super acid, meaning it is stronger than 100% sulfuric acid. However, calling it a super acid is an understatement.

Fluoroantimonic Acid has the chemical symbol HSbF6, meaning it consists of one hydrogen atom, one antimony atom, and six fluorine atoms. It is created by a mixture of hydrofluoric acid and antimony pentafluoride.

It is so acidic that it doesn’t even make sense to measure it on the ph scale, which measures acids in an aqueous solution. The Hammett acidity function gives Fluoroantimonic Acid a value of -21, whereas sulfuric acid is -12.  Fluoroantimonic Acid is approximately 20 quintillion times stronger than sulfuric acid. 

Fluoroantimonic Acid will burn through almost every organic compound and is so strong that it can even react with glass and is used in etching glass, which means that you can’t store it in normal laboratory test tubes. The only known substance where you can store Fluoroantimonic Acid is Teflon. 

Fluoroantimonic Acid is a colorless liquid, and needless to say, breathing its vapor is deadly. 

It is used in helping chemical reactions. It’s also used to etch glass, enhance the quality of gasoline by raising octane levels, make plastics, and engineer explosives like grenades.

The chemical which is considered the most toxic on a gram-for-gram basis is Dimethyl Cadmium.

Dimethyl Cadmium is extremely poisonous, with a lethal dose consisting of only a few millionths of a gram. It is also extremely volatile and can easily burst into flame.

It is in a class of similar organometallic compounds, such as dimethyl mercury and dimethyl zinc, all of which are extremely toxic and volatile. 

These chemicals are so bad that most chemists won’t even bother to work with them because the risks are so great. If even a small amount should become airborne, it can lead to death. If it doesn’t kill you instantly, it will probably cause long-term complications and probably cancer. 

The next dangerous substance is one that is considered the most unstable substance and hence the most explosive substance: Azidoazide Azide. 

The chemical symbol for Azidoazide Azide is C2N14. If you know a little bit about chemistry, you might have noticed that that is a lot of nitrogen atoms.  There are a bunch of them strung together in a way such that they are barely holding on to each other.

As such, even the slightest shock or movement will cause it to explode. It is so unstable that even trying to take measurements of it of any kind is almost impossible. Researchers who tried to get an infrared spectrum of the substance couldn’t because hitting it with a weak laser beam caused it to explode.

It is not produced commercially, and there is no known use for the chemical. Even if there were a use for it, there would be no practical way to use it, given how unstable it is. 

Dangerousness isn’t always measured by the ability of a substance to kill or destroy. In 1889, in Freiberg, Germany, the chemist Albert Ladenburg made an accidental discovery that everyone around him knew about almost immediately. 


In his laboratory, he created Thioacetone, the world’s smelliest substance. 

In the process of trying to distill it, an area with a radius of a half-mile around his laboratory, or 750 meters, was struck with a smell so bad that it caused vomiting, nausea, and unconsciousness.

In 1967, researchers at the Esso Petroleum Company were working with Thioacetone when they had a minor mishap. They reported what happened next:

Recently we found ourselves with an odour problem beyond our worst expectations. During early experiments, a stopper jumped from a bottle of residues, and, although replaced at once, resulted in an immediate complaint of nausea and sickness from colleagues working in a building two hundred yards [180 m] away. Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant. 

It isn’t just the smell of Thioacetone that is noteworthy, but how little of it is required and how fast the smell seems to spread.

One of the most famous deadly chemicals is Potassium cyanide, or as it is just commonly called, cyanide.

Potassium cyanide is a white solid salt that looks at first glance like sugar. 

Potassium cyanide, unlike many of the other substances I’ve mentioned, actually has industrial uses. It was used in wet plate film photography to make images stable and no longer sensitive to light. It is also used in gold mining to process gold from raw ore.

It also happens to be extremely poisonous. 

Ingesting it can lead to death in a few minutes. It was the preferred method of suicide by many top Nazi leaders, including Eva Braun, Joseph Goebbels, and Heinrich Himmler.  Herman Goering had a hidden capsule of Potassium cyanide that he used to kill himself while awaiting execution. 

The mass suicide in Jonestown, Guyana, was done with Potassium cyanide.

Potassium cyanide results in the body being unable to use the oxygen found in red blood cells. 

Another poison that has been used in assassinations is Polonium-210.

Polonium-210 is a radioactive isotope of polonium. It is a very strong alpha emitter that has a half-life of 138 days. 


If you remember back to my episode on radiation, there are two things you need to remember. The first is that alpha radiation is generally not a problem and is very easy to block. A sheet of paper, clothing, dead skin cells, and even the air can block alpha radiation. 

However, it can be extremely dangerous if you ingest it. 

The second fact is that the shorter the half-life of something is, the more radioactive it is. 

In the case of Polonium-210, both of these things come together to make it a tool for assassins. 

Polonium is a very rare element. There isn’t just polonium sitting around. Moreover, because of its very short half-life, Polonium-210 has to be created in a nuclear reactor rather recently for it to be of any use. 

Former KGB agent Alexander Litvinenko was killed via Polonium-210 poisoning in London in 2006. A small amount of it was put into his tea which he drank. Once ingested, it is impossible to stop, and there is no antidote because it’s radioactive. It isn’t a matter of neutralizing a chemical.

From an assassin’s point of view, it is relatively safe to handle, unlike a nerve agent. 

It also leaves a tell-tale signature. Polonium-210 is impossible for regular people to get as it can’t just be synthesized in a laboratory. It requires a nuclear reactor. 

So, it is a poison that is deadly but also sends a message. 

Speaking of nerve agents, they are some of the deadliest chemicals ever known to exist, and they were created for just that purpose. 

Nerve agents are a class of highly toxic chemical compounds that disrupt the functioning of the nervous system.

Sarin gas is a compound that many people might have heard of. It is 26 times more deadly than potassium cyanide. Sarin was developed in 1938 in Germany in an attempt to create pesticides.

While both sides manufactured Sarin during the Cold War, the only known military uses of it were by Saddam Hussein and the Iraqi army in 1988. It was used against Kurdish rebels and against Iranian soldiers during the Iran-Iraq War. 

There have been other cases of Sarin being used for assassinations and attacks on individuals. 

As bad as Sarin is, it isn’t even close to being the worst nerve agent. VX, short for “venomous agent X,” was developed in 1952 in Britain and is colorless and odorless. Unlike other nerve agents, it doesn’t decompose quickly after exposure to the atmosphere. 

The UN determined that Cuban forces used VX against rebels in Angola in the 1980s. Sadam Hussein tried to develop VX gas but was unable to manufacture it. 

A Japanese religious cult known as Aum Shinrikyo used Sarin gas in a terrorist attack in 1995 and managed to synthesize several hundred grams of VX which were used to assassinate one of the members they thought was a spy.

In 2017, Kim Jong-Nam, half-brother of North Korean leader Kim Jong-un, was killed at the Kuala Lumpur Airport using VX applied to his face.

However, VX isn’t the worst. Soviet chemists created a class of nerve agents known as Novichok, which are believed to be five to eight times more deadly than VX.

The only known uses of it have been in assassination attempts. In particular, former Russian army officer Sergei Skripal and Russian opposition leader Alexei Navalny.

I’ll close with the substances which are considered to be the most deadly substances known: Botulinum Toxins.

Unlike pretty much everything else I’ve mentioned in this episode, Botulinum Toxins are not manmade. They are found naturally and are created by the bacteria that cause botulism. 

There are seven known types of botulinum toxins, which are named types A through G. 

A lethal dose can be as small as 1.3 nanograms or a billionth of a gram. 

Every other substance I’ve mentioned is either heavily controlled or worked with under very strict laboratory conditions because they are so dangerous. 

Botulinum Toxins, however, are actually used in medical procedures. If you have ever heard of a botox injection, well, botox is nothing more than a nice-sounding name for Botulinum Toxin A….the world’s most deadliest substance.

Botox injections are designed to paralyze the muscles at the point at which it is injected. It is often used as a treatment for muscle conditions where a muscle may have involuntary spasms. However, its most common use is as a cosmetic treatment to get rid of wrinkles. 

If Botulinum Toxins are so dangerous, why don’t Botox injects kill you? It is because they are so incredibly diluted that they only have an effect in the localized area of the injection. 

That being said, there can be side effects from Botox, and there have been reported cases of people being killed. So, this is one of those things you should most definitely seek the advice of a doctor before you get treatment.

These are just a few of the truly horrible chemicals that exist. Thankfully, you don’t really have to worry about any of them. They are so dangerous that they are usually only manufactured in small amounts, if they are manufactured at all. 

I, of course, didn’t mention the one substance that kills more people than every other combined: Dihydrogen Monoxide. I will have to leave the discussion of that deadly chemical for a future episode.


The Executive Producer of Everything Everywhere Daily is Charles Daniel.

The associate producers are Thor Thomsen and Peter Bennett.

Today’s review comes from listener jpbamabucks22 over on Apple Podcasts in the United States. They write:

Completionist pass requested

I found this podcast when searching for something about the Holodomor and just kept going from there. 10 months later and I have finally finished. These bite-sized overviews of so so many topics make it easy to learn new things every day. Please point me toward the completionist club location here in Alabama, I’m hoping it’s near a lake, the beach, or Bryant-Denny Stadium (Roll Tide). Btw, that brings up a great topic idea, college football stadiums.

Thanks, JP! To find the hidden location of the Alabama completionist club, you have to stand on the 50-yard line of  Bryant-Denny Stadium at the exact moment of the winter solstice. If it is a full moon, the light of the moon will shine through a gap in the statue of Bear Bryant which will point you to the next step in the puzzle.

Hint: you’ll probably have to break into Nick Saban’s office.

Remember, if you leave a review or send me a boostagram, you too can have it read on the show.