Deadliest Substances in the World

Let's explore the deadliest substances in the world!

March 22, 2023・

18 min read

Our bodies are such intricate machines that we aren’t even close to fully understanding them. But even absolutely miniscule amounts of some toxins, like cyanide, can grind that machine to an indefinite halt!

So, grab yourself a hazmat suit and stay behind the protective screen you’re reading this on! Because from snake venom to killer beans, we’re about to find out what the deadliest substance on this planet really is.

Cyanide

Have you ever heard the phrase “an apple a day keeps the doctor away”? Sure you have, but it turns out 30 apples a day will have quite the opposite effect. That’s because apple seeds and many other organic foods actually contain traces of cyanide.

Cyanide is a chemical compound which at the right or wrong dose, can be extremely deadly. It only takes about 250 milligrams, or a quarter of a paperclip’s worth, in a 180lb human for it to be fatal.

Cyanide can enter the body as either a gas called hydrogen cyanide, or as crystalized salts. Once inside, it stops your cells from using oxygen. This creates a massive problem, especially for your heart, kidneys, and brain, as they require the most oxygen to keep ticking on.

And cyanide acts fast! If swallowed, you’d be a goner in a few minutes, but inhalation could take as little as a few seconds before the lack of oxygen causes your whole body to shut down!

Fortunately, you’d have to gobble about 150 apple seeds to actually consume enough of the stuff to prove fatal. And unless you enjoy hanging around inside fumigated houses, you won’t be in any danger of inhaling it, either.

Lead

You might have thought that the most dangerous substances would be green glowing liquids bubbling away in a secret lab. But one non-glowing, silvery metal took the lives of almost a million people in 2019 alone!

That metal is lead and it’s found in the earth’s crust itself. The fatal dose for lead is relatively high, around 36 grams. But that’s not the freaky part. If you’re exposed to it, the scary substance can absorb into your bones and stay there for a whopping 30 years!

And once it's inside, it’s bad news. The highly toxic metal releases things called “radicals” into your tissues and bloodstream. These are highly reactive atoms or molecules that can imitate useful metals found naturally in the body, like calcium.

By tricking your body into thinking they’re calcium ions, they can bypass the protective barrier around the brain and interfere with its functionality. Over time, this can lead to a wide range of intellectual disabilities and developmental problems that are completely Incurable.

Despite its astounding toxicity though, lead is still used in airplane fuel, some color pigments for paint, and, most disturbingly, children’s toys! This is because it softens plastic, making it more flexible and able to return to its original shape if stretched.

Kids will chew pretty much anything, so their chances of swallowing small amounts of lead are much higher than adults’. And, to make matters worse, they’re more vulnerable to lead absorption too.

Mercury

If you have already had your temperature taken the “baby-way”, you might be terrified of thermometers. That fear gets worse once you find out that mercury, the liquid metal inside thermometers, is incredibly toxic!

And sadly, as toxic metals specialist Karen Wetterhahn found out, there's no cure once you’re sick. Back in August 1996, Wetterhahn was researching an immensely hazardous compound called dimethylmercury when a drop of the liquid fell onto her protective latex gloves.

It turns out that she wasn't protected enough, as dimethylmercury can pass through latex and was absorbed into her skin, without her realizing! Indeed, there were no symptoms until 3 months later, when she started getting unexplainable stomach cramps.

After 5 months, she began losing her speech. Just 3 weeks after that, she was completely incapacitated. Her life support was switched off in June 1997, less than a year after her first exposure. And she’d been completely healthy before.

While most people are unlikely to have issues with dimethylmercury, a similar toxic compound, methylmercury, is found in seafood, and it can be life-threatening.

Methylmercury is found across our oceans and is absorbed by plankton. Small fish eat this plankton and absorb the methylmercury from it. Those small fish are eaten by bigger fish, which absorb the compound from both the fish and the plankton.

Even bigger fish come along, and the cycle goes on, each fish accumulating more methylmercury at is does so. Eventually, those fish find their way onto our dinner plates, ready to pass all that methylmercury straight to you!

In moderation, fish is healthy. But eat too much and your hands, feet and mouth would start tingling. That’s the sign to stop and happens after eating about 40mg of methylmercury. At doses of around 200mg though, someone’s sleeping with the fishes.

Batrachotoxin

You have probably heard about the story of the Princess and the Frog. You know, girl meets frog, girl kisses frog, frog becomes handsome prince. Luckily for the princess though, she didn’t go smooching a poison dart frog. That’s because their skin produces Batrachotoxin, a tremendously poisonous alkaloid.

Alkaloids are naturally occurring compounds that contain at least one nitrogen atom. Many are completely safe but not Batrachotoxin. And the indigenous people of western Colombia, where the poisonous frogs are found, knew this very well.

They’d coat blow-darts with the toxin when they went hunting or needed to protect themselves. But the frogs are too deadly to touch! So, to extract the venom, they’d impale a frog on a stick and hold it over a fire until it literally sweat it out!

Batrachotoxin binds to the ends of nerve receptors and causes sodium ions to flood into the nerves and muscle cells. This irreversibly damages the cells within muscle fibers, keeping them permanently contracted and unable to relax. Eventually, it fully paralyzes them. And certain muscles, like the heart, are incredibly sensitive, likely to fail in under 10 minutes.

Because the frogs’ cells don’t rely on the same sodium channels as ours do, the toxin has no effect on them! In our case however, just 163-micrograms, only slightly heavier than two grains of salt, is enough for someone to be writing our obituaries or ribbituaries!

That’s 1,000 times deadlier than cyanide. Indeed, even though poison dart frogs are only about an inch long, they can churn out enough toxin to end your life 7-times over.

Dimethyl Cadmium

Remember how toxic dimethylmercury was? Compared to its evil cousin, dimethyl cadmium, it’s nothing! Dimethyl cadmium is so volatile, it can explode with the slightest agitation. Which isn’t ideal, especially considering it’s found in mines.

This extraordinarily reactive compound has a burning desire to simplify its chemical structure. To do this, it’ll steal electrons from almost any other compound it comes into contact with, generating a violent thermal reaction as it does so.

If you spilt enough dimethyl cadmium, it’d react so intensely with oxygen in the air that it’d explode, releasing clouds of poisonous cadmium oxide smoke. So, if you survived the initial blast, it’d be far from over.

Breathing in as little as a few millionths of a gram of this stuff would kickstart the beginning of the end! It tears through your body, ripping the electrons from your cells and preventing them from transferring energy throughout your body. With no energy, your organs begin to fail.

Even if you’re lucky enough to survive the initial exposure, don’t celebrate too soon. Dimethyl cadmium is extremely carcinogenic, so the chances of you getting seriously sick are still very high. Because of this, dimethyl cadmium isn’t utilized much by scientists.

Some experts argue that gram for gram, dimethyl cadmium is the most dangerous chemical in the world! Essentially, working with this is the scientific equivalent of covering yourself in salmon and trying to outrun a hungry bear.

Arsenic

When someone describes something as “fit for a king”, they’re normally describing something exquisite. In the case of arsenic though, it fits the mold for a totally different reason. Arsenic is a near-completely odorless and tasteless liquid. And it’s extremely poisonous. Which means that, throughout history, it’s been used for some pretty nefarious reasons.

Back in the 15th and 16th centuries, the Spanish-Italian noble family, the House of Borgia, were big fans of the substance. By dissolving arsenic crystals into wine or sprinkling it on food, they were able to dispose of powerful enemies with very little trace.

Any sudden mysterious illness just looked like cholera, a waterborne infection that was rampant at the time. Both gave victims severe nausea, vomiting, and irresistible urges to go potty. Plus, just 70mg is enough to dispatch your enemies, that’s about a tenth of a teaspoon! And after 48 hours, it’s only detectable in the hair and fingernails of the victim!

Due to a lack of understanding though, arsenic was used for all kinds of reasons way back in the day. In Victorian England, companies put it in everything from clothing dyes to wallpaper, resulting in grisly skin reactions and sickness.

Craziest of all, women could even buy special cosmetic products laced with arsenic that supposedly removed skin blemishes. All the while, it was simultaneously being sold as rat poison! It sounds like these people had more arsenic than sense!

Taipan Venom

One of the rules we should all live by is to stay away from snakes. Especially if that snake has a venom so deadly, just one bite’s worth could send 100 people slithering to an early grave. The name of that snake the Australian Inland Taipan.

Each bite of this rare snake delivers 45 milligrams of venomous cocktail straight into your veins, and just half-a-milligram is enough to send you six feet under. Special neurotoxins in the venom block the nerves in your body from giving and receiving signals, severely damaging your ability to do anything from walking to remembering your own name.

Even worse, a different kind of toxin called myotoxins kills your muscle cells, causing total paralysis! Add in an enzyme called hyaluronidase, which increases the poison’s absorption rate, and you’ve got a recipe for disaster! The most gruesome ingredient of all though is hemotoxin. Just a single drop can turn a vial of blood into a thick blob of jelly!

Despite all this, amazingly there are no reports of human death by Inland Taipan snakebite. The antivenom is so effective at containing the rapid spread that if it’s administered within 45 minutes, you’ll probably be okay!

Strychnine

If you’re ever in the jungles of India or Southeast Asia and you start to feel a bit peckish, choose your snacks wisely! While the small orange berries of the Strychnos nux-vomica might look sweet, their seeds contain high levels of the toxic alkaloid strychnine.

If you consumed as little as 80mg of strychnine, which is a little more than a grain of wheat, you’d suffer wildly painful symptoms. After only 10 minutes, all your muscles would start convulsing, growing more and more violent as the seconds passed. After two or three entire hours of this excruciating experience, the muscles that control your breathing would stop working and end your suffering for good.

Appallingly, the same Victorian doctors that recommended cyanide as a beauty aid thought tiny doses of strychnine could be beneficial too! You could buy strychnine pills for treating paralysis, to help you study harder, and even to assist in some late-night mattress wrestling.

To avoid bumping off all their patients, doctors administered it in doses as low as one twenty-fourth of a grain of wheat. And they sold chocolate coated pills too!

Sarin

Some substances are so deadly that they’re not just banned from public use, they’re banned full stop. Sarin is just such a substance. Originally developed as a man-made pesticide in 1938, the odorless, colorless liquid became internationally outlawed in 1997 after a string of horrifying attacks on civilians. Even so, sarin has been used across Syria as recently as 2018.

It’s an extremely potent nerve agent that evaporates into a toxic gas at just 71.6 degrees Fahrenheit. If you breathe it in, it’ll cause a myriad of awful symptoms from headaches to confusion, to weakness and diarrhea. And at higher doses, it quickly blocks your nerve endings, preventing your muscles from being able to relax.

So, you’ll not only feel terrible, but every part of you will also be tensing and cramping up. Eventually, anyone unfortunate enough to encounter a lethal dose of sarin will fall into a coma and suffocate.

So just how potent is it? If you mixed a mere sixteenth of a teaspoon of sarin with 264 gallons of water, one swig would be enough to have you pushing daisies after just 2 minutes! That’s a whopping 26 times more deadly than cyanide!

Furthermore, even if you got stuck in a cloud of the stuff, you wouldn't be able to just hold your breath as the deadly gas will absorb directly into your eyes and skin regardless.

Nicotine

We all know smoking cigarettes is bad for your health. But for all the dangerous manmade chemicals in cigarettes, one of the naturally occurring substances could cause you the most harm. Nicotine, the addictive chemical of the tobacco plant, is extremely deadly in its purest form.

Exactly how much you’d have to consume however is still under debate. Some estimates put it as low as 50-milligrams, but it’s more realistic to say around 500-milligrams or the weight of half a US dollar bill!

It’s unlikely you’re going to overdose on nicotine from smoking cigarettes. Your body only absorbs about one-tenth of the nicotine in one, which is about a milligram. But many e-cigarettes pose a much bigger risk.

Some nicotine liquids are sold at strengths of up to 36-milligrams per milliliter! Even at this strength, you’d have to vape an absolute butt-ton to overdose. But that’s not the risk, if you touch a high strength e-liquid, the nicotine can be absorbed straight through your skin and make its way to your brain.

Once inside, it causes a blockade between your brain and the nerves controlling your muscles, and can lead to vomiting, seizures, and even death. Accidentally getting some on your hand will be fine, but I’d advise against getting in a bath full of the stuff. You’d go out like a puff of smoke!

Anatoxin-A

Some toxins, like anatoxin-a, have badass nicknames like “Very Fast Death Factor”. This nickname makes a lot of sense because it’s the silent killer responsible for wiping out herds of cows across North America since the 1980s! After drinking contaminated water, cattle have been found lying stone cold just minutes later.

It’s produced by cyanobacteria, a type of bacteria that lives in freshwater bodies around the world. In other words, where cows drink from. Anatoxin-a is so deadly because once it’s inside you, it binds to things called nicotinic acetylcholine receptors. These receptors are responsible for controlling your muscles.

Normally, they open and close depending on what you’re doing. But after anatoxin-a has attached itself to them, it forces them to stay open and overstimulates your muscles to the point of exhaustion and paralysis. You might lose coordination, start twitching, convulse, and eventually be unable to breathe.

The lethal dose is still somewhat shrouded in mystery though. When injected in mice, it’s overwhelmingly low, roughly one five-hundred-thousandth of a teaspoon. But symptoms don’t even start showing in humans until around a sixteenth of a teaspoon. That’s still not much at all.

Don’t panic though! That next glass of water won’t leave you face down in the sink. Our drinking water goes through a lot of different processes to make sure it’s free of anything dangerous. Just try and avoid drinking from any dodgy looking ponds or streams.

Ricin

Do you like eating beans? Just make sure that you’re not eating the beans of a castor plant, because they contain a deadly toxin called ricin. If you squeeze the oil from castor beans, you’re left with a mushy pulp from which the toxin can be extracted. But it’s also released just from chewing on them!

And only 80mg, or about 8 beans, is enough to make you a "has-bean". But the amount can be as little as 22 millionths of a gram if injected directly into your bloodstream. Ricin is a ribosome-inactivating protein or RIP, a fairly appropriate name.

Basically, it wrecks your ribosomes, which produce protein for your cells. Without protein, your cells and you cease to function. Indeed, you’ll be Resting in Peace within about 72 hours of ingesting the RIP.

And they’ll be a bad 72 hours. First, you’ll feel a bit sick. This will get worse, until you’re vomiting and pooping all over the place, resulting in severe dehydration. Within a couple of days, you might start having seizures too. Finally, your organs will give out completely.

Indeed, it's been used to devastating effect in more recent times too. Georgi Markov, a Bulgarian writer and defector, was “removed” by the Bulgarian Secret Service in 1978 when a suspected ricin pellet was shot into his leg from a modified umbrella!

Tetrodotoxin

I love sushi! But it blows my mind how fish and rice can be so expensive. That said, it’s not worth cheaping out. Badly prepared seafood is the leading cause of intoxication from tetrodotoxin, a poison you really don’t want to mess with!

It’s found in a wide range of seafood, but most famously in pufferfish. And as little as 1-2mg, the weight of half a mosquito, is enough for an average human to become worm food.

That’s because tetrodotoxin attacks the channels between nerves and prevents them from passing messages, rendering the tissues within your muscles practically useless. Symptoms start showing up in just 10 minutes. The first sign is a tingling sensation in the lips, which rapidly spreads to the arms and legs. This doesn’t last long.

Soon, the victim becomes totally paralyzed, their breathing labored and difficult. In most cases, the unfortunate soul remains totally conscious throughout the whole horrific ordeal. Until, well, I think we all know how this ends. Worst of all, there’s no antidote! The best treatment is administering breathing support and offering your hopes and prayers.

Bacterium Clostridium Botulinum

At the beginning of the 20th century, canned food production was becoming a nearly billion-dollar industry. But little did these early tin-novators know, their products were a breeding ground for one of the world’s deadliest toxins, the bacterium clostridium botulinum.

Unlike most organisms, it thrives in places devoid of oxygen, so a sealed can of food provides the perfect conditions. Once inside, it creates spores, which are miniscule reproductive units capable of multiplying incredibly quickly.

So, the deadly bacterium just grows and grows. And the lethal dose is incomprehensibly miniscule. Only 2 nanograms, that’s two-billionths of a gram, will have an unlucky eater kicking the bucket. That’s the same size as a single grain of rice cut into a staggering 12.5-million little pieces!

Ingesting this bacterium causes botulism, and you don’t want to get this sucker. Starting from your face down, all your muscles will go weak, before becoming completely paralyzed! At this point, unless you get speedy help, it’ll all be over. Luckily, because of better food safety standards, cases nowadays are very rare.

Polonium-210

Remember back at the beginning of this article I mentioned about cyanide? If you thought that sounded dangerous, it's nearly irrelevant when compared to Polonium-210. This is a rare, highly radioactive metal used in the production of nuclear bombs and it’s pretty deadly.

By weight alone, it’s around 250,000 times as toxic as hydrogen cyanide, the lethal dose can be as little as 0.089 micrograms! That’s like taking a single grain of table salt and breaking it into 674 pieces.

Indeed, just one gram is enough to make 50-million people incredibly sick, and another 50 million into worm food! That’s the population of New York six times over, all gone, from one tiny gram.

Thankfully, getting a whole gram is near impossible. Polonium-210 exists in such minute amounts in nature that it’s often undetectable! What makes it so unbelievably deadly then? Polonium-210 atoms have an excess of energy inside their nuclei. Unable to contain this energy, they fire out heavy, highly energized alpha particles.

These have protons and neutrons, but no electrons, and that’s bad news. The particles are too chonky to get through your skin, but they can get inside your body via contaminated air, food, or water!

And once they do, they’ll tear through you and steal your cells’ electrons as they do so. This seriously damages your DNA and can cause cell mutations. All these things can lead to cancer, organ failure or even apoptosis, where your cells just give up the ghost.

Alexander Litvinenko was a Russian defector, and is currently the only known case of deliberate Polonium-210 poisoning. After Russian agents spiked his tea with 10 micrograms, or 200 times the lethal dose for ingestion, Litvinenko became horribly sick.

The image below is the last known photo of him, taken less than three weeks after he was poisoned. Just days later, he died.

If you enjoyed learning about the deadliest substances in the world, you might want to read our article about the strongest acids ever. Thanks for reading!