Top 5 Deadliest Substances on Earth

Top 5 Deadliest Substances on Earth

It’s a story straight out of a Bond film. On September 7th, 1978, Bulgarian journalist Georgi Markov, a communist defector working for the BBC, was walking across the Waterloo Bridge in London, when he felt a slight sting in his right thigh. He looked behind him and saw a man picking an umbrella up off the ground. By that evening he had developed a fever. Four days later he was dead. The cause of death: poisoning. Markov had been assassinated using an umbrella rigged to fire a pellet laced with one of the most powerful natural toxins in the world: Ricin. Ricin is one of the deadliest natural substances that is not found in an animal. It’s found in the beans of the castor plant. Just 500 micrograms of this stuff, that’s 5/10 000 of what a paperclip weighs, is enough to kill a man. And as potent as it is, ricin isn’t even close to being the most poisonous natural substance on Earth. There are poisons that lurk in bacteria, plants, and fungi all over the place, and they’re not just found in exotic, tropical locales or, like, 1970’s London. They’re pretty much everywhere, and the fact is, they’re there for good reasons. But what is it about their chemical makeup that makes them so poisonous? How do their toxins attack the human body with such deadly efficency? And why does my thigh suddenly feel all tingly? Is that an umbrella!!? [Theme music] Not only is it morbid to list the most deadly toxins in nature, it’s also nearly impossible. There are a lot of plants, fungi and bacteria out there capable of killing you if eaten, inhaled, or injected. And there are also a lot of variables to make it hard to quantify exactly how poisonous something is. Everything from the age of the victim to the antibodies in your system can effect how potent a substance is. There is however, one exception. No-one disputes that the most lethal toxic substance known to man natural or otherwise is produced by the tiny bacterium Clostridium botulinum. You probably know it by the disease it causes, botulism. Just how deadly is the botulinum toxin? One way experts use to measure the lethality of a poison is a method called the “Lethal dose 50%”, Which is the dose required to kill half the members of a tested population. Since, for obvious reasons, you can’t run these tests on humans, toxicologists usually gets this number, often called the LD50, by using an endlessly unfourtunate creature: The laboratory mouse. LD50 is measured in a ratio of milligrams of toxin to kilograms of bodyweight, and in the case of the botulinum toxin it’s about one nanogram, a billionth of a gram, per kilogram. That means that a crystal of botulinum the size of a grain of sand, would be enough to kill 9,600 people. The bacteria are actually really common and the spores they produce are found in soil and water all over the world. The problem starts when they germinate into active cells, at which point they begin to produce seven different toxins, four of which are deadly to humans. C. botulinum thrives in low-oxygen environments, and the ten to thirty cases reported each year in the U.S. are usually the result of eating improperly canned food, since canning removes oxygen from food to preserve it. But if the food isn’t heated properly the spores can stick around and set up shop in that can of Texas chili. Botulinum spores can also be found in honey, and if you eat them they can find a nice oxygen free nook of your body to hang out in. Kids and adults can ward off these spores before they germinate, but infants cannot, which is why babies under 12 months old should never eat honey. The spores are poisonous because they secrete a neurotoxin as a waste product. It works by blocking the release of a neurotransmitter called acetylcholine, which controls muscle contractions. This effectively makes every muscle in the victim’s body go limp. Within several days without antitoxin the victim will asphyxiate from the inability to breathe. But yes, thanks to science, and all those poor lab mice, there is an antitoxin. But why in the name of Mathieu Orfila would a bacterium evolve to fart the deadliest poison on earth into its host? The answer remains a mystery. One theory is that the toxins are not aimed at the host, but rather at competitor bacteria. They create conditions where benign bacteria cannot survive, giving the evil bacteria a chance to spread. The host, in this case a human, is often just in the way of this process. So compared to the botulinum toxins, cyanide is like eating play dough. Well, not really. Do not eat cyanide! Not only will it kill your face, it’s also one of the most rapidly acting poisons in the world. It’s found in cigarette smoke, burning plastics, also a surprising number of natural foods including almonds and the seeds of apricots and apples. The LD50 of sodium cyanide, a common form, is 6.4 mg per kg of bodyweight, or over 6 million times less deadly than botulinum. But that said, it’s been a popular and effective tool of death for everyone from Emperor Nero to Agatha Christie. Cyanide is a carbon atom triple bonded to a nitrogen atom. What makes it such a fast killer is that it binds to proteins in your cells mitochondria, the tiny power plants that keep your cells going, and keeps them from using oxygen, basically asphyxiating the body at a cellular level. It is true that some fruits and nuts contain cyanide. Apple seeds for instance contain a chemical that releases cyanide when it comes into contact with digestive enzymes. This is a good way to deter critters from digesting up all your seeds if you’re a fruit, but there’s not enough poison to kill them, or us. Though I guess I wouldn’t make a point of like eating a bowl of apple seeds. The good news is that if you happen to suffer from cyanide poisoning, there’s always vitamin B12. The B12 that you get at the store actually contains cyanide as part of its gloriously complex molecular structure, so high doses of a precursor to the vitamin can literally pull the cyanide off of your poisoned mitochondria, and then you just pee out the poison in the form of B12. Now, back to our Bulgarian friend. Well the castor plant that killed him is next on our list. It’s native to East Africa, but grows pretty much anywhere it’s warm, including the southwestern United States. The toxin it produces, ricin, is a protein found in the castor bean, but the poison itself is made from the mash that’s left over after grinding the beans into oil. When the oil is heated the ricin protein denatures or changes shape, which renders it harmless. So the toxin doesn’t end up in the oil itself, which is used widely as a laxative. Or used to be. Not so much anymore. Cause gross. But when inhaled, ingested, or injected, untreated ricin is readily absorbed by the body’s cells. Once inside it inactivates the ribosomes, which manufacture proteins that your cells need to survive and reproduce, and once the protein train stops, life stops. Just a single ricin molecule is capable of inactivating 1,500 ribosomes per minute as it kills the cell. You may feel the effects within a few hours, but ricin is generally a slow acting poison, taking 1-3 days to cause death. Hence its popularity with assassins over the years who want to distance themselves from their crime. The tiny platinum plug found in Markov’s leg had two tiny channels drilled into it, each able to hold about 1/5 of a milligram of the poison. But that was more than enough to kill Markov or any other human. And the toxicity of ricin can change depending on how it enters the body. Taken orally its LD50 is about 20 milligrams per kilogram of bodyweight, about 8 castor beans worth of the poison, but if it’s injected, like the way Markov got it, it’s just 1 tiny microgram per kilogram. Antidotes to ricin, sad to say, are still in the early stages of development, but because ricin takes several days to kill, compounds are being investigated that can block it from reaching ribosomes in new cells in the body. And strangely enough ricin is also being investigated as a possible cancer treatment, because of its ability to trigger that protein-stopping self destruct mechanism in cells, including, of course, cancer cells. Now, if you ever come across a strychnine tree, and yes there is such a thing, my advice is to stay as far away as possible. It’s native to India and Southeast Asia, and its bark contains a poison called brucine, but the real lethality comes from the trees round green-to-orange fruit which contains the alkaloid strychnine. Tests on both sad pigeons and sad rats have pegged the LD50 for strychnine at between 3 and 14 milligram per kilograms when taken orally, which puts it in a similar category of lethalness as ricin. But the threat here is a neurotoxin that affects the nerves in the spinal cord that control muscle contraction. Essentially it blocks the chemicals that control nerve signals to muscle. By blocking that chemical, strychnine puts your muscles in a state of constant stimulation, causing seizures until the point of exhaustion and respiratory failure, in as little as 30 minutes. This does not sound like a pleasant way to die. Finally, no roster of natural poisons would be complete without a visit to the kingdom fungi, because although few of its thousands of species are poisonous, some of the ones that are contain toxins that would give botulism a run for its money, called amatoxins. The two most dangerous of these mushrooms contain the most lethal poison of its kind, called amanitin, and they have the not so cryptic names of Death Cap and Destroying Angel. The oral LD50 of amanitin containing mushrooms is between 0.1 and 0.2 milligrams per kilogram. So we’re talking at least 30 times deadlier than strychnine. Amatoxins are essentially rings of amino acids that interfere with enzymes that, again are responsible for the production of lifegiving proteins in your cells, but here they specifically target your liver and kidney cells. Part of the reason they’re so dangerous is that symptoms are delayed for 6 to 24 hours after ingestion so victims only know there’s something wrong when their liver and kidneys begin to fail, causing vomiting and diarrhea, which is often mistaken in emergency rooms as the flu, another reason the poisoning is often fatal. Most of these deaths in the U.S. are from the misidentification of mushrooms by immigrants from Asia, where these particular species of fungi don’t exist and instead have quite edible lookalikes. In cases that are caught early enough, massive doses of milk thistle extract can stop the worst of the damage – the extract contains chemicals that block the uptake of the toxin in liver cells. But in the worst cases the victim can only be saved by a liver transplant. Now I should probably stop, now that I’m just completely paranoid about everything from strange men with umbrellas, to all of the formerly beautiful mushrooms in the world. The good news is that scientists, and lab mice, have been working hard developing anti-toxins to these most poisonous natural substances, so that if we do come across one of them, we might not die. And in a very few cases these terribly toxic substances may even be used to save us one day, by targeting cancer cells. So, thank you for watching this episode of SciShow. If you have any questions, comments or suggestions, we’re on Facebook and Twitter, and of course down in the comments below. And if you want to keep getting smarter with us here at SciShow, you can go to, and subscribe. Bam! [Theme music]

100 thoughts on “Top 5 Deadliest Substances on Earth”

  1. Raw honey have a lot of acids and other chemicals any flies or insects that get onto it cannot live it can strip the nutrients from a human' s body if it is not diluted properly . I used one table spoon of raw honey with 1/2 lemon' s juice in 16 oz hot water it made my nose run with mucus and I Coughed up hunks of cold ( mucus) my lungs was cleaned after I drank it . For one month . My stomach felt empty I had to eat often and drink a lot of water. I kept putting off going to the hospital I am retired from working in the health field for 25 year. I knew drinking distilled water was one way to clean my system. It took a few weeks I am back to normal now. I threw the jar of honey in the garbage. ( I can live without honey period..)

  2. It is extremely rare to develope botulism from honey. When it does happen, it's usually to children 4 + under.
    Honey does,nt spoil naturally EVER, unless HUMANS screw up, Contaminating It.
    Stored honey has been found in old abandoned homesteads, and was found edible.
    Apples/Apple presses, are more likely to cause botulism, due to the often faulty cleaning measures. Especially when a fool does'nt know how to properly do something.

  3. What is the second most deadly chemical known to man? Mercury with plutonium the first. So, why is Mercury put in childhood and flu vaccinations? Because the Rockefeller and Bill Gates Foundations have a depopulation agenda on going. Children develop autism and cancer at an early rate. Older folks are sucked into flu vaccinations to weaken their immune system and kill them quicker. Ask New York state health workers why they refused mandatory vaccinations a while back.

  4. Read Creator’s food guidelines… btw Honey is on the list. Do your research in all areas…🐵🙈🙉

  5. Cyanide in seeds is 100% wrong, the seeds from apples, avocados, apricots, cherries, nectarines, peaches contain vitamin B17/laetril a known cancer preventer & fighter. I have them in my smoothies 2 to 3 times a week 2 to 3 apples with seeds 1 avocado with seed with other fruits & vegetables.

  6. Organic Mercury. Ive had nightmares about it. It causes a slow horrifying death where over months your nerves deteriorate and eventually you become a mind trapped inside a body with no connection between the two and then you just die which I imagine would be a relief at that point. There is no cure because it gathers in all fatty tissues & your brain is mostly fat.

  7. cancer patients become guinea pigs once they are in a treatment protocol their doctor tells them not to take any supplements not because the supplements may actually help the cancer grow but because they don't want your use of supplements to cloud their data on treatment outcomes. If the supplement eliminates the cancer the data will erroneously indicate that it was the treatment that saved you.

  8. It's very interesting, thank you. I once saw a list of poison plants with pictures and what each does to a person. I think this should be taught in elementary school!

  9. Scishow I wish you’d commented on how strychnine used to be seen in countless medicines including hypodermic tablets which were about the size of half a tic tac and designed to fully dissolve quite quickly thus leaving them ready to be injected directly into your body.

  10. So something I'm eating that causes muscle cramps has strychnine as a compound with it? He said vitamin B12 has cyanide in it? Yet people use that in everyday lives. Brain like his can be completely deleted. And re indoctrinated. Again. To serve the purpose! But from whom?

  11. You forgot marijuana. It MUST be dangerous because governments the world over wage war on the people who try to kill themselves with it.

  12. But… but… I've been told that if something is natural (like marijuana) it's good for you or at least won't harm you. Hmmph.

  13. WAY more castor oil was used ( and to some extent still is) to lubricate racing engines and machinery which is used for food production.

  14. Strychnine: A schedule one poison. Although this very fast acting and very fatal poison can and almost always is fatal there are people that believe that the risk of accidental death is worth it as it has a very powerful stimulant effect to the nervous system in very small doses.   It is STILL on the list of drugs tested for when doing doping tests on athletes

  15. Great video, I love the host…looks like he just gotta out of bed, in a short he slept in and didn't try to fuss with his hair at all. I am not being sarcastic…I dig the relaxed, non-fake look like ALL news anchor people seem to have…great video, thanx for making/sharing.

  16. You didn't come even close to the most deadly substances on earth, other than botulism.. most of the most poisons and toxins are found on the oceans, , like pufferfish, and stonefish, etc.. and there's other fungi that match the amanitas, plus venomous species in the tropics, etc.

  17. Young man. You look unkempt and dirty…A shower and a clean shave would do wonders…
    Is that look getting you social traction?

  18. Good to see that you bullshitted with doublespeak long enough to stretch this little video past the 10 minute payday mark.

  19. Can you do anything original? Keep waving your hands in space. The NEEED for attention and to look like
    an expert is a cruel master. Try reading the comments below. Get a real job.

  20. The gas which often eminates from the bottom of Our 14 year old Labrador , Peppa , is the deadliest substance on this part of planet earth . 🇨🇳

  21. What about lead ? What about black people ? When you combine the two of them. It accounts for several people a day in this country being shot dead.

  22. Stopped at 2:49 realizing I should clean out the garage instead ! Should have known that a caption of "Deadliest Substances" with a pic of delicious Honey would be an invitation into someones Brainwashed Propaganda ! As penance for my stupidity – Garage ! I will Conquer You !|!|!

  23. Lots of mosquito's wanting to inject me in my state…but the one's carrying umbrellas are the one's you really have to worry about.

  24. Mentions mistakes & misdiagnoses often happen among emergency room personnel … Applies to many situations & mistakes rarely resolved but misinformation exploited for propaganda (prescription pain relief medication ruse supposedly caused opioid crisis when all involves abuse & illicit narcotics along with alcohol & other substances).

  25. Apricot seeds are one of the best destroyers of cancer out there. Just as he ^ said about apple seeds though, you have to eat them in small amounts.

  26. Diamtheyl Cadmium is worse than all of these. Its extremely toxic(not like botulinum but still) it explodes in water, ignites from friction, and decomposes into a friction sensitive powder that explodes.

  27. I've no idea why, but that Bulgarian dissident, Georgi Markov, is buried 20 miles from me in a tiny village called Whitchurch Canonicorum… along with Saint Wite.

  28. And, I can’t understand why women deliberately have Botulinum injections for wrinkles. That’s what Botox really is.

  29. Actualy many Seed of the plants in the family Rosaceae (Cherrys, Pears, Apples and more) contain cyanide in smallsr to bigger dosage

  30. The deadliest substance on earth is the dreaded homo sapien or Human. It thrives by its ability to adapt quickly and its ability to destroy an ecosystem without just cause. It kills anything that gets in its way.

  31. We already have cannabis oil to kill cancer cells by opening up the formerly closed gates on the cell wall surfaces , thus allowing in the enzymes that cause apoptosis . Then we also have GcMAF .

  32. So botulism competes with other cells by killing it's environment? In other words the Brazilian government is human botulism?

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