Science, Tech, Math › Science 10 Molecules You Don't Want to Mess With Dangerous Chemicals to Avoid Share Flipboard Email Print Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 10, 2019 Any molecule could be dangerous in the right setting, but this is a list of 10 nasties you'd do well to avoid. We've included a couple of horrific molecules you'll likely never encounter, but many chemicals on this list may be lurking in your home. 01 of 10 Hydrogen Peroxide LAGUNA DESIGN / Getty Images If you have a bottle of hydrogen peroxide (H2O2) in your medicine cabinet, it's weak sauce, diluted to 3% peroxide in water. Yet, it's powerful enough to kill germs even at this low concentration. The more concentrated stuff you can buy at a beauty supply store is about 30-40% peroxide and breaks open the hair shaft to strip color. The pure stuff is such a strong oxidizer it would strip the skin from your bones and then likely dissolve them, too. Of course, it wouldn't come to that, because once you exceed 70% concentration, hydrogen peroxide goes boom at the slightest touch. 02 of 10 Hydrogen Fluoride The space-filling structure of hydrogen fluoride or hydrofluoric acid. Ben Mills / Wikimedia Commons / Public Domain Hydrogen fluoride (HF) is also known as hydrofluoric acid. If they had to put a real chemical a the fictitious alien's blood to dissolve through the skin and the hull of a spaceship, this would be the stuff. HF is considered a 'weak' acid because it doesn't fully dissociate in water, but it's plenty corrosive. If it doesn't dissolve your body outright (its use in the television series Breaking Bad), then touching a solution of it will do something worse. HF passes through your skin to attack and dissolve living bone. 03 of 10 Nicotine ALFRED PASIEKA/SCIENCE PHOTO LIBRARY / Getty Images Plants use nicotine as a natural form of pest control. It's highly effective because nicotine is one of the most potent toxins in the world. Humans interact with nicotine intentionally, sometimes with lethal consequences. The Centers for Disease Control cite a lethal dose of 60 milligrams of nicotine to kill a 150-pound adult, although the actual dose for a Grim Reaper encounter may be higher or lower, depending on your sensitivity to the chemical. People have killed themselves or others by applying too many nicotine patches or overdosing on the liquid used for vaping. 04 of 10 Batrachotoxin Laguna Design / Getty Images Batrachotoxin is the nasty alkaloid used for poison darts. The molecule is the most potent non-peptide poisons known to man, with a lethal dose of 100 micrograms for a 150-pound person. That's about the size of two grains of salt. The molecule kills by permanently preventing neurons from communicating with muscles, like, you know... the ones you need in order to breathe and your heart. There is no antidote, although there are two (also poisonous) treatments -- one involves tetrodotoxin from pufferfish and the other uses saxitoxin from red tide. It's worth noting that you can keep poison dart frogs as pets. They won't excrete the deadly poison unless you feed them melyrid beetles. 05 of 10 Sulfur Trioxide Ben Mills / Wikimedia Commons / Public Domain Sulfur trioxide is a molecule with the formula SO3. It is the precursor to acid rain. Acid rain isn't great for the environment, but it's not deadly dangerous to touch it. Sulfur trioxide, on the other hand, is bad news. It reacts violently with water, giving off clouds of highly corrosive sulfuric acid. If the chemical burn doesn't do you in, there is still the intense physical heat of the reaction. This chemical is widely used in certain industrial settings, but at least your safe from it at home. 06 of 10 Dimethylmercury videophoto / Getty Images Mercury is toxic in all of its forms, but this organometallic compound is one of the worst. It can be inhaled, plus it can cross into your body through intact skin. There may be no indication of exposure until you fall over dead from the neurotoxic effects. The New England Journal of Medicine describes a case in which a chemist died months after handling a sample of dimethylmercury. She was working in a ventilated fume hood and wearing gloves. Nasty stuff. 07 of 10 Ethylene Glycol LAGUNA DESIGN / Getty Images You know ethylene glycol as antifreeze. This molecule isn't as toxic as others on this list, yet it poses more of a threat because it's relatively common and because the poisonous chemical has a sweet taste. If you put a single ounce of this poison syrup on your pancakes, they'll carry you out from breakfast in a body bag. The poison is particularly dangerous for children and pets because they either won't read the warning label or else don't care what it says. 08 of 10 Thioacetone PishT / Wikimedia Commons / CC BY-SA 4.0 Thioacetone, (CH3)2CS, won't melt your face off or explode, but it's dangerous in another way. This ketone smells like it burped forth from hell's septic tank. Production of thioacetone led to the evacuation of the German city of Freiburg in 1889, from a chemical reaction that produced "an offensive smell which spread rapidly over a great area of the town causing fainting, vomiting and a panic evacuation." You can't simply wait around for the stink to dissipate, because it never will. Your best bet is to treat the air with nitrogen oxides and burn anything that came into physical contact with the molecule. 09 of 10 Strychnine Wellcome Images / Wikimedia Commons / CC BY 4.0 Strychnine is a bitter white alkaloid, commonly used as a pesticide. It's less toxic than some poisons (1–2 mg/kg orally in humans) but more widely available. Inhaling, injecting, ingesting, or absorbing it across your eyes or mouth will give you convulsions and possibly death by asphyxia. The compound comes from the Asian plant Strychnos nux-vomica. The toxin is still found in some rat poisons. People get exposed to the chemical when it washes into water or when they use street drugs that have been contaminated with it. There's a chance of surviving if you're exposed. That's good because there is no cure for the poison. 10 of 10 Formaldehyde Buyenlarge / Getty Images Formaldehyde, CH2O, makes the list because you are exposed to this dangerous chemical, probably on a daily basis. It's found in nail polish, wood smoke, smog, automobile exhaust, foam insulation, paint, carpet, and a host of other products and processes. Formaldehyde is toxic to all animals. In humans, it causes issues ranging from headaches and allergies to reproductive problems and cancer. It's dangerous because it's a toxic chemical you can't escape, no matter how hard you try. The good news is that formaldehyde has a characteristic odor. The bad news is that if you can detect the odor, you've been exposed to way beyond the recommended limit of the compound.