85

The odour threshold for hydrogen cyanide $(\ce{HCN})$ is in fact quite a bit lower than the lethal toxicity threshold. Data for $\ce{HCN}$ can be found in many places, but here and here are a couple of good references. That subset of the human population that can detect bitter almonds do so at a threshold of $0.58$ to $\pu{5 ppm}$. The lethal exposure dose ...


45

Forget about the apple seeds, they contain about 1 to 4 mg amygdalin per gramm seeds (DOI). Instead, collect apricot seeds during the right season, the amygdalin content varies though the year and can be as high as 5% of the dry weight of the seed (DOI). It is probably advantagenous to break the husk with a nut cracker, a plier, etc. and cut the softer inner ...


45

Alle Dinge sind Gift, und nichts ist ohne Gift, allein die Dosis macht dass ein Ding kein Gift ist (The dose makes the poison) - Paracelsus Poisons (I'm going to use this as an umbrella term for "toxins" and "venom" as well. Bear in mind though, they are not the same thing) have been known since antiquity. Back in the good old days, you figured out if ...


38

I will start my answer with a preface that the website linked to in the question is a pseudoscience website (and I am glad that it has vanished from the face of this earth, only accessible via the Wayback Machine). These people use scientific-sounding jargon that sounds impressive to the lay reader, but any actual scientist will know that it is simply ...


35

Recognize that a whiff of most toxins, even in high concentration, will probably not kill you. You need a sufficient concentration in your blood - which means you have to actually get a certain number of HCN molecules to penetrate across the mucosa of the lung and into the blood stream. Typical breathing volume is about 500 mL (tidal volume), about 1/40th of ...


34

Table salt! What would be worse than putting sodium (it can spontaneously combust if you get it wet) and chlorine (used as a war gas in WWI) all over your food? Then there's water which always contains some $\ce{OH-}$ (an active ingredient in Drano) and $\ce{H+}$ (that stuff eats through metal, man). Although those aren't elements. And hiding inside every $...


32

Methanol isn't particularly toxic in and of itself, although it's no walk in the park. If methanol flowed through the body without being broken down, it would cause roughly the same kind of harm as ethanol, i.e. intoxication. The real culprit is one of its metabolic products, methanoic acid, also known as formic acid. To understand how formic acid, ...


29

Based on what I gathered from this Wikipedia article, Yes. Drinking copious amounts of water can prove fatal. The proper term is "Water intoxication". When you start taking in a lot of water (by "a lot" I mean more water than your body can excrete via sweat or urine), the interstitial fluid that bathe the cells that form your (living) tissue end up getting ...


28

The problem arises from the metabolized products of methanol. Methanol oxidizes in the liver by an enzyme called alcohol dehydrogenase to formaldehyde which is further metabolized to formic acid by another enzyme called aldehyde dehydrogenase. This formic acid is the source for acute toxicity associated with methanol poisoning. Accumulation of this chemical ...


28

Fluorine is much more reactive than chlorine and would certainly cause more damage to living tissues. You can even check out https://www.youtube.com/watch?v=vtWp45Eewtw for some fun demonstrations of its oxidizing power too! Likewise, compared to chlorine gas, I'd assume fluorine munitions would be significantly harder to manufacture, store, and handle for ...


27

Cyanide is a pretty good ligand for coordination compounds. The electron pair on carbon (which, incidentally, also carries the Lewis structure’s formal charge) is located in the HOMO — much like as in $\ce{CO}$, whose molecular orbitals can be found in this answer by Martin (replace oxygen with nitrogen to arrive at $\ce{CN-}$) — making it a good Lewis base ...


26

It depends on what the poison is. If we take the colloquial use of the word and include toxins and venoms, many are things like proteins that will certainly denature or otherwise degrade, eventually becoming harmless. e.g. tetrodotoxin, ricin, botulinum, etc. I would expect that type of poison to have the shortest shelf-life as they are relatively fragile. ...


23

The toxicity is primarily due to radioactivity and to absorption by the body, where that radioactivity can act internally. There is, "significant deposition of plutonium in the liver and in the "actively metabolizing" portion of bone," according to Miner and Schonfeld. Many $\ce{Pu}$ isotopes are primarily alpha-emitters, with "high ...


21

Yes. See Jury Rules Against Radio Station After Water-Drinking Contest Kills Calif. Mom The husband of a California woman who died after participating in a radio station's water drinking contest said he hopes a jury's $16.5 million compensation award following a wrongful death lawsuit will send a message to other corporations dealing with the public. .....


21

Do not do it !! ( putting acidic, or rather any juice to copper bottles ) You are in danger of copper poisoning. Generally, by food processing laws, copper is not allowed to be in direct contact with food, as there is danger of copper contamination. Especially acidic liquids, like vinegar or citrus juices, directly slowly dissolve copper in presence of ...


21

Under biological conditions it is almost impossible to release HCN Free cyanide can be released from potassium ferrocyanide by heating or by strongly acidic conditions (and some heat). Neither of these conditions is possible in a living organism. The reason why this is so is because the cyanide ligands are very strongly bound to the iron (in slightly more ...


20

Metallic lead is very low risk. Lead compounds are fairly poisonous: they slowly build up in the body and cause many harmful effects. But lead metal is very inert and you would need to do something fairly risky with it to create much likleihood of generating dangerous lead compounds. Don't eat it, for example. Don't put it in contact with food (especially ...


20

Of course no. Botulotoxin is probably the strongest known, and still its $\rm LD_{50}$ is counted in nanograms per kilogram, which is pretty manageable. Sure, working with such tiny amounts requires some special measures, but still, it is way greater than one molecule. You can divide it again, and again, and again. So it goes.


19

Actual toxicity other than radioactivity is not, as far as I know, very well studied. Quite simply, most of the danger is the radioactivity in general, as well as the toxicity of decay products (uranium and americium). Basic knowledge of biochemistry though suggests that it should be toxic for the same reasons that most high atomic weight metals are, namely ...


18

The enzyme alcohol dehydroganase converts the methanol to formaldehyde in the body. Formaldehyde is then converted to formic acid. Formaldehyde can cause blindness before being converted to formic acid, while formic acid causes acidosis as Williham Totland points out. See Biochemical Aspects of Methanol Poisoning for more information.


18

Gatterman reports (Org. Synth. 1927, 7, 50, as a footnote) that people who smoke regularly have enhanced sensitivity to the smell of cyanide gas, and he recommend smoking while preparing it! Organic Synthesis Collective Volume 1 1941 314-315 Just opening the NaCN container, most regular (and former regular) smokers can smell the trace amount of HCN formed ...


18

Mercury is toxic, but you need to carefully define what you mean by toxic or you draw incorrect conclusions Toxic is a broad term. It means a lot of different things. The timescale matters. Some toxic things take years to exhibit their effects; others act instantly. A binary distinction between toxic and not-toxic is pretty meaningless: you need to define ...


17

Diborane. NIOSH gives NFPA 4-4-4-W:


16

No, it is not toxic to touch solid lead. Lead poisoning results from ingestion: paints used to contain lead-based materials, and kids would sometimes eat the peeling paint leading to health problems. inhalation: if you were grinding or polishing a block of lead and fine particles were generated, you might inhale them if you weren't using the proper ...


16

As you already correctly deduced, the discovery of poisons was in former times quite accidental, but once its potency was discovered, the (mis)use of it was predictable. It must also be said that our ancestors were very careless with poisonous substances. The old houses used wallpapers and paint which were spiked with arsenic, lead and antimony. Copper ...


16

From Encylopedia Britannica: Of the platinum metals, osmium is the most rapidly attacked by air. The powdered metal, even at room temperature, exudes the characteristic odour of the poisonous, volatile tetroxide, OsO4. Osmium tetroxide is remarkably toxic and is not good stuff to have out in the open. Do not do this!


14

Honestly, you probably wouldn't be able to get this done with just a highschool chem lab, at least not to a high purity (whether or not this is needed is debatable; in fact it could be interesting in the story because it would give a clue as to how it was produced, whereas pure cyanide wouldn't really tell the detective much). Having said that, apples don't ...


13

Fluorine is in the first place much more reactive than chlorine. In contrary to chlorine, it would not damage biological tissues. It would destroy them. Pure fluorine could put the body on self-ignited fire. Its production and manipulation would be much more expensive and difficult. It reacts with water vapor and near anything it meets. It would have also ...


12

How do we tell or suspect one compound to be carcinogenic? As written in the comments to the question, this the result of large studies on the human population, correlating blood or urine levels of some substance to instances of cancer. Alternatively or concurrently, studies on animal models, such as mice, rats or even in-vitro studies may be carried out. ...


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