let me start by saying that I'm not planning on poisoning anyone I want to get that out of the way up front but I did recently notice that one very common poisoning method is no longer a viable option it's ethylene glycol the most common ingredient in automotive antifreeze ethylene glycol poisoning is slow painful and often not deadly but it was a common enough issue for manufacturers to voluntarily make a change so it is no longer a viable option for poisoning someone that is the bottom line takeaway here this video not an instruction manual for poisoning your enemies no poisoning here demo attempting to freeze water ethylene glycol in a solution of a 50 50 mixture of the two ethylene glycol was first synthesized in 1856 and it is a deceptively simple looking molecule it's got two carbons with some hydrogens attached and two hydroxyl groups that's it and it's the most common chemical added to engine coolant systems to keep them from freezing up or boiling over so you would think that it must have a super low freezing point right well it doesn't the freezing point of ethylene glycol alone is about negative 13 degrees Celsius or around 9 degrees Fahrenheit A little producer birdie named Andrew tells me that when he lived in Montana those temperatures would just call it a late spring it's a bad joke Andrew so we're going to need something with a lower freezing point than that to keep our cars running but something interesting happens when you mix ethylene glycol with water so water freezes at zero degrees but as you add more ethylene glycol the freezing point drops lower and lower get to a one-to-one ratio and the freezing point is nearly negative 40 degrees at 60 ethylene glycol the freezing point is even lower but if you keep adding more eventually that freezing point starts to go back up if you get to 100 ethylene glycol you're all the way back up to negative 12 degrees now I know we're here to talk about poison but this freezing point thing is too fascinating for me to just gloss over and understanding how ethylene glycol works as an antifreeze will help you understand how it also works as a poison it is so so weird and unbelievable that I just want to show you this phenomenon actually happening roll the demo [Music] later the water is solid the antifreeze oh yeah okay antifreeze is starting to freeze here and now the mixture mixture is still totally liquid oh yeah look at that so what is going on here why does mixing water and ethylene glycol drop the freezing point so dramatically between either of their individual components well in general anytime there's a question about what's going on with water you should just start by guessing that it's hydrogen bonds it's always hydrogen bonding we talk about hydrogen bonding pretty regularly on this channel so if you need a refresher on that you can check out the video that I did a few months ago about why water is so weird it's hydrogen bonding when hydrogen and oxygen bond to each other the oxygen ends up with a slight negative charge and the hydrogen with a slight positive charge because of those partial charges neighboring molecules with oh groups can attract one another with the oxygen on one molecule attracting the hydrogen on another now take another look at the ethylene glycol molecule do you see what's happening those oh groups sticking out on either end of the molecule are interacting with water molecules and vice versa that is important because in order to freeze two of the same kind of molecule basically just have to bump into one another while moving slowly enough to just lock into place but in a solution of ethylene glycol and water each chemical is constantly interacting with the other this means that a water molecule is less likely to run into another water molecule and freeze since the oh groups are constantly attracting one another it's much harder for either ethylene glycol or water to freeze to itself this is the same reason that ethanol dissolves own water and if you remember our recent whiskey video you'll remember that this is essential to understanding how distillation works and I'm not just saying this to plug our other video although you should go watch that right after this I'm saying this because ethylene glycol actually is an alcohol in ethanol you have two carbons attached to an oh group at one end in ethylene glycol you have two carbons with an oh group on each end it's very similar and this is where your body starts to run into problems ethanol is also a poison but it's a poison that your body knows how to deal with if you ingest ethanol your body gets to work breaking it down two enzymes in particular get the ball rolling alcohol dehydrogenase and aldehyde dehydrogenase these enzymes work together to convert that ethanol into acetyl as I always struggle with this word acetaldete acetate oh these enzymes work together to convert that ethanol into acid aldehyde and then acetate which can then be easily broken down into carbon dioxide and water if you ingest ethylene glycol these same two enzymes get to work breaking it down but this chemical process does not produce acetate instead with ethylene glycol alcohol dehydrogenase and aldehyde dehydrogenase produce something called glycolic acid and from there everything goes off the rails glycolic acid sticks around in your body long enough to cause metabolic acidosis meaning that the acid builds up in your system and your whole body's pH starts to drop glycolic acid is more chemically similar to lactate than it is to acetate so at this point the biochemical process totally jumps the rails to a completely different process with enzymes that aren't even involved in processing ethanol lactate dehydrogenase is really important for cellular metabolism so it's basically everywhere in your body when it runs into glycolic acid it converts it to glycocilic acid which is a precursor to oxalic acid and large amounts of oxalic acid widely distributed through your body is really bad news oxalic acid grabs onto any calcium it can find and then precipitates out of solution meaning that it forms a solid that settles onto the surfaces of your veins kidney tubules and all kinds of other places where you don't want solids building up so I'm going to show you a visual of what happens in the body when oxalic acid is involved with a precipitate reaction experiment [Music] okay so I have a solution of calcium chloride and I have a solution of oxalic acid so I'm going to pour a little bit of calcium chloride into the oxalic acid and as you can see right now both of these are just Clear Solutions right they're totally dissolved no problems however when the oxalic acid and the calcium chloride combined they're going to fall out of solution and form a precipitate they're going to form a solid and you can see almost immediately they start to form a precipitate it goes cloudy and that is a solid that is coming out of solution you do not want this solid accumulating in your veins that would be very very bad you really do not want this precipitation happening in your body the process destroys your kidneys first before leading to multi-system organ dysfunction at the same time you'll have seizures and every muscle in your body will start to spasm and cramp it is not a good time and if this sounds miserable Enough by itself keep in mind that this excruciating process plays out for days or even weeks this is a nasty poison ethylene glycol has an intensely sweet flavor while we can't quantify exactly how sweet it taste for humans because no one is going to participate in that study we know that any animals that stumble across it are likely to keep drinking it until all of the symptoms I just talked about start to happen and in fact at one point it was estimated that just in the United States 90 000 animals and 4 000 children were drinking ethylene glycol each year 4 000 kids and because it has an extremely high toxicity and a purely sweet taste small amounts could easily be mixed into sweet drinks things like soda juice or maybe even a little vodka crayon honestly I feel like uncomfortable having these things this close so in 2012 manufacturers of antifreeze voluntarily agreed to start adding a bittering agent to their products the bittering agent is called denatonium benzoate and it should sound familiar if you're a fan of this channel judging by George's reaction there I don't think that you could easily hide this in someone's drink anymore and while that covers Us for intentional homicidal poisonings unfortunately studies that have looked at accidental pediatric poisonings found no change after adding the bittering agent God that's depressing so given all of that why do we have so much of this stuff lying around seems like there has to be a better option for antifreeze and engine coolant right well we've tried propylene glycol has been suggested as a good option it's been used for decades in food coloring and flavoring as a solvent in intravenous and oral medications and more recently as one of the main ingredients of Vape juice unfortunately it's not as effective of a coolant as ethylene glycol it doesn't lower the freezing point of water as effectively and it's more expensive to manufacture but because it is so safe and ethylene glycol is so dangerous a lot of people think that those are trade-offs worth making in 2015 some researchers developed a propylene glycol solution with metal oxide nanoparticles that actually prove to be more effective than ethylene glycol in theory this could even allow car engines to be built with smaller radiators saving weight and improving fuel efficiency in the process but this hasn't been rolled out to market yet and if it eventually is the cost will likely be significantly higher than ethylene glycol so for now we are stuck using this very effective poison in our cars but at least it tastes worse now I guess before you go we're looking for your feedback each of your PBS digital Studios conducts an audience survey it helps us to understand what you like and what you want to see more of you also get to help PBS pick new shows it only takes a few minutes but your feedback is extremely valuable to us there's a link in the description thanks in advance because we've been talking about poisoning here if you know someone who's in suicidal crisis or emotional distress please call 988