All About Antifreeze: Why Car Fluid/Human Poison Tastes Great
Disclaimer: If you are having immediate issues with antifreeze or ethylene glycol exposure please contact poison control at (800) 222-1222. Or if a pet has faced exposure call the ASPCA Animal Poison Control Center Phone Number at (888) 426-4435. This article is meant for education on antifreeze exposure and not meant for immediate medical attention.
Second Disclaimer: The purpose of this article is to educate people on the dangers of unintentionally poisoning yourself. Please do not use the contents of this post to harm yourself or others.
Third Disclaimer: Content warning, towards the end of this post I talk briefly about suicide.
Now that I think I covered all my legal bases its time to talk about car fluids and why they taste so good. I’m not a car person or a mechanic but as the name suggests antifreeze is a fluid that allows cars to not freeze over. This works by lowering the freezing point of water so water molecules no longer turn to ice under 32 degrees Fahrenheit or 0 degrees Celsius. Antifreeze compounds are present in many different animals and plants. Certain types of fish, frogs, and pine trees are examples of antifreeze being used in nature to, well, not freeze. So if antifreeze compounds are common in nature why don’t we have issues of children and pets getting poisoned from pine needles? There’s a few reasons for that but we need to cover some basic chemistry and anatomy real quick. I know, I’m sorry.
The main difference between antifreeze that you put in your car and antifreeze that pine needles use to stay alive during the winter is the chemical structure of the antifreeze molecules (1). The main compound of commercial car antifreeze is a compound called ethylene glycol. This compound has a big name but is pretty tiny compared to other organic molecules. Shown below is the chemical structure of ethylene glycol and various pine tree antifreeze compounds.
Chemical Structures of Ethylene Glycol
For reference for all these diagrams:
C= Carbon
O=Oxygen
H=Hydrogen
One line = molecular bound
Double line = double molecular bond
Additional note, if you see a blank line you can assume the angle of lines is a carbon with as many hydrogen atoms bonded as possible.
Made with ChemSketch.
Structures of Common Pine Tree Antifreeze
Here is the chemical structure of ethylene glycol next to various naturally occurring evergreen antifreeze compounds.
Other than the size of the molecule, the only thing you need to remember for the rest of this post is the “-OH” on the ends. That’s an oxygen-hydrogen pairing, but because I’m such a smarty pants they will be referred to as hydroxyl groups. These hydroxyl ends are what allow for the antifreeze to lower the freezing temperature of water when added to water and are responsible for the sweetness of antifreeze. We will talk more about this later.
Where to find Ethylene Glycol
Ethylene glycol is used for a few different things. As previously stated it is used as the main ingredient in car antifreeze. It is also used to make polyester fabrics and plastics (2).These products use ethylene glycol in production, it doesn't contain the compound in the finished product. It will not poison you but I still recommend you don’t eat polyester and plastics.
Ethylene glycol based antifreeze can also be found in some snowglobes. From what I have gathered this is to make sure they don’t freeze and break during shipping or while on display in the winter season.
But the form of ethylene glycol that you will encounter the most will be in car antifreeze. This can be found in homes, a mechanic’s garage, or even underneath cars if they have a leak. Antifreeze can make its way into the environment mostly through improper handling or leaks. Boats, planes, and cars can potentially contain ethylene glycol. This isn’t as common but I wanted to make the point that this can be found in more places than on your garage’s shelf. But allow me part with some sage wisdom; don’t lick puddles of liquid you find in the street.
If it's hazardous why do we keep it around?
It is cheap to make and great at what it does. When added to water the compound lowers the freezing point of the mixture and allows for engines to run at colder temperatures (3). When an engine is not running antifreeze prevents damage by preventing ice from forming and expanding inside the engine. Weirdly enough when added to water ethylene glycol also raises the boiling point of the mixture, allowing it to withstand a higher temperature before turning to steam. Ethylene glycol can also be considered an “antiboil” substance but that’s not nearly as great as a selling point. Most of the time they use the lame term “coolant.”
If this is meant for cars why does it taste sweet?
As we said before ethylene glycol has a hydroxyl group, an oxygen-hydrogen pair, at each of its ends. This makes the compound an alcohol, generally as any chemical compound with a hydroxyl group. Not the fun type of alcohol; the boring chemist kind. Generally the chemical classification of alcohols is sweet tasting (4). The hydroxyl groups are what makes this substance so delectable because these groups are recognized as sweet to our taste buds. There are exceptions to this rule so please don’t start drinking rubbing alcohol. It will be painful. Be normal and try some Everclear instead. But to drive this point home here is an example of the chemical structure of regular ol’ table sugar or if you are snooty, sucrose.
Structures of Sucrose and Ethylene Glycol
Common table sugar next to ethylene glycol. Take note of the amount of hydroxyl, -OH, groups on the drawings.
Even though sucrose isn’t an alcohol it has a ton of those hydroxyl groups which is what taste buds recognize as sweet through hydrogen bonding to our taste buds (5). Call it a coincidence or chemistry, antifreeze meant for cars tastes sweet to the tongue.
Do people actually ingest this stuff?
Yes. I will now provide possible scenarios.
Normally it’s an accident. It’s can potentially be little people, or how you say, babies. Just humor me for a second. Imagine that you are a baby or toddler again. You just got done shitting your pants and being fed your afternoon snack of Caprisun and Lunchables. While your parent is exhausted from dealing with you, you wander to the garage and find a gallon of bright blue, sweet smelling liquid. Do you think it's more Caprisun, Gatorade, HI-C? You probably can’t read so it’s possible.
Or maybe you are a cat or a dog that senses a sweet smelling liquid underneath that large metal beast that’s kept in the street. You may also be a spiteful family member looking to kill your “deadbeat” spouse without them noticing.
All joking aside, all three of these scenarios are possible. Accidental ingestion of ethylene glycol occurs in adults too. Animals don’t know any better. And while not the most effective poison it can kill if abused (6).
During my research I found the latest available annual report from the American Association of Poison Control Centers (7). In 2018 there were 6,411 reported cases of ingestion of ethylene glycol based automotive chemicals resulting in 5 deaths. Most of these were unintentional but some were intentional. There were also 849 non-automotive based ethylene glycol exposures resulting in 14 deaths. I try to make these posts somewhat entertaining and fun while still educating but this matter can be very real. If you would like to read the full statistics provided go down to the sources below. It’s a large report but if you use the Control+F function, or Command+F if you use Mac, to find the instances of “ethylene glycol” it's easier to find. Or use the table of contents if you are old fashioned.
Animals usually have a rough time after ingesting ethylene glycol. Firstly they can’t exactly say “Hey I’ve been poisoned,” so they rely on a human to call the animal poison control on their behalf. Secondly pets are smaller than humans and a relatively small amount of ethylene glycol to a human will affect a pet more quickly and harshly. According to the Humane Society 10,000 pets die each year from ethylene glycol based antifreeze (8).
Antifreeze Poisoning Symptoms
I don’t feel qualified to talk at length about the medical implications of antifreeze or ethylene glycol poisonings. A reminder, if you have immediate issues with ingestion of antifreeze call the poison control or pet poison control numbers listed at the top of this page. I will give the basics and link my more respectable sources below if anyone is adventurous and curious for the nitty-gritty of the medical details.
Ethylene glycol if left alone isn’t really poisonous. It’s how our body digests or metabolizes ethylene glycol which makes it harmful. After ethylene glycol enters the body our body metabolizes it into oxalic acid, which is highly toxic and potentially deadly (9).
In humans the first signs of ethylene glycol poisoning can happen within thirty minutes to twelve hours after ingestion. Symptoms include: slurred speech, nausea, vomiting, disorientation, and drowsiness. These symptoms are very close to being drunk, but can last for the whole intoxication period which can be up to three days. So unless you are a college frat star this should look pretty out of the ordinary.
The second stage of intoxication occurs twelve to twenty-four hours after ingestion. Symptoms include: shallow and rapid breathing, fluid in the lungs, a rapid and possibly irregular heartbeat, muscle spasms, and shock. At this point this is an alarming set of circumstances for anyone. A person should get to an emergency room or at the very least get instructions from Poison Control. Most deaths occur at this point.
The third and final stage of intoxication occurs twenty-four to seventy-two hours after ingestion. In addition to the other two stages occurring in this stage; symptoms include: low urine output, rapid heart rate, and kidney failure. If you get to this point and survive you will have permanent kidney damage. Get medical attention before this.
This is by no means a comprehensive list but sources (10) and (11) were used to compile this crash course. So check them out if you would like to know more or use it as a start point of finding out more.
In pets the symptoms are similar but manifest slightly different and much quicker. One teaspoon of antifreeze may be enough to be deadly for a cat and one to two being deadly to a dog relative to their size (12). I will not talk about these bummer symptoms any longer but please check source (12) for more information on pet symptoms.
Battling Sweetness
Between the chemistry lesson and death statistics this post has been a bummer. So what is being done to curb accidental antifreeze ingestion? In 2003 the United States House of Representatives introduced a bill that would require antifreeze that contains ethylene glycol at a concentration of ten percent or more would require a bittering agent (13). This bill would introduce the industry standard of making antifreeze less tasty. Unfortunately it was introduced to the house but never passed (14).
Even though the federal bill never passed some manufacturers still and state governments took it upon themselves to curb antifreeze consumption via a bittering of the antifreeze. In Michigan as of 2015 the state government decided to have all antifreeze manufacturers include the bittering agent, denatonium benzoate, to their products to prevent unintentional poisonings (15). I have to deliver some bummer news again because studies have shown adding denatonium benzoate had little to no effect. The products that had the bittering agent, denatonium benzoate, had no noticeable effect in decreasing accidental or suicidal poisonings in volunteer studies (16). There could be a number of reasons why this didn’t work. Denatonium benzoate has no research on its effects when consumed. It's just meant to be super bitter. So is denatonium benzoate also poisonous in large amounts? Is ethylene glycol just too sweet? Who knows. I couldn’t find recent articles on the subject but even if it prevents a handful of unintentional poisonings I’d argue it's still worth a including.
The best thing you can do to combat consumption is to keep the substance locked up in your house if you own antifreeze (17). You can also try to keep your pets on a literal tight leash in parking lots or garages where a car could be leaking antifreeze. This is not common but for anyone extra cautious. In the event that antifreeze is consumed by a person or pet please remember to call the numbers at the top of this post.
Conclusion
If you have read this far, thank you. I understand this post includes a good amount of medical jargon, chemistry, anatomy, etc. but if you take away one thing from this post please lock up antifreeze so no one can eat it. Antifreeze is for cars, not people.
If you have any suggestions for future articles or comments on this one please feel free to leave an anonymous tip via the Contact page on this website. Or the social media links work too if you’d rather that.
Thumbnail photo by @timmossholder.
Sources Cited:
1 Why Pines Are Evergreen. www.earthdate.org/node/139.
2 Ethylene Glycol. thechemco.com/chemical/ethylene-glycol/.
3 “What Is Ethylene Glycol?” What Is Ethylene Glycol?, www.americanchemistry.com/ProductsTechnology/Ethylene-Glycols-2/What-is-Ethylene-Glycol/.
4 “Sweetness.” Sweetness - an Overview | ScienceDirect Topics, www.sciencedirect.com/topics/nursing-and-health-professions/sweetness.
5 Why Is Sugar Sweet?, butane.chem.uiuc.edu/pshapley/GenChem2/B4/index.html.
6 Friedman, Megan. “A Mother and Daughter Plotted to Kill Their Family With Antifreeze, One at a Time.” Cosmopolitan, Cosmopolitan, 13 July 2017, www.cosmopolitan.com/lifestyle/a6943101/diane-rachel-staudte-antifreeze-murder-plot/.
7 American Association of Poison Control Centers (AAPCC) - Annual Report, aapcc.org/annual-reports.
8 “The Dangers of Antifreeze to Your Pet, and What to Do About It • MSPCA-Angell.” MSPCA, www.mspca.org/angell_services/the-dangers-of-antifreeze/.
9 “Oxalic Acid Safety Data Safety.” Ecolab Inc., safetydata.ecolab.com/svc/GetPdf/OXALIC_ACID_English?sid=975383&cntry=NZ&langid=en-GB&langtype=RFC1766LangCode&locale=en&pdfname=OXALIC_ACID_English.pdf
10 “Environmental Health and Medicine Education.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, www.atsdr.cdc.gov/csem/csem.asp?csem=12&po=9.
11 “Antifreeze Poisoning: Symptoms, Treatment, and Prevention.” Medical News Today, MediLexicon International, www.medicalnewstoday.com/articles/324807#summary.
12 “Antifreeze Poisoning in Dogs.” Pet Poison Helpline, 3 Mar. 2020, www.petpoisonhelpline.com/pet-safety-tips/antifreeze-poisoning-in-dogs-cats-ethylene-glycol-poisoning/.
13 Ackerman, and Gary L. “H.R.1563 - 108th Congress (2003-2004): To Require Engine Coolant and Antifreeze to Contain a Bittering Agent so as to Render It Unpalatable.” Congress.gov, 10 Apr. 2003, www.congress.gov/bill/108th-congress/house-bill/01563.
14 “To Require Engine Coolant and Antifreeze to Contain a Bittering Agent so as to Render It Unpalatable. (2003 - H.R. 1563).” GovTrack.us, www.govtrack.us/congress/bills/108/hr1563.
15 “Bill to Infuse Engine Coolant Products with Bittering Agent Advances in Mich.” AAHA Home, www.aaha.org/publications/newstat/articles/2013-05/bill-to-infuse-engine-coolant-products-with-bittering-agent-advances-in-mich/.
16 Soloway, Rose Ann Gould. “Taste Changes Don't Stop Poisonings.” Poison Control Expert Help Online or by Phone, National Capital Poison Center, 31 July 2019, www.poison.org/articles/2009-oct/taste-changes-dont-stop-poisonings.
17 Soloway, Ann Gould. “Prevent Cold Weather Poisonings.” Poison Control Expert Help Online or by Phone, National Capital Poison Center, 31 July 2019, www.poison.org/articles/2008-dec/prevent-poisonings-during-cold-weather.
