Answers With Joe, Random Thursdays

How Scientists Accidentally Created The World’s Worst Smell

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Thioacetone is a chemical whose smell is so bad, it’s almost impossible to believe. Weirdly, it was created from a chemical that you can find in candy. But it opens up questions about how smell works and why we react to smells the way we do.

TRANSCRIPT:

We’ve all kinda gotten used to COVID-19 at this point and we’ve heard all the weird effects it can have on the body but one of the weirdest has to be that it makes you lose your sense of smell.

Remember when it was still new and we were learning new things about it all the time, how weird that was? Remember panicking if you thought you weren’t smelling something at the level you thought you should?

We only have 5 senses, and this disease, for reasons we still don’t understand two years later, turns one of them off.

Imagine if it made you blind temporarily, or deaf, or you couldn’t feel anything you touched?

I guess there are other diseases that do that actually.

But the point is, everybody who lost their sense of smell talks about how weird it makes everything, how it makes it hard to eat because food all tastes like Elmers glue.

Don’t know what you got till it’s gone I guess.

But there are some instances where not having a sense of smell would probably be a good thing. For example if you were ever to run across a certain chemical called Thioacetone; considered by many to be the worst smell in the world.

What’s the worst thing you’ve ever smelled? Really, think about it, put it in the comments. I bet just thinking about it brings you back to a vivid memory of some kind. Probably not a great one. Maybe it’s even something that traumatized you. And you’re now spiraling into a dark abyss of pain you thought you had escaped. A door you thought you had permanently shut. And now you’re back inside of it, trapped, screaming into the uncaring void…

…Sorry I just made you do that.

But that’s the power of smell, it’s wired directly into our emotional centers, it’s our most primal sense. And yet, we still don’t really know how it works.

I know that sounds like clickbait, but it’s true, there’s no single agreed-upon theory of smell.

What we do know is that a smell happens when an odor molecule binds to a receptor within the nasal cavity.

That smell is then interpreted by the glomerulus which gets a bunch of information from other receptors in the nose called olfactory receptor neurons, and then combines all that info together into what we call smell.

And that is about how deep our understanding goes, we’re still struggling to figure out how exactly our olfactory receptors detect the molecules in the first place.

There are competing theories.

Docking theory of olfaction: Purposes a very 1:1 match. It’s kind-of a lock and key situation where a molecule key fits into a receptor lock. Each receptor is either on or off and the number of different receptors tells the brain how to interpret it.

Odotope theory: Is similar to docking theory except that molecules can fit several types of receptors and vice versa. It’s more of a matter of processing the signal through the noise.

Vibration theory of olfaction: That the molecules fit into receptors but the receptors are actually interpreting the vibrations of the molecules at the atomic level.

This one is pretty controversial, it also posits that quantum tunneling is involved which is totally nuts, so it’s heavily debated. I just think it’s funny that smelling science has drama.

But because we don’t know exactly how it works, it turns out you can’t really measure stink.

Or I should say you can measure the concentration of a smell but good or bad is rather subjective. One person’s stinky cheese or dripping gasoline odor is someone else’s bouquet of roses. Noses are weird.

So there is no objective scale of smells like, say scoville units that measure spiciness by the level of capsaicin in a food.

What we can gather is people’s reactions to the stink and see just how universally hated it is. Then we can look at how much this chemical can disperse and still be detected. And from that, of course, we can create a weapon.

Because humans gonna human.

Yes, the US Department of Defense studied smell in order to create a non-lethal stink bomb to use against the enemy.

One person who consulted on the stink bomb project was a cognitive psychologist named Pamela Dalton.

She said that the DOD had created a lot of different smelly chemicals and gave her access to their stink inventory.

She zeroed in on one that the government used to simulate large military latrines to test cleaning products on.

From this base of stink Dalton went on to create what she dubbed the “stench soup” she described the soup as smelling like “Satan on a throne of Onions” and that she couldn’t imagine a worse smell.

Well, she might not be able to imagine it, but there is a worse smell. FAR worse.

In the year 1889, German scientists were working with a chemical called Trithioacetone, which today is used as a flavorant in candy. So fairly harmless chemical, but as they were experimenting with it, they “cracked” that molecule.

Turning Trithioacetone into just thioacetone. And it turns out that while good things may come in threes, one is the loneliest number.

Because this compound smells in a profound way.

Almost supernatural.

Okay, so let me take a second and tell you what I really wanted to do with this video.

I heard about thioacetone and my YouTuber clickbait brain took off I was like, I’m gonna get my hands on some of this stuff. I’m gonna take just a tiny bit of it and go down to the park and rub it on a tree and then shoot people reacting to it as they walked by.

I mean I’m not really into prank videos but smell is a difficult thing to get across visually so I really wanted to show someone reacting to it, either other people or myself, I’d title it, “I Smelled The Worst Thing In The World” And I’d even do the whole Thumbnail wow face, put a red circle in there, I was ready to sell out big time.

…But then I read some of the stories about thioacetone.

And yeah… That’s not going to happen.

When the German chemists accidentally made a small amount of thioacetone, they also accidentally spilled a little of it.

And apparently one little quirk of thioacetone is it spreads through the air so fast that the people standing right next to it don’t actually smell it right away.

And by the time they picked up on the smell in their lab, people were literally passing out and vomiting in the streets of Friberg.

A newspaper at the time described it as “an offensive smell which spread rapidly over a great area of the town causing fainting, vomiting and a panic evacuation.”

They literally tipped over a beaker and it caused people to evacuate their homes and businesses up to a half a mile away in all directions in a matter of seconds.

That’s some fast stank.

Thioacetone popped up again in England in 1967.

British researchers Victor Burnop & Kenneth Latham were using thioketones to synthesize new polymers, and made a terrible mistake.

They left a bottle of residue open for a moment. In that time a building filled with people 200 yards away started to become overwhelmed by an unspeakable odor and nausea soon followed.

Just having a bottle open for a few seconds caused people to get sick in another building two football fields away.

At around that same time Professor Mayer at Dresden University of Technology stumbled upon it while experimenting with chemical compounds called thioketones.

He had heard about thioacetone and wanted to experience it for himself. And even though he was fully prepared to smell something awful, he was still blown away by it. Saying…

He calls it red. I’ve heard it described as brown and orange as well.

Oh, and another thing about thioacetone – it lingers.

As if the pungent smell wasn’t bad enough, apparently it’s described as “sticky” and will get embedded in your clothes and hair.

There was a story of some chemists that were exposed to thioacetone in a lab and even though they followed all the protocols and washed it off and everything, later that day when they went to a restaurant, the other patrons complained about their smell to the manager so much he literally sprayed deodorant on them at their table.

There’s Stench, And Then There Is Thioacetone, the World’s Stinkiest Chemical

But all of these stories are from a long time ago, it’s actually hard to find modern accounts of scientists working with Thioacetone, because I think they did enough research.

It doesn’t seem to have any other uses, it just stinks, really bad, really really bad. Enough said.

It’s literally like a WMD of smell, and it’s just not worth messing with it.

Because smelly spills happen all the time.

One of these spills happened in the city of Rouen (row-on) in Normandy, France.

There they have a chemical plant run by Lubrizol. And in 2013 they had a large chemical spill.

That chemical was heated by the air and evaporated, filling the air with the smell of rotten eggs that the wind carried for hundreds of miles, as far away as London.

People in Rouen reported feeling nauseous and having migranes from it.

The chemical spilled? Wasn’t Thioacetone actually but its baby brother mercaptan which is often put into natural gas lines to detect gas leaks.

Yeah, the use of mercaptan in gas lines goes back to… you guessed it… The Victorians!

I mentioned in one of my many Victorian videos that when gas lines first started appearing in homes, lots of people died of gas leaks, because natural gas is odorless and they didn’t know there was a leak. So they started adding mercaptan to it.

The human nose can detect 1.6 parts per billion of mercaptan, so you can imagine just how intense the odor must have been when pure mercaptan was floating over Europe.

The reason is the sulphur in the molecule, and the human nose is so good at detecting sulphur it is thought even a single molecule can even be detected.

Fun Fact:

The human nose is also really good at detecting the scent of vanilla (scientifically known as Vanillin). Vanillin has an even lower detection threshold of 2.0×10-7 mg/m3.

Yeah, apparently if you took an oil tanker full of pure vanillin and poured it out, it would literally make the whole planet smell like vanilla. The whole planet.

Which would kinda turn the whole planet into Disneyland. They pipe in vanilla scent through vents along main street Disneyland.

But back to thioacetone, why? Why is this stuff so bad? Especially when you consider it was derived from something that goes in candy? Chemistry is weird.

Thioacetone is derived from the Thiol group aka sulfur family.

Thiols are sulfur analogues of alcohol (Thi = Sulfur ol=alchol)

Humans evolved to avoid them because rotten things tend to release sulfurs. And rotting things tend to also contain you know, death and disease; stink, saving lives.

After a couple thousand years of evolutionary pressures, and now we are grossed out by dumpsters on breezy summer nights. Looking at you South Dallas.

Ultimately that is really what our human perception of stink is supposed to do. It’s what all of our senses are supposed to do, keep us alive.

Thioacetone really shows just how powerful chemistry can be and arguably dangerous, I can’t imagine what two oil trucks of thioacetone being tipped over would smell like. International smells like death day…week?

But luckily that’s very unlikely to happen. It doesn’t seem to have any use so there’s not a lot of factories making the stuff.

Like it’s so bad that you can’t even weaponize it, which is why the DOD was experimenting with other things. Try to smoke out some bad guys or disperse a crowd with thioacetone and all your guys will pass out in their own vomit too.

So even though my original plan for this video was kinda thwarted, maybe some things are best just left as a mystery.

Perhaps shelving thioacetone for good is the wise thing to do.

Researching into this episode made me appreciate my nose, as silly as that may sound.

I found myself taking time to really smell things around me, because most of our surroundings we grow used to and “smell blind” to but taking time to take deep breaths allowed me to appreciate new scents in my home and outside.

Smell is also powerfully tied to our memories and our emotions on an almost animal instinctual level. Most people can remember a smell, be it the smell of their grandmother’s house or their favorite flower.

It is very integral to who we are as humans, it enriches the world around us. Smell keeps us safe, and also leads us to food or water. One of the lowest concentrations of smell humans can detect is the scent of rain.

That scent, geosmin, can be as faint as 400 parts per trillion and still be detected, which really speaks to just how ancient and well tuned our booger factory is.

So it’s not all horrible. I asked you earlier to think of the worst thing you’ve ever smelled, how about I leave you on an upbeat, what’s your favorite smell? What’s a smell that takes you to your happy place?

And maybe as you go about your day, take a minute from time to time to focus on your nose and the smells around you. You might find it gives you a more rounded out experience, besides, it just helps you live in the moment, which is always good.

 

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