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Humans love to make perfumes and fragrances from the weirdest sources, And to protect those sources, we sometimes come up with synthetic alternatives....which then create their own sets of environmental problems.

Hosted by: Stefan Chin

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Images:
https://commons.wikimedia.org/wiki/File:Ecomare_-_ambergris_van_potvis_in_2012_(potvis2012-ambergris-2164-em).jpg
https://commons.wikimedia.org/wiki/File:Ambergris.jpg
https://commons.wikimedia.org/wiki/File:Test_tubes_of_porphyrine_solution_under_UV.tif
https://commons.wikimedia.org/wiki/File:Primary_Form_of_Musk.jpg
https://commons.wikimedia.org/wiki/File:Santali1.JPG
https://commons.wikimedia.org/wiki/File:Santali2.JPG
https://commons.wikimedia.org/wiki/File:SandalwoodEssOil.png
https://commons.wikimedia.org/wiki/File:Santalum_album_(Chandan)_in_Hyderabad,_AP_W_IMG_0029.jpg
https://commons.wikimedia.org/wiki/File:Indonesia_Madagascar_Locator.svg
[♪ INTRO].

Humans love to make perfumes and fragrances from the weirdest sources, from endangered plants, to extremely expensive marine poop, to the crotch glands of rare animals. And historically, people have gotten so excited over these strange sources of scent that we’ve exploited them to near extinction.

So, chemists trying to protect the environment had to come up with synthetic ways to reproduce natural fragrance compounds. Now, that’s harder than you might think. Because we can't just 3D print any molecule we like… at least, not yet.

It’s a complex puzzle requiring just the right ingredients, and it’s different for every chemical. And often, the synthetic solution to one sustainability disaster creates new trouble of its own, from health problems to environmental contamination. So here are four stories of how humans exploited a source of natural fragrance, then tried to save it through synthetics… and then had to save themselves from the chemicals that they made.

If you take a whiff of perfumes like Light Blue by Dolce & Gabbana or Midnight Poison by Christian Dior, you might detect a subtle musky aroma. Some have likened it to the wood in old churches. But it comes from ambergris.

In addition to smelling nice, it fixes perfume on the skin so the scent lasts longer. Ambergris looks like a yellow-gray rock that washes up on beaches. And for millennia, people used it for medicine, incense, and perfume… without knowing what it was.

Perfumers theorized it might be anything from petrified lynx urine to a kind of amber. Hence the French name, “ambergris,” meaning gray amber. But we eventually figured out its true nature.

It’s sperm whale poop! A sperm whale eats around 400 kilograms of squid per day. But it can’t digest their beaks.

Researchers think the whale produces compounds in its gut to help protect itself from those hard, poky beaks. And we think those anti-beak compounds are what go into making ambergris. Once expelled, this block of feces floats through the ocean, where it can eventually wash up on a beach and work on its tan.

But finding this highly prized poop is a pretty rare occurrence. Only 1% of sperm whales make ambergris. And only about 0.5% of the substance’s mass converts into odor compounds.

So ambergris is pricey. Plus, sperm whales are in danger of extinction. Meaning in some countries, ambergris isn’t just expensive, it’s flat out illegal to buy and sell.

But it’s still really useful for perfume. So scientists have scrambled to make a synthetic equivalent. But first, they had to analyze its chemistry.

Up to 45% of ambergris is ambrein, an odorless organic compound that scientists think is created by the whale’s gut bacteria. Ambergris also contains light-sensitive substances called porphyrins. When porphyrins absorb light, the energy from that reaction creates super-unstable oxygen compounds that transform ambrein into aromatic compounds including ambrox.

And in the 1940s, ambrox was identified. As the main fragrance compound in ambergris. In 1950, a Swiss company identified ambrox’s chemical structure and developed a way to synthesize it from a plant: clary sage.

But even though it helps preserve sperm whales, the industrial synthesis of ambrox is very resource-heavy. It also uses large amounts of toxic substances, like chromium trioxide, which can induce genetic defects and is highly dangerous to aquatic life. So even though scientists had a way to make fake ambergris, they needed to do better.

Researchers discovered that, by changing out certain chemicals, for example by using hydrogen peroxide, they cut down on the chemical waste generated in the process. And those tweaks also meant they got 20 times more stuff out of the process. Which is great news for fans of sperm whale poop across the world.

Now, another musky-scented animal discharge is, musk. This earthy, animalistic odor has been used in perfumes for thousands of years. It’s also been used as an aphrodisiac, on the basis that some animals use it to attract mates.

See, undiluted musk is a pee-smelling secretion from the scent glands of some mammals. There are other animals that make musk. But in the perfume industry, “musk” usually refers specifically to secretions from a gland near the genitals of the male musk deer.

And because musk was so desirable, people hunted the deer nearly to extinction. Clearly, chemists needed to invent an alternative. But as it turned out, the first synthetic musk was produced by accident.

In 1888, a researcher trying to create better explosives accidentally made something that smelled like musk. Soon after, the synthetic nitro musk craze exploded. And nitro musks have formed a big part of most perfumes, including the famous Chanel N°5.

But in 1981, Japanese scientists were the first to sound the alarm about how dangerous nitro musks might be. Synthetic musks accumulate everywhere, both in the environment, and in the bodies of animals. They’ve been found in rivers, lakes, fish, birds and mammals, including human blood and breastmilk.

Now, we don’t know for sure that they’re toxic to humans. But animal studies show that nitro musks can inhibit the activity of proteins that allow cells to expel toxins. And since that can cause cancer, the use of nitro musks in cosmetic products has been banned in many countries.

The perfume industry has largely replaced them with polycyclic musks, which account for 90% of all musky scents used in the perfume industry. But it turns out that was a bit of an oopsie, because polycyclic musks have been found to accumulate in environments and organisms basically as much as their nitro cousins. And early research suggests they can be toxic to marine life.

So it turns out that’s not the alternative we were looking for. But one does exist. And it involves something that doesn’t just smell like musk.

It’s actually part of musk. Back in 1906, scientists isolated the main aromatic compound in deer musk and called it muscone. Chemists started synthesizing muscone in 1934.

And it seems like it’s not too hard, for example, it’s possible to use citronella oil as a starting point. Muscone is a type of macrocyclic musk, which are much more expensive and complicated to synthesize than their polycyclic cousins. But in theory, they should have less environmental impact because they break down more easily, so they shouldn’t accumulate so much.

Plus, their price is expected to come down as our technology improves and we get better at making them. Now, not every fragrant compound involves animal excretions. Sometimes, we derive scents from plants.

And one of the most legendary is sandalwood. Species of sandalwood tree grow naturally everywhere from Fiji to Chile. But in perfumery, the word “sandalwood” usually refers to Santalum album, a species native to India.

Their woody, spicy fragrance comes from the wood and its oil. And it’s been used in medicine, religion, and perfumery since Ancient Egypt. These days, sandalwood scent is used in incense, lotions, and perfumes like Dior’s Hypnotic Poison or Crystal Noir by Versace.

Starting in the 18th century, the Indian government held a monopoly on sandalwood trade, and commercial planting was forbidden. Sandalwood trees became really hard to come by, driving the price so high that sandalwood oil is sometimes called “liquid gold.” In addition, sandalwood suffered decades of devastating fires, disease and smuggling. In the 90s, it was designated as in danger of extinction in the wild.

The Indian government has since relaxed its planting restrictions, and plantations have been popping up in countries like Australia and Indonesia. But, it can take 15 years until sandalwood is ready to harvest. So it will be a while before the new plantations can top off the shortage.

Meanwhile, most of the perfume industry chooses the synthetic option. Researchers identified the structure of santalol, the main aromatic compound in sandalwood, in 1921. But it wasn’t until 1991 that scientists discovered that the true essence of sandalwood lies in only one isomer of santalol.

An isomer is a version of a compound that has the same number of the same atoms, but they’re arranged differently. With this discovery, chemists were able to more accurately synthesize the scent of sandalwood. But they still had to deal with the environmental impacts of the process.

Santalol is synthetized from pine resin, which can be extracted without killing the tree. But the synthesis generates a lot of chemical waste that needs to be treated and stored. And it can also contaminate soil and water.

So researchers are working on new catalysts that would limit the environmental impact of synthetic sandalwood production until the trees can bounce back. Another aromatic plant that’s a victim of its own popularity is vanilla. It’s a type of orchid native to Mexico, and it was highly valued by the ancient Aztecs, who used it to flavor their chocolate drinks.

Today, it’s mainly grown in Madagascar and Indonesia. And because it’s been exploited and its habitat has been destroyed, vanilla is a protected species in the wild. But even in industrial conditions, cultivating it is a difficult process.

See, when colonizers took vanilla plants from Mexico to other countries, they didn’t take their pollinators along for the ride. So, vanilla flowers need to be pollinated manually, one by one. And it takes 600 pollinated flowers to make a kilogram of vanilla beans.

And the beans only contain 2% of the main flavor compound, vanillin. Part of the world’s demand for vanilla is still satisfied by extracts distilled from the beans, because consumers prefer to see the label “natural” on vanilla-flavored products. But this growing desire for “all natural” ingredients jacks up the price of vanilla, which has risen by 2,000% since 2012 and comes close to the price of silver.

That’s why around 90% of the world’s vanilla flavor comes from synthetic vanillin. Vanillin was first synthesized in 1874 from coniferyl alcohol, which is obtained from pine bark. In 1876, the industry switched to a more efficient method using compounds derived from petroleum and clove oil.

In the 1930s, the dominant process switched again to one that used natural ingredients that people assumed were more sustainable: the waste from paper production. This method uses lignin, the main ingredient of wood. Lignin naturally degrades to vanillin, giving second-hand bookstores that classic sweet smell.

Most vanillin came from lignin until the early 1990s, when a change in how paper is produced made that cheap waste product less available. People also started looking at the whole lifecycle of a product. And they noticed that, even though reusing industrial waste sounded sustainable, making vanillin from lignin generates 160 tons of highly corrosive waste per one ton of vanillin.

These days, more than 90% of vanillin is synthesized from petroleum. The process generates little waste compared to the earlier methods. Vanillin is used in around 2% of all food products, in multiple perfumes and colognes, and in the pharmaceutical synthesis of drugs like levodopa, one of the main treatments for Parkinson’s disease.

So because vanillin is everywhere, even tiny steps toward making its synthesis greener go a long way towards preserving the environment. But we can definitely still do better. Because as we mentioned, vanillin comes from petroleum, which ties it to the oil trade.

So researchers have been looking for more sustainable alternatives. One new approach makes vanillin from ferulic acid, which is found in many plants. By the way, another natural source of vanilla-like scent does come from animal excretions.

In this case, glands on a beaver’s butt. So, synthetic versions of natural fragrances have a lot of advantages. They can protect vulnerable species, and they generally don’t involve animal butts.

Also, manufacturers can be sure they don’t contain unwanted allergens, which can happen with natural fragrances. But let’s be honest. A lot of companies that turn to synthetics are trying to save money.

Not exploiting a natural resource is more of a side effect. So that does nothing to ensure synthetic alternatives will be good for the environment. It’s a good reminder that we can’t really tell how good or bad a chemical is for the environment without looking at the whole picture, how it’s made and where that stuff comes from.

And it’s a reminder that even when we fix something that we were doing wrong, we can often still do better. And smell great while we’re at it. Thank you for watching this episode of SciShow, and thanks to this month’s President of Science, Matthew Brant, for helping us make it happen.

Your support means a lot to us. And so do all of our patrons, so thanks to you too! If you want to get involved and help us make SciShow, you can head over to patreon.com/scishow. [♪ OUTRO].