Can mouthwash make your mouth “dentist clean?” Episode 74

How can Listerine claim to make your mouth “dentist clean?” Perry and I break it down for you in this week’s show. And…more beauty science news!

Take our St. Patrick’s Day Beauty Science Quiz!

Are these statements about Irish Spring soap true or false? Listen to the show for the answers.

1. The first Irish Spring commercial in 1972 featured the same voice actor who did the Leprechaun from Lucky Charms cereal.
2. “Manly but I like it too” is arguably Irish Spring’s most famous slogan. One of its lesser known slogans was “You smell like you’re worth exploring.”
3. When Irish Spring launched in 1970, the first country it launched in was not Ireland but Germany.
4. The original Irish Spring soap bar contained Irish Moss Extract.
5. Irish Spring’s late 1990s “Up your kilt” campaign was dropped in the EU because it was too perceived to be too Anti-Scottish.

Claim to Fame: Can mouthwash really make your mouth “dentist clean?”

This is the segment where we look at the claims of popular beauty products and explain what the claim really means, how the company might support the claim, and most importantly, if the claim really makes enough of a difference for you to buy the product. Today we’re talking about Listerne Ultra Clean mouthwash.

Here’s the claim:

“Powerful DENTIST CLEAN feeling up to 3x longer*”
*vs brushing alone.


What does the claim mean?

What do you think when you first see the claim in this picture?  When I saw it, the words “DENTIST CLEAN” jumped out at me because they’re in a much larger, bold font. So I thought this product makes your mouth as clean as a visit to the dentist. That’s impressive.

The second thing that struck me was the numerical part of the claim because it says it lasts three times longer. Wow that is a powerful claim. How the heck do they do that?

Finally the first part of the claim caught my eye which says “feeling.” Then I realized what they had done. They’re not claiming your mouth is as clean as a dentist makes it or that that cleanliness last longer than a dental visit. They’re saying it makes your mouth feel as clean as a dentist visit. That’s much different! It also makes it clear that they’re just comparing the mouthwash performance to to brushing alone. Now that we understand the entire claim in its entirety, let’s talk about how they could support this.

How could they support this claim?

It’s really deceptively simple. Since they have defined the claim as a feeling they don’t have to do any instrumental analysis or chemical analysis. They can simply use a consumer panel. They could ask panelists something like… “on a 1 to 5 scale rate how clean your mouth feels after a dentist visit’ and then on that same scale rate “how clean your mouth feels after using this product.” Or they could say something like “Compared to a trip to the dentist rate how clean this product makes your mouth feel.”

Another set of questions could be crafted to support the 3x longer claim. Again one question could be “how long does your mouth feel clean after brushing alone” and another could be “How long does your mouth feel clean after using Listerine.” The difference doesn’t even have to be that great. For example if brushing alone makes your mouth feel fresh for 20 minutes and this product makes it feel fresh for an hour you have data to support three times longer.

Once again this is our guess of how they support the claim – they could be doing something much more rigorous and involved but I don’t think you would really need to. What we’ve just described is enough to establish basic clean support.

Should this claim persuade you to buy the product?

There’s nothing here that indicates this product is better than any other mouthwash. If they said “Listerine keeps your mouth feeling fresh three times longer than Scope” then that might be a compelling reason to buy one over the other. Without that kind of relevant comparison this claim isn’t very compelling and certainly shouldn’t be the thing to make you buy the product. (That doesn’t mean this is a bad product – it just means don’t be tricked into buying a product just based on the claims.)

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Cayetana from Mexico says “You will learn, laugh and save a buck or two next time you buy cosmetics.”

HalfPintPete from Sweden likes how we “tackle controversial aspects , such as natural greenwashing, animal testing, and the lies that some companies use to make us buy their products.” He recommends the show to “everyone who would like to know more about the secrets behind the makeup.”

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Beauty Science News

More on self preserving cosmetics
I want to start with a follow up to our discussion on self preserving products from a few weeks ago.

We talked about Lush products and that self preserving systems may have a shorter shelf life. Therefore if you buy a big jar of a self preserved product you may having to throw it away before you use it up. Obviously that’s not a good value for the consumer.

After that show we were contacted by a start up cosmetic company that has a novel approach that could help solve that problem. The company is Stowaway Cosmetics and they make cosmetics in teeny tiny sizes. The founder of the company, Julie Fredrickson, described their proposition like this: For example…”mascara expires way before you can use it but BIG MAKEUP still sells enormous sizes that no one can finish because we all seem to have bought into the idea that more is better.”

I was intrigued by this – smaller sizes are used up more quickly which MAY make it easier to get by with a self-preserving system. I also found it interesting that they were able to devise smaller sizes of lipsticks and mascaras – that’s easier said than done because it requires custom packaging development.

In the spirit of transparency, I have to say that they were kind enough to send us some free samples to try. And, according to our product evaluator they’re all terrific. So, if you find this approach appealing, you can find them at

A final note of self-preserved systems…I just read that a European company is putting preservatives into the plastic packaging so the product itself can be unpreserved or at least minimally preserved. It’ll be interesting to see if this catches on.

Silicones from cosmetics are unexpectedly found in the Antarctic
Here’s something many of you may have not considered. Your hair shine spray may be contaminating Antarctica. How’s that you say? You’ve never been to Antarctica you say? Well, it comes down to silicones. There is a common ingredient in shine sprays called Cyclomethicone. You’ll also find it in hair conditioners, skin lotions, and any other place where you want to get the benefits of silicone without the negative side effect of it weighing down hair and building up.

Silicones are used in cosmetics because they provide excellent shine, they’re very slippery, and they can feel nice on the surface. Cyclomethicone is particularly useful because it is a volatile ingredient which means that it evaporates. Another silicone called Dimethicone is also commonly used but once you put it on your skin or hair it stays there where it can attract dirt and build up over time.

But cyclomethicone just evaporates away. And this is the problem. Scientists thought that silicone would just evaporate into the atmosphere and get broken down by hydroxyl radical in the atmosphere. The molecules would degrade so there wouldn’t be any significant build up in the environment. But it turns out that cyclomethicone doesn’t degrade as readily as was thought. These researchers found an abundant amount of cycsiloxanes in a couple pristine, remote ecosystems which prompted them to investigate other places on the planet.

They took some soil samples from a variety of locations in Antarctica and were surprised to find the presence of cyclic volatile methylsiloxanes. These are the same ingredients used in cosmetics. Somehow the molecules evaporate into the atmosphere, get spread around the planet, then fall back to Earth (probably trapped in snow flakes or something).

So, your cosmetics could be contaminating Antarctica.

Before you start calling for a ban on cyclomethicone in cosmetics (it’s already been done by a lot of groups actually), you should consider two things. First, this work needs to be repeated. It’s really easy to contaminate the samples and until another lab repeats the investigation we can’t be certain that these results are real. Science always requires duplication.

Second, there is no evidence that the compound has any negative effect on the environment. Just because you find an ingredient in the soil doesn’t mean that it will automatically be a negative thing. It might, or maybe not.

So, if you are super cautious about you impact on the environment you might want to avoid products with cyclomethicone. But in reality, you’re probably not making much difference anyway.

Don’t use crayons as makeup!
 There’s a thread on Reddit called Makeup Addition which has some very interesting discussions. One poster gave an 4 point excellent explanation of why you shouldn’t use crayons as makeup – which I’ll quickly review.

The first point had to do with crayons being “non-toxic.” If crayons are non-toxic why couldn’t they be used in makeup? It’s probably because the lack of toxicity refers to a kid accidentally eating a crayon one time. That doesn’t mean the product is designed to be used on your lips where it can be ingested over a long period of time. It’s the whole “dose makes the poison” discussion.

The second has to do with what happens to a crayon when it is accidentally swallowed. The wax that is typically used in crayons has a higher melting temperature than body temperature and crayons aren’t very soluble in acid so a lot of pigments stay stuck in the wax mixture and just pass through your body. But, when crayons are used to make makeup they may be mixed with a wax or oil with a lower melting point to make it spreadable. That could change the solubility of the pigments and make them more likely to be absorbed by your body, which is not good.

Third, and perhaps the most critical point, is that crayons don’t use colorants that are approved by the FDA for on the lips. These are strictly regulated in cosmetics but in crayons they are not.

And lastly is the practical consideration that crayons dont make very good lipstick. They don’t spread well and they won’t stay on your lips the way a well formulated product will. So, all things considered, this is not a good idea.

More beauty bloggers launching their own cosmetic line
I see that a bunch of beauty bloggers are making a splash by launching their own brands. According to this Yahoo! Beauty article they are giving supermodels and celebrities a run for their money in terms of product endorsements. The most famous beauty blogger turned cosmetic brand is Michelle Phan who made a splash last year or the year before by launch a brand with L’Oreal. Well there are others including Emily Weiss who has a line of moisturizers and lip balms, Cara Brook who has a makeup line, Elizabeth Dehn who has a line of Organic beauty products, and a surprising entry…a guy, Eric Bandholz who has a brand called Beardbrand. He’s got a red beard and a good following so I guess that makes sense. I’ll be curious to see how these brands do. I mean if you can get a following on the Internet you should be able to get enough consumers to buy your stuff.

Hey, why don’t we have our own beauty brand? We’ve got a big audience and we’ve been at this a lot longer than many of these people. Actually, we have thought of it but there are a number of reasons we haven’t launched our own line. Mainly, it’s pretty hard to tell people about the BS claims of the cosmetic world while simultaneously trying to sell them products. You should always be hyper skeptical of anyone who is giving you advice about a product they are selling.

Reverse shampoo to get rid of gunk
After being in the industry for so long I thought I’d seen it all but here’s an interesting shampoo tip that I’ve never heard of.

This comes from Herbal Essences celebrity stylist Charles Baker Strahan who says that styling products are hard to wash out because when water comes in contact with styling gunk “it congeals and acts as a barrier, so your shampoo can’t get in and break it up.” His solution is to apply shampoo directly to dry hair and THEN get in the shower to rinse it out. This way the styling gunk doesn’t have a chance to congeal and create that blockage. Therefore, your shampoo cleans your hair better. Isn’t that interesting?

It’s true that styling resins can swell up and form an outer layer that is hydrated which then slows the penetration of water to the inner layer. That’s especially true for some old school styling agents like PVP. It’s also true that modern styling polymers are very water resistant which is why you can’t wash them out very well with water alone.

I think this tip MAY help. The advantage is that it does put a higher relative concentration of surfactant in contact with the gunk that you want to wash away. But, there are there are two potential downsides. One is that some styling agents are more cationic and shampoos tend to be anionic which means they could form an insoluble complex.

The other issue is one of potential irritation. You’re putting a higher concentration of surfactant in direct contact with your skin which could make it more irritating. I don’t think this is a huge risk but it’s worth mentioning.

But the best thing is we don’t have to just speculate on this. You could easily do one of our half head tests to get to the bottom of it. Assuming you’ve styled your hair such that you have equal amounts of styling gunk on both sides you could just sort of split your hair down the middle and to one half apply shampoo first and on the other half don’t apply anything. Then get in the shower and wet your hair and apply shampoo to the other side. After washing and rinsing if you can’t tell a difference between the two sides then this method probably isn’t providing any benefit.

Beauty beverages are the fastest growing segment in beauty products
Here’s a story I saw about the drinkable beauty market. We’ve talked a bit about the ‘beauty from within’ trend in the past and I’m always intrigued to see where this is going. In truth, there isn’t a lot of science to support the notion that you can drink your way to better skin but I do believe that eventually this could be the future of cosmetics. Wouldn’t it be a lot easier just to drink your beauty products rather than having to smear them on your skin?

According to market analysts the nutricosmetics market will reach $7.4 billion in worldwide says. That’s a lot! To give you an idea of comparison the natural cosmetic market is about $30 billion. The total cosmetic market is about $450 billion. But they say the nutricosmetics, or ingestible cosmetics as I like to say is the strongest growing segment. It also represents the intersection between the cosmetic industry and the beverage industry.

I think cosmetic companies are in a better spot to take advantage of this trend but companies like Coke and Pepsi might also try their hand at these types of products. After all, it will likely be food scientists formulating these products. This is a good reason for cosmetic scientists to brush up on their food product formulating. The ingredients are a bit different.

They say that there is a bunch of research that documents the links between beauty, health and supplements but the reality is there isn’t much good research. In fact, like I said there is scant evidence that any supplement can be taken to specifically improve your skin condition.

I guess it doesn’t matter much though because we live in a world where people want to believe. People want to believe that taking vitamins or other supplements will improve their health and now apparently, their appearance too.

It’s also an area that is much less regulated than cosmetics so these companies can make much stronger claims without as much data to back up what they are saying. And consumers keep buying…sigh.

Anyway, look for more of these beauty products to be launched in the future. Just don’t look for them to actually work at least any time soon. The science just isn’t there.