Transcription
Peptides are having a moment, and if you've been in a Sephora or scrolled through a skincare brand's website lately, you've probably noticed they're on everything: serums, eye creams, moisturizers. And the pitch is always the same. Peptides signal your skin to produce more collagen, so you get firmer, smoother, younger-looking skin.
Peptide on an ingredient list is not a single thing. And a subset of the ones being marketed hardest have a chemistry problem that most people don't know to look for. I'm Dr. Yvonne Burkart, a PhD toxicologist and mom of two, and I've spent my career studying how environmental chemicals interact with the body. What I want to walk you through today is something that I call the fluorine swap, a modification some manufacturers make to a peptide that can turn it into a forever chemical. And what makes this worth paying attention to is that you're putting this on your face every day and leaving it there.
Let's start with what a peptide actually is, because the trend is real and the underlying chemistry does work. Peptides are short chains of amino acids. Your body already makes thousands of them naturally. In skincare, the ones that get the most attention are the kind that signal your skin cells to produce more collagen, the structural protein that keeps the skin firm. As collagen production slows with age, skin starts to lose that structure. So, the logic of using a collagen signaling peptide topically is legitimate. That part is not the problem, though.
The problem is what some manufacturers do to a peptide before it goes into the bottle. To make a peptide more stable on the skin, last longer, and resist breaking down, some companies chemically modify it by adding fluorine atoms to the structure. That carbon-fluorine bond is one of the strongest bonds in all of chemistry, and it does not break down easily. That is exactly the property that makes a PFAS a forever chemical. PFAS stands for per- and polyfluoroalkyl substances, and what defines them as a class is that same carbon-fluorine bond, which resists degradation. So, the modification that makes a peptide perform better in your serum is the same modification that can place it in the PFAS family.
I call this the fluorine swap, and there's a real marketed anti-aging ingredient that's a perfect example of this. It's called trifluoroacetyl tripeptide-2. It shows up in anti-aging serums and firming creams sold for smoothing and lifting of the skin. I actually flagged this one when I reviewed a celebrity skin care line, and it's the one I want to walk through here because the name does the work for us. Trifluoro at the front of the name means that three fluorine atoms were added to this peptide. That's the chemical modification. That's the fluorine swap right there in the ingredient name. And here's why that matters. That fluorine is what makes a PFAS a forever chemical. It doesn't break down, not in the environment, and not easily in the body, either. So, when you apply a product with this ingredient every morning and every night, you're not just putting on a peptide. You may be adding to your daily chemical burden in a way that most people have never thought to consider. That's the part the anti-aging peptide marketing does not tell you.
So, a few years ago, as I mentioned, I made a video about a celebrity skin care brand that marketed themselves as having consciously clean formulas, which eliminate over 2,700 ingredients of concern, including specifically named PFAS. So, at first glance, nothing jumped out as obviously problematic, and it looked like a decent brand. But, when I looked closely at the ingredients list on a moisturizer, I noticed a fluorinated peptide, specifically trifluoroacetyl tripeptide-2. I did a double-take because here was a brand whose own product directly contradicted its marketing, and it was not obvious at first glance because there was a separate page that mentioned specifically about the ingredients that they don't use or ban in their products, but then I checked the ingredients list on the actual product page, and there it was, just like staring at me. So, I was pretty surprised. And that's exactly why this is worth knowing how to spot yourself rather than relying on a brand's claims about what it has or hasn't eliminated.
So, you might be thinking, "Well, don't a lot of ingredients absorb into the skin and just get processed out?" Well, that's a fair question, but skin care is different from something you rinse off. In this case, the moisturizer is a leave-on product that you put it on the same place on your face every day for several years. And what the research is starting to show is that skin absorption from fluorinated cosmetics may be a more significant PFAS exposure route than most people have considered. A 2025 study published in Environmental Science and Technology screened 64 beauty products and found PFAS in 61 of them. For products that listed a fluorinated ingredient specifically, exposure levels were significantly higher. For regular users, the estimated daily exposure from those fluorinated products exceeded the European Food Safety Authority's recommended threshold. The researchers noted that dermal absorption from fluorinated compounds ranked as the second largest PFAS exposure route in the general population after food. That study tested cosmetics on a broad scale, which included sunscreens, foundations, cleansers, not peptide serum specifically. But, the chemistry is the same. Fluorinated ingredient, same carbon-fluorine bond, same absorption question. PFAS as a class have been associated in research with endocrine disruption, immune effects, cancer, and other health concerns. The evidence is still developing, and I want to be careful not to overstate what we currently know. But, that's exactly why the exposure route matters. And I want to say this clearly. This is not a reason to panic or a reason to clear out everything in your skin care cabinet. That's not what this is about. It's a reason to understand what you're actually applying so you can make an informed decision.
Now, here's where where label problem comes in, and it's a real gap, and it's not an accident. A fluorinated peptide almost never announces itself on the package as a PFAS. It shows up under its full INCI name, which stands for the International Nomenclature of Cosmetic Ingredients. It can be long, and it might sound highly chemical, and it's easy to scroll past. Research has shown that fluorinated cosmetics can carry PFAS even beyond what's listed, including breakdown products and precursors that weren't declared by the manufacturer. Companies aren't required to flag fluorinated ingredients in a way that a shopper would recognize as a PFAS signal. So, a product can say clean on the front and anti-aging peptide complex in the marketing, while a fluorinated compound sits in the ingredient list with no indication of what it actually is. I understand why that's frustrating to hear, and tighter regulation around ingredient disclosure would genuinely help close this gap. But, you don't need to wait for that to make an informed decision today.
Here's what to look for. Pull up the ingredients list on any peptide product that you're using or considering. You're looking for these prefixes: fluoro, perfluoro, polyfluoro, or trifluoro. Any peptide name that starts with one of these is a fluorinated compound. Not every peptide is fluorinated, and the majority are not. So, this is not about avoiding peptides altogether, but rather it's about knowing the one prefix in the ingredient name that tells you that something different is going on. And you don't need to memorize chemistry to do this. All you need to do is recognize those four prefixes, and a quick scan of the ingredients list is all it takes. And remember that peptides are not the problem. The fluorine swap is the one thing to watch out for, and now you know exactly what it looks like. One prefix on a label, and you'll catch it every time.
Peptides can genuinely be good for your skin. In fact, I use a peptide serum, and I think it's great. Knowing this one thing means that you get to use them without that uncertainty hanging over the decision. I covered this same kind of label reading skill, how to spot what marketing won't tell you in The Low-Tox Solution, my new book, which is available for pre-order now. I've gone ahead and added the link to the description.
Now, remember how we talked about PFAS resisting breakdown, not in the environment and not in the body. A lot of them are also lipophilic, meaning they're attracted to fat and tend to accumulate in fat tissue over time. There's a specific moment when what's stored in the fat tissue doesn't stay stored. And what triggers it is something that most people think of as one of the healthiest decisions they can make, weight loss. I call it the fat release effect, and it's one of the most important pieces of context that almost never makes it into mainstream weight loss conversations. In my next video, I walk you through exactly what gets released when fat cells break down, why the pace matters more than what people realize, and three things you can do to actively support your body while it's happening. I'll see you on the next video.