You’ve probably seen the headlines: "Toxic Forever Chemicals Found in Makeup!" It sounds scary. But how do scientists actually know if PFAS are in your mascara, foundation, or sunscreen?
It turns out, testing cosmetics is a tricky detective game. Let's break down the steps scientists use and why some tests are better than others for your favourite products.
The Suspect: "Organic Fluorine"
PFAS are a huge family of chemicals. What they all have in common is a super strong bond between Carbon and Fluorine atoms.
Instead of trying to find every single one of the thousands of PFAS chemicals, scientists often start by looking for that tell-tale Fluorine signature. First they look for Fluorine (F) and if there is fluorine present then they will go further and do Total Organic Fluorine (TOF) testing.
A positive TOF test means the product almost certainly contains PFAS. We just don't know which ones. It's a great, cheap first step to screen products and say, "Yep, there's something fishy here that needs a closer look." It is also great because as we know 15000+PFAS have NOT been studied and so knowing the percentage of organic fluorine in a product gives us some indication of how safe it is.
The Closer Look: Specific PFAS Testing
If the TOF test flags a product, the next step is to call in the big guns: a machine called a Liquid Chromatograph-Mass Spectrometer (LC-MS).
This machine is the ultimate detective. It can:
- Separate all the ingredients in the complex makeup formula.
- Identify the specific PFAS chemicals by their unique "fingerprint" (like PFOS, PFOA, or others).
- Measure exactly how much of each one is present.
This is the most accurate method. It's like the scanner not only finds the orange jersey but also reads the name on the back: "Oh, it's this specific PFAS chemical, and there's this much of it.
The Problem: The Test That Can't Solve the Case (EOF)
There's another test sometimes discussed called Extractable Organic Fluorine (EOF) testing. For cosmetics, this test has a major flaw.
Here’s the problem:
- The Process: An EOF test involves burning the sample at a very high temperature. Any fluorine that is released is measured.
- The Cosmetics Crash: Makeup and skincare are complex cocktails. They're filled with other completely safe ingredients that also contain fluorine.
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- Common Examples: Some preservatives, sunscreen agents (like oxybenzone), and even some moisturizing ingredients have natural fluorine bonds that are NOT PFAS.
Why EOF is Bad for Cosmetics:
When you burn a moisturizer with a fluorine-based preservative in an EOF test, the machine detects the fluorine and shouts, "I found PFAS!" But it's wrong. It found a harmless, legal ingredient that just happens to also contain fluorine.
It's like our scanner from before is set off by any orange object—an orange jersey, an orange traffic cone, or someone's orange lunchbox. It creates false positives and isn't reliable for these complex products.
The Takeaway: How to Crack the Cosmetics Case
- TOF Testing is a good, broad screening tool to red-flag products that need more investigation.
- Specific LC-MS Testing is the only way to know for sure which specific PFAS are present and how much is there.
- EOF Testing is not reliable for cosmetics because it gets confused by other safe ingredients and can give false results.
So, when you see a study claiming PFAS are in makeup, the most trustworthy ones are those that use the specific LC-MS method to prove exactly what was found. It's the difference between a guess and a solid piece of evidence