The chemicals that do not wash off

You can read an ingredient list carefully, take a photograph of it, look up every name on it — and still not find the thing you were looking for.

In 2021 a team at the University of Notre Dame, led by Heather Whitehead, took 231 cosmetics off the shelves of shops in the United States and Canada and screened them for total fluorine. Fluorine is not itself the problem. It is a marker: a high fluorine reading is a strong signal that per- and polyfluoroalkyl substances — PFAS, the group commonly called forever chemicals — have been added to the product.

The readings were not marginal. Fifty-six percent of the foundations and eye products carried high fluorine. So did 47 percent of the mascaras and 48 percent of the lip products. Waterproof mascara was the worst single category tested, at roughly 82 percent.

The part that matters is the label

Here is the finding that changed how we read a box. PFAS appeared on the ingredient list of only 8 percent of the products tested. The chemicals were in more than half of them. They were declared on fewer than one in twelve.

That gap is not a scandal of one brand. It is a structural feature of how cosmetics are labelled, and it means a careful shopper reading a careful label can still be wrong.

More than half the products carried the marker. Fewer than one in twelve declared it.

The picture has not improved with time. In January 2026 the FDA reported finding more than 50 intentionally added PFAS ingredients across some 1,700 personal care products. Intentionally added is the phrase to sit with. These are not traces drifting in from a factory floor. They are there because they do a job — they make a formula spread evenly, cling to skin, and survive water.

Why they are used at all

PFAS are genuinely good at what they do. The same chemistry that makes a mascara survive a swim makes a foundation sit flat all day. The Notre Dame team found the highest fluorine readings clustered in exactly the products sold on that promise: long-wearing, wear-resistant, waterproof.

The concern is what happens afterwards. PFAS are called forever chemicals because the carbon–fluorine bond does not readily break down, in a landfill or in a body. Some of the compounds in this family are associated with health effects at low exposures. Many of the thousands in the group have never been studied at all.

What we do with this

We are not going to tell you to throw anything away. We will tell you what changed here:

• We treat “long-wearing” and “waterproof” as a flag, not as a feature. Those were the categories with the highest readings.
• We stopped trusting the absence of a name. A short ingredient list is meaningful. An ingredient list that simply does not mention PFAS is not.
• We look for certifications that test the finished product, because they test what is in the tube rather than what was meant to be.
• We prefer fewer ingredients. A five-ingredient oil has fewer places for anything to hide.

That last one is why the face oil in our shop is the one it is. Five ingredients, no fragrance, and a certification that looks at the finished formula. It is not a guarantee. It is the closest thing to one that a shopper can actually check.