Do Period Pants Contain PFAS? Toxins & Chemical Safety

What are PFAS and why are they called forever chemicals?

PFAS are a family of thousands of man-made chemicals built around carbon-fluorine bonds, which are among the strongest in chemistry. That strength is the whole point: PFAS shrug off water, oil, grease and heat. It’s also the problem, because almost nothing in the body or the environment can break them down, so they persist longer than any other man-made substance. That’s where “forever chemicals” comes from.

The European Chemicals Agency puts the group in the thousands. The UK’s Health and Safety Executive uses a narrower chemical definition (substances with at least one fully fluorinated carbon, or two or more adjacent CF2 groups), but either way it’s a large family, not one ingredient you can look up.

Why would PFAS be in period pants?

PFAS go into fabrics to make them repel water and resist stains, which is exactly what a leak-proof gusset is trying to do. A manufacturer looking for a quick way to stop fluid soaking through, or to keep a black gusset looking clean, has an off-the-shelf finish to hand.

There’s a second route that has nothing to do with intent. PFAS are so widespread in factories, water and processing chemicals that trace amounts can end up in a textile nobody treated on purpose. Brand A’s safety page makes this distinction clearly: deliberate use for repellency on one hand, unintended contamination on the other. It matters when you read test results, because a reading of a few parts per billion tells a different story from thousands.

Have PFAS been found in period underwear?

Yes, in several rounds of independent testing, though never in every pair.

Two things matter when you read that table. First, “found PFAS” covers everything from a trace to a treated gusset, and only the 2025 study separated the two: close to 30% of products had PFAS added on purpose, while the rest of the detailed subset carried smaller amounts. Second, the 2025 co-author’s view was that PFAS aren’t needed for these products to work, which is also what Which? concluded.

Mamavation, for its part, said plainly that it makes no claim about what level is safe. Nobody does yet. That honesty is the right template for brands too.

What happened with the US class action over PFAS?

A US period underwear brand agreed in November 2022 to pay up to US$5 million to settle a class action over PFAS in its underwear, while denying the allegations. The complaint, filed in May 2022, said third-party tests had found short-chain PFAS in the pants and that marketing them as organic, sustainable and non-toxic misled buyers.

Anyone who’d bought that brand’s pants between 12 November 2016 and 28 November 2022 could claim US$7 a pair for up to three pairs, or US$3.50 a pair without proof of purchase, or a 35% voucher, before the deadline of 12 April 2023. The brand said PFAS had never been part of its product design.

The settlement did something else that gets less attention. According to Women’s Voices for the Earth, it required the brand to disclose its use of Agion antibacterial nanotechnology (a silver-based treatment) and to stop claiming those particles don’t migrate. It didn’t require removal. So the case was never only about PFAS; it was about what a brand says versus what’s in the fabric.

Are PFAS regulated in UK period pants?

No, not specifically. There’s no UK rule that limits PFAS in textiles and no requirement to label them on clothing. What exists is a patchwork.

The EU is further along. REACH Entry 68 limits C9-C14 PFCAs to 25 ppb for the acids and salts and 260 ppb for related substances, in force since February 2023, and Entry 79 caps PFHxA at 25 ppb from October 2026. A broad restriction covering almost all PFAS was submitted to ECHA by five countries in January 2023. Some UK brands test against the EU limits even though GB law doesn’t require it.

Does OEKO-TEX certification mean PFAS-free?

No, it doesn’t. OEKO-TEX STANDARD 100 bans intentional PFAS use and tests certified products against limits, but OEKO-TEX says itself that it doesn’t certify anything as “PFAS-free”.

What the standard does is still useful. Intentional PFAS use is banned across OEKO-TEX certifications. From 1 January 2026 certified products must meet 25 ppb for each regulated PFAS plus a total fluorine limit, tested in two steps under EN 17681-1:2025: first the regulated PFAS individually, then total fluorine as a catch-all. Which? noted separately that STANDARD 100 says nothing about silver, which is a different concern with its own article in this series.

So a current STANDARD 100 certificate tells you the material passed a defined PFAS screen at a point in time. It doesn’t tell you the finished pant was tested, or that every one of thousands of PFAS is absent. Treat it as strong evidence, not a guarantee.

What other chemicals should you watch for?

Silver is the other additive consumer testers have flagged in period pants, and Annahitah’s pants contain none of it. Which? found silver in seven of 12 UK brands in 2023, used as an antimicrobial, and called it unnecessary. The silver article in this series covers that in full.

Which?’s 2023 tests also screened for chromium VI, cadmium and arsenic (none found) and lead (trace amounts in two brands, under the legal limit). Lead and the other heavy metals have legal limits in textiles, which is why they rarely show up; silver has none, and PFAS in UK textiles have none, which is why they do. “Toxin” is a loose word. When you see it, ask which substance the brand means and which rule, if any, covers it.

What should you ask a brand before buying?

Ask how they test, not whether they “are free from” something. A brand that has done the work can answer these in a sentence each.

• Do your supplier agreements prohibit intentional PFAS use, and in which materials?
• Which test method do you use: a speciated test under EN 17681-1 for named PFAS, a total fluorine screen, or both? Which lab, and what reporting limit?
• Was the finished pant tested, including the gusset, or only the outer fabric? When?
• Do you hold a current OEKO-TEX STANDARD 100 certificate, and will you share it?
• Do you use any water-repellent, stain-resistant or antimicrobial finish, and what’s in it?
• Do you avoid saying “PFAS-free”, given that no test can prove total absence?

That last question sounds odd, but it’s a good tell. Brand A says it avoids absolute PFAS-free claims because no test proves total absence, and it publishes its reporting limits instead. Brand B dropped the phrase “PFAS-free” in 2026 in favour of “designed to be free from”, backed by STANDARD 100 certificates. Brand C says it doesn’t deliberately use PFAS but that environmental traces could still be detected. Brand D says “PFAS-free, always” and points readers to a separate claims page for the evidence. Careful wording tends to mean the brand has looked hard at the question.

Where does Annahitah stand on PFAS?

Annahitah doesn’t publish a PFAS test result, and it doesn’t claim its pants are PFAS-free. What it does say is that its pants contain no silver and that its suppliers are certified by GOTS and OEKO-TEX. OEKO-TEX STANDARD 100 includes the PFAS screen described above, but a certified supplier isn’t the same as a published test on the finished pant, and Annahitah doesn’t claim one.

The site’s Our Mission page talks about PFAS in disposable products, not about tests on its own range, so don’t read it as a PFAS claim. If you want more, email hello@annahitah.com and ask the questions in the list above. A straight answer about method, lab and date is what you’re after.

Annahitah’s tagline is “no leaks, no toxins, no sweat”, and its toxin-free period pants are silver-free and made with materials from GOTS and OEKO-TEX certified suppliers. That isn’t a PFAS-free claim, so email about PFAS testing before you decide.