"Forever Chemicals" in Period Underwear: What South African Women Need to Know About PFAS

PFAS have been in the news on and off for a few years now — turning up in everything from non-stick pans to raincoats to, as it turns out, period underwear. That last one tends to catch people off guard. It's one thing to hear that a chemical group is widespread; it's another to learn it might be sitting in a fabric worn against intimate skin for hours at a stretch. So what's actually going on, and what should you be checking for before you buy?

What Exactly Are PFAS?

PFAS — per- and polyfluoroalkyl substances — are a family of synthetic chemicals prized in manufacturing for one specific trait: they resist water, oil, and staining exceptionally well. That's precisely why they earned the nickname "forever chemicals" — the same carbon-fluorine bonds that make them so effective at repelling liquid also make them almost indestructible, both in the environment and inside the human body, where they can persist for years.

That persistence is the real concern. Bodies belonging to organisations like the European Environment Agency have linked PFAS exposure to a fairly serious list of health effects: liver damage, thyroid disruption, broader hormonal interference, fertility difficulties, and an elevated risk of certain cancers. None of that is exactly what you want to hear about a product worn close to intimate tissue for extended periods each month.

This is also the same broad category of concern — endocrine-disrupting chemicals — behind the National Consumer Commission's current investigation into several South African sanitary brands, following a University of the Free State study on the topic. Different specific compound, same underlying question: what's actually in the products we use monthly, and is anyone independently checking?

What an Independent Test Actually Found

A few years back, the US consumer advocacy group Mamavation ran independent lab testing across more than 50 menstrual products, spanning period underwear, pads, and tampons. The results weren't reassuring — roughly two-thirds of the period underwear tested came back positive for PFAS indicators, with some products showing notably high concentrations.

It's worth being precise about what that means: this wasn't one brand or one bad batch, it was a category-wide pattern across a market largely built on "leak-proof" marketing claims — claims that, structurally, often rely on exactly the kind of fluorinated, water-resistant treatments PFAS are used for.

Where Gentle Day Stands

Because most PFAS compounds share strong carbon-fluorine bonds, testing for fluorine is a standard, reliable way to screen for likely PFAS contamination. Gentle Day period underwear has been tested on that basis, and no fluorine was detected — meaning the range is PFAS-free by the same screening method used in the Mamavation testing.

This isn't an abstract commitment for us. I use these products myself, as do my daughter, colleagues, and — by extension — thousands of women who trust the brand every month. That's exactly why getting this right matters: comfort and reliability are the baseline, not the whole story.

Why This Actually Matters

Absorbency and comfort are the obvious things people shop for in period underwear, but what the fabric is treated with matters just as much, precisely because it's worn for hours against skin that's more absorbent than most other parts of the body. Choosing products manufactured without unnecessary chemical treatments isn't about paranoia — it's about not having to wonder.

Gentle Day's approach here comes down to a few concrete commitments: no intentionally added PFAS or similarly unnecessary chemical treatments, hypoallergenic and dermatologically tested materials, and a broader push toward menstrual products that are both safe and sustainable for the long term.

How to Shop Smarter for Menstrual Products

• Be wary of ultra-cheap, unbranded options. Products from marketplaces with no traceable manufacturer or testing history are the least likely to have been independently screened for anything.
• Favour brands that show their work. Look for companies that publish testing results, list certifications, and are specific about materials rather than vague about "safety."
• Pass the information on. The more women who know PFAS testing is something to ask about, the more pressure the whole category comes under to actually test.