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Thinx PFAS Lawsuit: Is Period Underwear Safe?

multicolor underwear hanging outside on clothing line - PFAS in Thinx lawsuit

Thinx PFAS Lawsuit

Well, apparently it’s PFAS week on StyleWise. I received an email this morning informing me that I qualify for compensation in a class action lawsuit settlement against Thinx Period Underwear. It begs the question: is period underwear safe?

According to the settlement email, those who qualify for compensation include anyone who purchased the:

Cotton Brief, Cotton Bikini, Cotton Thong, Sport, Hiphugger, Hi-Waist, Boyshort, French Cut, Cheeky, and Thong, sold between November 12, 2016 and November 28, 2022 (“Thinx Period Underwear”).

While I knew that independent lab tests had verified that Thinx contained PFAS in 2020, I was surprised that the legal battle around it had been ongoing for so long.

And I was even more surprised that products purchased as late as November 2022 were included. I had assumed that the issue had been addressed and resolved.

How else could Thinx continue selling an unsafe product? It seems to have something to do with changing regulations and continued uncertainties about how PFAS affects the body over time.

woman wear bright red sports bra and stands in yoga pose with hands behind her back

What is PFAS?

PFAS (Per- and Polyfluorinated Substances) are used in all sorts of products, from clothing to shoes to cookware. They make materials nonstick, water-resistant, sweat-wicking, and smooth to the touch. You might find them in rain gear, exercise clothing, boots, pans, and period underwear.

But there’s a big, glaring problem. PFAS, sometimes called “forever chemicals,” are toxic. Side effects of PFAS exposure include lowered immunity in children, liver damage, thyroid disease, kidney disease, kidney and testicular cancer, pregnancy issues, and more.

Most recently, clothing companies like Shein and cookware brands have been exposed for selling products containing PFAS.

Is Thinx Safe?

Sierra Club broke the story on PFAS in Thinx and other period underwear in 2020. While there seemed to be initial outrage, Thinx managed public opinion well, releasing new disclaimers on their site. Around that time, my friend Rene did a deep dive into the literature surrounding testing for PFAS. She determined that Thinx products were likely safe.

Part of her assessment is centered around the fact that Thinx is both OEKO-TEX and REACH certified for fabric and total product safety. Unfortunately, Mamavation investigated further and found that both certifications belong to Thinx’s suppliers rather than Thinx themselves. This means that the final product is not being tested.

Interestingly, Thinx has denied that their products were ever intentionally designed to include PFAS. Their product safety page currently states that PFAS “are not intentionally added” to products at any stage of manufacturing. The moisture-impermeable layer is said to be coated with PU (polyurethane).

But products were tested again in 2021 and continued to show levels of PFAS considered to be unsafe. It’s unclear whether PFAS is a result of mislabeling and lack of transparency during manufacturing, a side effect of production, or an intentional component of design that Thinx would rather us not know about.

The Data on PFAS

On another note, it’s not exactly clear what constitutes a safe level of PFAS, especially in clothing.

The EPA (Environmental Protection Agency) previously allowed up to 70 ppt (parts per trillion) of certain types of PFAS in drinking water. As of 2022, they are trying to get that number as close to 0 ppt as possible.

That decision was made based on data that shows that prolonged exposure to PFAS contributes to the health issues I listed above. That makes sense. If PFAS is found in trace amounts in practically everything, the longer we live with it, the worse the impact.

For comparison, Thinx organic hip hugger briefs were found to have 3,267 ppm (parts per million) of fluorine (a component of PFAS) in Mamavation’s 2020 testing.

While the PFAS in clothing are not directly ingested, we know that the vagina’s mucus membrane and surrounding sex organs are more absorbent than skin, making period product safety an important issue.

But Dr. Joe Schwarcz is not convinced that PFAS represents a significant safety risk in clothing:

All of this is to say that we cannot come to a conclusion about the risk, if any, posed by the tiny amounts of PFASs, phthalates or inorganics detected in fabrics. My guess is that absorption of any of these into the bloodstream would be inconsequential.

McGill University

What it comes down to, however, is that because PFAS are still relatively new in clothing, we simply don’t have the far-reaching data we need to draw a definitive conclusion.

All that to say: if Thinx products are still found to contains PFAS, consumers are likely at risk. PFAS have infiltrated much of our food and water already. It makes sense to reduce exposure where we can.

woman with medium caramel skin and back tattoo sits in gray underwear - PFAS in Thinx lawsuit

Is other period underwear safe?

This really depends. Thinx’s competitor, Knix, is also facing a lawsuit for PFAS. But Mamavation did extensive testing for toxic chemicals in period underwear and can recommend a few.

It is worth cautioning that chemical replacements for PFAS may be just as bad, or worse, than PFAS. New finishes haven’t been as rigorously tested, so it’s best to wait until we receive more data. The best alternative is to select a period underwear that uses only verifiably-safe, organic materials.

Of course, if PFAS in period underwear is what makes them leak-resistant, then products not containing it will be less effective.

As someone who has relied on Thinx for years, I am still wavering on what steps to take. We know that disposable and insertable period products can be toxic, as well. So it’s not simply a matter of avoiding Thinx.

How to Submit a Claim

If you think you are qualified to receive a benefit from the Thinx class action lawsuit, check your junk mail for a claim number and pin. If you don’t see it, head to the claims site and file a new claim. Customers are entitled to receive up to $21 in cash.

Just remember that signing up for the class action benefit (even if you did so involuntarily by making a purchase and receiving a claim number) means you waive your right to sue in the future. You must exclude yourself manually on the official website for the Thinx lawsuit.

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Leah Wise is the founder of StyleWise Blog. She has been writing, speaking, and consulting on sustainable fashion, the fair trade and secondhand supply chain, and digital marketing for over ten years. An Episcopal priest, Leah holds a B.A. in Religion from Florida State University and an M.Div. from Yale Divinity School. When not working, you can find her looking for treasures at the thrift store.

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