The Short Answer
Older Thinx underwear tested positive for alarming levels of PFAS, but the company claims current products are safe. In 2020, independent lab testing found up to 3,264 parts per million (ppm) of fluorineāa key indicator of toxic "forever chemicals"āin the crotch of Thinx underwear.
The brand settled a $5 million class-action lawsuit in 2023. While Thinx denies ever intentionally adding PFAS to their products, they have since overhauled their manufacturing agreements and now publish third-party testing to prove their current lineup is PFAS-free. However, due to their contamination history and continued use of antimicrobial silver treatments, we still give Thinx a caution rating. Is Thinx Safe
Why This Matters
PFAS are "forever chemicals" that accumulate in the human body. They are notoriously linked to a host of health issues, including reproductive harm, immune system disruption, and certain cancers. Is There Pfas In Period Underwear
The vaginal area is highly vascular and absorbs chemicals rapidly. Wearing period underwear contaminated with PFAS means these toxic compounds are placed directly against one of the most sensitive, absorbent parts of your body for hours at a time. Are Organic Pads Worth It
The 3,264 ppm finding was highly significant. According to the nuclear scientist who tested the original products, levels this high strongly suggested the chemicals were intentionally added to create the underwear's signature stain-resistant barrier, rather than being mere background contamination. Which Period Underwear Has Pfas
What's Actually In Thinx Period Underwear
- PFAS (Historically) ā Older pairs contained high levels of fluorine, pointing to polyfluoroalkyl substances used for waterproofing and stain resistance. Period Underwear No Pfas
- Nanosilver (Agion) ā Thinx uses an antimicrobial silver treatment to prevent odors, which can disrupt healthy vaginal flora and environmental waterways. Is Silver In Period Underwear Safe
- Synthetic Fabrics ā Alongside cotton, the leakproof layers rely on polyurethane, elastane, and polyester to trap moisture.
What to Look For
Green Flags:
- Third-party PFAS testing ā Look for brands that publish actual lab results showing non-detectable levels of total fluorine.
- GOTS Certified Organic Cotton ā Ensures the cotton base was grown without synthetic pesticides or harsh chemical fertilizers.
- PFAS-free guarantees ā Seek out brands that explicitly ban forever chemicals in their supply chain contracts.
Red Flags:
- "Stain-resistant" or "water-repellent" marketing ā These buzzwords are often industry code for chemical treatments.
- Undisclosed odor control ā Hidden antimicrobial treatments like nanosilver can irritate sensitive skin and disrupt your pH.
- Lack of transparency ā If a brand refuses to share their lab tests or OEKO-TEX certifications, assume the worst.
The Best Options
If you're looking for leakproof protection without the chemical baggage, skip the legacy brands and choose companies with spotless testing records. Safest Period Underwear
| Brand | Product | Verdict | Why |
|---|---|---|---|
| Saalt | Wear Everyday Underwear | ā | Routinely tests PFAS-free and avoids controversial nanosilver. Is Saalt Period Underwear Clean |
| Thinx | Classic Period Underwear | ā ļø | Current products test clean, but their history and nanosilver use warrant caution. |
| Knix | Leakproof Underwear | š« | Settled a similar PFAS lawsuit after independent tests found fluorine. Is Knix Clean |
The Bottom Line
1. Throw away older Thinx. If you bought pairs between 2016 and 2022, they likely contain high levels of PFAS and should be retired.
2. Look for transparent testing. Don't just trust slick marketing claims; demand to see independent lab results for total fluorine.
3. Watch out for silver. Even if a brand is totally PFAS-free, check if they use antimicrobial nanosilver, which carries its own separate health risks.
FAQ
Did Thinx admit to using PFAS?
No, Thinx maintains that PFAS were never part of their product design. In the 2023 settlement, they denied all allegations of wrongdoing, claiming any presence of the chemicals was unintentional contamination from the supply chain.
Is Knix safer than Thinx?
Not necessarily. Knix recently settled its own $1.4 million class-action lawsuit after independent testing revealed fluorine in their period underwear, meaning both major brands share a similar contamination history. Thinx Vs Knix
Can you wash PFAS out of period underwear?
Eventually, but it poisons the water supply. Experts note that while repeated washing might degrade the chemical coating on your underwear, those forever chemicals are simply being flushed down the drain to permanently contaminate local waterways.