PFAS score
Knix · Period Underwear
Knix Women's Super Leakproof Dream Boxers
Skip until Knix discloses coating chemistry or provides third-party testing.
Knix's leak-proof boxers rely on a waterproof coating to block menstrual fluid, but the brand does not publicly disclose the chemical composition of that coating. Waterproof textiles commonly use PFAS-based water-repellent coating (water-repellent coating) treatments.
The safe swap
JAMA Organic
LOLA Organic Cotton Period Underwear
100/100 safety
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
Fabric with waterproof/leak-resistant coating (unspecified chemistry)
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Waterproof / stain-resistant treatment
water-repellent coating treatments have historically used PFAS.
Category baseline
period care is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 45% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Period Underwear
JAMA Organic
LOLA Organic Cotton Period Underwear
Organic cotton with moisture-wicking gusset
Lower PFAS concern, organic cotton base with no waterproof claims, but brand doesn't explicitly address PFAS.
✓Verified PFAS-free by a third party
JAMA Organic
Organyc Certified Organic Cotton Disposable Period Underwear for Sensitive Skin
certified organic cotton with absorbent core
Lower concern, organic cotton base suggests minimal PFAS risk, but no explicit PFAS statement limits confidence.
✓Verified PFAS-free by a third party
Ruby Love
Women's Hipster Period Underwear
organic cotton with waterproof coating
Lower concern, PFAS-free verified; buy with confidence.
✓Lab test found no PFAS
More period underwear grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.