Modibodi Basic Mid-Rise Brief Black
A water-repellent or grease-resistant treatment of unstated chemistry, with a brand PFAS statement we have not verified.
Modibodi says it does not intentionally use PFAS in its period underwear. We record that as an unverified brand claim. Mamavation reported no fluorine detected in Modibodi period underwear. Its record describes a water-repellent or grease-resistant treatment of unstated chemistry, which is still counted.
Brand says: “Modibodi says it does not intentionally use PFAS in its period underwear.”
We flunk more products than we pass. This one earned its grade. How we grade
Material
Organic cotton with waterproof leak-proof lining
Brand disclosure
Brand claims PFAS-free
Lab data
No PFAS found in testing
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What Modibodi Basic Mid-Rise Brief Black is made of, ingredients and materials
The Brief pairs organic cotton (grown without synthetic pesticides, reducing skin exposure to agrochemical residues) with an unstated waterproof lining designed to prevent leakage. Organic cotton eliminates one major source of pesticide contamination common in conventional cotton textiles. The waterproof layer chemistry is the key variable, Modibodi states it is PFAS-free, but the exact treatment method (polyurethane laminate, wax, natural oils, or other polymer) is not disclosed in public materials.
What’s concerning
Waterproof / stain-resistant treatment
Water-repellent coating treatments have historically used PFAS.
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
Waterproof lining degradation and leachables
The unstated composition of the waterproof layer means its aging behavior and potential leachate compounds cannot be fully assessed. Polymeric linings can break down with repeated washing and heat, though no specific safety issues have been reported for this brand.
Bacterial or fungal growth on lining if stored wet
The waterproof layer, like all moisture-barrier textiles, can trap moisture and promote microbial growth if not fully dried before storage. This is a usage and care risk, not a manufacturing hazard.
PFAS
Modibodi claims PFAS-free chemistry, but the specific coating technology is not named and the claim has not been independently verified by third-party testing. The brand's disclosure is stronger than industry standard, but the exact polymer remains opaque.
Source, ATSDR ↗What’s reassuring
Brand-stated PFAS-free
The brand states this product is PFAS-free. We have not verified the claim.
No PFAS found in lab test
No PFAS detected in independent testing.
Formaldehyde / VOCs
No formaldehyde-releasing dyes or finishes are documented for Modibodi products. However, standard cotton dyeing practices can introduce formaldehyde resins; Modibodi does not explicitly state that dyes or treatments are formaldehyde-free.
Source, ATSDR ↗Azo dye safety
Black dyes in textiles can contain azo compounds; Modibodi does not publicly disclose whether restricted azo dyes are avoided in the black colorway. This is standard across the period underwear category.
How is this PFAS grade calculated?
The brand's record and disclosure
Modibodi has made explicit PFAS-free claims in marketing and sustainability communications, though independent third-party verification of this claim is not publicly documented. The brand publishes material composition and has engaged with chemical safety topics in customer communication. No recalls or regulatory warnings specific to Modibodi period underwear have been recorded. Transparency on the exact waterproof coating chemistry remains limited, which is typical for the category but represents a disclosure gap.
How it compares in its category
Period underwear has become mainstream, with competitors including Thinx, Knix, and Aerie using similar organic cotton and proprietary waterproof linings. Most brands do not publicly name their lining materials, making Modibodi's PFAS statement a relative strength. Organic cotton base is shared among premium and eco-focused brands. The mid-rise cut and black colorway are standard offerings; dye chemistry and formaldehyde-resin finishes are not typically disclosed by any major period underwear brand.
If you buy it
Wash in cool to warm water (not hot) to preserve waterproof integrity and avoid potential softening of the lining. Avoid bleach, fabric softeners, and high heat drying, all of which can compromise the waterproof layer over time. Air dry or use low heat. Replace when leakage becomes visible, typically every 2 years with normal use. Store in a dry environment to prevent mold on the lining.
What is not known about PFAS in this product?
- Basis
- Model estimate, 35% confidence, not a lab result
- Lab test
- Independent test found none
- Brand statement
- Modibodi has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
What are the PFAS-free alternatives to Modibodi Basic Mid-Rise Brief Black?
- organic cotton, waterproof backing layer
- A third party reports verifying it as PFAS-free
- Coating degradation and microparticle shedding
2 hazards checked on this product, all on its full breakdown.
- organic cotton blend, water-resistant gusset
- The brand calls it PFAS-free, which we have not verified
- Microplastic shedding from water-resistant barrier
- Organic cotton, wood pulp fiber
- The brand calls it PFAS-free, which we have not verified
- Azo dyes and synthetic dyes
2 hazards checked on this product, all on its full breakdown.
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.