Modibodi Basic Full Period Brief
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, lycra blend with waterproof gusset treatment
Brand disclosure
Brand claims PFAS-free
Lab data
No PFAS found in testing
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What Modibodi Basic Full Period Brief is made of, ingredients and materials
Modibodi Basic uses organic cotton blended with lycra (spandex) as the primary material, which eliminates synthetic dye and pesticide residues common in conventional cotton. The waterproof gusset is a chemical treatment applied to the crotch area to prevent menstrual fluid leakage without requiring disposable absorbent materials. The brand states this treatment is PFAS-free, but the specific chemistry (silicone-based, wax-based, or other polymer) is not disclosed in publicly available materials. Organic cotton certification and lycra content are both low-toxicity choices compared to fully synthetic alternatives.
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 gusset treatment (unspecified chemistry)
Brand claims PFAS-free but does not publicly disclose the alternative polymer chemistry (silicone, polyurethane, hydrocarbon wax, or other). Unverified treatment poses low but unquantifiable residual risk of skin contact with undisclosed substances during prolonged wear in warm, wet conditions.
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
Organic cotton and stated PFAS-free approach suggest avoidance of formaldehyde-based wrinkle or water-resist finishes. No formaldehyde reports on record for Modibodi products.
Source, ATSDR ↗Azo dyes and synthetic colorants
Organic cotton certification typically excludes high-risk azo dyes and heavy-metal mordants. No azo dye safety warnings or recalls reported for this brand.
Antimony (polyester trace contaminant)
Product uses organic cotton and lycra, not polyester, so antimony contamination pathway does not apply.
Skin irritation from dyes or finishes (contact dermatitis)
Organic certification and PFAS-free claim reduce typical irritant exposure, but individual sensitivity to lycra or residual dyes is possible. No widespread dermatitis complaints reported for this product.
How is this PFAS grade calculated?
The brand's record and disclosure
Modibodi has stated that their products contain no PFAS in their sustainability marketing and product labeling, positioning themselves as a lower concern alternative to disposable menstrual products. The brand has not published third-party test results or technical safety data sheets confirming the waterproof treatment chemistry. No product recalls, contamination incidents, or regulatory violations have been publicly reported for this product line. Their PFAS claim remains a marketing statement rather than an independently verified certification.
How it compares in its category
Period underwear as a category sits between disposable pads (single-use plastic/chemical concern) and reusable cloth pads (no chemical treatment). Modibodi's use of organic cotton + lycra is standard for premium reusable period underwear and avoids synthetic polyester, which can carry antimony or flame retardants. The unverified waterproof gusset treatment is the main differentiator; many competitors (Thinx, Knix) also use undisclosed water-repellent finishes, making this category-wide transparency gap rather than brand-specific. Organic certification is less common than conventional cotton in this segment.
If you buy it
Wash separately from other laundry on cold water before first wear to remove any finishing chemicals. Air-dry rather than machine-dry to preserve the waterproof gusset treatment and lycra elasticity; heat degrades both. Replace every 1-2 years of regular use when elastic loses tension or absorbency noticeably declines. Do not bleach, use fabric softener, or tumble-dry, as these damage the water-repellent layer.
What is not known about PFAS in this product?
- Basis
- Model estimate, 45% 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 Full Period Brief?
- 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.