What to Know About PFAS in Period Underwear

April 9, 2026

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Period underwear has become a trusted choice for millions seeking comfort, reusability, and a smaller environmental footprint than traditional disposables. Yet an important question lingers: are these garments quietly delivering more than leak protection? Recent university research in the United States has uncovered measurable levels of per- and polyfluoroalkyl substances better known as PFAS or “forever chemicals” in many reusable menstrual and incontinence products. What to Know About PFAS in Period Underwear draws directly from the most credible American studies and emerging state-level responses to give readers a clear, evidence-based picture.

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Key Findings from Leading U.S. University Research

Scientists at the University of Notre Dame, collaborating with colleagues at Indiana University's Paul H. O'Neill School of Public and Environmental Affairs, have conducted some of the most thorough examinations of PFAS in intimate reusable products. Their 2025 pilot study, published in Environmental Science & Technology Letters, tested 59 items including period underwear, reusable pads, menstrual cups, and incontinence underwear by analyzing 323 separate fabric layers with sensitive spectroscopy methods.

Roughly 30 percent of the samples displayed PFAS concentrations suggesting intentional addition during manufacturing. Period underwear showed the highest rate of deliberate fluorination at 33 percent, compared with 25 percent for reusable pads. Earlier testing by the same Notre Dame group in 2023 found even more striking results in certain period-underwear styles: total fluorine concentrations reached as high as 100,000 parts per million, indicating that PFAS accounted for up to 10 percent of the garment's weight in those cases.

What the Data Reveals About Real Products

The research team deliberately avoided naming specific brands, yet the overall patterns speak clearly. In most samples about 71 percent detected PFAS levels were low enough to be explained by incidental transfer from packaging or manufacturing equipment rather than purposeful treatment. Higher concentrations, however, clustered in the moisture-management layers of period underwear, pointing to the historic use of fluorinated compounds to achieve water repellency and stain resistance.

One frequently detected compound in products sold in North America was 8:2 fluorotelomer alcohol (8:2 FTOH), a substance that food-packaging manufacturers had already phased out years earlier because of its long residence time in the human body. Importantly, the studies demonstrated that high performance is possible without intentional PFAS: numerous tested products managed absorbency and leak protection effectively using alternative chemistries or untreated fabrics. Earlier investigative work by the lead Notre Dame physicist in 2019 contributed to a $5 million class-action settlement involving one well-known period-underwear label, highlighting how independent testing can influence corporate accountability.

Established Health Concerns Linked to PFAS

U.S. public-health authorities have documented widespread exposure to PFAS. The Centers for Disease Control and Prevention estimates these persistent chemicals are present in the blood of more than 99 percent of Americans. Because PFAS do not readily break down, they accumulate in tissues over time.

Reproductive challenges, including reduced fertility
Disruption of thyroid and other hormone systems
Diminished vaccine response and weakened immunity
Elevated risk of kidney and testicular cancers
Adverse pregnancy outcomes such as low birth weight, preeclampsia, and developmental effects in children

Period underwear rests against highly permeable vulvar and perineal skin for extended periods, creating a direct and prolonged exposure pathway that researchers consider especially noteworthy. Even modest concentrations become significant when the same garment is worn repeatedly across many cycles and years.

State-Level Regulation Gaining Momentum

New York enacted the first comprehensive statewide prohibition on intentionally added PFAS and several additional concerning substances in menstrual products, including period underwear. The measure, effective December 2026, bans the sale of any covered item that contains these chemicals as deliberately added ingredients.

Assemblymember Linda B. Rosenthal, a principal sponsor, emphasized consumer safety: “New Yorkers must be able to trust that menstrual products, including pads, tampons and period underwear, they use in and around the most sensitive areas of their bodies are free of toxins.” The legislation explicitly references university data showing elevated PFAS in both reusable and disposable categories. Several other states are now considering comparable labeling rules or outright bans, reflecting a broader push for transparency in feminine-hygiene markets across the country.

Practical Hurdles Facing Manufacturers and Shoppers

Creating reliable period underwear has traditionally relied on synthetic textiles engineered to wick moisture while blocking leaks. For decades, PFAS offered manufacturers an efficient way to achieve those properties. Transitioning to alternatives demands significant research, reformulation, and supply-chain adjustments investments that can strain smaller brands in particular.

Shoppers encounter difficulties of their own. Without mandatory federal ingredient labeling, it remains challenging to identify truly PFAS-free options. The 2025 study further complicated matters by showing that trace contamination can migrate from packaging even when no treatment was applied to the fabric itself. Communities of color and women in the United States already face higher average exposure to environmental contaminants, making equitable access to safer intimate products a pressing public-health priority.

Pathways to Safer Innovation and Market Advantage

The combination of rigorous university evidence and New York's pioneering legislation creates strong incentives for companies to accelerate development of PFAS-free period underwear. Brands that successfully adopt advanced non-fluorinated treatments, high-performance natural fibers, or novel layering designs can differentiate themselves in an increasingly health-aware market.

The Notre Dame researchers repeatedly stressed that effective, leak-resistant products already exist without intentional PFAS, proving the technical feasibility of change. Forward-leaning companies stand to gain loyalty from consumers who prioritize verified safety, as well as favorable attention from regulators and third-party certifiers. Academic and public-health laboratories have signaled willingness to collaborate on standardized testing methods, offering credible validation that could translate into lasting competitive strength.

Expert Guidance and Next Steps for Consumers

Graham Peaslee, the Notre Dame physicist who spearheaded much of the PFAS detection work, offered a succinct assessment: “Treating these products with PFAS is not essential… we should move away from any non-essential use of PFAS in consumer products.”

Until comprehensive national labeling becomes reality, practical actions remain within reach. Seek out brands that publish independent, third-party test results for PFAS. Advocate for legislation modeled on New York's approach in additional states. And continue pressing manufacturers for full ingredient disclosure. In the United States the scientific record is now unambiguous, state-level momentum continues to build, and the opportunity to drive meaningful improvement has rarely been clearer.

The discussion surrounding period underwear has evolved far beyond absorbency and sustainability. Thanks to persistent university research and decisive policy responses, it now focuses squarely on protecting long-term health an issue that deserves sustained attention and collective action.

Frequently Asked Questions

What are PFAS, and why are they found in period underwear?

PFAS (per- and polyfluoroalkyl substances), often called "forever chemicals," are synthetic compounds historically used in period underwear to achieve water repellency and leak resistance. University of Notre Dame research found that roughly 33% of period underwear samples showed PFAS concentrations consistent with intentional manufacturing use. Because these chemicals don't break down easily, they accumulate in the body over time, raising significant health concerns for regular wearers.

Is period underwear with PFAS dangerous to your health?

Health authorities including the CDC have linked PFAS exposure to serious conditions such as reduced fertility, hormone disruption, weakened immunity, and elevated cancer risk. Period underwear is worn against highly permeable skin for extended periods, creating a direct exposure pathway that researchers consider particularly concerning. The risk compounds over time, since the same garments are worn repeatedly across many menstrual cycles and years.

How can I find PFAS-free period underwear?

Look for brands that publish independent, third-party lab test results confirming the absence of PFAS in their products. Notre Dame researchers confirmed that high-performance, leak-resistant period underwear can be made without intentional PFAS, so safer alternatives do exist. New York State has also enacted legislation banning intentionally added PFAS in menstrual products effective December 2026, which may help guide consumers toward compliant brands as the regulation takes effect.

Disclaimer: The above helpful resources content contains personal opinions and experiences. The information provided is for general knowledge and does not constitute professional advice.

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