Reusable period underwear and washable pads promise fewer disposable products, less monthly waste, and freedom from discovering an empty tampon box at the worst possible moment. However, a peer-reviewed study published in 2025 adds an uncomfortable wrinkle: some reusable menstrual products appear to contain per- and polyfluoroalkyl substances, better known as PFAS or “forever chemicals.”
The findings do not mean every pair of period underwear is dangerous, nor do they prove that wearing one causes illness. They do reveal a transparency problem. Consumers often cannot tell whether PFAS were used in a product’s absorbent layers, moisture barrier, or textile finishesand “eco-friendly” packaging does not automatically answer the chemistry question.
What Did the Reusable Period Product Study Find?
Researchers from the University of Notre Dame and Indiana University examined 59 new reusable menstrual and incontinence products sold across several international markets. The five product categories included period underwear, reusable menstrual pads, menstrual cups, reusable incontinence underwear, and reusable incontinence pads.
Because many of these products are built like tiny textile lasagnas, the team tested individual layers rather than treating each item as a single uniform material. In total, 323 layers were screened using particle-induced gamma-ray emission spectroscopy, or PIGE.
First, Researchers Screened for Total Fluorine
PIGE detects total fluorine, which scientists use as a screening indicator for possible PFAS treatment. Fluorine alone does not identify a particular PFAS, and a screening result should not be translated into “this product will make you sick.” However, unusually high fluorine concentrations can indicate that fluorinated chemistry was intentionally used to produce a technical effect, such as water, oil, or stain resistance.
The researchers classified products with more than 110 parts per million of total fluorine as likely intentionally fluorinated. Approximately 33% of the period underwear and 25% of the reusable pads crossed that threshold. Overall, 71.2% of the tested products had lower concentrations that were categorized as not intentionally fluorinated.
That distinction matters. “Not intentionally fluorinated” does not always mean absolutely PFAS-free. Low concentrations can arise from contaminated raw materials, processing equipment, packaging, or other parts of the supply chain.
Detailed Testing Confirmed Specific PFAS
The team selected 19 products for more detailed chemical analysis covering 42 targeted PFAS. Specific PFAS were detected in all 19 of those extracted products, with total targeted concentrations ranging from roughly 21 to 2,200 nanograms per gram of material.
Neutral PFAS, particularly 6:2 and 8:2 fluorotelomer alcohols, were among the most abundant chemicals identified. The prominence of 8:2 fluorotelomer alcohol attracted attention because it can transform into PFOA, a persistent and extensively studied PFAS, inside the body or environment.
The encouraging finding was that at least one product in every category showed no evidence of intentional fluorination. In plain English: manufacturers can make functional reusable period products without deliberately adding PFAS. Leak protection does not require a forever-chemical membership card.
Why Would PFAS Be Used in Period Underwear or Pads?
PFAS are a large family of synthetic chemicals valued for their resistance to water, grease, heat, and stains. Those properties have made them useful in products ranging from firefighting foam and food packaging to outdoor clothing and cosmetics.
In reusable period underwear, a fluorinated treatment may be applied to a moisture-resistant outer layer, fabric coating, or stain-resistant finish. A washable pad may contain a similar barrier designed to keep fluid from reaching clothing. The study frequently found fluorinated material in only one layer, which helps explain why a package listing “cotton” or “organic cotton” does not necessarily describe the entire product.
PFAS are called forever chemicals because many resist natural degradation. Some accumulate in people and animals, while others move readily through water and soil. Washing a treated textile can also send chemicals or PFAS-containing fibers into wastewater. Eventually, discarded products may become another source of landfill contamination.
Do PFAS in Period Products Create a Health Risk?
Exposure to certain well-studied PFAS has been associated with higher cholesterol, reduced antibody responses to some vaccines, changes in liver enzymes, pregnancy-induced hypertension, small reductions in birth weight, and increased risks of kidney or testicular cancer. These findings do not apply equally to every chemical in the enormous PFAS family, and the effect of an exposure depends on the compound, dose, duration, and individual circumstances.
The new menstrual-product study did not measure PFAS in users’ blood, calculate the dose absorbed through skin, or track health outcomes. It therefore establishes a potential source of exposurenot proof that period underwear causes a particular disease.
Skin Absorption Remains an Important Unknown
Federal health guidance identifies contaminated food and water as major exposure routes for the general population and describes overall dermal absorption as limited. The picture may be different for certain neutral PFAS, which laboratory research suggests can pass through skin more readily than some charged compounds.
Period underwear and reusable pads can remain against warm, moist skin for hours, often repeatedly over several years. Researchers have not yet determined how much PFAS migrates out of these products during wear, whether menstruation changes absorption, or how washing and aging affect chemical release. Those unanswered questions justify better testing without justifying panic.
What the Study Cannot Tell You
- It does not show that every reusable period product contains intentionally added PFAS.
- It does not rank brands or guarantee that every production batch has the same composition.
- Total fluorine screening cannot, by itself, identify individual PFAS or calculate a person’s exposure.
- The study does not prove that wearing a tested product causes cancer, infertility, or another medical condition.
- It does not establish a safe wear time or a medical exposure threshold for PFAS in period underwear.
How to Shop for PFAS-Free Period Underwear and Pads
You do not need a chemistry degree or a portable particle accelerator in the laundry room. You do need more information than a leaf logo and the word “natural” printed in reassuring beige.
Ask Whether PFAS Are Intentionally Added
Look for a direct statement that no PFAS, fluoropolymers, or other fluorinated treatments are intentionally added to any product layer. “PFOA-free” is too narrow because PFOA is only one PFAS. Similarly, “free from harmful chemicals” sounds comforting but may reveal very little about the test panel.
Useful questions for a manufacturer include:
- Do you intentionally add PFAS to the fabric, absorbent core, waterproof barrier, elastic, or finish?
- Has the finished productnot merely one fabric samplebeen independently tested?
- Did testing measure total organic fluorine as well as specific PFAS?
- What were the detection limits, test date, laboratory, and production batch?
- Will the company provide a current laboratory report rather than a marketing summary?
Read Material Lists Carefully
Organic cotton can be a comfortable skin-contact layer, but it does not describe hidden waterproof components. Examine the complete construction and watch for terms such as “fluorinated,” “fluoropolymer,” “PTFE,” “perfluoro,” or “polyfluoro.” Their absence does not prove a product is PFAS-free, but their presence deserves an explanation.
Independent textile certifications can provide valuable information about numerous restricted substances. Still, certification standards, chemical lists, limits, and test dates vary. Treat a certification as evidence to examinenot a magical force field around the underwear.
Do Not Throw Everything Away in a Panic
If a company supplies credible, recent testing and confirms that it does not intentionally use PFAS, continued use may be reasonable. If the brand gives evasive answers, relies only on “PFOA-free” language, or cannot explain its waterproof layer, replacing the product during your next normal purchase cycle is a practical precaution.
Do not try to “wash out” PFAS with bleach, boiling water, or aggressive detergents. There is no validated home method for removing these chemicals, and harsh treatment may damage absorbency, elastic, and leak barriers while moving contaminants into wastewater.
Should You Get a PFAS Blood Test?
PFAS blood tests can measure selected compounds, but they usually cannot identify the source of exposure or predict whether an individual will develop a health problem. There is also no routine medical treatment that removes PFAS based solely on a test result.
If you live near a known contaminated site, have substantial occupational exposure, or are concerned about contaminated drinking water, discuss the situation with a healthcare professional or local health department. Wearing period underwear by itself is not evidence that you have received a medically significant PFAS dose.
Stop using any menstrual product that causes itching, burning, sores, unusual discharge, or persistent irritation. Those symptoms require ordinary clinical evaluation; they are not a reliable way to diagnose PFAS exposure.
Regulation Is Beginning to Catch Up
Menstrual pads and some other menstrual products fall within the FDA’s medical-device framework, which addresses matters such as materials, biocompatibility, performance, and labeling. However, federal oversight has not historically given shoppers a simple PFAS disclosure on every box of period underwear or reusable pads.
Several states have started acting. California has prohibited intentionally added PFAS in menstrual products since January 1, 2025 and is developing testing and enforcement requirements. New York’s restriction on intentionally added PFAS in new apparel also took effect in 2025. Other states have adopted or proposed restrictions affecting menstrual products, apparel, or consumer textiles.
These policies can influence products far beyond state borders because national manufacturers rarely enjoy maintaining 14 different versions of the same pair of underwear. Clear federal standards, standardized laboratory methods, ingredient disclosure, and routine finished-product testing would give consumers more consistent protection.
Reusable Does Not Have to Mean Chemically Questionable
The study should not be interpreted as a verdict against reusable menstrual care. Washable products can reduce disposable waste, save money over time, and offer comfortable options for people who dislike tampons, cups, or conventional pads.
The better conclusion is that environmental benefits and chemical safety must travel together. A product should not solve one pollution problem by quietly sewing another into the moisture barrier. Because most tested items did not show evidence of intentional fluorination, PFAS-free design appears both possible and practical.
A Realistic Consumer Experience: From PFAS Alarm to a Sensible Routine
The following is a composite scenario based on common consumer experiences and the practical questions raised by the research. It is not a clinical case report.
Imagine Maya, who has used reusable period underwear for two years. She bought several pairs because they were comfortable, reduced bathroom-trash chaos, and handled overnight leaks better than her former pad-and-pajama engineering project. Then she sees a headline about toxic PFAS in period underwear. Her first reaction is understandable: stare suspiciously at the laundry basket as if it has joined a chemical conspiracy.
Instead of immediately throwing away products that may or may not contain PFAS, Maya checks the manufacturer’s website. The page says the underwear is “PFOA-free” and “made without harmful substances.” Neither statement answers whether other PFAS are used. She emails customer service and asks whether any fluorinated treatments or fluoropolymers are intentionally added to any layer.
The first reply repeats the marketing language. Maya politely asks again, requesting an independent report for total organic fluorine and targeted PFAS testing of the finished garment. This time, the company admits that it tests selected fabrics but cannot provide results for the complete product. That is not proof of contamination, but it is not enough transparency for her next purchase.
Maya keeps two newer pairs temporarily while researching replacements. She compares brands based on absorbency, fit, cost, fabric construction, PFAS policies, and available laboratory reports. One company publishes a recent report with detection limits and batch information. Another simply displays a green badge invented by its own marketing department. Maya chooses the first. The badge was cute, but the data had better posture.
Her first PFAS-conscious purchase is not perfect. The waistband rolls, and the advertised “heavy flow” capacity turns out to mean “heavy flow, provided you remain perfectly still.” She learns to buy one pair before committing to a full set. After wearing and washing it through two cycles, she orders more in the size and absorbency level that actually work.
She also builds a low-drama care routine. Used underwear is rinsed in cool water when the manufacturer recommends it, washed with mild detergent, and dried completely before storage. She avoids fabric softener because it can coat absorbent fibers, and she does not boil or bleach the garment in an attempt to remove invisible chemicals. On heavy days, she combines period underwear with a menstrual cup or a PFAS-conscious reusable pad, reducing the risk of leaks without wearing one saturated product for an unnecessarily long time.
For her teenage niece, Maya takes an even simpler approach. She explains that the study found a problem in some products, not all products, and that PFAS exposure is a long-term public-health issue rather than an emergency caused by one night of wear. Together, they look for clear material information, independent testing, a comfortable fit, and an easy return policy.
The biggest change is not fear; it is a better purchasing standard. Maya now saves test reports, checks whether company claims have been updated, and asks questions before replacing worn-out products. She still appreciates reusable period care. She simply expects the “sustainable” label to cover chemistry as well as trash reductionand that is a perfectly reasonable expectation.
Conclusion
The study offers a warning, not a reason for panic. Some reusable period underwear and pads contained fluorine levels consistent with intentional PFAS use, while many others did not. The research also leaves major questions about skin absorption, actual exposure doses, and long-term health effects unanswered.
Consumers can respond by asking precise questions, favoring current independent testing, and avoiding vague claims that mention only PFOA. Manufacturers, meanwhile, have a straightforward assignment: make reusable period products that manage fluids without leaving customers to solve a chemistry mystery every month.
