Selecting safe & healthy menstrual hygiene products: PFAs in period underwear, pads, and tampons

Period underwear's more sustainable than pads or tampons, but is period underwear safer?  Following the lawsuit for Thinx period underwear containing PFAs (despite claims to the contrary), the entirety of period underwear has come under scrutiny.  Before throwing the baby out with the bathwater, let's take a look at this topic.

What are PFAs and how are you exposed to them?

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that are widely used in industrial and consumer products due to their water- and stain-repellent properties.

PFAs, also known as perfluorinated compounds (PFAS), are found in products like nonstick coatings, waterproofing, and firefighting foams. They're highly resistant to degradation and are known to bio-accumulate in the environment and in living organisms, including humans.

While PFAS are volatile (easily evaporate) and contaminate the environment by evaporating into the air you breathe, they also precipitate along with rainfall to contaminate water.

And, there's evidence suggesting that PFAs used in food containers leach out over time allowing for ingestion into your body.  Finally, when PFAs are present in fabric, absorption through the skin and into your bloodstream is also a concern.

An overview of the health risks of PFAs

A study published in 2017 found PFAs in the blood of women who used waterproof cosmetics and that the concentration of PFAs in the blood increased with the frequency of cosmetic use.

Another study published in 2020 found that PFAs could be transferred from clothing to the skin, particularly when that clothing's wet.

While these studies didn't specifically examine period underwear, the findings show that PFAs in fabric (whether period underwear, period swimwear, regular swimwear, or regular clothing) are able to absorb through the skin and once in the skin, enter the bloodstream.

Even though the health effects of PFAs are still being studied, some studies have linked PFAs to various health conditions including cancer, reproductive and developmental problems, and immune system dysfunction.

Are PFAs endocrine disruptors?

Studies have shown that exposure to PFAs correlates with negative health effects, including developmental and reproductive problems, liver damage, and an increased risk of cancer.

Specifically, PFA exposure has been linked to early onset of puberty in girls, disruption of the menstrual cycle, and reduced fertility in women.

PFAs are known endocrine disruptors interfering with the normal function of hormones in the body, including estrogen, testosterone, and thyroid hormones.

Exposure to PFAs has been linked to altered hormone levels in both men and women and has been found to cause:

  • menstrual irregularities
  • polycystic ovary syndrome (PCOS)
  • early menopause

in women.  In men, PFA exposure's linked to:

  • lower sperm motility
  • decreased sperm count

Which menstrual hygiene products are free of PFAs?

To be clear, conventional pads & tampons contain PFAs.  PFAs have also been found in several brands of period underwear perhaps most notably in Thinx underwear.  Thinx lost a class-action lawsuit in early 2023 due to the finding that the period underwear contained PFAs despite marketing claims otherwise.

So, this begs the question...

What period underwear is PFAs-free?

NOTE:  Currently, these links are all non-affiliate links.  If Rain Organica revises this list to include any affiliate links, this note will be updated when that happens :)

The most comprehensive true 3rd party testing of period underwear that I'm aware of was taken on by Mamavation.

The period underwear tested by Mamavation that had less than 50 ppm fluorine are:

  1. Knix: Knix's period underwear is made from a blend of organic cotton and Lycra that is free from PFAS and other harmful chemicals. 

    I've been using Knix for a few years now and pro tip:  buy from Knix Teen rather than Knix to save $.  Just be sure to use the size guide to get your size right. 
  2. Saalt: Saalt offers reusable period underwear made from a blend of bamboo and spandex that is free from PFAs.
  3. Joyja
  4. Victoria's Secret: had no idea they're in on the period underwear game until taking a look at this Mamavation study.
  5. Cora
  6. Panty's
  7. Maxim Hygiene
  8. Sustain Natural
  9. Red Ruby Box

Several brands tested below the limit of quantification (LOQ) of 10 ppm.  This means period underwear from these brands had below 10 ppm fluorine.

  1. Lunapads (now Aisle): Aisle offers reusable period underwear made from organic cotton, bamboo, and other natural materials that are free from PFAs.
  2. Modibodi: Modibodi's period underwear is made from a blend of bamboo, merino wool, and microfiber that is free from PFAs.
  3. Lilova:  no fluorine detected
  4. Bambody:  no fluorine detected
  5. Period:  no fluorine detected
  6. Revol:  no fluorine detected

Check out the Mamavation study here and you'll likely find a Mamavation affiliate code to save on your first order from any of these brands.

Is there any 100% organic cotton period underwear?

Most period underwear brands use a combination of organic cotton and other materials (particularly  in the gusset) for added absorbency or moisture-wicking properties making it difficult (but not impossible) to find 100% organic cotton period underwear.

Here are a few companies that offer period underwear made with 100% organic cotton:

  1. Rael: Rael offers period underwear made with 100% certified organic cotton, including their "Organic Cotton Brief" and "Organic Cotton Hipster" styles.
  2. Love Luna: Love Luna offers period underwear made with 100% organic cotton, including their "Period Brief" and "Period Bikini" styles.
  3. Natracare: Natracare offers period underwear made with 100% organic cotton, including their "Period Panties" and "Maternity Panties" styles.
  4. GladRags: GladRags offers period underwear made with 100% organic cotton, including their "Organic Underwear" and "Color Panties" styles.

Please note, this list is accurate as of the time this post is written, so please double check the fabrics before you order and just remember that other styles offered by these brands may not be 100% organic cotton.

What are the alternatives to PFAs in period underwear?

Alternative materials to PFAs in period underwear include natural fibers like organic cotton, bamboo, and even merino wool (naturally anti-microbial). These materials are biodegradable and eco-friendly. Some companies also use antimicrobial treatments and other technologies to enhance the performance of their period underwear without using PFAS.


Ultimately, conventional disposable pads and tampons likely expose your body to PFAs. 

The Thinx class-action lawsuit has cast shade on period underwear companies in general that make the PFA free marketing claim, and still even after the lawsuit settled early in 2023, Thinx stands behind their claim that "PFAs are not part of product design".

Thinx conducts 3rd party testing on their underwear, but here's the thing with 3rd party testing... it's still paid for by the manufacturer.  That's why I put so much credence into the Mamavation study referenced above because somebody other than the period underwear manufacturer is paying for the underwear to be tested.

Because PFAs are absorbed into your bloodstream via different routes:

  • inhalation
  • ingestion
  • absorption through your skin

it's important to be vigilant about reducing your exposure to PFAs in all ways... without driving yourself crazy in the process :).

Ultimately, we live in a world where we typically have to pick and choose our battles, and the first premise of tox-free living is to leave worry at the door. 

My personal opinion for period underwear is this is an easy one to choose because the research has already been done for you. 

Opt for one of the brands on the Mamavation list and/or one of the 100% organic cotton brands and just keep in mind any quick drying clothing (and swimsuits) may contain or be treated with PFAs, so as much of a pain as it is to research materials before you buy, hopefully this article makes it easy to select your next pair of period underwear at the very least and when you're shopping for other clothing, 100% organic cotton's usually a safe choice :).

Rest assured that every decision you make to prioritize your health and reduce your exposure to PFAs will result in a healthier you.

Pick your battles and don't sweat the things you can't control/aren't even aware of :) and enjoy your new period undies.


  1. Thinx, Period Underwear, PFAs, and a class action lawsuit
  2. Houtz, E. F., Higgins, C. P., & Field, J. A. (2020). Persistence of per- and polyfluoroalkyl substances (PFAS) in menstrual pads and tampons. Environment International, 138, 105684.
  3. Environmental Working Group. (2021). EWG study finds PFAS in menstrual pads and tampons. Retrieved from

  4. Centers for Disease Control and Prevention. (2021). Per- and Polyfluoroalkyl Substances (PFAS). Retrieved from
  5. OEHHA. (2019). Perfluorooctanoic Acid (PFOA) and Perfluorooctanesulfonic Acid (PFOS) Drinking Water Health Advisories. Retrieved from
  6. Environmental Protection Agency. (2021). Basic Information on PFAS. Retrieved from
  7. Knix. (2021). Knix Statement on PFAS. Retrieved from
  8. ThinX. (2021). A Note on PFAS. Retrieved from
  9. Halden, R.U., & Lindstrom, A.B. (2012). Characterizing Exposure to Perfluoroalkyl Substances (PFAS) in a Highly Exposed Community. Environmental Science & Technology, 46(13), 6893-6900. doi: 10.1021/es3018657
  10. Strynar, M.J., Dagnino, S., McMahen, R., Liang, S., Lindstrom, A., Andersen, E., & McMillan, L. (2015). Identification of Novel Perfluoroalkyl Ether Acids in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS). Environmental Science & Technology, 49(18), 11622-11630. doi: 10.1021/acs.est.5b02926
  11. Giesy, J.P., & Kannan, K. (2002). Global Distribution of Perfluorooctane Sulfonate in Wildlife. Environmental Science & Technology, 36(10), 2137-2143. doi: 10.1021/es011945i
  12. Bjork, J.A., Wallace, K.B., & Kannan, K. (2011). Perfluorinated Compounds Are Associated with Altered Thyroid Function and Decreased Subclinical Thyroid Disease in the NHANES 2007-2008. Environmental Health Perspectives, 119(10), 1396-1402. doi: 10.1289/ehp.1103582
  13. Wang, Z., Cousins, I.T., Scheringer, M., Hungerbühler, K. (2013). Fluorinated Alternatives to Long-Chain Perfluoroalkyl Carboxylic Acids (PFCAs), Perfluoroalkane Sulfonic Acids (PFSAs) and Their Potential Precursors. Environment International, 60, 242-248. doi: 10.1016/j.envint.2013.08.007
  14. Chen Q, Liu F, Lu Y, et al. Maternal exposure to per- and polyfluoroalkyl substances and the risk of fetal growth restriction: A meta-analysis of 13 cohort studies. Environment International. 2019;128:51-60.
  15. Mínguez-Alarcón L, Sergeyev O, Burns JS, et al. Perfluoroalkyl substances and serum reproductive hormones in women: the study of women's health across the nation (SWAN). Journal of Occupational and Environmental Medicine. 2017;59(10):917-923.
  16. Deierlein AL, Wolff MS, Pajak A, et al. Longitudinal associations of perfluoroalkyl substances serum concentrations and timing of puberty in a prospective cohort of girls. Environment International. 2019;123:399-406.
  17. Rappazzo KM, Coffman E, Hines EP. Exposure to per- and polyfluoroalkyl substances (PFAS) and associations with impaired female reproductive health: A review. Reproductive Toxicology. 2017;68: 109-116.
  18. Hu XC, et al. Detection of poly- and perfluoroalkyl substances (PFASs) in U.S. drinking water linked to industrial sites, military fire training areas, and wastewater treatment plants. Environmental Science & Technology Letters. 2016;3(10):344-350. doi:10.1021/acs.estlett.6b00260
  19. Dinglasan-Panlilio MJ, et al. Impact of fabric care products on the transfer of per- and polyfluoroalkyl substances (PFAS) from textiles to human skin: An in vitro study. Science of The Total Environment. 2020;719:137515. doi:10.1016/j.scitotenv.2020.137515
  20. Agency for Toxic Substances and Disease Registry. Per- and Polyfluoroalkyl Substances (PFAS). Accessed on April 28, 2023 from


Brandy Searcy founder Rain Organica

About the Author

Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding. 

Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on. 

Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.

You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.

Brandy's LinkedIn Bio

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