What’s this I’ve been hearing about chemicals in period underwear? Are they safe?

Reproductive Health

Don’t panic. It’s unlikely that Thinx or other period underwear pose a risk to your health, but there are still some unknowns.

A recent U.S. class action lawsuit against Thinx claimed its advertisement that Thinx are “organic, sustainable, and nontoxic” was misleading. This news has understandably made a lot of people who use these products nervous.

⚈ What are these toxic chemicals?

✳️ PFAS (per- and polyfluoroalkyl substances) are often called “forever chemicals” because they are basically indestructible.

✳️ PFAS are found in almost every consumer product you can think of and are often used to make clothing water-resistant (enter Thinx).

✳️ PFAS can contaminate anything they touch (e.g., if they are in food wrappers they can be in your food) and don’t degrade naturally or get broken down by our bodies. They build up in our bodies and in the environment.

✳️ PFAS may be linked with several health risks, including messing with hormones, and, in pregnancy, they may lead to to high blood pressure and low birth weight. They are also a potential carcinogen (cause cancer). The evidence for all of these things is not 100% established and causality is difficult to prove. Many of the studies were done in animals exposed to much higher doses of PFAS than would happen for the average human.

At this point, you might be freaking out. PFAS sound pretty bad, and who would want that entering your body through period underwear? Take a deep breath and keep reading.

⚈ What should I do if I’ve already used Thinx?

If you have already been using Thinx, there is no reason to panic. It seems unlikely that PFAS from period underwear would enter your body in large enough quantities to be concerning. Some have suggested that the PFAS disappear after a few laundry cycles, although it’s unclear whether that’s true.

There are still things to be concerned about when it comes to Thinx and other similar period-related products. First of all, as you’ve probably guessed by now, there’s just a lot we don’t know about PFAS. We do not know their risk to human health and in what circumstances they are most likely to enter the body at high doses. So it’s understandable to be cautious about some of these products moving forward. In addition, there are clear environmental concerns with something like Thinx, because the PFAS from them may enter the water supply when you wash your underwear. So even though PFAS may not enter your body from Thinx underwear and immediately harm you, there still might be reasons to reconsider using them. On the other hand, there are environmental benefits of using period underwear versus pads and tampons, and period underwear may confer a certain amount of comfort and security to many people who menstruate. So there doesn’t seem to be a clear reason to toss them in the trash at present.

So what should you do? Bottom line – Don’t panic, but do become a more informed consumer. Read up on PFAS and period products (and think about other products in your life too!). And consider whether you can live with some of the uncertainty on this topic.

In the meantime, stay well and stay informed!


Those Nerdy Girls


Additional Links and Resources:

Jen Gunter on Thinx and period underwear

NYT article on PFAS and the Thinx lawsuit

Link to original Those Nerdy Girls Facebook post