Is My Period Underwear Poisoning Me??

This post contains a video, which you can also view here. To support more videos like this, head to!


Last week I very dismissively welcomed new viewers to my channel but this week I’d like to make up for that with a genuine welcome and a helpful tip (slash reminder for returning viewers): every video on my channel includes a link in the description that will take you to a full transcript plus links to every study, article, or whatever I mention in the video! Also, be sure to stick around until the end of the video for a new bonus thing I’m testing out.

Okay, let’s dive in with a fun little joke: what do you get when you combine a lack of scientific knowledge with a lack of legal knowledge?

Answer: a headache. If you’re me.

“IF YOU ARE USING @Thinx period panties STOP USING THEM NOW!!!,” Tweeted @harkshetweets last week. “Thinx is essentially admitting to wrongdoing by settling a case in which plaintiffs found (through independent testing) toxic chemicals in their panties which can cause cancer/disease/decreased fertility. PLS SHARE!!!”

And share they did, with that tweet racking up nearly 20,000 retweets as of this recording and inspiring replies like “OMG IM WEARING THESE RIGHT F*#€¥ING NOW!!!!!!” and “Yooo I’m literally wearing them right now ?. I won’t be home for 6 hours.” WOMAN this is an EMERGENCY, you get those devil bloomers off your vulva RIGHT NOW! I don’t care if you’re stuck in a toll booth, you wait for a Mini Cooper to come through and you GO FOR IT. 

Also “Im cryinggggggggg” to which the original poster replied “I’m so sorry. For what it’s worth, I cried all day. ?” I’m sorry WHAT???? You are CRYING? Because an underpants company settled a lawsuit? My sisters. My brothers. My nonbinary siblings. All my relatives who are concerned with liquids leaking from their no-no areas. Do. Not. Panic. Don’t cry. Don’t rip your underpants off in the middle of your workday, that’s gonna get you a one-way ticket to HR.

Okay, so what are we talking about, here? Thinx is a company that produces “period underwear,” which is made of absorbent cloth on the inside with a water-resistant outer layer. It allows people to go about their day without worrying about blood seeping past tampons, menstrual cups, and pads to make an unsightly spot on their white pedal-pushers. They catch the blood, and then you rinse them out in the shower and throw them in the wash and line dry them and wear them again. Saves money, waste, and embarrassment. Win win.

As I mentioned in a video last week, I don’t accept sponsorships for these videos so what I’m saying next comes directly from my heart: these underpants are life-changing. I own several pairs. Had they been around when I hit puberty, my entire life would be different. I’m serious! I would be way less funny, for a start. I assume most of my sense of humor comes from horrific events in my childhood and bleeding through my jeans in elementary school is absolutely on the list. I got my first period before school and my mother sent me off to school with the most insufficient panty liner on the market and zero instruction on what to do next. It was like handing Danny Torrence a Kleenex and sending him to the elevator bank. And I spent the next 20 years being extraordinarily paranoid, and covering for that by also being extremely sarcastic and pretending I don’t really care if someone sees a red stain on my butt, whatever, who cares, etc!

If I had had Thinx, I would have minced around high school in a genuinely carefree manner, never needing to maintain a constant defense against my own body or the mocking of my peers! I mean yes, I would have still been in marching band, and Latin, and you know what actually having Thinx probably would have just made me slightly less tightly wound and it would have been nice, that’s all.

So that’s what Thinx are. Their success has spawned an entire industry of period undies from several brands, and they and others have also started expanding their line to cover issues like incontinence, which is awesome because most childfree humans with working uteruses really only get a limited amount of time where they no longer worry about menstruation and have yet to start worrying about incontinence.

The cause for all the pearl-clutching last week was that Thinx just settled a three-year long lawsuit about per-and polyfluoroalkyl substances, or “PFAS.” It was a class action lawsuit that requires Thinx to pay out a few bucks to everyone who bought their underpants. I’ll explain PFAS in a second but first, here are two points I’d like to emphasize regarding court cases and science: this was a case based on marketing, not necessarily safety, and NO court case can ever decide what is and is not actually true from a scientific perspective. The Scopes “monkey trial” didn’t prove that evolution is a lie, just as Kitzmiller v. Dover didn’t prove that “intelligent design” is a lie. Court trials are in a completely different realm from science, cases that call for specific decisions that are decided by either one person or a small handful of people, none of whom need to know anything about the scientific method to reach their verdict.

Finally, people and companies settle lawsuits all the time without admitting guilt – even in criminal murder trials! Lawsuits are long, expensive, and energy-sapping, and sometimes people decide that it’s better to settle and move on even if they feel the settlement is unfair or doesn’t reflect reality. So our original Tweeter was very, very wrong in stating that “Thinx is essentially admitting to wrongdoing.” As the official settlement website states, “Thinx denies all of the allegations made in the lawsuit and denies that Thinx did anything improper or unlawful,” and “The proposed settlement is not an admission of guilt or wrongdoing of any kind by Thinx.”

The class action lawsuit alleged that Thinx’s marketing “led consumers to believe that Thinx Underwear is a safe, healthy and sustainable choice for women, and that it is free of harmful chemicals.” But some consumers sent their underwear to independent labs who found PFAS and silver nanoparticles, which their lawsuit alleged are “a safety hazard to the female body and the environment.” Why did they go with “female” when Thinx uses inclusive language that markets to all genders? I’m not positive but from perusing the documents my best guess is because their claim that silver nanoparticles (a natural anti-bacterial) are harmful relies on a blog post that states that while there are no studies on the subject, it’s theoretically possible that these nanoparticles could kill healthy bacteria in the vagina, and while there are no studies on silver nanoparticles in clothing, scientists did once find that they accumulated in vaginal cells when it was injected directly into the vagina. Of rabbits. 

And while there is no research on whether or not they can move from clothing into the bloodstream, that could maybe happen and maybe a future study will find that. Also you shouldn’t wear them in MRI machines.

Anyway, because all these scientifically unproven harms only apply to vaginas (rabbit vaginas), I guess they thought it was safest to go with “female?” I don’t know, man.

I should mention now that while there is no evidence that silver nanoparticles, which are very commonly used in clothing to prevent odor, are dangerous to humans, that doesn’t mean they aren’t. Future research could certainly find that! But it hasn’t yet. So, in my opinion, it’s not something that the average person needs to worry about.

That brings us to PFAS, also known as “forever chemicals” thanks to the annoying fact that they just don’t seem to break down very well, if at all. I talked about them in this video from 2020, when I said:

“You would know PFAS for their use in nonstick coatings and waterproofing on boots and jackets, but they’re so much more common than that. They’re used in firefighting foam, candy wrappers, cosmetics, plastic manufacturing, wire insulation, and basically anything that resists water or oil. Because they’re so widely used and because most of them don’t easily break down, they get into our soil, our water supply, and yes, even our blood.”

That list of products was VERY abbreviated. PFAS are basically in EVERYTHING now, whether they were put there on purpose or not. The Thinx lawsuit alleged that the levels found in the underwear were so high that they must have been used by the company on purpose, though Thinx disputes that and says that in the future they’re going to crack down on their suppliers to make sure that they aren’t sneaking PFAS into any of the raw materials they use.

So, they’re everywhere, but are they dangerous? Well, there are actually a lot of different PFAS, and some of them, like PFOA (used in Teflon), have shown signs of possibly being toxic, which is why the US has begun monitoring and regulating it. The biggest risk appears to be in the manufacturing of it, but it could also be harmful if enough of it flakes off of the products we use.

Other PFAS are still being studied to figure out if they’re harmful. Again, as I said in 2020:

“The very real problem here with PFAS, the one that you might want to be concerned about, is that the US government doesn’t mind manufacturers using a new, untested-on-humans chemical until it starts causing problems in the general population. It’s more of a “don’t ask permission; beg forgiveness” sort of deal that helps products get to market faster at the possible expense of consumers’ health and wellbeing. Yay, capitalism!”

All of this is to say that no one really knows if the PFAS found in Thinx are dangerous, and if they are, in what quantities it’s something we need to be concerned about.

But we do know that PFAS are everywhere: “Cleaning products.

Water-resistant fabrics, such as rain jackets, umbrellas and tents.

Grease-resistant paper.

Nonstick cookware.

Personal care products, like shampoo, dental floss, nail polish, and eye makeup.

Stain-resistant coatings used on carpets, upholstery, and other fabrics.”

And more! So many more. So our original Tweeter could have accurately tweeted instead “IF YOU ARE USING (dental floss) STOP USING (IT) NOW!!!” Because as sensitive and absorbent as your vulva is, the inside of your mouth is pretty similar, and I don’t think anyone is shoving Thinx underpants up inside their bodies, or chewing on them. I hope. I mean. Not to kink shame. Actually come to think of it, while I don’t accept corporate sponsors for this channel I COULD use some new undies and so I would consider…actually no never mind I don’t want to deal with you freaks.

Anyway, my point is that this is not something to panic about. PFAS in general is a topic to feel concerned about, in a general sense, and possibly in an existential sense concerning what we humans have done to our planet and to ourselves in the interest of not needing to use butter when we cook an egg. You can certainly try to avoid direct exposure to PFAS by not living next to a manufacturing plant (you lucky billionaire) or by avoiding using certain products like nonstick pans and takeout containers, but at this point it does seem like avoiding PFAS entirely would be like avoiding urine by only swimming in the no pissing section of the pool.

As for me, I’ll keep using period undies when I have a period, because it’s convenient and I’ve seen no evidence that it’s harmful. As always, I reserve the right to change my mind if the evidence does emerge.

Thanks to those of you who made it all the way to the end of this video! I’m about to roll the credits but I wanted to let you know that I’ve decided to start ending my videos with a bonus photo or video of my dog, Indy, that you won’t be able to find anywhere else on my social media. Seeing the secret Indy will be like joining a club. The “all the way to the end” club. I see you and I appreciate you.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor. Twitter @rebeccawatson Mastodon Instagram @actuallyrebeccawatson TikTok @actuallyrebeccawatson YouTube @rebeccawatson BlueSky

Related Articles

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Back to top button