Is my dental floss actually toxic? Why TikTok is abuzz with “forever chemicals” in our oral care

In a world where health advice comes from so-called experts on Instagram and Tiktok, it’s increasingly more difficult to know what’s true and what’s not. It’s also likely you’ve recently come across a video on such platforms warning of the toxic dangers of dental floss.

It happened to me a few weeks ago when my mom came over to my house with a box of $10 “non-toxic” floss. My current, and cheaper, floss was putting my health at risk, she said. When I asked for more details, she said my floss has “forever chemicals” in it and those can get into my bloodstream via the act of flossing — or so she heard, on TikTok.

As a regular at my dentist, and twice-a-day flosser, I’ve never been told to stop using dental floss (although my dentist recently tried to sell me hard on a water flosser). Sure enough, a search on TikTok yielded a cascade of videos echoing what my mom told me. It’s true that The Centers for Disease Control and Prevention (CDC) cites dental floss on a list of products that could contain PFAS, but does that mean that said floss is toxic and my health is at risk to be compromised in return? Is paying more for a non-toxic floss better?

Substances like PFAS and PFOA (perfluorooctanoic acid) are called forever chemicals because they essentially do not break down either in the natural environment or in our own bodies. From a technological perspective, it’s this durability that makes them so popular. Putting PFAS in a fabric will make them more protected against staining. PFAS on a cooking pan can create non-stick coatings. I have PFAS to thank for the invention of waterproof mascara. And yet, their popularity comes with a significant cost to human health. Forever chemicals have been linked to serious health issues like cancer, high blood pressure, infertility,  high blood pressure, liver disease and low sperm count. Unfortunately, scientists suspect PFAS are everywhere and virtually indestructible. Until recently, they’ve been nearly impossible to destroy.

It turns out that TikTok videos claiming dental floss is toxic don’t just stem from the fact that so many products are full of forever chemicals. In 2019, a study published in the Journal of Exposure Science & Environmental Epidemiology found that women who flossed with Oral-B Glide dental floss had higher levels of PFHxS (perfluorohexanesulfonic acid), a type of PFAS, in their bodies compared to those women who didn’t. Scientists who conducted the study measured 11 different PFAS chemicals in blood samples taken from 178 middle-aged women.

To better understand the connection between flossing and PFAS levels in blood, the researchers proceeded to test 18 dental flosses for the presence of fluorine, a PFAS marker, using a technique called particle-induced gamma-ray emission (PIGE) spectroscopy. Six tested positive for fluorine — including all three Glide products.

“This is the first study to show that using dental floss containing PFAS is associated with a higher body burden of these toxic chemicals,” said lead author Katie Boronow.

In the study the authors said additional research was needed to better understand the potential of PFAS in floss traveling into saliva and being ingested. In an FAQ about the study, the authors further elaborated on why they believed floss was the culprit of higher PFAS levels in the women in the first place. Indeed, since people are frequently exposed to PFAS from multiple sources, it could have been something else. But the researchers explained that they used a model specifically to find out how much exposure can be attributed to each source, which would disqualify other sources. Using the same model, the researchers found that having stain-resistant carpet or furniture, or living in a city with a PFAS-contaminated drinking water supply, were also linked to elevated PFAS levels. Among African Americans, eating food prepared in coated cardboard containers were linked to higher PFAS levels.

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“Our model showed that there was a statistically significant association between flossing with Oral-B Glide and higher blood levels of PFHxS,” the authors stated. “This suggests that some of the exposure came from flossing.”

Scientists at the Silent Spring Institute, a research organization focused on uncovering environmental causes of breast cancer and other health-related topics, stated they first suspected that dental flosses were made with PTFE for a variety of reasons. First, Glide floss is a product manufactured by Gore (known by consumers for its waterproof “GORE-TEX” technology), which makes a variety of consumer and industrial products using polytetrafluoroethylene (PTFE) — more commonly known by its trade name, Teflon. On the Oral B website, it lists Polytetrafluorethylene floss (PTFE) as a type of dental floss and describes the material as one that “slides between the teeth easily and is less likely to shred compared to standard floss.”

Since this study, there haven’t been any additional studies published in a peer-reviewed journal specifically focusing on dental floss and PFAS. However, in September 2022, a health blog called Mamavation tested 39 different tooth floss products for fluorine, and found that 13 out of 39 products had indications of PFAS. On the high end, Oral-B Glide tested to have 248,900 parts per million (ppm) of fluorine. (Salon reached out to Glide and didn’t receive a response before publication).

“Finding organic fluorine over 240,000 ppm in any product meant to go inside your mouth and thus could be easily ingested is very concerning,” Linda Birnbaum, scientist emeritus and former director of the National Institute of Environmental Health Sciences and National Toxicology Program, said at the time. “These levels that we are seeing from some of these dental floss products do not reflect levels that are safe for human consumption.”

Birnbaum said PFAS could be building up inside consumers every time they floss their teeth, “creating a situation that can lead to chronic disease,” she said.

The good news is with the relatively little research available, scientists are hopeful that not all dental floss has PFAS.

“There are already a wide variety of brands that offer PFAS-free dental floss that work great,” Katie Pelch, a scientist with NRDC (Natural Resources Defense Council), told Salon via email. “There is no reason for brands to continue to pollute the environment and our bodies by adding unnecessary, toxic ‘forever chemicals’ to products like dental floss.”

Pelch said it is concerning that some companies are using PFAS in dental floss. “Floss can be made to slide more easily between the teeth without risking exposure to toxic forever chemicals,” Pelch said, adding that to avoid PFAS in floss, consumers should avoid products marketed as “gliding” or “nonstick” and look instead for products that list natural waxes.

The take away isn’t to stop flossing entirely. As recently as 2021 a study reported that flossing was associated with reduced cognitive impairment and dementia. Analyzing 172 participants, the researchers wrote “These results highlight the importance of preserving the health of the teeth and not just retaining the teeth.” Teresa Yang, a dentist in Los Angeles, told Salon via email she’d like to see a follow-up to this study “to determine the significance of the floss PFA content relative to other sources.”

“Don’t overreact to one finding from a study of less than 200 women,” Yang told Salon. “Rather, wait for additional research that either confirms or dispels the initial findings and provides more concrete and specific information.”

Yang said flossing is “one of the best things you can do for your overall health.” 

But scientists say this is yet another example for the need of restrictions on PFAS. 

“In the future, it should become easier to identify PFAS-free floss, as more states enact laws to reduce unnecessary uses of PFAS,” Pelch said. “Minnesota recently became the first state to ban PFAS in dental floss, beginning in 2032.”