How many times has your dentist told you to floss your teeth? Lots, right? But flossing can be a drag, especially if you use the unwaxed kind. It gets stuck or shreds. That’s why waxed or slippery floss is so popular. But a new study raises questions about the chemicals used to make dental floss and other substances slippery. PFAS stands for a tongue twister: polyfluoroalkyl substances. They’re found in lots of nonstick chemicals and they are suspected of causing substantial mischief, including thyroid problems.
PFAS Are Hard to Avoid:
There are a bunch of PFASs. They’re all impossible to pronounce. Here are just a few example:
PFOA (perfluorooctanoic acid)
PFOS (perfluorooctanesulfonic acid)
PFNA (perfluorononanoic acid)
PFHxS (perfluorohexanesulfonic acid)
These PFASs are used in all sorts of places you might not suspect. They are found in nonstick cookware and stain-repellent sprays. Carpets and furniture may be coated with PFAS to prevent stains from sticking to the fibers. Grease-resistant packaging may also have PFAS. Think pizza boxes or paper containers that hold French fries. Most surprising to us, though, was the report that suggested there are PFASs in some dental floss products (Journal of Exposure Science & Environmental Epidemiology, online, Jan. 8, 2019).
Why Should We Care About PFAS?
The authors of the article cited above state:
“Given their extensive use and persistent nature, it is unsurprising that PFASs have been detected in water and soil, and in the bodies of almost all Americans. Exposure to the long-chain PFASs perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) has been linked to kidney and testicular cancer, decreased semen quality, and ulcerative colitis in adults, and to thyroid disease, immune response, and lowered sex and growth hormones in children.”
PFAS and Thyroid Problems:
There appears to be a link between exposure to PFASs and thyroid disease. One chemical in particular, PFOA, has been associated with both hypo and hyperthyroidism. This was the conclusion of of the C8 Science Panel (July 30, 2012). These scientists evaluated exposure of residents in Parkersburg, WV, to PFOA.
Ask veterinarians about the epidemic of hyperthyroidism in cats. It is a mystery, but there is tantalizing research to suggest that higher levels of PFASs in the environment could be associated with increasing amounts of feline hyperthyroidism (Wang, et al, Environmental Toxicology and Chemistry, Sept. 19, 2018). Another class of chemicals, PBDEs that are used as flame retardants, may also be contributing. If you are interested, here is a fascinating article by Emily Anthes in The New York Times (May 16, 2017) titled “The Mystery of the Wasting House-Cats.”
What About Dental Floss?
The article in the Journal of Exposure Science & Environmental Epidemiology (online, Jan. 8, 2019) describes blood levels of PFASs in 178 middle-aged women.
The investigators found:
“Flossing with Oral-B Glide was associated with higher levels of PFHxS. All three Glide products that we tested contained fluorine, consistent with available information that Oral-B Glide is made with PTFE and supporting our hypothesis that Oral-B Glide is a potential exposure source for PFASs. In addition, three other flosses also tested positive for fluorine, including two of three store-brand products advertised as ‘compare to Oral-B Glide’ on the package, and one described online as ‘single strand Teflon®fiber’.”
The researchers conclude:
“While this study did not capture all the potentially important sources of PFASs, our results strengthen the evidence for exposure to PFASs from food packaging and implicate exposure from PTFE-based dental floss for the first time—a finding that warrants prompt follow-up in a future study.”