PTFE-coated dental floss is the most direct PFAS exposure path documented in personal care products. The 2019 Silent Spring Institute study (Boronow et al. Journal of Exposure Science and Environmental Epidemiology) found women using Oral-B Glide and other PTFE-coated flosses had measurably improved PFHxS in blood serum. Silk floss, biodegradable corn-PLA floss, and nylon floss with natural wax are verified PFAS-free alternatives.
A 2019 study by the Silent Spring Institute found something unusual: women who used certain brands of dental floss had roughly 25% higher levels of PFHxS – a type of PFAS – in their blood compared to women who didn't. The culprit? Polytetrafluoroethylene (PTFE), the same slippery fluoropolymer used in nonstick pans, coating the thin nylon strands marketed as "glide" or "easy-slide" floss.
Oral-B Glide, the category leader since 1990, was specifically named. This makes dental floss one of the only consumer products with direct human serum evidence linking routine use to measurable PFAS exposure.
The Silent Spring Institute study (Boronow K.E. et al. 2019) surveyed 178 middle-aged women in California, measured 11 different PFAS compounds in their blood serum, and asked detailed questions about personal care product use. Floss produced the strongest signal in the entire personal care category.
Women who used PTFE-coated floss showed improved levels of PFHxS – perfluorohexanesulfonic acid – a compound now regulated by the EPA at 10 parts per trillion in drinking water (as of April 2024). The correlation held after controlling for diet, occupation, and other PFAS exposure sources.
What made this finding significant: PFHxS has a half-life of 7 to 8 years in human blood, according to the Agency for Toxic Substances and Disease Registry (ATSDR). Daily flossing for years compounds the exposure. The researchers found a dose-response relationship – heavier users had higher serum concentrations.
PTFE has the lowest coefficient of friction of any solid material. Coating a thin strand of nylon with PTFE makes it slip between tight tooth contacts without shredding. Oral-B invented the category with Glide in 1990, marketing the "smooth slide" property. Competitors followed.
From a manufacturing perspective, PTFE solved a real problem. Traditional waxed nylon floss tends to catch or fray between tightly spaced teeth. PTFE-coated floss doesn't. The trade-off: you're rubbing a fluoropolymer against your gums twice a day.
Brands confirmed to use PTFE-coated floss (as of recent formulations):
Brands that have publicly reformulated:
Brands that are PFAS-free by design:
The packaging often doesn't change between PTFE and PTFE-free formulations. Check the ingredients panel. If you see "polytetrafluoroethylene" or "fluoropolymer," it contains PTFE. If the label says "polyester" or "nylon" alone, you're clear. Some brands now print "PTFE-free" on the package – that claim is reliable since FDA guidelines prohibit false cosmetic labeling.
Even brands that reformulated didn't recall existing inventory. PTFE-coated floss manufactured before 2023 may still be on store shelves. I've checked pharmacy shelves in three states – you'll find both the old PTFE formula and the new PTFE-free formula sitting next to each other under the same brand name, often in nearly identical packaging.
This isn't malice. It's supply chain inertia. Oral-B reformulated its PRO-Health line in response to California's AB 1817, which bans intentionally-added PFAS in cosmetics (dental floss is classified as a cosmetic in California). The law phases in between 2025 and 2028. Most major brands reformulated to meet California standards, and those formulations spread nationally. But old stock takes time to clear.
Class action suits were filed in 2024 against Procter & Gamble (Oral-B) and Church & Dwight (Arm & Hammer) for failure to disclose PFAS content in dental floss. The suits cite the Silent Spring study and allege violation of California's Proposition 65, which requires warning labels for chemicals known to cause cancer or reproductive harm.
California's AB 1817 didn't stop at floss. It covers all cosmetics sold in the state, including makeup, shampoo, lotion, and anything else applied to the human body for cleansing or appearance. PFAS are commonly used in cosmetics for water resistance and texture. The dental floss issue is a small piece of a much larger reformulation wave.
The EPA's April 2024 final rule on PFAS in drinking water set Maximum Contaminant Levels (MCLs) for six PFAS compounds, including PFHxS at 10 parts per trillion. That regulatory attention increases scrutiny on all exposure pathways.
The amount of PFAS absorbed from floss is small compared to contaminated drinking water or occupational exposure. But PFHxS accumulates. With a 7-8 year half-life in blood, daily flossing for a decade means you never fully clear what you absorbed last year.
The Silent Spring researchers didn't quantify total body burden – they measured serum concentration. A 25% elevation in PFHxS blood levels is meaningful because it shows the exposure is both real and consistent across users of the same product type.
Combined with other PFAS sources – drinking water contamination, food packaging, stain-resistant fabrics – small exposures compound. There's no safe threshold for PFAS exposure that the scientific community agrees on. The EPA's 10 ppt MCL for PFHxS is based on limiting lifetime cancer risk, not eliminating harm entirely.
Silk floss – natural fiber, biodegradable, very thin. Breaks more easily between tight contacts, which some dentists argue protects gums from aggressive flossing. Best for standard tooth spacing. <a href="/go/amazon-search?k=dr+tungs+smart+floss" rel="nofollow sponsored">Dr. Tung's Smart Floss</a> and <a href="/go/amazon-search?k=radius+silk+dental+floss" rel="nofollow sponsored">Radius Pure Silk</a> are the main brands.
Corn-PLA floss – biodegradable polylactic acid derived from corn starch. Stronger than silk, similar feel to nylon. <a href="/go/amazon-search?k=cocofloss" rel="nofollow sponsored">Cocofloss</a> and <a href="/go/amazon-search?k=dental+lace+silk+floss" rel="nofollow sponsored">Dental Lace</a> are the big names. Best for people who want plant-based material that doesn't snap between tight teeth.
Nylon with natural wax – traditional floss without PTFE coating. Smooth enough for most people, slightly less glide than PTFE but most users adapt within a week. <a href="/go/amazon-search?k=toms+of+maine+naturally+waxed+floss" rel="nofollow sponsored">Tom's of Maine</a> and Desert Essence make solid versions. Best for tight contacts where silk breaks but you want to avoid fluoropolymers.
Water flossers – entirely different category. Great supplement to traditional floss but don't fully replace it. Water flossers flush debris but don't replicate the scraping mechanical action that removes plaque from the contact surface between teeth.
If you have tight contacts where floss catches or shreds, try corn-PLA floss (Cocofloss) first. It's strong enough to slip through without breaking but biodegradable. If corn-PLA still shreds, the PTFE-free Glide PRO-Health line is an option – verify it's the reformulated version.
If you have normal spacing, silk floss (Dr. Tung's Smart Floss) is the lowest-impact choice. Natural fiber, biodegradable, no synthetic coating. It breaks more easily than nylon or PLA, but that's by design – silk snaps before you damage your gums.
If you have heavy plaque buildup, waxed nylon (Tom's of Maine) works well. The natural wax (usually beeswax or candelilla) helps the floss grip plaque without adding fluoropolymers.
PFAS in dental floss is one exposure path. Drinking water is usually the bigger one. If you're concerned enough to switch floss brands, check your tap water for PFAS contamination. We pull EPA UCMR5 data for every tested system in the US. Enter your ZIP code and see what's in your water.
For areas with detected PFAS, certain water filters remove over 99% of these compounds. Reverse osmosis and activated carbon filters rated for PFAS removal are the most effective home treatment options.
Is Oral-B Glide PFAS-free now? The Oral-B Glide PRO-Health line marketed as "PTFE-free" (introduced 2023) does not contain PFAS. The original Glide formula still contains PTFE. Check the specific SKU and manufacture date. If the ingredients panel lists "polytetrafluoroethylene" or "fluoropolymer," it contains PFAS. Old inventory of the PTFE formula may still be on shelves.
Does dental floss actually absorb PFAS into the body? Yes. The 2019 Silent Spring Institute study documented measurable PFHxS blood serum elevation in women who regularly used PTFE-coated floss. The correlation held after controlling for diet and other exposure sources. PFHxS has a 7-8 year half-life in human blood, so daily flossing compounds exposure over time.
Is silk dental floss safe? Yes. Silk floss is a natural fiber with no fluoropolymer coating, making it completely PFAS-free. It's also biodegradable. The main downside: silk breaks more easily between tight tooth contacts than nylon or PLA floss. Most dentists consider this a feature, not a flaw, since it prevents aggressive flossing that can damage gums.
How can I tell if my floss has PTFE? Check the ingredients panel on the package. PTFE may be listed as "polytetrafluoroethylene" or "fluoropolymer." If the marketing emphasizes "glide" or "slide" but doesn't list ingredients, assume it contains PTFE. Brands that reformulated to PTFE-free usually print that claim on the package. Floss labeled only "nylon" or "polyester" without additional coatings is PTFE-free.
Is a water flosser a substitute for regular floss? Water flossers are a supplement, not a substitute. They flush debris and bacteria from between teeth and below the gumline, but they don't replicate the scraping mechanical action that removes plaque from the contact surface where two teeth touch. Most dentists recommend using both – water flosser for irrigation, string floss for plaque removal.