People may absorb toxic industrial chemicals from some brands of dental floss, a new study says. It’s the latest evidence that Americans are routinely exposed to this vast class of chemicals, known as PFAS, some of which have been linked to heart disease and cancer.
Women who said they flossed with Oral-B Glide floss had higher levels of a PFAS called perfluorohexane sulfonic acid (PFHxS) in their blood than those who didn’t, researchers reported Tuesday in the Journal of Exposure Science & Environmental Epidemiology.
“I’m not trying to tell people, ‘don’t floss,’” Katie Boronow, a staff scientist at the Silent Spring Institute in Newton, Massachusetts, who was part of the study, told BuzzFeed News. “It’s about choosing safer products.”
Although scientists have known that PFAS are used in Glide, “this finding suggests that it may be more important than expected,” said Courtney Carignan, an associate professor of food science and toxicology at Michigan State University who was not part of the study.
In addition to looking at the women’s blood levels, the researchers analyzed the chemical makeup of 18 types of dental floss. Six tested positive for fluorine, an element that they said indicates the presence of PFAS compounds. Those products were CVS Health EaseBetween SuperSlip Dental Floss Waxed, Oral-B Glide Pro-Health Mint and Glide Pro-Health Original, Crest Glide Deep Clean Cool Mint Floss, Safeway Signature Care Mint Waxed Comfort Floss, and Colgate Total Dental Floss Mint.
“The safety of the people who use our products is our number one priority. Our dental floss undergoes thorough safety testing and we stand by the safety of all our products,” a spokesperson for Procter & Gamble, the company that owns the Oral-B and Crest brand, told BuzzFeed News by email.
A spokesperson for CVS Pharmacy said by email that the company is “committed to assuring that the products we offer are safe, work as intended, comply with regulations and satisfy customers. We will be reviewing the study and will also contact the supplier of this product.”
Colgate-Palmolive and Safeway did not respond to requests for comment from BuzzFeed News.
PFAS compounds are used in the manufacture of many consumer products, including Teflon and nonstick cookware, waterproofed shoes and clothes, carpets, upholstery, and some kinds of food packaging. (Colgate’s website describes its Total Dental Floss as a “single-strand Teflon fiber.”)
Firefighting foams used at airports and military bases also contain PFAS chemicals. The Department of Defense has identified 126 sites near military bases with PFAS in their drinking water sources. Dozens of municipalities near chemical factories that once made PFAS products are finding the compounds in the public water systems.
Philippe Grandjean, a professor of environmental health at Harvard who was not involved with the study, told BuzzFeed News in an email that he found the results meaningful, despite the possibility that survey participants could have been exposed to PFAS from other sources, too.
“Non-stick pans have [a] larger surface but we don’t chew on them like dental floss,” Grandjean said.
Rita Loch-Caruso, a professor of environmental health at the University of Michigan who was not involved with the study, pointed out that fluoride — which also contains fluorine — is sometimes added to dental products. “It would have been nice to see them discuss whether fluoride could have been contributing to the fluorine measurements on the floss,” she told BuzzFeed News.
Boronow said that none of the products were advertised to contain fluoride for dental health.
The survey included 178 women, 87 of whom were black and 91 non-Hispanic white. The authors noted that follow-up work should include other ethnicities.
The goal of the study, Boronow said, was to get a clearer idea of how people absorbed the chemicals. “Aside from people who have contaminated drinking water or are exposed to PFAS chemicals at work, we don’t know what the most important sources of exposure are,” she said.
Dan Vergano contributed reporting.