by Noah Orenstein DMD, MDSc, FACP
Patients have forever questioned the value of waxed versus non-waxed floss. Although non- waxed floss enables better plaque removal than waxed, people with fillings or crowns often complain about non-waxed floss tearing or ripping. As a result of this common challenge, dental floss manufacturers have developed different products to help people circumvent these issues. One of such involves a set of compounds called per- and polyfluoroalkyl substances (PFAS). Polytetrafluoroethylene, one of these PFAS substances has been added to dental floss to help the floss move between the teeth.
PFAS are a group of compounds that resist both fats and water, which is why they are used in many products including water and stain resistant fabrics, non-stick appliances and cookware, and some types of dental floss. You may have heard of one of these compounds before: polytetrafluoroethylene, otherwise known as Teflon. As these products have become more widespread, scientists have become interested in their potential health impact.
A paper recently published in the Journal of Exposure Science & Environmental Epidemiology, investigated the levels of PFAS compounds in the blood of 178 middle-aged women. The study found one of the PFAS compounds used in Glide dental floss to be higher in subjects who flossed versus those that did not. This article was picked up in the mainstream media and received a lot of attention. Although these types of articles can help to bring awareness, it is important that before drawing possibly disproportional conclusions, one has a clear understanding of the nature of the study.
In this case, the McGill University Office for Science and Society provided an analysis of the original article citing many issues:
First, they make clear the difference between finding the presence of PFAS in the bloodstream and true toxicity. As PFAS are measured at the part per TRILLION (ppt) level, just because Glide flossers were found to have a higher level of PFAS than non-flossers, does not indicate that the PFAS were present at a level of concern for true toxicity. Additionally, the authors indicate that based on the original study design, with the widespread prevalence of PFAS in our environment, there is no way to truly conclude that the compound’s presence in these subjects came exclusively from exposure to the floss.
Second, although the article was able to identify that overall, users of Glide flossers had a higher amount of PFAS in their blood stream than non-flossers, the research does not include how often people flossed, and additionally shows large ranges in the presence of these compounds. This detail limits the ability to draw a direct link between the variables. Within the actual data there were many ‘flossing’ subjects that actually had lower measured PFAS levels than ‘non-flossing’ subjects, which further weakens the validity of the data.
Given the amount of limitations to the study, we cannot conclude that Glide floss contributes to blood toxicity by PFAS, nor does it provide a reason to be concerned about changing one’s dental floss or oral hygiene patterns. That being said, this article should encourage us to continue leaning and researching the substances that are being put into our manufactured goods. Hopefully this article will contribute to more research being conducted on these topics.
So, for all of you that were hoping to use this as an excuse to stop flossing, it looks like you will have to continue searching for another reason!
Schwarcz, Joe “Is Dental Floss Toxic.” Office for Science and Society, McGill University, 18 January 2019, mcgill.ca/oss/article/health/dental-floss-toxic
K.E. Boronow, J.G. Brody, L.A. Schaider, G.F. Peaslee, L. Havas, B.A. Cohn. 2019. “Serum concentrations of PFAS’s and exposure-related behaviors in African American and non-Hispanic white women“. Journal of Exposure Science & Environmental Epidemiology. DOI: 10.1038/s41370-018-0109-y