Flossing your way to cancer

Toxins are everywhere these days. In your water, in your food, in your beauty products, in mostly everything you consume or surround yourself with. Most importantly, toxins are in the headlines. The media has done a great job sensationalizing many toxicology papers and creating eye-catching headlines, like mine, that are not necessarily correct.

Earlier this year, USA Today released an article titled “Oral-B Glide floss tied to potentially toxic PFAS chemicals, study suggests” and Medical News Today released a similar piece titled “Flossing could increase exposure to toxic chemicals”. These were all based on a recent article published using self-reported data from the Child Health and Development Studies in Oakland, CA. Due to the media sensationalizing this study, it is important to break down the headlines and understand what was actually said and done.

Figure 1. Structure of PFOA: a non-polymer PFAS

Figure 2. Structure of PFOS: a non-polymer PFAS

Figure 3. Structure of PFTE: a polymer PFAS. n signifies that this basic chemical unit is repeated multiple times to form a polymer.

The toxins of focus in the article, as the USA Today headline states, are PFAS. PFAS, short for per- and polyfluoroalkyl substances, are man-made chemicals that have been used in industry and consumer products for nearly 70 years. PFAS are fluorosurfactants which are a group of chemicals whose properties originate from a substitution of hydrogen with fluorine along the carbon backbone. PFAS include chemicals like PFOA, PFOS, and GenX and can be found in non-stick cookware, water-repellent materials, some cosmetics, food packaging, and products that resist grease, water, and oil. PFAS encompass many substances and the EPA has a list that includes over 5000 PFAS substances. The PFAS substances can be divided into two major families: polymer and non-polymer. Polymers and non-polymers are differentiated from each other by size, with polymers being a chemical made of many repeating units of non-polymers. The non-polymer PFAS include PFOA and PFOS and are the most commonly detected in the environment. The polymer PFAS are larger molecules than the non-polymer substances and include PFTE.

In the study described, they measured a total of 11 non-polymer PFAS (including PFOA and PFOS) in blood samples in 178 middle-aged women and collected data on behaviors that they believed would influence PFAS exposure. These behaviors included using things like non-stick cookware, microwave popcorn, glide floss (Oral-B), coated cardboard containers, seafood, and stain-resistant carpet and furniture. This is the first paper to consider dental floss as an exposure to PFAS. To narrow down the brand and type of floss, the researchers did something interesting. They analyzed 18 different floss types for the presence of fluorine and used it to evaluate the plausibility of PFAS exposure from dental floss. They found Oral-B Glide dental floss and two other dental floss products to have detectable levels of fluorine.

Fluorine is a chemical that is represented by the letter F on the periodic table of elements. We commonly know it as fluoride, which is made when you combine fluorine and a metal, like sodium. Fluoride can be a common component in many of our dental products, although Oral-B’s website does not specify whether their Glide floss contains any. They do have an instructional page that takes you through the different types of dental floss, where you can see a very familiar looking word: polytetrafluoroethylene (PTFE). PTFE is the most commonly used chemical for Teflon coating and is in the polymer family of PFAS which is not the same class as PFOA and PFOS (these are non-polymers).

The article does take notice of the report that Oral-B Glide is manufactured from PTFE; however, it is confusing why they chose to evaluate PFAS non-polymer exposure when the Oral-B Glide Floss is made with PTFE which is a PFAS polymer. It is particularly perplexing since the studies that describe the toxicity of PTFE are few in number, in comparison to PFOA, and the results do not present substantial conclusions. This is when a little chemistry knowledge is needed. PFOA is commonly used in the synthesis of PTFE and is an established dangerous chemical. Additionally, PTFE may also contain PFCA (another type of PFAS). The studies done to assess the presence of these PFAS in PTFE were done with non-stick pans while applying high levels of heat to see if PFOA and PFCA gases were released. It seems a stretch to imagine that dental floss would undergo enough heat to release these more dangerous toxins and thus contribute to the circulating levels of non-polymer PFAS. However, it is possible that PFTE, when metabolized by the body, breaks down into these more toxic metabolites.

It is mentioned in the discussion of the article that “PFASs are detected in PTFE-based dental floss…” and cites two papers. One of the papers clearly shows that PFOA was detected in both dental floss and dental tape. However, the concentration is minute in comparison to PFTE cookware, PFTE film/sealant tape, and popcorn bags. There is one main thing to keep in mind from this seemingly damning paper. It is unclear from their methods how they measured the PFOA in the dental floss/tape, but it is clear that it was not under circumstances that would mimic human use. The researchers for this paper note that since “…PFTE does not dissolve…” you have to measure PFOA presence by extracting from a ground or powdered material.

All in all, it is important for studies to assess the potential sources of exposure and hold industry accountable. However, it is important when evaluating new sources of exposure to be sure that the exposure in question could be significantly contributing to your toxins of interest. For the case of Oral-B Glide, it is possible that the PTFE used in this dental floss is contributing to elevated levels of PFAS in people’s bloodstream. Nevertheless, we currently do not have the research to support this connection, and so it is important to be mindful with our results and not let the media sensationalize them.

Peer edited by: Isabel Newsome and Nicholas Martinez.

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