Flossing seems linked with toxic chemical buildup.
Per- and polyfluoroalkyl substances (PFAS) have become a daily part of human life.
These water- and greaseproof substances are present in many products — from fast food containers to certain types of clothing.
Humans also face exposure to them through contaminated water and even dust.
However, what is most concerning — according to the Environmental Protection Agency (EPA) — is that these manmade chemicals continue to build up in the body without breaking down.
Regular exposure to PFAS has led some researchers to examine their impact on human health. So far, results have shown a link to health issues such as high cholesterol, kidney and testicular cancer, and thyroid disease.
A new study has delved further into typical human behaviors to see whether any were associated with PFAS exposure. Participants were 178 middle-aged women, of whom half were African-American and the other half were non-Hispanic white.
These women were already part of the Public Health Institute's Child Health and Development Studies, which enrolled pregnant women living in Oakland, CA, in 1959–1967. Its aim was to determine the impact that environmental chemicals and other things have on disease.
The PFAS levels of floss
Scientists from the Silent Spring Institute and the Public Health Institute in Berkeley, CA, used blood samples taken from the women in 2010–2013.
They examined the samples to find levels of 11 types of PFAS. They also interviewed each woman at some point in 2015–2016, asking a series of questions about behaviors potentially linked with PFAS exposure.
They addressed food consumption, dental flossing, and stain-resistant furniture and carpets.
Once the scientists had determined all the blood measurements, they compared them against the answers the women gave. They took into account factors such as whether people lived in areas where water was contaminated with PFAS.
The results appear in the Journal of Exposure Science & Environmental Epidemiology.
The most striking observation the study made was that certain dental floss seemed to result in elevated levels of PFAS.
The researchers studied this association further by testing 18 different flosses for the presence of fluorine, which also indicates the presence of PFAS.
They revealed that Glide flosses and three non-Glide flosses came back positive for fluorine. This matched the results that found that women who used a certain brand of Glide floss had higher levels of a PFAS called PFHxS in their blood.
Other findings included that African-American women who reported regularly eating preprepared food in coated cardboard packaging, such as takeout, had higher levels of four types of PFAS in their blood. This was compared with women who reported rarely eating that kind of food.
Living in an area with a PFAS-contaminated water supply and living in a house with stain-resistant carpets or furniture also showed links to higher PFAS levels in the blood.
The scientists also note that non-Hispanic white women had elevated levels of two PFAS: PFOA and PFHxS.
It is unclear why this was not the case for African-American women, but this difference could be down to a different kind of behavior that the researchers did not measure.
The number of participants and the fact that the majority lived in California are also limitations, along with the lack of research into Hispanic and Asian-American people. Despite this:
"[T]his is the first study to show that using dental floss containing PFAS is associated with a higher body burden of these toxic chemicals. The good news is, based on our findings, consumers can choose flosses that don't contain PFAS."
Lead study author Katie Boronow
She explains that the findings go some way toward proving that consumer products do increase exposure to PFAS, and that companies should look at "restricting these chemicals" as a priority.