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A recent study led by researchers from Duke University, conducted with colleagues from Wayne State University and the University of North Carolina at Charlotte, found that four of the top-rated anti-fog sprays contained up to 20.7 milligrams of per- and polyfluoroalkyl substances (PFAS) per milliliter of solution.1 This study has received a lot of exposure in popular media, and it should not be overlooked. The researchers used several creative approaches to obtain a comprehensive characterization of the anti-fog sprays, including using total organic fluorine measurements, GC-MS methods and both nominal mass and accurate mass instruments. A unique finding of the study was the detection of fluorotelomer ethoxylates (FTEOs), which are relatively unknown PFAS compounds.2
Why are PFAS used in anti-fog sprays?
Anti-fog sprays have properties that are very similar to the properties of nonstick surfaces (used in kitchen pans, for example) and water-repellent surfaces (used in waterproof coats and jackets, for instance).3 The increased use of protective gear, such as masks and face shields, due to the Covid-19 pandemic has driven an increase in the use of anti-fog sprays. Eyeglasses that fog while wearing protective equipment can be very challenging for some individuals, particularly those who must wear gear for a prolonged period.4 This is where anti-fog sprays can help by creating a film on glass surfaces to prevent water from gathering and creating a fog.
While this may alleviate the initial frustration of fogged glasses, similar to other products that make our lives more straightforward (such as raincoats and nonstick pans), anti-fog sprays have a hidden ingredient and extra cost: PFAS. Since the early 2000s, PFAS have been increasingly monitored as their effects have become more topical and as regulations have been implemented.5 While this complex family of synthetic compounds has been produced since the mid-20th century, PFAS have recently become a concern due to their potentially harmful effects on human and animal health.6
Although products such as nonstick pans and anti-fog sprays are very effective and convenient, we need to be mindful of their potential long-term effects. As highlighted by the Duke-led study, very little is known about the toxicity of FTEOs.
How can mass spectrometry identify PFAS in our consumer products?
The presence of PFAS in anti-fog sprays was a surprise to many people, but perhaps it shouldn’t have been. A PFAS inventory assessment from 2020 showed that PFAS were found in more than 200 “use categories,” from textiles and firefighting to climbing ropes and artificial turf.7 The results of the assessment clearly demonstrated the PFAS are (almost) everywhere.
Fortunately, mass spectrometry can help us understand which consumer products contain PFAS, and what specific PFAS are present in those products. This is important because PFAS in consumer products may directly (via dermal exposure, for example) or indirectly (via transfer to house dust, for instance) contribute to PFAS exposure and ultimately human health risk. For example, nominal mass spectrometers (such as triple quadrupole and QTRAP instruments) provide high selectivity and sensitivity when analyzing for a group of known PFAS.
But what about unknown PFAS, or PFAS “dark matter”? High-resolution accurate mass instruments (such as QTOF systems) can use non-targeted acquisition methods to detect these unknown PFAS compounds. In addition, MS/MS spectral libraries can be used to determine the identity of these unknowns. The Duke-led study was an excellent use of mass spectrometry to interrogate the PFAS content of anti-fog sprays, and this analysis technique could be extended to the many thousands of products on our store shelves.
1 Duke University, Nicholas School of the Environment. High Levels of PFAS Found in Anti-Fogging Sprays and Cloths. January 5, 2022. https://nicholas.duke.edu/news/high-levels-pfas-found-anti-fogging-sprays-and-cloths
2 Herkert, N. J. et al. Characterization of Per- and Polyfluorinated Alkyl Substances Present in Commercial Anti-fog Products and Their In Vitro Adipogenic Activity. Environ. Sci. Technol. 2022, 56, 2, 1162–1173. https://pubs.acs.org/doi/pdf/10.1021/acs.est.1c06990
3 Zanolli, L. Why you need to know about PFAS, the chemicals in pizza boxes and rainwear. The Guardian, May 23, 2019. https://www.theguardian.com/us-news/2019/may/23/pfas-everyday-products-toxics-guide
4 Quick Sheen. Why Are Anti-fog Sprays On The Rise? How Can They Be Of Great Help? https://www.quicksheen.com/why-are-anti-fog-sprays-on-the-rise-how-can-they-be-of-great-help/
5 Interstate Technology and Regulatory Council (ITRC). History and Use of Per- and Polyfluoroalkyl Substances (PFAS). April 2020. https://pfas-1.itrcweb.org/fact_sheets_page/PFAS_Fact_Sheet_History_and_Use_April2020.pdf
6 United States Environmental Protection Agency. PFAS Explained. https://www.epa.gov/pfas/pfas-explained
7 Glüge, J. et al. An overview of the uses of per- and polyfluoroalkyl substances (PFAS). Environ. Sci.: Processes Impacts, 2020, 22, 2345–2373. https://pubs.rsc.org/en/content/articlelanding/2020/em/d0em00291g