Written by Dr. Graham F. Peaslee, Department of Physics and Astronomy at the University of Notre Dame

Per- and Polyfluorinated Alkyl Substances (PFAS) are a class of man-made chemicals that have recently emerged as one of our biggest global environmental pollution issues, ever1. Known as the “Forever Chemicals”, the costs of cleaning up these pollutants are on a par with global warming and ocean acidification and the process seems just as intractable at the moment.

These chemicals were discovered during World War II, and there are now over 14000 different chemicals identified (with names) in this category. More than 1400 of them have been widely used in over 200 different industrial and commercial applications2. Some of the best known are PerFluoro Octanoic Acid (PFOA) and PerFluoro Sulfonic Acid (PFOS), which became the focus of a huge lawsuit against the chemical companies that made these particular chemicals in the US (featured in the 2019 movie “Dark Waters”). The result of this lawsuit was an independent scientific study into the toxicity of these two environmentally persistent chemicals with over 69,000 participants in Little Hocking, Ohio. Six diseases (including two cancers) were unmistakably linked to low level of PFOA and PFOS in drinking water in this population, although there were suggestive trends of adverse human health effects in dozens of other diseases back in 2012 when this report was first published3. 

A graphic of a tree with the letters PFAS on the trunk, branching into Polyfluoroalkyls and perfluoroalkyls (which branches into the ltters PFOS, PFHxS, PFNA, PFOA, PFDA)

Since then, the number of publications linking PFAS to adverse human and environmental health effects has grown to over 10,000 publications.  This class of chemicals is extremely persistent in the environment, some are bioaccumulative, and most show some sort of toxicity when measured.

The other reason to worry about these chemicals is that they are everywhere around us – thanks to a mostly unfettered manufacturing of PFAS between 1950 and 2020. These chemicals are mostly used as surfactants – molecules that lie on the interface between air and water, or between water and oil.

We know them as non-stick cookware (Teflon pans), waterproof textiles, aqueous film forming foams – airport firefighting foams used daily by defense departments around the world between 1969 and 2019, and waterproofing agents for carpets, food packaging and even certain cosmetics and personal care product. Widespread production and use of these chemicals (in these and >200 other use categories) has led to their widespread release into the environment. This involves widely publicized pollution “events” related to manufacturing facilities in the US and abroad, but also the release of these chemicals into the environment from their disposal.

In the US, for example, most consumer products are disposed of in landfills. When products decay back into their constituent elements (over decades in landfills) these chemicals persist for hundred and even thousands of years and can escape into the environment through the leachate from landfills.  This, coupled with the widespread use of firefighting foams directly into fires in the environment, and the wonderful solubility that most of these PFAS share, has led to the largest drinking water contamination issue the US has ever experienced. This is reflected in scary on-line maps by both non-profit organizations (EWG) and the Government (EPA)4,5. The difference between these two maps reflect the difference sources of information obtained and used, and both are thought to be incomplete.  Of course, the problem is global, and a typical European map of PFAS contamination looks just as bleak6. All three maps updated to mid-2024 are shown in Figure 1. 

Figure 1:  Known PFAS contamination sites in 2024 from References 4, 5, and 6. 

Even a cursory estimate of the number of people and places exposed to PFAS, and the long-term health costs associated with the exposure puts PFAS into a leading role when discussing worldwide costs of pollution, and the costs required to clean up PFAS. There is currently no economically feasible way to clean up PFAS from our drinking water, surface water, irrigation water, ground water, and we continue to produce these chemicals, albeit there is evidence that production is starting to slow down7as we recognize the enormous costs of clean up. There are also lots of people (here in Indiana and around the world), who are working on novel methods to both identify PFAS more quickly and to remove them from the environment. The best thing we can do as consumers is to learn more about these chemicals, where they are used, and how to avoid them in the materials we purchase. Market demand and increasing regulation will eventually reduce the use of these chemicals.

References
  1. “Outside the Safe Operating Space of a New Planetary Boundary for Per- and Polyfluoroalkyl Substances (PFAS),” Ian T. Cousins, Jana H. Johansson, Matthew E. Salter, Bo Sha, and Martin Scheringer, 2022. Environmental Science & Technology, 56(16), 11172-11179.
  2. “An overview of the uses of per-and polyfluoroalkyl substances (PFAS)”, Glüge, J., Scheringer, M., Cousins, I.T., DeWitt, J.C., Goldenman, G., Herzke, D., Lohmann, R., Ng, C.A., Trier, X. and Wang, Z., 2020. Environmental Science: Processes & Impacts, 22(12), pp.2345-2373.  
  3. C8 Science Panel website   
  4. Environmental Working Group, map of PFAS contamination
  5. US Environmental Protection Agency ECHO website
  6. LeMonde European PFAS website
  7. “Is a Seismic Shift in the Landscape of PFAS Uses Occurring?”, Scheringer, M., Cousins, I.T. and Goldenman, G., 2024., Environmental Science & Technology, 58(16), pp.6843-6845.