PFAS has been drawing a lot of attention in the industry as well as the media. In this post, we’ll separate the myths from the facts and discuss the various treatment solutions.
What exactly is PFAS?
PFAS is the acronym given to a whole gamut of man-made compounds (Per- and polyfluoroalkyl substances) which are fluorinated to various degrees. Carbon fluorine bonds are one of the strongest single bonds in chemistry, which is what makes PFAS so useful, but also hard to destroy. There are over 4000 variants of PFAS in existence (with more added all the time), although labs are currently set up to test for around 18.
The two most recognized PFAS molecules are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid). These molecules have similar properties to each other including: contains 8 carbon atoms, completely fluorinated, low pKa (acidic and found in a charge state in neutral pH waters), oleophilic (strong affinity to oil), and strong surface adsorption potential. The reactivity of these molecules are quite low and thus will have long half-lives compared to their non-fluorinated counterparts.
Since the 1940s, PFAS’ popularity began to increase for its use as a surfactant and water repellent compounds (like Scotch Guard) and as a key component in non-stick surfaces. PFAS is also found in refrigerants, Teflon, Gore-Tex, and aqueous film-forming foam (AFFF), which is used widely in the military and other industries to fight certain types of fires. As you can see, PFAS are pretty useful.
The Rick Astley of chemical compounds, PFAS is never gonna let you down. Except unlike Rick, it might hurt you. Because it’s a compound that seldom occurs in nature, organisms—like people, or landfill bugs—haven’t needed to develop specific enzymes to break PFAS down. This means it bioaccumulates. For example, if a fish ingested water with PFAS in it, the fish would retain the PFAS. We’d eat the fish, we get the PFAS. It’s a chemical baton pass with humans at the top of the food chain.
PFAS and human health risks
The link between PFAS and specific health problems hasn’t been absolutely proven, although it is believed that PFAS acts as an endocrine disruptor, which means if humans are walking around with a bioaccumulation of PFAS in our bodies it can interfere with hormonal interactions and functions.
But before you throw away your Rachel Ray pans and Gore-Tex jacket, it’s important to point out that these light ‘household’ uses are unlikely to be dangerous. In fact, it’s PFAS laden waste going into landfills that may pose a much more significant health risk. Though it doesn’t break down, PFAS can wear or slough off of surfaces over time (as the other compounds decompose) and then leach out of landfills into the water supply in a somewhat more concentrated form.
In the recent decade, the EPA has continued to lower the safety threshold for PFOA from 400 ppt (2009-2016) to 70 ppt (recent). Some states have even taken this limit further such as Vermont which has set their limit as 20 ppt. In 2016, Canada issued a document looking at PFOA in water and proposed a maximum acceptable concentration of 200 ppt; we expect this level to decrease with increased research and decreases seen in the United States.
What happens when PFAS contaminates soil or water? Read more: