At their core, per- and polyfluoroalkyl substances (PFAS) are defined by one of the strongest chemical bonds in nature, the carbon–fluorine (C–F) bond. This bond is what makes PFAS both incredibly useful and environmentally persistent. The carbon–fluorine bond is nearly unbreakable under natural conditions, giving PFAS their famous resistance to heat, oil, water, and chemical degradation.
PFAS compounds vary in structure and function, but they share a common feature: a carbon chain fully or partially saturated with fluorine atoms. This structure creates molecules that repel both water and grease, ideal for nonstick, waterproof, and stain-resistant applications.
The two most studied PFAS compounds are PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate), both historically used in Teflon and firefighting foams. Although phased out in the United States, they’ve been replaced by newer “short-chain” PFAS that remain chemically similar and still raise environmental concerns.
Because PFAS are so chemically stable, conventional treatment processes, like chlorination or biodegradation, have little effect on them. This is why even trace releases can persist for decades in soil, groundwater, and human tissues. Understanding the chemistry of PFAS is critical to developing new technologies capable of breaking these bonds and removing PFAS safely from the environment.
PFAS can enter the environment at nearly every stage of their lifecycle, from manufacturing and product use to disposal. Factories producing or using PFAS release emissions into the air, wastewater, and solid waste streams. When these materials are discharged into rivers, seep into soil, or accumulate in landfills, PFAS can migrate into groundwater and surface water supplies.
Firefighting foams, known as aqueous film-forming foams (AFFF), are one of the largest historical sources of PFAS contamination. These foams were widely used at airports, military bases, and industrial sites to combat fuel fires. Over time, runoff from training grounds and spill sites has seeped into aquifers, leading to extensive contamination plumes.
PFAS are also released from consumer products such as water-resistant clothing, nonstick cookware, and food packaging. When these items degrade or are incinerated, PFAS can leach or vaporize into the environment. Even wastewater treatment plants, which are not designed to filter PFAS, can inadvertently redistribute them through sludge and effluent.
Once PFAS reach water supplies, they move easily and spread widely. Their mobility means that contamination detected miles away from an industrial site can often be traced back to legacy discharges or diffuse pollution sources.
PFAS are called “forever chemicals” for a reason, they resist breakdown by sunlight, bacteria, and most natural processes. Their unique molecular structure, built around a strong carbon–fluorine backbone, makes them nearly indestructible in the environment. This stability means PFAS can remain in groundwater, rivers, and soil for decades or even centuries.
Equally concerning is their ability to bioaccumulate, that is, to build up in living organisms over time. PFAS bind to proteins in blood and liver tissue rather than accumulating in fat, allowing them to persist in the body long after exposure ends. Studies have shown measurable PFAS levels in wildlife across the globe, from polar bears to fish in local streams, illustrating how far these chemicals can travel through food chains.
In humans, chronic exposure, even at low levels, can lead to rising PFAS concentrations in the bloodstream. Because the body excretes them slowly, typically over several years, repeated intake through drinking water or food leads to long-term buildup.
This combination of persistence and bioaccumulation makes PFAS one of the most challenging environmental pollutants ever encountered. Controlling PFAS contamination requires not just cleanup, but prevention, limiting their use and release before they can enter the ecosystem.