WHAT ARE PFAS?
And Why PFAS is Becoming a Bigger Problem
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What are PFAS? Understanding per- and polyfluoroalkyl substances (PFAS): what they are, where they come from, and what is being done to control PFAS contamination can help regulators, utilities, and business leaders make informed decisions and get ahead of new PFAS compliance and testing requirements. On this page, we provide clear, practical answers to some of the most common questions asked about PFAS contamination.
THE PROBLEM WITH PFAS
PFAS are bioaccumulative, meaning they build up in the bloodstream and tissue. Since at least the 80s, research has found links between PFOS and PFOA (2 common PFAS chemicals) and a number of health problems such as: chronic kidney disease, thyroid issues, certain types of cancers, etc. More research is being done by the U.S. EPA and others to determine the toxicity of the thousands of other PFAS that are or have been widely used in industry and consumer products.
SOURCES OF PFAS
Industry is a common source of PFAS contamination – both the manufacturers of PFAS chemicals and those that use them in the products they make. Of course, industry isn’t the only source. Download our infographic to learn about the many ways PFAS contamination can enter and be spread throughout the environment.
What are PFAS? FAQ
Q: Can PFAS be found in nature?
PFAS are synthetic chemicals that have been manufactured and used since the mid‑20th century in products like nonstick coatings, stain repellents, and firefighting foams. Due to the environmental persistence of these compounds, elevated levels of PFAS can be detected in many natural settings—including drinking water, rivers, wildlife, and even human blood. In other words, PFAS are found throughout nature, not because they occur naturally, but because decades of use have allowed them to spread and accumulate over time.
Q: Why are PFAS so environmentally persistent?
PFAS are extremely persistent because their carbon-fluorine bonds are among the strongest in nature, making them very resistant to heat, sunlight, and chemical reactions that would normally degrade chemicals. Their structures also allow them to repel both water and oil, so they do not easily dissolve or degrade in soil or water.
Many PFAS are mobile and can travel long distances in groundwater or air and bind to proteins in plants and animals. This allows them to cycle through ecosystems rather than being metabolized or excreted quickly. As a result, once released, PFAS can remain in the environment and living organisms for years to decades.
Q: Why are PFAS called “forever chemicals”?
Due to their environmental persistence, PFAS were dubbed the “forever chemicals” in the media around 2018. However, this is a bit of a misnomer. Like other chemicals, PFAS degrade over time, although the rate at which they break down is impacted by several factors, e.g., their molecular structure, chain length, and the type of functional group attached to the fluorinated carbon chain. Longer-chain, fully fluorinated “terminal” PFAS tend to be the most persistent, while some polyfluorinated precursors can slowly transform into more stable PFAS compounds rather than fully breaking down. Most PFAS in use today fall into this latter category and are not by any means “forever”.
Environmental conditions also matter, including temperature, sunlight, pH, the presence of reactive species (like radicals), and whether the PFAS is in water, soil, or sediment. Microbial communities, organic carbon content, and competing contaminants can further influence the stability of PFAS compounds. As more research is done on the conditions and factors that degrade PFAS into less harmful compounds, scientists are using this information to develop new ways to treat PFAS contamination in the environment.
Q: What is the difference between a long-chain and short-chain PFAS?
Long-chain and short-chain PFAS are distinguished mainly by the length of their fluorinated carbon backbone. Long-chain PFAS typically have 7 or more carbons for perfluoroalkyl sulfonic acids (like PFOS) or 8 or more for perfluoroalkyl carboxylic acids (like PFOA). Short-chain PFAS have fewer carbons in their chain, although the number of carbons can vary by classification system. Examples of PFAS that may be considered short-chain PFAS include:
* Indicates the number of carbons in the perfluorinated chain.
This structural difference matters because long-chain PFAS generally have longer biological half-lives and greater toxicity levels; whereas short-chain PFAS move more easily in water and may clear from the body faster, possibly leading to less toxicity. That said, many short-chain PFAS are still highly persistent, migrate more readily in the environment, and can be more difficult to remove from drinking water than long-chain PFAS.
- HFPO‑DA (hexafluoropropylene oxide dimer acid)/GenX: 6 carbons*
- PFBS (perfluorobutane sulfonic acid): 4 carbons
- PFHxS (perfluorohexane sulfonic acid): 6 carbons
- PFBA (perfluorobutanoic acid): 4 carbons
- PFPeA (perfluoropentanoic acid): 5 carbons
- PFHxA (perfluorohexanoic acid): 6 carbons
* Indicates the number of carbons in the perfluorinated chain.
This structural difference matters because long-chain PFAS generally have longer biological half-lives and greater toxicity levels; whereas short-chain PFAS move more easily in water and may clear from the body faster, possibly leading to less toxicity. That said, many short-chain PFAS are still highly persistent, migrate more readily in the environment, and can be more difficult to remove from drinking water than long-chain PFAS.
Q: What are Ultra Short Chain PFAS?
Ultra short chain PFAS have very short, fluorinated carbon backbones—typically two or three carbons long. Common examples include trifluoroacetic acid (TFA, two carbons) and perfluoropropanoic acid (PFPrA, three carbons).
Because of their tiny size and high solubility, ultra short chain PFAS move very easily in water, are difficult to remove using conventional treatment technologies, and are often detectable in rain, surface water, groundwater, and even remote environments. They tend not to bioaccumulate as easily as many longer-chain PFAS, but their persistence and mobility raise concerns about long-term, low-level exposure for people and ecosystems.
Q: How can PFAS be removed from drinking water?
The U.S. EPA has identified several Best Available Technologies (BATs) for public water systems: granular activated carbon (GAC), PFAS selective ion exchange (IX) resins, and high-pressure membranes such as reverse osmosis (RO) or nanofiltration (NF). These processes can reduce many regulated PFAS, especially long-chain compounds, to very low levels. However, they also create spent media or brine that contains PFAS and must be carefully managed as waste.
On-Demand Webinar
Navigating PFAS in Drinking Water: Treatability Insights and Analytical Overview
Q: Are there any PFAS destruction technologies?
EPA’s Interim Guidance on the Destruction and Disposal of PFAS and Materials Containing PFAS describes the current state of science for the primary large-scale PFAS destruction options: thermal treatment (such as certain hazardous waste incinerators, cement kilns, and GAC reactivation units operated under stringent conditions), permitted landfills designed to minimize leachate and emissions, and underground injection in deep, regulated wells. The EPA updates the interim guidance periodically as new insights from PFAS remediation research becomes available.
In addition, developers in industry, startups, and research labs are racing to move beyond traditional approaches to PFAS remediation. Many teams are refining separation methods such as foam fractionation, advanced ion exchange, and high-pressure membranes to concentrate PFAS into small waste streams, then pairing them with high-energy destruction processes like supercritical water oxidation, electrochemical oxidation, plasma, and novel photochemical or catalytic systems that can break the carbon-fluorine bond and convert PFAS into harmless end products.
How can I learn more about PFAS?
You can learn more about PFAS by exploring the PFAS.com Resources page, a central hub for PFAS education featuring fact sheets, guides, case studies, ebooks, infographics, webinars, and videos, along with curated news sources and external links to help you quickly find what you need
CHOOSE THE RIGHT TEST METHOD
There are several test methods available to detect PFAS. Choosing
the right method requires knowing what you’re testing and why.
PFAS MATTERS
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