PFAS stands for per- and polyfluoroalkyl substances. The name refers to a large class of synthetic chemicals that share one structural feature: carbon atoms bonded to fluorine atoms.
That bond is the core of the problem.
The Chemistry, in Plain Terms
Carbon-fluorine bonds are extraordinarily stable. The fluorine atoms form a protective shell around the carbon chain, making PFAS highly resistant to heat, water, oil, and biological degradation. That’s why manufacturers started using them in the 1940s — they made surfaces nonstick, made fabric waterproof, and made firefighting foam effective.
The same stability that makes PFAS useful makes them persistent. They don’t break down in soil. They don’t break down in water. They don’t break down in your body. They build up.
Toxicologists call this “bioaccumulation.” PFAS accumulate in blood, liver, and kidneys. Humans absorb them through contaminated drinking water, food, air, and contact with PFAS-containing products. The half-life of PFOA in the human body is roughly 3.5 years, meaning it takes that long for your body to eliminate half of what’s present — assuming you stop adding more.
What Products Contain PFAS
The list is long. Some major categories:
Nonstick cookware. Teflon (PTFE) itself doesn’t leach PFAS at cooking temperatures under normal use. But the manufacturing process historically used PFOA, and lower-quality pans can degrade and release PFAS particles when overheated.
Stain-resistant fabric treatments. Scotchgard, Gore-Tex, and similar treatments. Many brands have moved to PFAS-free alternatives, but older products still off-gas.
Aqueous film-forming foam (AFFF). The firefighting foam used at military bases and airports since the 1960s. When foam was applied in training exercises, it soaked into the ground and entered groundwater. This is the primary source of drinking water contamination near military installations.
Food packaging. Grease-resistant coatings on fast food bags, pizza boxes, and microwave popcorn bags. The FDA has phased out most approvals, but products with older packaging may still use them.
Personal care products. Some mascaras, foundations, and lip products contain PFAS for long-wear and water-resistance properties. The FDA doesn’t currently require PFAS disclosure in cosmetics.
Short-Chain vs. Long-Chain PFAS
Regulatory action started with the longest-chain compounds — PFOA (C8) and PFOS (C8) — because they were the most studied and the most widespread. 3M and DuPont phased them out in the early 2000s.
Manufacturers replaced them with shorter-chain PFAS: PFBS, PFHxS, GenX. The marketing framing was that shorter chains don’t accumulate as much in the body. That’s partially true — shorter-chain PFAS have shorter biological half-lives. But they’re equally persistent in the environment and show similar contamination patterns in water sources. The 2024 EPA rule covers six specific compounds, including some short-chain variants.
The Gap Between Regulation and Research
The EPA has now regulated six PFAS compounds in drinking water. But there are over 12,000 known PFAS compounds, and the vast majority have no regulatory limit. Utilities only test for what they’re required to test for.
A 2023 USGS study estimated that 45% of US tap water samples contained at least one detectable PFAS compound. The study used expanded analytical methods that detected more compounds than standard utility testing covers.
The practical takeaway: your Consumer Confidence Report won’t necessarily show the full picture of PFAS in your water.
What You Can Do
A mail-in lab test is the most reliable way to screen your own water. Look for labs that use EPA Method 533 or Method 537.1, which detect the widest range of PFAS compounds.
If your results show PFAS at any level you’re concerned about, a reverse osmosis system certified to NSF/ANSI 58 is the most effective point-of-use treatment. RO removes 90–99% of PFOA and PFOS.
See the full removal guide: How to Remove PFAS from Drinking Water
For context on health risks: PFAS Health Effects: What the Research Shows