The term “forever chemicals” did not originate in a chemistry lab. It did not emerge from peer-reviewed literature, a toxicological risk assessment, or an EPA working group. It came from policy, legal, and advocacy circles as a way to communicate urgency around per- and polyfluoroalkyl substance: “PFAS” to a public that was not going to read a 400-page EPA guidance document. “Forever Chemicals” is a Political Term.
As rhetorical strategy, it worked. “Forever chemicals” helped move PFAS from a niche technical issue debated among environmental engineers and industrial hygienists into mainstream regulatory focus. It accelerated monitoring programs, drove research funding, shifted litigation, and pushed product reformulation across dozens of industries. Credit where it is due: the term accomplished what it was designed to accomplish.
The problem is that policy built on rhetorical shortcuts tends to produce blunt instruments. And when the instruments are blunt and the underlying science is nuanced, the compliance burden falls indiscriminately while actual risk reduction is uneven. That is where we are with PFAS regulation right now, and the water treatment industry, which sits at the intersection of PFAS as a contamination problem and PFAS as a chemistry used in treatment equipment, has more at stake in getting this right than almost any other sector.
Before we get into the chemistry of specific compound classes, there is a definitional history that most people discussing PFAS (including most regulators) do not know. It matters directly to this argument.
The PFAS acronym did not always mean what it means today
Here is something that rarely surfaces in public PFAS discussions: the term “PFAS” itself has undergone multiple rounds of definitional expansion, and each expansion swept in a larger and more chemically diverse universe of compounds. Understanding that history makes clear that the current regulatory treatment of PFAS as a monolithic class is not a scientific conclusion — it is the accumulated result of successive terminological decisions made for administrative and policy reasons.
In the early 2000s, when concerns about PFOA and PFOS were first receiving serious regulatory attention following 3M’s voluntary phaseout announcement in 2000, the scientific literature used a proliferation of inconsistent terms. According to a 2021 paper in Environmental Science & Technology by Wang et al. documenting the updated OECD PFAS definition, early communications about these compounds used terms including “per- and polyfluorinated chemicals,” “perfluorinated organics,” “perfluorochemical surfactants,” and “highly fluorinated compounds” (often interchangeably), often referring to the same specific problem compounds. The terminology was a mess, and different research groups could not reliably compare notes because they were not using standardized language.
As far as I can tell, the PFAS acronym itself was first formally defined and put into wider scientific use by Hekster et al. in 2002 and 2003, as documented by Buck et al. in their 2011 terminology paper in Integrated Environmental Assessment and Management (the first and still most-cited attempt to rigorously standardize PFAS language). Critically, that original PFAS usage emerged from European environmental monitoring research focused specifically on fluorinated compounds detected in the environment, wildlife, and human blood. The compounds of concern were the surfactant-active, mobile, bioavailable molecules (PFOA, PFOS, and their relatives) that were showing up in occupational blood studies and later in general population monitoring. The structural definition was specific: PFAS required the presence of a perfluoroalkyl moiety of the form −CnF2n+1. Fluoropolymers like PTFE, which do not contain that moiety in the relevant structural sense, were not the intended targets of the original classification framework.
Buck et al. 2011 formalized this framework, establishing 42 families and subfamilies covering 268 individual compounds with structural formulas and CAS registry numbers. The paper explicitly addressed fluorinated polymers as a distinct category – not because fluoropolymers were considered harmless without examination, but because their environmental and biological behavior is categorically different from the smaller-molecule PFAS the field had been monitoring and studying.
Then, in 2021, the OECD substantially expanded the definition. The revised framework covers any fluorinated substance containing at least one fully fluorinated methyl or methylene carbon atom (removing the perfluoroalkyl moiety requirement that had anchored the Buck et al. structure). That single definitional change expanded the PFAS universe from a few hundred well-characterized compounds of established environmental concern to potentially millions of structures. The EPA’s CompTox database currently lists approximately 14,735 unique PFAS compounds. PubChem, applying the broadest structural criteria, identifies over 7 million.
The regulatory frameworks being built today (including New Mexico’s 20.13.2 NMAC) are largely built on the post-2021 expansive definition. That definition was designed to be precautionary and comprehensive, intended to capture compounds whose risks are not yet fully characterized before they become established contaminants. The precautionary logic has merit as a monitoring posture. But applying that definition in product prohibition and mandatory disclosure regulations, without differentiating risk profiles, creates compliance obligations proportionate to the breadth of the chemical class, not to documented hazard. That is a consequential policy design problem.
What “Forever” actually means
The chemical property that earned PFAS the “forever” label is persistence: resistance to degradation under normal environmental conditions. The carbon-fluorine bond is among the strongest in organic chemistry, with bond dissociation energies in the range of 105–130 kcal/mol. That stability is precisely why PFAS compounds were engineered for applications demanding chemical and thermal resistance: nonstick coatings, fire suppression foams, food packaging barriers, waterproof textiles, and fluid-contact surfaces in water treatment equipment.
The C-F bond’s stability means PFAS compounds resist biological metabolism, acid and base hydrolysis, photolytic breakdown under ambient UV, and most oxidative chemical processes. In environmental matrices (soil, sediment, surface water, groundwater) many PFAS compounds persist for decades or longer without meaningful degradation.
“Environmentally persistent” is a more accurate technical descriptor than “forever chemical.” Persistence is a spectrum, not a binary condition. Not all PFAS compounds persist to the same degree, by the same mechanisms, or with the same consequences in biological systems. And persistence does not equal toxicity. A compound can be highly stable in the environment while posing minimal risk to human health, or relatively short-lived while causing significant harm during its residence time. Risk depends on chemistry, exposure route, dose, and duration — not persistence alone.
Treating all PFAS as though they interact identically with ecosystems and biology is not a precautionary posture. It is an inaccurate one, and inaccuracy in regulatory design produces misaligned outcomes.
The long-chain problem
The PFAS compounds that warranted the original alarm — and that alarm was justified — are the long-chain perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), particularly PFOA (C8) and PFOS (C8). Their behavior in biological systems is now thoroughly characterized.
Long-chain PFAS bioaccumulate. They bind to serum albumin and other proteins in blood plasma, concentrate in liver tissue, and are excreted slowly enough that body burden builds with repeated exposure. Human half-lives for PFOA are estimated at 3.5 to 8 years. PFOS half-lives are longer still. These are not compounds that enter the body and clear quickly. They reside.
The epidemiological and toxicological evidence linking long-chain PFAS to adverse health outcomes is substantial: associations with kidney and testicular cancers, thyroid hormone disruption, immune suppression in developing immune systems, elevated cholesterol, pregnancy-induced hypertension, and developmental harm. The National Academies of Sciences, Engineering, and Medicine published a comprehensive review in 2022 establishing clinical guidance for PFAS exposure — treating specific cancers and immune effects as having sufficient evidence for clinical action at defined serum concentrations. That is a major scientific institution telling physicians to treat these exposures seriously.
Environmental persistence compounds the biological problem. PFOA and PFOS contamination in groundwater does not attenuate naturally over practical timeframes. Remediation is expensive, technically demanding, and often not feasible for affected communities. The contamination problems in communities near fluorochemical manufacturing sites, military airfields where AFFF was used for decades, and landfills receiving PFAS-containing industrial waste — those are real, serious, and in many cases irreversible.
The regulatory response to long-chain PFAS is proportionate to the evidence. EPA MCLs for PFOA and PFOS at 4 parts per trillion, product prohibitions targeting applications where alternatives exist, full supply chain disclosure requirements (all defensible). I have no quarrel with any of it.
The short-chain question
Short-chain PFAS (generally perfluoroalkyl compounds with carbon chains of six or fewer carbons) were introduced as substitutes for long-chain compounds following the voluntary phaseout agreements beginning in 2000.
The substitution logic was sound: shorter chains are less prone to bioaccumulation because they bind less strongly to serum proteins and clear more readily. The human half-life of perfluorobutanoic acid (PFBA, C4) is approximately 3 days, versus years for PFOA. Perfluoropropionic acid (PFPrA, C3) clears faster still.
This reduced bioaccumulation potential is real and meaningful. But short-chain substitution created different problems, primarily environmental mobility. Short-chain PFAS are more water-soluble and less likely to sorb onto soil particles than long-chain counterparts, meaning they travel farther and faster in groundwater. They have appeared in drinking water supplies at distances from contamination sources where long-chain PFAS would have attenuated. The tradeoff between bioaccumulation potential and environmental mobility is a genuine scientific tension.
Trifluoroacetic acid (TFA) is the most extreme example in this category. TFA is the simplest perfluorocarboxylic acid (a two-carbon compound) and it is accumulating in the global environment at an accelerating rate, primarily as a degradation product of HCFCs, HFCs, and increasingly HFOs like HFO-1234yf now standard in automotive air conditioning. Modeling published in Geophysical Research Letters in early 2026 estimated global TFA deposition at approximately 21,800 tonnes per year in 2022 – a 3.5-fold increase from 2000. HFOs degrade to TFA almost completely within days to weeks in the atmosphere. That production rate will continue climbing as HFO adoption expands.
TFA is extremely water soluble and mobile. It is shown to accumulate in terminal sinks (oceans, deep aquifers) from which it does not naturally cycle out. The persistence and irreversibility are real concerns. But its toxicological profile differs substantially from long-chain PFAS. TFA does not bioaccumulate in animal tissue. Its human half-life is approximately 16 hours. The UN Environment Programme’s Environmental Effects Assessment Panel concluded in their 2024 update that TFA poses minimal ecosystem risk through at least 2100 under projected emission scenarios, with ocean concentrations forecast to remain orders of magnitude below no-observed-effect concentrations for aquatic life.
Germany’s Federal Institute for Risk Assessment proposed in May 2025 classifying TFA as a Reproductive Toxicity Category 1B substance based on high-dose animal studies. That finding deserves evaluation. But high-dose rabbit studies at hundreds of milligrams per kilogram per day are not equivalent in evidentiary weight to the epidemiological data linking PFOA and PFOS to cancer outcomes in human populations at environmental concentrations. Continued monitoring of TFA is well justified. Regulatory treatment identical to long-chain bioaccumulative PFAS requires more.
Fluoropolymers
The most significant source of confusion in PFAS regulatory discourse is the treatment of fluoropolymers. This is the category with the most direct bearing on water treatment equipment and the water quality industry at large.
PTFE, PVDF, FEP, ETFE, and their structural relatives are polymeric materials with carbon-fluorine backbones. They contain fluorine. Under the OECD’s 2021 expanded definition, they qualify structurally as PFAS. But as Buck et al. 2011 documented explicitly, fluoropolymers were treated as a distinct category in the original PFAS scientific framework precisely because their environmental and biological properties are categorically different from small-molecule PFAS. The 2021 definitional expansion swept them in without that distinction (a point noted in the subsequent scientific commentary on the revised definition).
Fluoropolymers are high-molecular-weight solids. They do not dissolve in water under normal conditions. They do not migrate into blood or tissue in ways analogous to PFOA or PFOS. In characterization studies, PTFE particles that enter the body pass through without meaningful systemic absorption. The chemical inertness that makes PTFE valuable for potable water contact applications (valve seats, carbon binders, membranes, O-rings, membrane seals, etc…) is the same property that makes it biologically inert.
This is not an industry argument. It is the position of the researchers who built the original PFAS classification framework. New Mexico’s rule acknowledges it, including an exemption for solid-state fluoropolymers with per- or polyfluorinated carbon-only backbones, directly reflecting the scientific literature’s differentiation between polymer and non-polymer fluorine chemistry.
Here’s the critical operational nuance: bulk PTFE components are different from PFAS used as processing aids, surface treatments, or manufacturing additives. The former has a credible basis for differential regulatory treatment. The latter require case-by-case evaluation. Manufacturers who assume fluoropolymer-containing products are categorically exempt without compound-specific verification are taking a compliance risk. Manufacturers who assume they must eliminate all fluorine chemistry without regard to form and function are making decisions that may degrade product performance and impose costs with marginal public health benefit.
Precision matters more than passion
There is a phase transition happening in PFAS policy. The first phase (establishing that PFAS contamination is a serious, widespread public health problem requiring regulatory action) is largely complete for long-chain bioaccumulative PFAS.
The second phase is calibration. The question now shifts from “should we regulate PFAS?” to “which PFAS, in which contexts, at what levels of obligation, proportionate to what documented risk?” That calibration requires a framework that distinguishes between compound classes; the approach that the original scientific literature explicitly recommended, and that subsequent definitional expansions obscured.
The definitional history matters here. The PFAS “concept”issue” began as a focused, surfactant-centered monitoring framework for specific mobile and bioaccumulative compounds. It has since been expanded by administrative and policy processes into a definition encompassing millions of chemical structures; not because the risk evidence expanded proportionately, but because precautionary comprehensiveness became the regulatory priority. Both the original focused intent and the current expansive scope are documented in the peer-reviewed literature. The policy debate should engage with both, not just the latter.
Overly broad language produces misaligned regulations, unintended compliance costs, and public confusion about real versus theoretical risk. Effective PFAS policy must be chemistry-specific, exposure-based, and outcome-focused; not driven by terminology designed to provoke urgency. As the field moves into its calibration phase, that distinction is not academic. It is the difference between regulation that reduces actual harm and regulation that performs concern while misallocating resources.
What now?
For practitioners in water treatment, compound-level fluency about PFAS is becoming a professional requirement.
When a customer asks about PFAS in their water, we need to explain which compounds appear in their test results (or have been disclosed on their Consumer Confidence Report), what the known health implications are at those specific concentrations, and what treatment technologies are effective for removal. “Forever chemicals are bad, here is our system” is not adequate at the technical level this conversation demands.
When a manufacturing partner claims PFAS-free product design, the right response is to ask which compounds were eliminated, from what applications, and what the replacement chemistry is. A product that eliminates fluoropolymer valve seats and replaces them with materials that have inferior chemical resistance or higher leach rates for other compounds is not a public health improvement.
The water treatment industry is at its best when it leads with technical credibility. PFAS gives us a concrete opportunity to demonstrate that — by engaging with the chemistry honestly, pushing for calibrated regulation that targets documented risk, and building products defensible on the science rather than the labeling. We are in a position to say clearly, with the citations to back it up, that not all PFAS are created equal — and that the regulatory framework should reflect that reality.
What a great time to be in the water business. But only if we do the work.
Additional reading
Buck RC, Franklin J, Berger U, et al. Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins. Integrated Environmental Assessment and Management. 2011;7(4):513–541. doi:10.1002/ieam.258
Wang Z, et al. A new OECD definition for per- and polyfluoroalkyl substances. Environmental Science & Technology. 2021. doi:10.1021/acs.est.1c06896
Hart JE, et al. Global TFA deposition from fluorinated gas atmospheric degradation. Geophysical Research Letters. 2026. doi:10.1029/2025GL119216
UNEP Environmental Effects Assessment Panel. 2024 Assessment Update. United Nations Environment Programme.
National Academies of Sciences, Engineering, and Medicine. Guidance on PFAS Exposure, Testing, and Clinical Follow-Up. National Academies Press, 2022.
BfR (German Federal Institute for Risk Assessment). Trifluoroacetic acid (TFA): Assessment for classification. Press release, May 2025.
Hekster FM, Laane RWPM, de Voogt P. Environmental and toxicity effects of perfluoroalkylated substances. Reviews of Environmental Contamination and Toxicology. 2003;179:99–121.