From “forever chemicals” to fluorine-free alternatives

Per- and polyfluoroalkyl substances (PFAS) are a large group of more than 10,000 synthetic chemicals widely used for providing heat, water, oil, and stain resistance in applications such as nonstick coatings, firefighting foam, and food packaging. These “forever chemicals” are hazardous for human health and the environment, motivating efforts to find suitable replacements (1). The concerns surrounding PFAS are particularly serious because of their unusual persistence and widespread use, resulting in the contamination of both indoor and outdoor environments. Transitioning to PFAS-free alternatives requires careful evaluation of trade-offs as well as accounting for uncertainties to determine the most effective short- and long-term research and development strategies.

Recent regulatory actions and legal settlements have accelerated the search for PFAS-free alternatives. The US Department of Defense, for example, ceased procuring PFAS-containing aqueous film–forming foams (AFFFs) in October 2023 and started listing fluorine-free foam in their qualified products database, following military specifications for F3 use in land-based and freshwater firefighting applications (2). The European Union is working on a plan to restrict the entire PFAS family in many applications after a proposal by the national authorities of Germany, Denmark, the Netherlands, Norway, and Sweden. The US Environmental Protection Agency (EPA) has set limits on six PFAS in drinking water and has designated two of them as hazardous substances under the Superfund law as part of the agency’s PFAS Strategic Roadmap. Chemical manufacturers Chemours, DuPont, and Corteva also agreed to multibillion-dollar settlements related to PFAS pollution. Separately, a recent ChemSec report estimated the annual global economic costs of PFAS at $16 trillion, identifying 12 major producer companies. Among them, 3M plans to end all PFAS production by 2025. Overall, heightened health and liability concerns are propelling a large-scale transition to PFAS-free alternatives (3). However, past experiences have shown that replacing chemicals with alternatives to reduce harm can result in unintended consequences and regrettable substitutions, as seen with the harm to human health caused by dry-cleaning solvents and chemicals used to manufacture plastics (i.e., bisphenol A and phthalates).

The transition away from PFAS has already occurred in some sectors, such as textiles, food packaging, cosmetics, and electronics manufacturing. However, completely phasing out PFAS while also avoiding regrettable substitutions still requires substantial additional efforts. The specific combination of problematic physicochemical properties (including extreme persistence and low removability from water), extensive and long-term exposure of humans and the environment, and a complex societal reliance on these chemicals presents formidable challenges (4). Therefore, addressing these challenges requires a comprehensive scientific understanding that incorporates the intricate relationships between PFAS uses, exposure pathways, and societal implications of the transition (see the figure).

PFAS alternatives require assessing trade-offs.

Per- and polyfluoroalkyl substances (PFAS) replacements need to balance the performance for industry with chemical safety and sustainability to avoid adverse environmental and health outcomes. An ideal PFAS replacement has eective functionality, minimal safety issues, and a minimal environmental footprint. Finding long-term and safer alternatives requires a range of considerations (outside the dotted circle) for responsible design.

Standard hazard assessment protocols often overlook the most concerning attributes of PFAS because they concentrate on bioaccumulation and acute effects rather than the extraordinary longevity and the impact of chronic low-dose exposure. Through numerous diverse uses in sectors such as surface treatment, firefighting, aerospace, and medicine over many decades, PFAS have permeated ecosystems and human lives globally (5). Their unparalleled persistence enables accumulation across generations with little natural degradation. Persistence on this scale means that pollution will linger substantially longer than over the few decades that conventional risk evaluations consider. Additionally, the chronic toxicity of many PFAS presents long-term health risks even at the low concentrations encountered in daily life. This impact is underaccounted for by short-term damage measurements (6). The ubiquity in the environment also raises questions of mixture effects that are currently underexplored. The multistressor aspects of PFAS toxicity, including effects on the immune system and the overall resilience of organisms to chemical and other agents, challenge current assessment frameworks.

Replacing PFAS effectively in the large number of diverse applications necessitates avoiding fragmentation of the assessment and replacement activities. Although targeted assessments and identification of the most important uses are needed, losing sight of the overarching goal to minimize exposure and risks could stall progress. Therefore, evaluations of PFAS-free alternatives should be maintained under a comprehensive phaseout blueprint or overall plan to circumvent piecemeal discussions in isolated sectors. Because of the vital role of PFAS in modern technologies, enhancing the resilience of the supply chain by developing PFAS-free alternatives that incorporate robustness and redundancy is crucial. This approach will help mitigate infrastructure dependencies and navigate complex global networks effectively (7). Thus, achieving progress in replacing PFAS necessitates implementing strategies that focus on reducing persistence while also incorporating realistic evaluation time frames that align with human health considerations. Only through comprehensive research that jointly investigates the roles and functions of PFAS in important applications can the chances of sustainable PFAS-free solutions be maximized.

One likely consequence of the surge in demand for products that minimize exposure to PFAS is an increasing rate at which new PFAS replacements are introduced to the marketplace for different uses (8). Ultimately, the slight advantage of PFAS in certain performance metrics pales in comparison with the consequences of inaction. Yet, an acceptable balance between functionality and protection of human health and the environment depends on incorporating principles of green chemistry along with a design strategy that takes into account everything from manufacturing to disposal (9). Open data sharing platforms present an opportunity to reduce duplication in the information-gathering effort worldwide, specifically related to PFAS emissions, uses, alternatives, and related aspects. Democratizing datasets and making them accessible across industry, government, and academia should maximize the collective knowledge on the availability and performance of PFAS-free alternatives. This fact-based dialogue and data exchange need to be accomplished while balancing out the protection of intellectual property. Complementing design-driven substitution with long-term computational modeling could help preemptively identify options that pose minimal future health and environmental issues while fulfilling needs (10).

Many industries already recognize that a world without PFAS is achievable. For example, major manufacturers in clothing, furniture, cosmetics, and other sectors have started phasing out PFAS, demonstrating that using PFAS is not essential to their business models. However, the situation is more complicated in the production and uses of fluoropolymers and in the semiconductor industry because of the demanding conditions and diverse applications of PFAS (8). Broad assessments of chemical or nonchemical alternatives in process and product design are necessary because of the many interlinked processes involving different PFAS uses, such as construction, aerospace, and electronics. PFAS-based materials are used in construction for waterproofing, sealants, and fire-resistant coatings. In aerospace, they are used in wiring insulation, hydraulic systems, and fuel seals. Similarly, the electronics industry relies on PFAS for circuit boards, connectors, coatings, and adhesives. Despite ongoing research and development, it remains unclear how widely alternatives are being adopted by manufacturers and to what extent the market still relies on PFAS-based processes. An overarching framework is essential to provide structure, but flexibility is also key.

With input on essential uses and exposure prioritization, sector recommendations can steer the way toward safer alternatives (11). A prime example is 3M’s development of a fluorine-free foam (F3) in 2003 that challenged the notion that PFAS were irreplaceable in firefighting applications. PFAS-containing AFFFs are highly effective because they create a continuous film over the fuel surface, suppressing vapors and extinguishing fires rapidly. This film formation is a distinctive property of PFAS that has proven difficult to replicate (2). By contrast, F3 formulations do not form such a film and rely primarily on a bubble blanket to contain fuel vapors, and their performance is more dependent on foam quality, such as aspiration and expansion ratios. Progress in F3 offers a crucial advantage by reducing environmental and long-term health impacts without compromising fire-suppression capabilities.

Progress inherently demands weighing trade-offs and uncertainties. Prioritizing accurate scientific evaluations over rhetoric and cooperation over defensiveness will be essential for the transition to safer alternatives (12). In this regard, several responses to the PFAS phaseout discussion by PFAS manufacturers have revealed three actions that should be avoided. This includes exclusively emphasizing the advantages of PFAS because doing so overlooks well-established health and environmental concerns. The profile of properties alone should not be the overriding factor in evaluating the use of PFAS. Another point is denial of the clear links between PFAS exposures and impacts. Claiming that no harm has been proven ignores evidence that increasingly points to risks even at very low levels of exposure (1, 13). Finally, exaggerating the consequences of eliminating PFAS use without evidence should also be avoided. This includes predicting a technological disaster or asserting that alternatives pose a threat to technological progress, such as the energy transition that is vital for mitigating climate change. Responsible solutions to the problem of pervasive PFAS uses require acknowledging both immediate and long-term impacts through life cycle analysis frameworks. A strategy that takes into account both timescales ensures that PFAS-free alternatives will avoid unintended issues while meeting essential needs.

For alternatives to PFAS, setting realistic expectations is important. Not all substitutes may immediately match the performance of well-established chemicals that have been optimized over decades of use (14). However, these differences do not outweigh the enormity of risks posed by PFAS and the large cost of remediating widespread contamination. Transitioning away from PFAS requires some trade-offs, at least temporarily, until alternative solutions can be further refined. Giving appropriate weight to health, safety, and environmental stewardship means that such compromises are necessary. With collaborative research and development, performance gaps will narrow over time, just as they have for many other regulated chemicals. Meanwhile, uses where adequate substitutes already exist should transition rapidly. Remaining applications can buy time through risk-reduction measures while innovation occurs. Continuing the widespread use of PFAS can no longer be justified given the consequences. Moving forward will take open-minded problem-solving and willingness to accept a diversity of different solutions (15). ■