Trifluoroacetic acid (TFA) has emerged as one of the most widespread and persistent fluorinated contaminants detected in the environment. As an ultra-short-chain member of the per- and polyfluoroalkyl substances (PFAS) family, TFA exhibits exceptional water solubility, high mobility, and extreme environmental persistence. Unlike legacy PFAS such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), TFA is primarily generated through the degradation of fluorinated refrigerants, pesticides, pharmaceuticals, and industrial chemicals. Recent monitoring studies have revealed its increasing occurrence in rainwater, groundwater, surface waters, drinking water, food products, and even human serum.
This review aims to summarize current knowledge regarding TFA sources, environmental occurrence, toxicological concerns, regulatory challenges, and treatment technologies. Results indicate that TFA is among the most prevalent fluorinated contaminants in aquatic environments and may represent a global contamination issue due to its irreversible accumulation. Although toxicological evidence remains limited, recent studies suggest potential developmental, reproductive, and ecological effects. Conventional water treatment processes show poor TFA removal efficiency, whereas reverse osmosis remains the most effective available technology. The absence of harmonized international regulations highlights the urgent need for enhanced monitoring programs, further toxicological investigations, and precautionary management strategies.
Introduction to PFAS and TFA
Per- and polyfluoroalkyl substances (PFAS) constitute a large family of synthetic fluorinated chemicals widely used in industrial and consumer applications because of their exceptional thermal stability and resistance to chemical degradation [1]. During the last two decades, PFAS have become a major environmental concern due to their persistence, mobility, bioaccumulation potential, and adverse health effects [2].
While regulatory efforts have primarily focused on long-chain PFAS such as PFOA and PFOS, increasing attention is now being directed toward ultra-short-chain PFAS and transformation products, particularly trifluoroacetic acid (TFA) [3]. TFA (CF₃COOH) is the simplest perfluorinated carboxylic acid and exhibits unique physicochemical properties, including high water solubility, negligible biodegradation, and extreme environmental persistence [4].
Unlike many legacy PFAS, TFA is rarely emitted directly into the environment. Instead, it is mainly formed through atmospheric and environmental degradation of fluorinated precursor compounds, including hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), fluorinated pesticides, pharmaceuticals, and industrial chemicals [5]. Consequently, environmental TFA concentrations are expected to increase despite the progressive phase-out of certain legacy PFAS.
Recent investigations have demonstrated the widespread occurrence of TFA in rainwater, groundwater, rivers, lakes, drinking water, food products, and human biological samples [6]. A recent assessment described TFA as a contaminant of planetary concern due to its continuous accumulation and global distribution [7].
The objectives of this review are to
- Examine the main sources and formation pathways of TFA,
- Evaluate its occurrence in water resources,
- Discuss toxicological and ecological concerns,
- Analyze current regulatory challenges, and
- Review available treatment technologies for water resource protection.
Materials and Methods
A structured literature review was conducted using Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar databases. Publications issued between 2015 and 2025 were considered, with particular emphasis on studies published after 2020.
The search strategy included combinations of the following keywords: “trifluoroacetic acid”, “TFA”, “ultra-short-chain PFAS”, “drinking water contamination”, “environmental occurrence”, “water treatment”, “toxicity”, and “environmental persistence”.
Peer-reviewed journal articles, international reports, and regulatory documents issued by organizations such as OECD, ECHA, EFSA, and US EPA were included. Studies focusing on environmental occurrence, analytical methods, toxicology, regulatory aspects, and treatment technologies were prioritized.
Results and Discussion
Sources and Formation Pathways of TFA
The primary environmental source of TFA is the degradation of fluorinated precursor compounds. Atmospheric oxidation of HFCs and HFOs generates TFA through complex photochemical pathways involving hydroxyl radicals [5]. While these refrigerants were introduced as climate-friendly alternatives to ozone-depleting substances, their degradation contributes significantly to global TFA production.
Agricultural activities represent another important source. Several fluorinated pesticides, including fluopyram and flufenacet, produce TFA during environmental degradation [8]. Industrial activities and pharmaceutical manufacturing may also contribute to localized contamination hotspots.
Environmental Occurrence in Water Resources
TFA has been detected in multiple environmental compartments worldwide. Atmospheric deposition plays a major role in its distribution, with measurable concentrations reported in rainwater, snow, and fog samples [9].
Surface waters frequently contain TFA due to atmospheric deposition and watershed runoff. Recent European monitoring campaigns have identified TFA as one of the most abundant fluorinated contaminants in rivers and lakes [10].
Groundwater contamination is of particular concern because TFA exhibits high mobility and low sorption capacity. Its migration through soil profiles facilitates long-term contamination of aquifers used for drinking water production [11].
TFA has also been detected in municipal drinking water systems, bottled water, and groundwater-fed supplies. Conventional treatment technologies often fail to remove the compound effectively, resulting in its persistence throughout drinking water distribution networks [12].
Toxicological and Ecotoxicological Concerns
Historically, TFA was considered less hazardous than long-chain PFAS because of its low bioaccumulation potential [13]. However, recent studies have raised concerns regarding chronic exposure and continuous environmental accumulation.
Experimental investigations suggest potential developmental, reproductive, and hepatic effects at elevated concentrations [14]. Ecotoxicological studies have reported adverse impacts on algae, aquatic plants, and microbial communities [15].
A major concern lies in the lack of long-term epidemiological data. The increasing presence of TFA in drinking water, food products, and human serum warrants further toxicological investigation and precautionary management approaches [7].
Regulatory Challenges and Water Management Implications
Despite increasing scientific concern, TFA remains largely unregulated worldwide. Existing regulations focus primarily on PFOS, PFOA, and a limited number of PFAS compounds [16].
The European Union Drinking Water Directive establishes limits for PFAS groups but does not currently define a specific parametric value for TFA [17]. Similarly, recent US EPA regulations do not specifically address TFA [18].
The combination of extreme persistence, increasing environmental concentrations, and toxicological uncertainty has led several researchers to advocate persistence-based regulation as a precautionary approach [19].
Water Treatment Technologies
Conventional water treatment processes such as coagulation, sedimentation, biological treatment, and activated carbon adsorption are generally ineffective for TFA removal [20].
Ion-exchange resins may achieve partial removal under specific conditions; however, performance remains variable [21]. Reverse osmosis currently represents the most effective available technology, with reported removal efficiencies often exceeding 90% [22].
Emerging technologies including electrochemical oxidation, plasma treatment, and advanced oxidation processes show promise but require further optimization before large-scale implementation [23].
Conclusions
Trifluoroacetic acid has emerged as one of the most widespread and persistent fluorinated contaminants affecting water resources worldwide. Its exceptional mobility, resistance to degradation, and continuous formation from fluorinated precursor compounds distinguish it from many other PFAS.
Although toxicological evidence remains incomplete, increasing detection frequencies in water resources, food products, and human biological samples justify precautionary management measures. Conventional water treatment technologies exhibit limited effectiveness, whereas reverse osmosis remains the most reliable removal option currently available.
Future research should focus on toxicological characterization, standardized analytical methods, environmental monitoring, and the development of cost-effective treatment technologies. Given projected increases in TFA emissions from refrigerants and pesticides, proactive regulatory frameworks and comprehensive surveillance programs will be essential to safeguard water resources and public health.
References
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