Should we monitor TFA in water as a proxy for other pollutants?

Trifluoroacetic acid (TFA) is attracting growing attention from water professionals, scientists, and regulators across Europe and beyond.  

Highly mobile, highly persistent, and increasingly present in both groundwater and surface water, TFA is now on the radar as a possible environmental contaminant of concern.

But do we need to monitor it routinely? Is it a useful warning signal, perhaps even a proxy, for emerging PFAS-related pollution, or is it a red herring that distracts from higher-priority risks?

Let's explore the arguments for and against monitoring TFA in water, based on recent research, particularly the 2023 final report from the German Environment Agency (UBA), which provides the most comprehensive spatial and pathway-specific analysis of TFA sources in water to date.

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What is TFA?

TFA (CF₃COOH, often present in water as the anion CF₃COO⁻) is a short-chain perfluorinated organic acid.  

It’s part of the wider family of organofluorines and is considered by some as a borderline member of the PFAS group, depending on the regulatory definition used.

While TFA can be synthesised directly and used industrially in pharmaceuticals and agrochemicals, most of the TFA found in the environment forms indirectly—as a terminal degradation product from a wide array of fluorinated compounds.  

These include:

• Refrigerants such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs), which degrade in the atmosphere to produce TFA via wet deposition.
• Fluorinated pesticides and plant protection products (PPPs), many of which contain CF₃ groups.
• Pharmaceuticals and biocides with CF₃ moieties.
• Industrial emissions, including the thermolysis of fluoropolymers during incineration or manufacturing processes.

The UBA report estimated that over 500 tonnes of TFA could form annually in Germany from PPPs alone, with another 100 tonnes arriving via precipitation.

Point-source emissions from industry have also been shown to cause significant local and downstream contamination, even in high-flow river systems like the Rhine.

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The case for monitoring TFA

1. TFA is extremely persistent and mobile

TFA is not effectively removed by conventional water treatment methods.  

It doesn’t bind to soils or sediments, doesn’t degrade under environmental conditions, and is not significantly removed by activated carbon, biological treatment, or ozonation.  

Once it enters the aquatic environment, it stays mobile and persistent, often described as a “forever chemical” in the same vein as other PFAS.

Its strong polarity and low volatility mean it rapidly dissolves and distributes through water bodies.  

This mobility makes it a potentially valuable tracer for studying the movement of waterborne contaminants.

2. It reflects diffuse and modern contamination pathways

Unlike legacy PFAS such as PFOA or PFOS, which are mostly regulated and declining in many jurisdictions, TFA points to current uses of fluorinated substances.  

It’s particularly valuable for identifying:

• The environmental impact of refrigerant replacements (e.g., HFO-1234yf),
• The PFAS footprint of pesticide and veterinary drug usage,
• Downstream contamination from poorly monitored industrial processes.

Because many of these sources are still poorly regulated or not covered by existing PFAS monitoring regimes, TFA monitoring could help flag problems that conventional PFAS surveillance would miss.

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3. It’s a useful baseline indicator

The German report found a consistent background concentration of around 0.3–0.4 µg/L in German surface waters due to atmospheric deposition alone.  

Elevated concentrations (>1 µg/L) often indicate local agricultural or industrial inputs.

As such, TFA can serve as a benchmark for identifying areas with anomalous or concerning contamination profiles.

4. Regulatory momentum is building

German authorities are advocating for the inclusion of TFA and other very persistent and mobile substances (vPvMs) in EU-level regulation.  

UBA’s report specifically calls for:

• Expanded monitoring programs by national and regional authorities,
• Development of mitigation strategies,
• Integration of TFA into regulatory frameworks, especially when health or ecological risks cannot yet be ruled out.

The case against monitoring TFA

1. TFA is not representative of most PFAS

While TFA is a perfluorinated compound, it behaves very differently from PFAS substances typically targeted in water monitoring, such as PFOS, PFOA, and GenX.  

Key differences include:

• No bioaccumulation: TFA does not accumulate in the food chain.
• Low toxicity: Current evidence suggests acute and chronic toxicity is low at environmental concentrations, although gaps remain.
• High polarity: It moves differently in water and through treatment systems compared to more hydrophobic PFAS.

This means TFA should not be used as a general proxy for PFAS presence or risk.

2. It has many non-PFAS sources

Using TFA as a PFAS indicator can be misleading. TFA may result from non-PFAS compounds like:

• Atmospheric breakdown of refrigerants and anaesthetics,
• Decomposition of pharmaceutical residues,
• Direct industrial use unrelated to PFAS manufacturing.

This makes it hard to draw regulatory or public health conclusions from its presence alone.

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3. It may dilute focus from high-risk substances

Some in the water monitoring and policy community worry that attention to TFA may undermine efforts to tackle PFAS with clearer health risks.  

In contexts with limited resources, prioritising TFA could pull focus from more urgent threats like PFHxS or PFNA, where clear toxicological and regulatory frameworks already exist.

4. Data and interpretive frameworks are still maturing

While Germany has led the way in mapping TFA inputs, many countries lack the baseline data or spatial models to interpret TFA concentrations meaningfully.  

Without clear standards, thresholds, or contextual data, there is a risk of overreacting (or underreacting, as the case may be) to TFA findings.

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So, where do we go from here?

The strongest consensus emerging from the latest science is that TFA should not be monitored as a stand-in for PFAS as a whole, but that it does deserve to be monitored as a pollutant and indicator in its own right.

For water professionals, this means:

• Incorporating TFA into targeted monitoring programs, especially near known sources like fluorochemical industries, pesticide-heavy agriculture, or areas affected by atmospheric deposition.
• Using TFA to support catchment-level models of fluorinated chemical transport and degradation.
• Advocating for clearer regulatory guidance on TFA thresholds and mitigation requirements.

TFA is not the next PFOA, but it is a chemical of growing importance in the evolving story of fluorinated substances in the environment.  

For professionals working in water quality monitoring, understanding its sources, significance, and limitations is key to anticipating future regulatory trends and protecting drinking water and ecosystems.

Monitoring TFA, in this context, is less about managing immediate toxic risk and more about staying ahead of a shifting landscape, one in which new-generation fluorinated chemicals are rapidly replacing old ones, often without the scrutiny they deserve.