Trifluoroacetic Acid Accumulates in Rainfall: Scientists Debate Its Dangers
Every time it rains or snows, a man-made chemical substance—trifluoroacetic acid—falls to the earth along with it. In recent decades, traces of this acid have been detected in rainwater across the globe, even in Arctic regions. Scientists are recording an increase in TFA concentration, raising concerns among ecologists and regulatory agencies. Some experts describe the accumulation of trifluoroacetic acid in precipitation as a "worrisome forecast for decades to come", while others argue that current levels of this compound are minuscule and do not pose a threat to human health.
What is Trifluoroacetic Acid (TFA)
Trifluoroacetic acid (TFA) is a synthetic organic acid that is structurally similar to acetic acid, but with fluorine atoms replacing hydrogen. The strong carbon-fluorine bonds make TFA extremely stable and nearly indestructible through natural processes. This substance belongs to the class of "forever chemicals" (PFAS)—fluorine-containing compounds capable of persisting in the environment for decades without breaking down.
Rising Concentrations: Recent Studies
Recent studies have shown a significant increase in the levels of trifluoroacetic acid in nature. Sample analyses have indicated a multiple-fold rise in TFA concentration: for example, in the foliage of trees in Germany, the level increased 5–10 times since the early 1980s, with similar increases observed in Arctic ice in Canada and groundwater in Denmark. These data suggest that emissions of TFA and its precursors over recent decades have led to a global accumulation of this "forever" acid, which now falls with atmospheric precipitation.
This is not the classic "acid rain" that would cause immediate acidification and forest die-off. However, the mere presence of an artificial acid in precipitation in even the most remote regions of the planet is considered a worrying signal. Ecologists warn that if TFA concentrations continue to rise, its accumulation may lead to undesirable ecological consequences in the future.
Sources of TFA in Nature
The main pathways for trifluoroacetic acid to enter the environment are as follows:
- Industrial emissions and leaks: Chemical and pharmaceutical companies use TFA in their processes. Small amounts of the acid may enter the environment during the production and disposal of products.
- Decomposition of fluorinated gases (refrigerants): Modern refrigerants release fluorinated gases (F-gases) into the atmosphere. For example, leaks of chlorofluorocarbons and their substitutes from air conditioning and refrigeration systems lead to the gradual conversion of these gases in the atmosphere into trifluoroacetic acid, which then precipitates as rain.
- Degradation of other compounds: Trifluoroacetic acid forms from the breakdown of certain pesticides and some persistent organic substances (for example, some PFAS). All these pathways contribute to the gradual accumulation of TFA in the environment.
Risks to Human Health
How dangerous is trifluoroacetic acid to humans? Current research has not identified significant toxicity of TFA at the levels observed in nature. In laboratory experiments, lethal doses of TFA for mice and rats were much higher than actual concentrations, and the substance exhibited extremely low acute toxicity. Furthermore, due to the small size of its molecule, TFA does not accumulate in the body: it easily dissolves in water and is rapidly excreted in urine, not building up in tissues. Therefore, a number of scientists believe that at the current pollution level, this acid poses no significant threat to health. Konstantin Miroshnikov, Doctor of Chemical Sciences and Corresponding Member of the Russian Academy of Sciences, notes that even a 5–10 times increase in TFA levels in precipitation still means negligible doses that are safe for humans. The United Nations Environment Programme (UNEP) also classifies TFA as a substance of minimal risk.
However, other experts warn that the absence of harm today does not guarantee safety tomorrow, as the substance gradually accumulates in the environment. Laboratory studies have shown that TFA exhibits biological activity, so it cannot be considered harmless.
Risks to Ecosystems
Research indicates that plants absorb trifluoroacetic acid from the soil along with water, after which it remains in their tissues. In laboratory experiments, very high concentrations of TFA slowed plant growth, although current pollution levels are not yet sufficient to cause direct harm. However, with further accumulation, negative changes could occur in particularly sensitive ecosystems, including soil degradation and inhibition of plant growth.
Scientific Debates and Regulatory Reactions
European scientists are sounding the alarm: in 2024, the rise in TFA concentrations was labeled a threat to global environmental safety. In response to these concerns, initial regulatory steps have begun. For instance, in Germany, relevant authorities have approached the European Chemicals Agency (ECHA) with a proposal to officially recognize TFA as a hazardous contaminant. Overall, the EU is contemplating a complete ban on all "forever chemicals," which would automatically include TFA.
Meanwhile, some experts and industry representatives maintain a more cautious stance. They argue that TFA differs from traditional PFAS: it does not accumulate in organisms and is found in the environment only in minuscule concentrations. Proponents of this view suggest that the majority of TFA gradually washes into the global ocean and disperses there without harm. Thus, regulators face a dilemma: on one hand, the precautionary principle calls for restricting the emissions of any "forever" chemicals without waiting for a dangerous threshold; on the other hand, stringent measures against TFA could impact entire industries. Solving this issue will require a balanced approach and further scientific research.
Outlook: A Look into the Future
Trifluoroacetic acid is already referred to as "invisible acid rain": this chemical does not cause immediate harm to nature but gradually accumulates in the waters and soils of the planet. There is currently no direct threat to human health, as concentrations are too low. However, TFA is extremely persistent and will remain in ecosystems for many years. If humanity continues to emit tons of such compounds annually, sooner or later, questions about their impact on water, soils, and living organisms will arise.
Underestimating the problem is not an option. While scientists continue to study trifluoroacetic acid, governments and businesses should already consider reducing emissions of "forever" chemicals and seeking safer alternatives. Such a proactive approach will help prevent a situation where, in a few decades, accumulated TFA transitions from a scientific fact to a serious ecological problem.
