Trifluoroacetic Acid (TFA) as a Planetary Boundary Threat
Abstract
Trifluoroacetic acid (TFA) belongs to the subclass of per- and polyfluoroalkyl substances (PFAS) known as ultra-short chain perfluoroalkyl acids (PFAAs). The initial wave of scientific interest surrounding TFA started in the mid-1990s and was related to the introduction of F-gases as novel refrigerants, as TFA is their common degradation product. F-gases were introduced after chlorofluorocarbons (CFC) were phased out under the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. In recent years, TFA has been commonly measured and reported alongside other PFAS, with alarmingly high concentrations detected across various environmental matrices, making TFA the most abundant PFAS in the environment.[1] Although early studies suggested that TFA and other short-chain PFAAs are less hazardous than long-chain PFAAs - due to their lower bioaccumulation in lipids and lower direct toxicity - more recent evidence highlights concerns about TFA's environmental persistence and very high accumulation in water matrices and especially plants. Although there are fewer toxicological data compared to long-chain PFAAs, we maintain that there are more than sufficient data to conclude that TFA poses a risk to humans and the environment and meets the criteria of a planetary boundary threat for novel entities.[1] We performed an analysis of the scientific literature on TFA to assess if there is sufficient evidence of its exceedance of a planetary boundary. According to Persson et al.[3], chemical poses a planetary boundary threat if three conditions are met: “Condition 1 (C1) – the pollution has a disruptive effect on a vital earth system process of which we are ignorant; Condition 2 (C2) – the disruptive effect is not discovered until the associated impacts are, or inevitably will be, manifested at a global scale; and Condition 3 (C3) the impacts are poorly reversible because the level of pollution in the global environment cannot be readily reduce”. To assess whether TFA meets these conditions, a review and analysis of the existing body of scientific literature on TFA’s environmental effects and exposure were conducted. In addition, current health advisory and regulatory values were assessed in this context. A review of the scientific literature was conducted to obtain an overview of average and maximum concentrations in diverse environmental media, with 43 studies spanning from the late 1990s to the 2020s selected and monitoring data reporting on TFA concentrations were analyzed. These were compared with potential disruptive effects on human health and the environment. We conclude from this that Condition 1 (C1) is fulfilled based on the many known and unknown thresholds that could be exceeded of which we are ignorant. Condition 2 (C2) is fulfilled as TFA is already present globally in all environmental media and Condition 3 (C3) is satisfied because the effects of TFA, once realized, will be irreversible for the foreseeable future, owing to its high persistence, mobility, and emissions from multiple sources. Acknowledgments. European Union’s Horizon 2020 research and innovation program project ZeroPM, under grant agreement No 101036756, and the Horizon Europe project ARAGORN under grant agreement 101112723.