Trifluoroacetic Acid in the Environment – Here Today, More Tomorrow

Session Summary From SETAC Maastricht

Hans Peter Arp, Norwegian Geotechnical Institute; Shira Joudan. University of Alberta; Mark Hanson, University of Manitoba (in abstentia); and Finnian Freeling, TZW: DVGW-Technologiezentrum Wasser (German Water Centre), Karlsruhe

The SETAC Europe 36th Annual Meeting in Maastricht, the Netherlands, featured the second dedicated session explicitly on trifluoroacetic acid (TFA) at a SETAC meeting, and the first in Europe, titled “Trifluoroacetic Acid in the Environment – Here Today, More Tomorrow.” The session, organized by the authors, drew a standing-room-only audience for the platform presentations that spilled into the hallway. Thirteen excellent poster presentations and a packed open invitation roundtable discussion further highlighted the growing interest in TFA across the global SETAC community.

The presentations in the dedicated session focused on the environmental chemistry of TFA and its precursors, particularly F-gases and pesticides, the presence of TFA in abiotic samples, regulatory concerns and data synthesis. Lacking was new experimental data on toxicity and bioaccumulation. Trevor VandenBoer, York University, presented on the importance of considering and measuring atmospheric gas phase PFCAs, including TFA, in isolation from particulate TFA, using his group’s newly developed passive samplers selective for gaseous TFA to better understand its environmental fate and distribution patterns. He reported variability in atmospheric TFA based on location and season. Cora Young, York University, introduced a metric for evaluating F-gas impacts, which considers the trade-offs of TFA formation versus global warming impact (CO₂ equivalents). This metric could facilitate current discussions on F-gas regulations by addressing the dual challenge of meeting climate goals while managing the rising accumulation of TFA. Christian Albers, Geological Survey of Denmark & Greenland, presented data on rising concentrations of TFA in Danish groundwater, which went from non-detects before 1960 to consistent increases up to present day. His group also studied the degradation of seven common pesticides containing C-CF₃ moieties in agricultural fields and found that they all form TFA, with amounts formed based on soil type and chemical structure. Rowan Stanforth, Fidra, reported TFA measured in 54 surface waters across the UK (97% detection rate) with potential concentration relation to catchment area and the presence of golf courses. Finally, Patrick van Hees, Eurofins Food & Feed/Örebro University, presented on TFA from potato cultivation with three C-CF₃ containing fungicides. Drainage water from the TFA experiment had similar concentrations to groundwater in nearby arable land in Sweden (circa 1.3 µg/L).

A major unifying theme was the effort to tease out the proportion of TFA coming from atmospheric precursors including F-gases and the proportion of TFA entering watersheds from agricultural point sources from C-CF₃ containing active ingredients and/or urban areas containing wastewater treatment effluent. Though data for F-gases and pesticides studies were presented, the potential of other sources such as pharmaceutical by-products and PFAS remediation by-products came up during later discussions, as noted below.  

In addition to the scientific session, the chairs hosted a 90-minute roundtable discussion with 43 attendees. The primary goal was to make connections amongst those working in the TFA space, whether they are researchers, regulators or consultants. Diverse scientists were present, but there was a clear lack of toxicologists (human and eco), despite increasing concern and ongoing uncertainty of toxicological impacts from chronic exposures. As a group, they discussed the scientific needs surrounding TFA moving forward and identified eight core topics below:

1. Precursors and pathways: Identifying and quantifying reactive sources of TFA and having reliable emission data of TFA-precursors especially in the atmosphere, as well as use data for pesticides/pharmaceuticals in agricultural and urban areas.
2. Emerging hotspots: Identifying why some TFA hotspots exist beyond fluorochemical production facilities, such as data centres, automobile industry, hospitals, etc.
3. Advanced adsorbents: Novel materials for the adsorption of TFA and other mobile ionic contaminants, both for advancing remediation and analytic sample preparation (SPE).
4. Human exposure: Addressing uncertainty around inhalation and potential toxicity of acidic (neutral) TFA, potential interactions with proteins, potential internal exposure from C-CF₃-containing pharmaceuticals, and importance of diverse food types for exposure, particularly grains and vegetables which are likely greater than drinking water.
5. Toxicity: The effects of chronic exposure to TFA remain poorly characterized for both human and ecological endpoints. There remain many untested modes of action (e.g., immunotoxicity, neurotoxicity, etc.) that warrant study.
6. Feedback loops in ecosystems: TFA accumulates in terrestrial food webs through processes such as plant uptake, but there are also feedback loops in which degrading plant material releases previously accumulated TFA back into soils, where it can re‑enter soil water and be taken up again by plants.
7. Remediation and desalinization as a point source of TFA: Some PFAS destruction technologies can potentially generate TFA, and reverse osmosis waste brine is expensive to treat for TFA removal, thereby making the discharge of such brines a hot spot of TFA emissions in the ocean and elsewhere.
8. Product sources and alternatives: leaching from batteries, cosmetics, and how TFA fits into Safe and Sustainable by Design.

It is clear that there is strong interest in TFA as a contaminant within the SETAC community as our understanding of its wide-ranging environmental presence grows. PFAS regulations are changing, and new technologies required to adapt to climate change are locking in the use of TFA-precursors. It was also noted that the session did not capture all TFA research presented at SETAC. Because TFA is relevant across a broad spectrum of scientific disciplines, the round table discussion also provided a valuable opportunity to gain a broader perspective on research taking place outside the dedicated session.

Considering the increasing interest and concern from regulators and the general public, there is a need to turn to science regarding the increasing concentrations of TFA in the environment to better understand the formation, fate pathways and impacts as TFA is not going anywhere soon. We encourage more SETAC researchers to consider TFA as an experimental priority so that we can produce new data to best inform regulatory development.

A session on TFA will be held again at the SETAC North America 47th Annual Meeting in Montreal this fall, titled “Small Molecule, Big Questions: Precursors, Pathways and Planetary Reach of Trifluoroacetic Acid” and co-chaired by Finnian Freeling, Hans Peter Arp, Mark Hanson and Cora Young. We hope to see you there!

Author contacts: [email protected], [email protected], [email protected] and [email protected]