The German NGO Deutsche Umwelthilfe (DUH) filed a lawsuit in December 2022 against the northern German state Schleswig-Holstein in the Schleswig Higher Administrative Court, alleging a failure to monitor trifluoracetic acid (TFA) in the Eider river basin.

TFA is an atmospheric degradation product of certain f-gases, notably HFO-1234yf, and descends from the atmosphere to Earth in rainfall. Its accumulation in drinking water has raised concerns about its eventual health impact in Germany and elsewhere in Europe.

The lawsuit comes in the wake of the European Chemicals Agency (ECHA), an agency of the EU, publishing a proposal from five European countries, including Germany, to restrict per- and polyfluoroalkyl substances (PFAS) – so called forever chemicals – including certain f-gases and TFA that are considered PFAS by the agency.

The lawsuit, one of the first to address TFA in the environment, points to degradation products of both commonly used f-gases and pesticides as the main sources of TFA in the river basin and calls for action by the federal state’s authority to prevent pollution. According to the NGO, the state government’s current management plan for the Eider river basin district is insufficient to achieve binding water protection goals, at both the national and European levels.

“TFA is a relatively unknown substance up to now, but with worryingly high concentration increases in our waters, said Jürgen Resch, Federal Managing Director of DUH. “The chemical does not degrade naturally and cannot be removed from water. Water suppliers in particular are already concerned about this. TFA spreads rapidly in the water cycle and has been shown to be toxic to some species of algae. We must therefore act preventively to rule out risks to health and the environment. Schleswig-Holstein has the obligation to include TFA in the water monitoring and status assessment and to specify strict reduction measures.”

Efforts are being made to determine the extent to which TFA in the Eider comes from nearby pesticides and f-gas decomposition. Even if today most of the TFA in the river is estimated to come from the decomposition of pesticides, the NGO reports that increasing use of fluorinated refrigerants that decompose into TFA is a growing concern and is estimated to increase in importance. In the lawsuit, the NGO calls for the state to support the switch to non-TFA forming alternatives, such as natural refrigerants, for instance in public procurement.

“With our lawsuit for clean water, we are calling on Schleswig-Holstein to finally take action,” says Dorothee Saar, Head of Transport and Air Pollution Control at DUH.

According to experts at the German research center Öko-Recherche, commonly used refrigerants such as the following yield these TFA percentages after atmospheric decomposition:

SubstanceTFA molar yield         Source
HFC-234fa<10%WMO (2010)
HFC-134a7–20%Wallington et al. (1996)
HFC-143a<10%Author estimate
HFC-365mfc<10%WMO (2010)
HFC-227ea100%WMO (2010)
HFO-1234yf100%Hurley et al. (2008)
HFO-1234ze(E)<10%WMO (2010)
HFO-1336mzz(Z)<20%Qing et al. (2018)
HFO-1225ye (E and Z)100%Author estimate 
HCFO-1233zd(E)2%Sulbaek Andersen et al. (2018)
HCFC-1224yd(Z)100%Author estimate