A final report prepared for the European Commission includes fluorinated gases in its PFAS scope and says the more prominent concern for this group is their degradation to trifluoroacetic acid (TFA). The study, prepared by WSP, Ricardo and Trinomics, covers four hypothetical scenarios for the European Economic Area through 2050.
The report says F-gases comprise hydrofluorocarbons, which account for approximately 90% of all F-gases, plus perfluorocarbons, sulfur hexafluoride and nitrogen trifluoride. In its review of human exposure, it says inhalation exposure occurs primarily following equipment leaks such as from refrigeration systems, recycling systems or other uses.
The study says TFA is likely to be the terminal end product from degradation of other PFAS, including the photolytic degradation of fluorinated gases emitted to air from air conditioning sources. For the TFA case study, it identifies fluorinated gases and fluorine-based organic pesticides as the two primary sources, and says F-gas emissions and emission projections from the universal PFAS restriction were used to determine current and future emission rates.
A literature review used in the report suggests that 20% to 70% of all fluorinated gases are converted to TFA in the atmosphere. The study uses 20% as its low estimate, 40% as its medium estimate and 70% as its high estimate, and says that under the business-as-usual scenario increasing emissions for fluorinated gases would cause “background” TFA concentrations to continue rising in the coming years.
For its 2024 baseline, the report uses TFA concentrations of 700 ng/l in background drinking water and 3,900 ng/l in elevated drinking water, 4,700 ng/l and 23,900 ng/l in surface water, and 300 ng/l and 3,200 ng/l in groundwater. In a hypothetical full-stop scenario, it says air conditioning systems, both mobile and static, would likely qualify as problematic recalls, with fluorinated-gas emissions continuing for 3-5 years after 2030, while emissions from products still in use such as air conditioning are computed to cease after 2033.