Monitoring of short chain PFAS, including TFA in sources of German drinking water
PFASs are a highly diverse group of substances, and knowledge about this group in water sources is still scarce, beyond the well-studied substances which includes TFA (trifluoroacetic acid). A recent paper ‘Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated’ [1] provided analytical data in water samples collected from 13 different sources of German drinking water for short-chain and ultra-short-chain PFASs, which includes TFA. The study covered 43 PFAS and made these observations about TFA.
Surface water, bank filtrate (water that has passed through a river or lake bank as a method of purification for drinking water production), groundwater, and raw water (water from the exact point of entry into the drinking water production plant) were included. TFA was the most dominant PFAS, with a maximum and median concentration of 12.4 and 0.9 μg/L, respectively, which is in line with previous monitoring programs in German surface waters. TFA is the most well-studied ultra-short-chain PFAS and has a drinking water health guidance value of 60 μg/L and a target value as a plant protection agent metabolite of 10 μg/L in Germany. It is expected that ultra-short-chain PFASs have very short half-lives in the body, preventing bioaccumulation.
Image Reproduced from EEAP. 2019. Environmental Effects and Interactions of Stratospheric Ozone Depletion, UV Radiation, and Climate Change. 2018 Assessment Report. Nairobi: Environmental Effects Assessment Panel, United Nations Environment Programme (UNEP) 390 pp. https://ozone.unep.org/science/assessment/eeap
TFA is known to be widespread in the aquatic environment and can be introduced into the water cycle through industrial processes and as a transformation product of pharmaceutical and agricultural products, among others. TFA is also a transformation product of some hydrofluorocarbon refrigerants in the atmosphere and may reach the aqueous environment via atmospheric deposition. The smaller the perfluorinated alkyl chain, the more soluble and the weaker the sorption of the PFAS to environmental media. Knowledge about ultra-short-chain homologues and their sources is scarce and often limited to few well-studied examples like TFA.
In conclusion, this paper finds TFA concentrations in line with previous studies, well below the German health guidance value of 60 μg/L and comments that TFA has a very short half-life in the body preventing bioaccumulation. TFA is well-studied.
Reference
[1] Ultra-Short-Chain PFASs in the Sources of German Drinking Water: Prevalent, Overlooked, Difficult to Remove, and Unregulated, I.J. Neuwald et al, Environ. Sci. Technol. 2022, 56, 6380−6390
More information about TFA as an atmospheric breakdown product - Fluorocarbons is available on the EFCTC website