TFA as an atmospheric breakdown product
TRIFLUOROACETIC ACID
(TFA)
TFA is a naturally occurring substance but can also be produced by the breakdown of some HFCs or some HFOs and some HCFCs in the atmosphere.
WHERE IS TFA FOUND?
HOW IS TFA DEPOSITED FROM DEGRADATION OF HFCs, HFOs and HCFOs
TFA deposition profile is linked to the TFA yield and atmospheric lifetime of the HFC or HFO
Any TFA from HFCs is deposited globally. HFOs have very short atmospheric lifetimes and the majority of any TFA produced is deposited regionally.
TFA is highly soluble and is scavenged from the atmosphere via rain, fog, and snow, as well as dry deposition.
POTENTIAL IMPACT OF TFA
Current and projected (to 2100) concentrations of TFA in the oceans provide a very large margin of exposure (thousand-fold) when compared to thresholds of toxicity and risks to the environment and human health are de minimis. TFA is of low toxicity in mammals.
THE EFFECTS OF F-GASES
Some HFCs, HCFCs and HFOs, containing the CF3-C group, can break down to TFA, the amount depending on the specific molecule. By 2050, the average TFA concentrations in sea water are projected to increase by 4 – 6 ng/L between 2020 and 2050 from atmospheric formation, deposition and subsequent transfer to the oceans, compared to oceanic concentrations of 10 ng/L up to 200 ng/L measured around year 2000. The TFA yields and other breakdown products for HFCs, HFOs and HCFOs can be found here.
TRANSPORT OF TFA TO THE OCEANS
TFA (trifluoroacetic acid and its salts) occurs naturally in the oceans, estimated at 61 -205 million tonnes formed over millions of years. It is well established that TFA is a ubiquitous natural component in rivers, lakes, and other surface water bodies. It is found in the environment as a salt. Natural sources are thought to include undersea volcanic vents.[1] Before 1947 extremely limited quantities (if any) of TFA were emitted from industrial sources, but it is found in the deep arctic ocean layers in waters with a reported 14C age of about 1000 years. Most PFAS have different properties from TFA.[2]
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 HFCs, HFOs and HCFOs in the atmosphere and reaches the aqueous environment via atmospheric deposition.
THE OCEANS ARE A TERMINAL SINK FOR TFA
EFCTC commissioned a study “Assessment of Possible Transport of Trifluoroacetic Acid from the Oceans to the Atmosphere” by Professor Simon L Clegg, University of East Anglia, to understand if significant quantities of TFA (Trifluoroacetic Acid) are transported to the troposphere from the oceans, with the potential of further transport over land. The study evaluated the potential for TFA to partition from aged sea salt aerosol, in the same way that HCl is partitioned from aged sea salt aerosol to the troposphere. There are published studies for HCl enabling a comparison to be made. This study was prompted in part due to the published papers showing significant transport of longer chain PFAS from the oceans to land (see explanatory note).
The results imply that acidified seasalt aerosols will not be a significant contributor to gas phase TFA except under a very limited set of conditions (low relative humidity RH, high temperature, polluted conditions, and for the small submicron fraction of the aerosol in which high acidities can be attained, thus limiting the total displacement of TFA). Under other conditions – especially high RH and low acidity – the aerosol appears likely to be a sink of TFA. The study concludes that TFA does not recycle in any significant quantities from the oceans to land, i.e. the ocean is a terminal sink for TFA.
For a surface seawater TFA concentration of 150 ng L-1 (a factor of 7.8×10-9 times that of Cl–), a literature model of global chlorine cycling suggests that there would be annual flux of TFA to the atmosphere in seasalt aerosol of about 14 tonnes annually. Acidification of seasalt aerosol by dissolution of HNO3 and from oxidation of dissolved dimethyl sulphide and SO2 to produce H2SO4 results in the expulsion of HCl to the gas phase through the Henry’s law equilibrium. Although TFA is a weaker acid than HCl, and its concentration in the aerosol very much lower than that of Cl–, the same mechanism can in principle apply.
The report reviews the current knowledge of the relevant thermodynamic properties of TFA – the acid dissociation constant and Henry’s law constant. Calculated equilibrium partial pressures of TFA above typical seasalt aerosols over a very wide range of pH are found to be lower than ambient gas phase concentrations (a few ng m-3) by a large margin, except at very low pH. The behaviour of TFA and HCl were also compared by calculating the equilibrium gas/liquid partitioning as a function of pH and for atmospheric liquid water contents ranging from aerosols in low relative humidity (RH) environments to those of cloud and fogwater. The patterns are similar: at atmospheric liquid water contents and pH typical of fog and cloud water the greatest fractions of both substances (approaching 100%) are expected to be in the aqueous phase. This is consistent with them both being removed by wet deposition. Conversely, at moderately acidic and low pH, and atmospheric liquid water contents typical of aerosols, the largest fractions of both total Cl– and total TFA per m3 of atmosphere will be found in the gas phase. Of the two acids, TFA has the greater tendency to partition into the gas phase. The predicted balance between gas and aerosol fractions of TFA is consistent with the limited number of atmospheric measurements that have been made.
Finally, literature models of global chlorine cycling allow an estimate to be made of the flux of TFA that would be displaced from acidified seasalt aerosol if the behaviour is analogous to that of HCl but scaled according to the concentrations of TFA and Cl– in surface seawater. This hypothetical value, although is unlikely to have practical relevance except possibly as an upper limit, is only 406 kg TFA/year globally.
The Report “Assessment of Possible Transport of Trifluoroacetic Acid from the Oceans to the Atmosphere” is available here. The report was prepared for EFCTC by Professor Simon L. Clegg, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ U.K. Professor Clegg’s key research interests are “Chemical thermodynamics of aqueous solutions; activity coefficient models and their application to problems in gas/aerosol partitioning in the atmosphere and air quality, brine chemistry, and solubility phenomena; predictive methods for physical properties of pure compounds (such as vapour pressures), and aqueous solutions; measurements of the properties of single aerosol particles using electrodynamic balances.”
Explanatory Note: Recent publications have reported experiments that have demonstrated effective enrichment of perfluoro alkyl acids (PFAAs) in nascent sea spray aerosols (SSA), suggesting that SSA are an important source of PFAAs to the atmosphere. The enrichment factor initially increases with increasing chain length from NPC=4 (NPC-number of perfluorinated carbons) with enrichment factors reported for NPCs from 4 to 11. The surfactant properties of these longer chain PFAAs are considered to contribute to the enhancement factors. However, the behaviour of surfactants can be influenced by many factors and could be more complex for surfactant mixtures. In contrast TFA is not a surfactant.
References: Influence of Water Concentrations of Perfluoroalkyl Acids (PFAAs) on Their Size-Resolved Enrichment in Nascent Sea Spray Aerosols, Bo Sha, Jana H. Johansson, Jonathan P. Benskin, Ian T. Cousins, and Matthew E. Salter, Environ. Sci. Technol. 2021, 55, 9489−9497, https://dx.doi.org/10.1021/acs.est.0c03804 ; and Sea Spray Aerosol (SSA) as a Source of Perfluoroalkyl Acids (PFAAs) to the Atmosphere: Field Evidence from Long-Term Air Monitoring Bo Sha, Jana H. Johansson, Peter Tunved, Pernilla Bohlin-Nizzetto, Ian T. Cousins, and Matthew E. Salter, Environ. Sci. Technol, https://doi.org/10.1021/acs.est.1c04277
[1] B. F. Scott, R. W. Macdonald, K. Kannan, A. Fisk, A. Witter, N. Yamashita, L. Durham, C. Spencer and D. C. G. Muir, Trifluoroacetate profiles in the Arctic, Atlantic, and Pacific Oceans, Environ. Sci. Technol., 2005, 39(17), 6555–6560.
[2] Montreal Protocol on Substances that Deplete the Ozone Layer UNEP 2022 Assessment Report of the
Environmental Effects Assessment Panel Chapter 6, pages 278-279 available at http://ozone.unep.org/science/eeap.
EFCTC Summary of latest information about TFA set out below: All the information below is taken from published sources and, in particular, from the 2022 Assessment Reports of the UNEP Environmental Effects Assessment Panel and the Scientific Assessment Panel for the Montreal Protocol. From these objective assessments, it is clear that the low dispersed levels of TFA that are forecast in the future, from the use of HFCs and HFOs, even with published worst case scenarios, are orders of magnitude below the levels that would have an adverse effect.
Environmental Effects Assessment Panel 2022 (EEAP 2022): TFA emissions until 2100 from HFCs and HFOs
EEAP 2022 and SAP 2022 have the same forecasts for the global generation and deposition of TFA, based on the assumption that that 50% of the future emissions of low-GWP alternatives are related to HFOs, from which it is assumed that 50% is HFO-1234yf, with a conversion rate of 100% to TFA. The calculation also assumes that the formation of TFA from HFC-134a is based on its expected mixing ratio of HFC-134a and its lifetime of 14 years. Conversion rates from the destroyed HFC-134a amounts to TFA were 7–20%. Releases of other potential sources of TFA were not included but are expected to be much smaller.
The emissions of TFA, from HFO-1234yf and HFC-134a, are estimated to increase concentrations in the global oceans from the nominal value of 200 ng acid equivalent/ L (equivalent to 239 ng TFA sodium salt/ L) in 2020, to 266–284 ng sodium salt/L in 2100 if evenly distributed across all oceans. “It should be noted that the geographic distribution of TFA released into the atmosphere across the globe has changed with the introduction of refrigerants and blowing agents such as HFOs with short atmospheric lifetimes (days). The longer atmospheric lifetimes of the older generation HFCs allowed wider and more even distribution of parent HFCs and deposition of TFA, across the globe. The HFOs will be degraded by tropospheric OH radicals closer to the source of release with resulting steeper gradients of concentration depending on wind direction and velocity. As a result of this uneven deposition, concentrations of TFA in surface waters will vary with flow rates and volumes of water.”
“Presence of TFA in precipitation and flowing waters will be driven by release from precursors and other sources as well as the hydrology and will likely fluctuate. Concentrations in terminal basins such as the oceans will fluctuate less but will be dependent on rates of inputs from precipitation and rivers. Once in the oceans, concentrations will be influenced by rates of input of fresh water as well as currents and mixing in the oceans. Current and projected (to 2100) concentrations of TFA in the oceans provide a very large margin of exposure (thousand-fold) when compared to thresholds of toxicity and risks to the environment and human health are de minimis. However, there is some uncertainty in the environmental toxicity values because only two marine species are included in the toxicity data set for aquatic species; and marine macrophytes, which are keystone species with respect to habitat, have not been tested.”
EEAP 2022: Human and environmental risks associated with TFA in the environment
Risks from exposure to TFA in terrestrial animals: EEAP 2022 described a report on the potential effects of TFA in mammals. “This was a report on the effects of exposure to TFA salts via drinking water in male laboratory rats. The tests followed OECD guidelines (Tests 417 and 452) and exposures were for 90, 370, and 412 days at concentrations in the drinking water of 0 (control), 30, 120, and 600 mg TFA acid equivalent/L. The latter concentration was equivalent to a daily intake of 37.8 mg TFA/kg (body mass). Responses measured were activity of the enzymes alanine-amino-transferase (ALT) and glutamate-pyruvate-transferase (GPT) in the blood. No significant effects were observed at 30 mg/L for any time of exposure but a significant increase in ALT activity was observed at 120 and 600 mg TFA acid equivalent/L at 370 days but not at 412 days. No effects on GPT were reported. In a second study with exposures for 14, 28, and 90 days to 0, 600, 1200, and 2400 mg TFA acid equivalent/L, no significant effects on ALT were observed. Increases in the activity of enzymes in or originating from the liver are considered as compensatory unless accompanied by physiological responses such as loss of weight. This reported effect does not change the conclusion that TFA is of low toxicity in mammals.”
“An extensive review of the potential effects of TFA in the environment published by the German Environmental Agency [1] did not identify any risks other than the persistence of TFA in the environment, which is a legislative rather than toxicological criterion. The concentrations of TFA in beer and tea discussed above are small when compared to the NOED of TFA in mammals. This indicates that the risk to humans from residues of TFA in beer and tea are de minimis (of little importance).”
Risks of exposure to TFA in aquatic organisms: EEAP 2022 reported one new toxicity test for an aquatic organism. This was a retest of the most sensitive alga (Raphidocelis subcapitata). The study protocol followed OECD guideline 201. Effect values were based on growth. A no observed effect concentration (NOEC) of 2.5 mg acid equivalent/L (2,500,000 ng/L) was reported based on inhibition of growth. The detailed report of the study was reviewed by ECHA and was classified as “reliable without restriction”, hence it has been used here in the characterisation of the toxicity of TFA to aquatic organisms.
“The margin of exposure between the distribution of no observed effect concentrations (NOEC) of trifluoroacetic acid salt from a range of studies and the observed and expected concentrations in the oceans and endorheic basins is several orders of magnitude and is indicative of de minimis risk.”
[1] UBA. (2021). Persistent Degradation Products of Halogenated Refrigerants and Blowing Agents in the Environment: Type, Environmental Concentrations, and Fate with Particular Regard to New Halogenated Substitutes with Low Global Warming Potential. Vol. FB000452/ENG. Umwelt Bundesamt, Dessau-Roßlau.
EEAP 2022: TFA conclusions and uncertainties
“The Montreal Protocol has led to the replacement of ODSs with fluorinated chemicals, some of which can undergo degradation in the atmosphere to give TFA in various yields. TFA is known to have a long environmental lifetime and accumulates in surface and ground waters. At present, there are large uncertainties associated with the concentrations of TFA in various environmental compartments in some regions, as well as the relative proportion of anthropogenic sources related to the Montreal Protocol, compared to the other anthropogenic and natural sources. There is some uncertainty in toxicity values because of the limited number of marine species tested. Current and predicted concentrations (to year 2100) of TFA in the oceans provide a large margin of exposure (thousand-fold) when compared to thresholds of toxicity.”
“Some uncertainties remain in our understanding of the sources, routes of formation, and environmental fate of TFA. Identification and quantification of potential natural sources of TFA are urgently needed. Similarly, better local/regional emission inventories are needed for short-lived precursors of TFA arising from CFC-replacements, as well as characterisation of all other anthropogenic sources of TFA. In addition, reliable estimates of yields of TFA are required for current and new replacement compounds and their partially oxidised degradation intermediates. Finally, there is some uncertainty in toxicity values for TFA because of the limited number of marine species tested.”
Scientific Assessment Panel 2022 Executive Summary, extracts relevant to HFOs and TFA
World Meteorological Organization Ozone Research and Monitoring – GAW Report No. 278: EXECUTIVE SUMMARY Scientific Assessment of Ozone Depletion: 2022
Executive Summary 2. Hydrofluorocarbons (HFCs)
The formation in the atmosphere of trifluoroacetic acid (TFA) is expected to increase in the coming decades due to increased use of HFOs and HCFOs. TFA, a breakdown product of some HFCs, HCFCs, HFOs and HCFOs, is a persistent chemical with potential harmful effects on animals, plants, and humans. The concentration of TFA in rainwater and ocean water is, in general, significantly below known toxicity limits at present. Potential environmental impacts of TFA require future evaluation due to its persistence. See explanatory note 1.
Scientific Summary of Chapter 2: Hydrofluorocarbons
Some HFCs and unsaturated HFCs (hydrofluoroolefins [HFOs]) degrade in the environment to produce trifluoroacetic acid (TFA), a persistent toxic chemical [see explanatory note 2]. HFO-1234yf has been increasingly used to replace HFC-134a as a mobile air conditioner (MAC) refrigerant. Measurements show that atmospheric background abundances of HFO-1234yf at Jungfraujoch, Switzerland have grown from less than 0.01 ppt before 2016 to annual median levels of 0.10 ppt in 2020. At the 2020 level, the oxidation of HFO-1234yf is likely producing a comparable, or potentially larger, amount of TFA than the oxidation of HFC-134a locally near Jungfraujoch. The measured and model simulated concentrations of TFA from the use of HFO-1234yf and other relevant HFOs, HFCs, HCFCs, and hydrochlorofluoroolefins (HCFOs) is, in general, significantly below known toxicity limits at present. However, the production of TFA in the atmosphere is expected to increase due to increased use of HFOs and HCFOs. Potential environmental impacts of TFA require future evaluation due to its persistence.
Chapter 7: Scenarios and Information for Policymakers
The Kigali Amendment’s control of high-GWP HFCs is expected to lead to overwhelmingly positive climate benefits. Nevertheless, there is a potential for certain negative side effects. Hydrofluoroolefins (HFOs) are increasingly used for replacing high-global warming potential (GWP) HFCs in refrigeration, foam blowing, and various other applications. This replacement leads to less climate change. However, high-volume usage of CCl4 (carbon tetrachloride) as a feedstock in the production of HFOs, a usage and production not controlled by the Montreal Protocol, could lead to sustained elevated abundances of CCl4 if current techniques are continued and some fraction of feedstock production continues to be emitted. A second side effect is that HFO-1234yf emitted into the atmosphere will be fully converted to the stable trifluoroacetic acid (TFA; see below).
Trifluoroacetic acid (TFA), which is produced in the atmosphere from the degradation of HFCs, HCFCs, HFOs, and HCFOs, is not expected to harm the environment over the next few decades, although some regional concerns have been raised; periodic evaluation of this assessment is suggested, as important gaps in our understanding remain. This assessment is based on updated estimates of the TFA formation from current atmospheric concentrations of HFCs and HCFCs (hydrochlorofluorocarbons) and their projected decline, as well as the expected increasing abundance of HFOs as HFC and HCFC replacements within the next years. With long-lived HFCs being replaced with high-TFA-producing, short-lived HFOs, more TFA will be formed in the atmosphere. Because of the shorter lifetime of HFOs, this TFA is expected to be deposited nearer to the location of emissions. Other anthropogenic sources of TFA, such as the incineration of polytetrafluoroethene (PTFE), could also contribute. In view of changing and potential unknown sources, concentrations of TFA should be monitored for changes in different parts of the environment, with a special focus on highly populated regions and on the remote ocean.
Explanatory note 1. There are other sources of TFA. The Environmental Effects Assessment Panel (EEAP) 2020 Summary Update 2020 for Policymakers commented that for TFA, an unknown amount originates from fugitive emissions from chemical manufacture, waste disposal sites, laboratory use, and degradation of pharmaceuticals, pesticides, and industrial chemicals containing the trifluoromethyl group. Available at Environmental Effects Assessment Panel (EEAP) | Ozone Secretariat (unep.org)
Explanatory note 2. Though trifluoroacetic acid fulfils the criteria for persistency, the available data indicate that it is neither fulfilling the criteria for toxic or bioaccumulative (PBT-substances), nor the criteria for very bioaccumulative substances (vPvB-substances) according to REACH directive, Annex XIII and as laid down in the TGD R.11 of the European Chemicals Agency (ECHA). Based on its robust dataset, TFA does not meet the criteria for acute or chronic aquatic toxicity classification according to the CLP and UN-GHS systems. Current concentrations of TFA salts and related compounds in soil and surface waters do not present risks of adverse effects in aquatic and terrestrial plants and animals and TFA salts are of low acute toxicity to mammals under conditions relevant to environmental exposure. See EEAP 2021. Neale, R. E., Barnes, P. W., Robson, T. M., Neale, P. J., Williamson, C. E., Zepp, R. G., et al. (2021). Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020. Photochemical & Photobiological Sciences. https://doi.org/10.1007/s43630-020-00001-x. See sections 7.8 to 7.11 for Trifluoroacetic acid (TFA).
TFA Drinking water guidance value in Germany: The Environmental Effects Assessment Panel comprehensive summary of Trifluoroacetic acid (TFA) effects states that humans could be exposed to TFA via drinking water and food but there is no evidence to date of adverse effects on health. The Federal Environment Agency UBA issued a revised guidance value for TFA in drinking water, based on improved toxicological studies availability for trifluoroacetate salts. This sets a drinking water health guidance value of 60 μg/L and a target value of 10 μg/L. The UBA was able to set a toxicologically justified LWTW for drinking water. The LWTW of 60 µg/L is based on the life-long tolerable daily intake of TFA via the drinking water (assumption: 2 L per day), in which no harm to human health is to be expected. This guideline replaces the health orientation value (GOW) of 3 µg/l (maximum values that apply if the toxicological data is incomplete). Relevant background information: From the 2021 EEAP scientific assessment, analysis of 1187 samples of rainwater collected in eight locations across Germany in 2018–2019 showed median and a precipitation-weighted mean concentration of TFA of 0.210 μg/L and 0.335 μg/L, respectively. The maximum measured concentration was 57 μg/L. The study on Future emissions and atmospheric fate of HFC-1234yf from mobile air conditioners in Europe assessed the future emissions of HFO-1234yf after a complete conversion of the European vehicle fleet and calculated that the use of HFO-1234yf would result in expected average values of 0.6 – 0.8 µg/L of TFA in European rainwater.
About TFA
What is TFA
TFA (trifluoroacetic acid and its salts). TFA is very stable in the environment as the trifluoroacetate ion (CF3COO–) which will be combined with counter-ions such as sodium, in seawater, or calcium or ammonium (NH4+) inland, to form neutral salts. “TFA” is used as shorthand for trifluoroacetic acid and its salts.
Naturally Occurring TFA
The oceans must have a large natural burden of TFA. An estimated 61 -205 million tonnes are present in the oceans, both coastal and deep-ocean seawater, having apparently accumulated over many million years from chemical reactions in or around sub-sea volcanic vents. When the oceanic burden was estimated in the period 1998-2002, less than half a million tonnes had resulted from industrial sources including pesticides and pharmaceuticals. The concentration in the oceans is small (up to about ~200 ng L−1 or ~ 2 x 10-10 g of TFA /g of sea water).
The evidence is that TFA occurs naturally
The evidence is clear and irrefutable that TFA occurs naturally in large quantities in the environment. TFA was detected in the deep arctic ocean, in waters with a reported 14C age of about 1000 years. At 3000 m depth in the Canadian Basin of the western Arctic Ocean TFA concentration was measured as 160 ng/L, similar to the concentrations measured in the Atlantic.
Where is TFA Found
TFA is found in the oceans. It was also found in samples of fog, rain, river and lake water analysed during the 1990s. Generally, soil retention of TFA is poor and the TFA will ultimately enter the aqueous environment.
TFA and Organisms
The salts of TFA are inert and not of toxicological or environmental concern in the small concentrations (up to ~200 ng L−1) that are present in the ocean.. Current and projected (to 2100) concentrations of TFA in the oceans provide a very large margin of exposure (thousand-fold) when compared to thresholds of toxicity and risks to the environment and human health are de minimis. TFA is of low toxicity in mammals.
Effect of TFA from HFCs, HFOs and HCFOs
Some HFCs, HFOs and HCFOs, containing the CF3-C group, can break down to TFA, the amount depending on the specific molecule. By 2050, the average TFA concentrations in sea water are projected to increase by 4 – 6 ng/L between 2020 and 2050 from atmospheric formation, deposition and subsequent transfer to the oceans, compared to oceanic concentrations of 10 ng/L up to 200 ng/L measured around year 2000.
TFA from other sources
TFA is produced as a breakdown product of a number of other chemicals, such as pesticides and pharmaceuticals, and is produced synthetically by the chemical industry.
The evidence is that TFA occurs naturally
The evidence is clear and irrefutable that TFA occurs naturally in large quantities in the environment. TFA was detected in the deep arctic ocean, in waters with a reported 14C age of about 1000 years. At 3000 m depth in the Canadian Basin of the western Arctic Ocean TFA concentration was measured as 160 ng/L, similar to the concentrations measured in the Atlantic.
A summary of the evidence that TFA occurs naturally can be downloaded here. A peer reviewed paper,[1] available here, provides complementary evidence that the quantity of TFA (61 – 205 million tonnes) measured in the oceans in the period 1998-2002 must include a large natural burden.
[1] Lindley, A. An Inventory of Fluorspar Production, Industrial Use, and Emissions of Trifluoroacetic Acid (TFA) in the Period 1930 to 1999. Journal of Geoscience and Environment Protection, Vol.11 No.3, March 2023 https://doi.org/10.4236/gep.2023.113001
TFA from HFCs and HFOs
TFA is produced as a breakdown product of some HFCs, some HFOs and some HCFOs. The yield of TFA from each substance is shown in this table. The yields are from UNEP 2022 Assessment Report of the Environmental Effects Assessment Panel.[1] This table also shows other breakdown products and provides references for the data sources. Some HCFCs (e.g. HCFC-123 and -124) also breakdown to produce TFA but these are no longer used in the EU and have essentially been phased out by the Montreal Protocol.
[1] EEAP 2022, Chapter 6, Appendix, SI 4 Estimated molar yields (%) of TFA from ODS replacements. Section SI 4.1.3 discusses CF3CHO, and the degradation of each substance is discussed.
More Resources
Environmental effects assessment panel issues comprehensive summary of TFA effects EFCTC Newsletter item from March 2021 ENVIRONMENTAL EFFECTS ASSESSMENT PANEL ISSUES COMPREHENSIVE SUMMARY OF TFA EFFECTS – Fluorocarbons
Neale, R. E., Barnes, P. W., Robson, T. M., Neale, P. J., Williamson, C. E., Zepp, R. G., et al. (2021). Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020. Photochemical & Photobiological Sciences. https://doi.org/10.1007/s43630-020-00001-x. See sections 7.8 to 7.11 for Trifluoroacetic acid (TFA).
UNEP Environmental Effects Assessment Panel Summary Update 2020 for Policymakers available at Environmental Effects Assessment Panel (EEAP) | Ozone Secretariat (unep.org)
TFA Drinking water guidance value in Germany EFCTC Newsletter item from March 2021 IN BRIEF: TFA DRINKING WATER GUIDANCE VALUE IN GERMANY – Fluorocarbons
Trifluoressigsäure (TFA)–Gewässerschutz im Spannungsfeld von toxikologischem Leitwert, Trinkwasserhygiene und Eintragsminimierung. Erläuterungen zur Einordnung des neuen Trinkwasserleitwerts von 60 μg/L.
20. Oktober 2020. Umweltbundesamt www.umweltbundesamt.de
UNEP Ozone Secretariat, Ecological Issues on the feasibility of managing HFCs: Focus on TFA Inter-sessional informal meeting, 12-13 June 2015 Informal Brief on Ecological Issues on HFCs June 2015 see EFCTC Learn about TFA from HFCs HFOs.pdf
IPCC/TEAP Special Report: Safeguarding the Ozone Layer and the Global Climate System Chapter 2
World Meteorological Organisation (2010): Global Ozone Research and Monitoring Project—Report No. 52. Chapter 1
Available at: https://www.wmo.int/pages/prog/arep/gaw/ozone_2010/documents/Ozone-Assessment-2010-complete.pdf
Environmental Risk Assessment of Trifluoroacetic Acid, Jean Charles Boutonnet et al; Human and Ecological Risk Assessment 5(1):59-124 · February 1999, available at https://www.researchgate.net/publication/254217782_Environmental_Risk_Assessment_of_Trifluoroacetic_Acid
Norwegian Environment Agency, 2017, Study on Environmental and Health Effects of HFO Refrigerants, Norwegian Environment Agency Report No. No. M-917|2017, Oslo, Norway,
[1] EFCTC Learn about environment & breakdown products: Fluoride in the Atmosphere: A very small contribution from HFCs, https://www.fluorocarbons.org/wp-content/uploads/2020/07/EFCTC_Learn_about_Fluoride_in_atm_small_HFC_contribution.pdf.
Papers on use of HFO-1234yf
- Henne, S.; Shallcross, D. E.; Reimann, S.; Xiao, P.; Brunner, D.;O’Doherty, S.; Buchmann, B., “Future emissions and atmospheric fate of HFC-1234yf from mobile air conditioners in Europe”, Environmental Science and Technology, 2012, 46, 1650−1658.
- Luecken, D. J.; Waterland, R. L.; Papasavva, S.; Taddonio, K. N.; Hutzell, W. T.; Rugh, J. P.; Andersen, S. O., “Ozone and TFA impacts in North America from degradation of 2,3,3,3-tetrafluoropropene (HFO-1234yf), a potential greenhouse gas replacement”, Environmental Science and Technology, 2010, 44, 343−348.
- Papasavva, S.; Luecken, D. J.; Waterland, R. L.; Taddonio, K. N.; Andersen, S. O., “Estimated 2017 refrigerant emissions of 2, 3, 3, 3-tetrafluoropropene (HFC-1234yf) in the United States resulting from automobile air conditioning”, Environmental Science and Technology, 2009, 43, 9252−9259.
- Kazil, J.; McKeen, S.; Kim, S. W.; Ahmadov, R.; Grell, G. A.; Talukdar, R. K.; Ravishankara, A. R., “Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO-1234yf”, J. Geophys. Res.-Atmos. 2014, 119, 14-059−14-079.
- Wang, Z.; Wang, Y.; Li, J.; Henne, S.; Zhang, B.; Hu, J.; Zhang, J., “Impacts of the Degradation of 2,3,3,3-Tetrafluoropropene into Trifluoroacetic Acid from Its Application in Automobile Air Conditioners in China, the United States, and Europe”, Environmental Science and Technology 2018, 52, 2819−2826.
- Liji M. David, Mary Barth, Lena Höglund-Isaksson, Pallav Purohit, Guus J. M. Velders, Sam Glaser, and A. R. Ravishankara, “Trifluoroacetic acid deposition from emissions of HFO-1234yf in India, China, and the Middle East”, Atmospheric Chemistry and Physics, 21, 14833–14849, 2021