Although they are essential for many sectors, PFAS molecules constitute an environmental problem. Therefore, some of them will be subjected to use prohibitions or limitations. Thinking about alternative solutions since now is undoubtedly a shrewd choice.
At the ATMOsphere (ATMO) Europe Summit 2024 Conference held at the end of November in Prague, a new interest group was launched – the Coalition for PFAS Free Cooling & Heating. They will focus on the promotion of HVAC&R cooling and heating technologies that use natural refrigerants and PFAS-free technologies. On its web page – http://pfasfreecoolingheating.eu – it defines itself as “a coalition of farsighted companies”. Why farsighted? But, especially, why the need for such a coalition?
PFAS, forever and everywhere
The answer to these questions was given during the above-mentioned conference in Prague, during which a whole morning was dedicated to the issue of PFAS molecules and, in particular, to one of them: TFA or trifluoroacetic acid.
PFAS or perfluoroalkyl and polyfluoroalkyl substances constitute a large family of thousands of chemical synthetic substances widely used in society. They find uses in a very broad array of consumer products and industrial applications, which range from food packages to clothing, from electronics to aviation and firefighting foams. They are appreciated for their capability of rejecting both grease and water, as well as for their high stability and resistance to high temperatures, due to their carbon-fluorine bond. However, this bond — one of the strongest in organic chemistry — is also responsible for their extreme persistence in the environment, reason for which they are labelled as “forever chemicals”.
One molecule, in particular, is a source of concern for the scientific world: TFA, perhaps the smallest in the whole family of PFAS. It is a highly mobile, and at the same time persistent, substance. It is formed as a degradation product of PFAS molecules containing at least one trifluoromethyl group (CF3). They are used in large quantities especially as plant protection products, refrigerant gases and propellants. Biocides, drugs and numerous industrial chemical products can release TFA.
Why is TFA causing concern?
TFA causes concern precisely owing to its mobility, which makes it a ubiquitous substance nowadays. In Switzerland, for instance, TFA is widely present in groundwaters. Its concentrations are 100-1000 times higher than the ones of the other PFAS molecules detected until now in groundwaters. As persistent artificial substance, TFA pollutes groundwaters in the whole Country and, according to the present knowledge, it is by far the most diffused artificial chemical substance in groundwaters[1].
In Germany, a wide-ranging monitoring on over 16,000 analysis points spread on the whole nation detected that “the substance has been found in groundwaters in 76% of monitoring sites and then almost everywhere. These results represent an important challenge, because the substance can be hardly removed technically during the water treatment”[2]. Contaminations of waters, of the soil and of plants have been found also in the United States, in China and even in Artic ices. Traces of TFA have been detected in the blood and in urines of people who live in distant places one another[3]. This means that currently the TFA has entered the food chain and, since – as explained during the already mentioned conference by prof. Michael Kauffeld, University of Karlsruhe – the halving time of TFA in the organism is 16 hours, this implies that, if continually assumed through drinking water or foods, its accumulation in the organism can take place.
A problem, because current scientific studies[4] have demonstrated that the exposure to determinate PFAS levels can cause:
- Adverse effects on reproduction, such as reduced fertility or increased blood pressure in pregnant women.
- Effects or delays in the child development, including low birth weight, accelerated puberty, bone changes or behavioural changes.
- Increased risk of some cancers, including prostate, kidney and testicular cancers.
- Reduced ability of the body’s immune system to fight infections, including a reduced response to vaccines.
- Interference with the body’s natural hormones.
- Increased cholesterol levels and/or risk of obesity.
In other words, these are not harmless molecules to health. It is no coincidence that these molecules are being dealt with by ECHA, the European Chemicals Agency that, following the restriction proposal presented by the national authorities of Denmark, Germany, the Netherlands, Norway and Sweden, is considering a possible ban on these molecules on a European scale.
TFA and refrigerants
Why does the question concern the HVAC&R sector? Because, as clearly explained in a document[5] signed by over 150 scientists who have worked with these molecules for years and know well characteristics, also fluorinated gases must be included in the PFAS class, because many of them persist in the environment or they decompose into trifluoroacetic acid TFA. The signatories of the mentioned document state: “We are concerned because TFA has been detected more and more frequently in people and drinking water all over the world”. Scholars affirm that the low global heating potential of some fluorinated gases does not justify their exclusion from the family of PFAS and they must be treated as such.
Concerning specifically the TFA, numerous studies have accumulated and demonstrate its important increase in ecosystems after the introduction of some HFO molecules used as refrigerants. It seems, in particular, that 1234yf can be a “good” precursor of TFA, much more powerful than R134a that it replaces in the mobile conditioning. Among the studies that indicate a worrying increase of TFA owing to the adoption of new refrigerants, we mention here the one dated October 2024 by Arp and colleagues[6] who publish an interesting comparison about the concentrations of TFA detected in various media before 2010 and after 2010. The graph (FIGURE 2) clearly shows an important rise of the TFA in the last decades in whatever media you look for it. The reason? According to scholars, the massive introduction of state-of-the-art refrigerants such as HFO, many of which would be precisely precursors of TFA.
Concerning this, the scientific literature has produced numerous documents about the fact that already today some fluorinated gases are a significant source of PFAS emissions, making up 63% of all PFAS emissions. These gases constitute over 70% of the global market of refrigerants. Inside this category, the use of HFO is constantly rising, having grown from 6% to 24% of the total volumes of fluorinated gases from 2016 to 2019. There is a list of single-component refrigerants defined as PFAS, which are R-125, R-134a, R-143a, R-1234yf, R-1234ze(E), R-1336mzz(E), R-1336mzz(Z), R-1224yd and R-1233zd(E)[7]. If we consider all the compounds that contain these refrigerants, it is evident that the vast majority of the refrigerants currently in use is strongly concerned by the proposal of PFAS restriction.
Not only refrigerants
Not only refrigerants are concerned by the restriction proposal, even if, owing to their nature and the fact they can escape in the ecosystem, refrigerants are the most looked after part. However, in the cold and heating sector there are other components that contain PFAS molecules. PFAS, for instance, are used in the electronics production process, as additives for lubricants, as photosensitizers to enhance the photosensitivity or as heat transfer fluids for immersion cooling or chemical vapour deposition. Sealing applications represent a critical use of fluoropolymers in the RACHP industry, where their unique properties – such as the chemical resistance, the temperature stability and the low friction – are indispensable to assure the duration, the safety and the efficiency of compressors and of RACHP systems. The bearings made with fluoropolymers like PTFE are fundamental to decrease the friction and the wear in compressors, granting the energy efficiency and a long duration of the system, even in harsh conditions such as the reduction of the oil viscosity caused by refrigerants.
The insulation of cables and wirings with materials like PTFE and FEP (PFAS) is essential for the safety and the reliability of internal electrical components, since it offers high electrical resistance, low flammability and an excellent duration in challenging environments.
Electronic components, such as printed circuit boards and condensers coated by fluoropolymers, offer a critical resistance to chemical agents and to temperatures, ensuring the reliability of HVAC&R control and monitoring systems.
In RACHP solutions that operate under extreme condition, including high pressures, temperature fluctuations and the exposure to chemical substances, nowadays PFAS-based materials play a very important role in overcoming these challenges[8].
PFAS-free HVAC&R?
The proposals of restriction to the use of PFAS might lead to the ban of many HFC and HFO refrigerants, as well as of many fluoropolymers used in a series of critical components for the refrigeration. Are there any alternatives for the HVAC&R sector? As far as refrigerants are concerned, the main alternatives to the molecules containing or generating PFAS are natural refrigerants, R-32 and R-152a. However, the restriction proposal proposes some exemptions for refrigerants. There might be, for instance, some exemptions for the temperature refrigeration under -50°C, for test equipment and lab measuring, refrigerated centrifuges, maintenance and recharging of existing HVAC/R appliances released on the market previously and for which no drop-in alternatives exist, and HVAC/R appliances in buildings where the national safety standards and building codes prohibit the use of alternatives.
For components other than refrigerants, alternative PFAS-free solutions are being developed. For the vast majority of uses in electronics, for instance, in semiconductors and in O-Rings, PFAS-free alternatives are the ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR) and hydrogenated nitrile butadiene rubber (HNBR), which are already used. OLAB Italian company at Torbole Casaglia (BS), for instance, manufactures O-Rings in EPDM, 100% PFAS-free.
Industry has not all solutions, yet, to meet a fully PFAS-free technology and at present PFAS are fundamental in many applications. However, also industry is convinced that, along next years, new solutions will be found, feasible alternatives also minimizing emissions, taking into account the possible restrictions and the concern that will emerge among consumers. For this reason, those who already today work at PFAS-free solutions may be defined farsighted, because they aim at solutions protected from any possible prohibition, precisely like those who some years ago started investing in natural refrigerants for their solutions and their customers, today being able to offer “timeless solutions”.
TFA: a global problem?
As already said, among all PFAS, the trifluoroacetic acid (TFA) is a particularly persistent and mobile substance, whose concentration has increased in several environmental media, including rainwater, soil, human blood, plants, the foods of vegetal origin and drinking water. Currently, TFA concentrations are higher by orders of magnitude than those of other per- and polyfluoroalkyl substances (PFAS). This accumulation is due to the fact that many PFAS have TFA as transformation product, including various fluorinated gases (F-gases), pesticides, drugs and chemical industrial products, besides the direct release of TFA produced industrially. Owing to the extreme persistence of TFA and continuous emissions, concentrations are increasing irreversibly. Moreover, TFA and other PFAS do not seem to be harmless either for the human health or for animals and the ecosystem. Due to all these trends and characteristics, many scholars affirm that TFA satisfy the criteria to be considered a menace on a planetary scale, owing to the rising exposure at planetary level, where potentially irreversible impacts on the vital processes of the earthly system might occur. The rational answer to this situation is the start of binding actions to reduce the emissions of TFA and of its numerous precursors.
A “Protocol of Montreal” for PFAS and TFA?
A recent publication entitled “Scientific Basis for Managing PFAS as a Chemical Class” [9] concludes that the combination of high persistence, accumulation potential, mobility and known and potential damages of the thousands of PFAS (per- and polyfluoroalkyl) substances identified until now justifies their management as a single class of chemical substances. The existing scientific evidences justify a regulatory approach of global type for PFAS, because the common negative effects are already documented for many compounds. Waiting for exhaustive data for every substance – as some parts suggest – would just allow the creation of further harms, considering that the PFAS pollution is often irreversible.
It seems a “Deja Vu”. In 1987 the protocol of Montreal considered CFC and HCFC (and today also HFC) as a single class of molecules because of the same negative effects caused to the environment – the ozone hole and today the climatic change. These molecules were everywhere, they cumulated and even if they were different one another – mainly for their uses – they were treated as a single class. We know the result: 198 Countries joined and the result was global. What if something similar was necessary for PFAS, too?
Then: farsighted, why?
The Coalition for PFAS Free Cooling & Heating is farsighted because it anticipates a crucial transition in the HVAC&R (heating, ventilation, air conditioned and refrigeration) sector towards more sustainable solutions, from different points of view:
- Ecologic prospect: supporting PFAS-free technologies demonstrates attention to future generations and to the environment;
- Regulatory prospect: global regulations are becoming stricter and stricter about PFAS. This coalition puts itself at a competitive advantage over emerging regulations, such as bans on their use.
- Technological prospect: investing in natural refrigerants and alternative technologies demonstrates an innovative approach, in conformity with the market requirements and fighting against climatic changes.
Why the need for a PFAS-free coalition?
The use of PFAS in HVAC&R systems represents a significant problem for the pollution of soil, waters and for human health. Promoting alternatives is a urgent answer to this challenge. The coalition aims at raising the awareness and at supporting industry in the adoption of PFAS free refrigerants. A coalition joins the forces of different companies, creating a more significant impact than individual efforts. Many operators in the sector are not fully aware of the implications connected with PFAS. The coalition may act as a guide to spread knowledge and to speed up the change.
[1] https://www.bafu.admin.ch/
[2] https://www.umweltbundesamt.de/en/publikationen/reducing-the-input-of-chemicals-into-waters
[3] https://pubs.acs.org/doi/full/10.1021/acs.est.2c06715
[4] https://www.epa.gov/
[5] https://drive.google.com/file/d/1YLB2zvWG5Ez6VeMqqbw77LpVEj0JTj1H/view
