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As detailed previously in first three parts of this series of articles, we have seen that the perfluorochemicals have a long history spanning more than 50 years and are far more complex than just considering PFOS, PFHxS and PFOA. Rather there are literally thousands of perfluorochemicals used in industry and commerce and focusing solely on a few named structures is unhelpful and a form of ‘tunnel vision’.

Currently there have been strong arguments put forward to treat PFAS as a class of chemical compounds, rather than as individual compounds each requiring the assessment of risk [Kwiatkowski et al (2020)], as a means of countering the disadvantages of concentrating on a few named PFAS. In seeking to regulate PFAS use the concept of ‘essential uses’ has been proposed by the Cousins group [Roy et al. (2022); Figuiére et al. (2023)].

Independent academic and regulatory interest in this class of compounds was virtually non-existent, with some notable exceptions, until the 3M Company announced in May 2000 that it was phasing-out all PFOS-based chemistry replacing it with PFBS chemistry (perfluorobutane sulfonic acid, the C4 homologue of PFOS). A notable exception which was highly relevant to understanding environmental contamination caused by AFFF foams was work published by Jennifer Field and her colleagues at Oregon State University around the same time or shortly after 3M announced its withdrawal from PFOS chemistry and foam manufacture [Moody et al. (2000); Schultz et al. (2004)].

Investigative activity concerning this class of compounds started shortly after the 3M announcement in May 2000. At first most of the contributions were from the industry itself or from groups funded by the industry. It was in the late 2000s that the independent scientific community realized that there were far more that needed investigating about the impact of PFAS both on human health and the environment, with the result that the number of peer-reviewed publications increased exponentially..

Publications concerned with PFAS in the run-up to May 2000 were only in the range of 5-10 per year. After May 2000 these increased to around 50 per year and have increased exponentially since now reaching ~1000/year, frequently associated with a parallel increase in articles on microplastics [Bakhshoodeh and Santos (2022)], from whom Figure 2(b) is taken.

Published studies on the scale of environmental by PFOS and PFOA were scarce before 2001, until Giesy and Kannan [Giesy and Kannan (2001) and subsequent papers] reported global presence of PFOS in wildlife, with Hansen et al. finding PFOS and PFOA downstream from a manufacturing facility on the Tennessee River [Hansen et al. (2002)], as well as in biological matrices using mass spectrometry [(Hansen et al. (2001)].

Although contamination of human blood samples with organofluorine chemicals not present in stored blood taken before fluorochemical manufacturing began had been reported some years earlier since the 1960s [Taves, D.R. (1966, 1968)] with Guy et al. (1976) reporting the presence of fluorochemicals in human plasma using NMR spectroscopy, tentatively identifying PFOA as the fluorochemical used in Scotchgard® as blood contaminant [Guy, W.S. et al. (1976)]. Although there was initial confusion whether this fluorochemical was indeed PFOA or PFOS, as a result of obfuscation and a refusal to identify PFOS by 3M, it was not until 25 years later that Hansen et al. (2001) reported that samples of human plasma contained PFOS (average 28.4 ng/ml), PFHxS (average 6.6 ng/ml) and PFOA (average 6.4 ng/ml), confirming Guy and Taves findings.

A lawsuit filed in 2010 by the Attorney General of the State of Minnesota against the 3M Company revealed that the company knew these chemicals were accumulated in human blood for more than 40 years and were toxic [Lerner (2018); Swanson (2019)].

Until about 2004 the scientific literature was dominated by papers from authors working directly for 3M or funded by the industry. Post 2004 there has been an exponential explosion of independent published work concerned with PFOS, PFOA and other PFAS, to the extent that these organofluorine compounds have been labelled ‘emerging contaminants’. PFAS have emerged as contaminants of concern for at least a decade. The current situation is that although we now know a considerable amount about the environmental distribution, fate and toxicity to biota of PFAS, it is the technology for the remediation and disposal of these highly persistent materials that should be regarded as ‘emerging science’.

As said before, we are not only talking of a few substances, but about a whole family of at least 6000 different perfluorocompounds which have been classified for at least one environmental, human health and/or physicochemical endpoint in the ECHA database. At the UN Stockholm Convention Persistent Organic Pollutants Review Committee meeting in Rome (POPRC-14) an indicative list of PFOA-related substances contained 4,700 entries.

Human health endpoints are considered of major importance for long-term exposure: carcinogenicity ©; mutagenicity (M0; reproductive toxicity (R); lactation effects (L) and specific organ toxicity (STOT). 388 PFAS have at least one of these five endpoints, of which 44 are registered in harmonized classification.

With regards to environmental hazards, 1129 PFAS have been registered by self-classification; most of them counting as both (M) mobile and/or very persistent (vP).

Under the EU chemicals legislation (REACH and ECHA) the risks posed by PFAS are classified using the PBT system indicating persistence (P or vP), bio-accumualation (B or vB), and toxicity (T). Recent proposals from the German Federal Environment Agency (UBA) also stress the importance of mobility (M or vM) especially for PFAS in view of their vP and vM properties [Arp et al. (2023)]. Chemicals may also be identified as Substances of Very High Concern (SVHC) under REACH EC1907/2006 if they have serious and often irreversible effects on human health or the environment. A recent example is perfluorononanoic acid or PFNA, a PFAS that is becoming more commonly found as a contaminant. In Europe there has been far more concern with individual components of the PBT classification whereas in the United States persistence on its own with accompanying toxicity is seen as less of a problem.

Persistence

PFAS or their perfluorinated degradation products are among the most chemically and physically stable organic compounds known. Their perfluorinated carbon chains resist environmental and metabolic degradation due to the very stable C-F bonds. For example, tetrafluoromethane, CF4 and the simple perfluorocarbon, has an estimated atmospheric half-life of ~50,000 years with a high global warming potential (GW) [Mühle et al.(2010)].

Commercially available perfluoro compounds are designed to degrade rapidly once released into the environment yielding PFCAs, PFECAs and PFSAs. Unfortunately, this has led in the past to totally spurious and misleading claims made by the industry especially in the United States that these materials are ‘biodegradable’ based on degradation of the non-fluorinated functional group and the OECD rule that a substance if ‘readily biodegradable’ if degradation reaches 60% (OECD 301B, D and F) or 70% (OECD301A and E) within 28 days. This does not mean that the PFAS, for example in firefighting AFFF, is completely biodegradable as the COD method using acid dichromate for the oxidation measurement to give the 100% level totally fails to account for any perfluorinated material present. Regrettably end-users have often assumed or been led to believe by salesmen, and perpetrated as a myth by certain manufacturer [Swanson, 2019], that ‘readily biodegradable’ means total degradation. As pointed out earlier it makes sense, however, to group all PFAS as non-degradable according to their stable degradation end-products.

Breakdown of the precursors often leads to the formation of PFAS intermediates and ultimate degradation products with increased mobility in water and/or air via oxidative chemical and biochemical degradation processes in the environment.
Lifetimes of the PFAS in the environment greatly exceed the criteria for very persistent (vP) substances in Annex XIII to REACH. If PFAS do degrade, they do it so slowly that it is not observable in standard tests. The extreme persistence of PFAS and their continued use leads to sustained exposure and increasing concentrations in all environment compartments. PFASs will remain in the environment for very long time, even if releases are minimized. Increasing or legacy contamination of the environment will increase the likelihood that known and unknown effects will occur on a generational timescale. This should invoke the application of the Precautionary Principle [Rio 1992; Preston, 2017] to any further dispersive use of PFAS.

Scientists pointed out in the Helsingør Statement on PFASs [Scheringer et al., 2014] as well as in the Madrid statement [Blum et al., 2015] that very high persistence on its own presents a problem and have named this the “P-sufficient approach” to regulatory action. Persistence alone justified the regulation of PFAS as a class in California [Balan et al., 2021].

Long range transport potential (LRTP)

PFAS can be transported by air, water and matrices to which they are adsorbed or absorbed, such as dust, sediments, marine aerosols, oceanic currents, atmospheric, migratory animals, or through matrices in which they are included as additive such as microplastics. Because of their remarkable resistance to degradation, this leads to global dispersion of PFAS over long distances from the point of release. It has been estimated, for example, that for volatile PFAS such as fluorotelomer alcohols in the upper atmosphere that global circulation times can be short as 7-10 days. The historical spread through LRTP of PFAS through deposition and contamination in the Arctic is well documented [Wilson et al. (AMAP) Secretariat, 2017].

The Inuit population in the Arctic has been reported as being some of the most contaminated humans on the planet as the PFAS concentrations in their blood is much higher than the average value for the general population. Being so far removed from any industrial source of PFAS, this contamination has been attributed mainly to their diet, which based on fish, polar bear and seal meat, with an impact on the immune response [Sonne et al., 2023].

Thus, PFAS contamination of the environment and biota is not limited geographically just to the source of the pollution but becomes widespread on a global scale due to dispersive use such as in firefighting foams, poor waste disposal techniques or industrial production, compounded by long-range transport in the atmosphere and oceans.

Mobility

It is generally considered that substances with moderate to high solubility in water associated with low adsorption potential have a high mobility in the aqueous environment. Various studies have shown that PFAS have a different behavior depending strongly on carbon chain length and on functionality.

As shown in the figure below shorter chain-length PFAS are associated with higher environmental mobility, water solubility and volatility, as well as lower toxicity and bio-accumulation potential than longer chain-length PFAS. The combination of extreme persistence and high mobility in the aqueous compartment and soils, especially for the shorter chain PFAS such as PFPeS and PFBS, leads to contamination of drinking water aquifers and rivers as well as uptake into the food chain – fish, plants and livestock.

Accumulation in plants

A recent review article on exposure routes, bio-accumulation and toxic effects of PFASs on plants shows that bio-accumulation processes of PFASs in plants highly vary because of the complexity of PFAS chemistry [Li et al., 2022].

Whereas short-chain PFASs typically accumulate in above-ground plant parts such as leaves, long-chain PFASs accumulate in roots and show lower translocation factors to the above-ground plant parts. This is influenced by the higher water solubility, lower molecular size and lower hydrophobicity of the short-chain PFASs. Studies also indicate that the short-chain PFCA are more effectively taken up by plants than the long-chain PFCA [Felizeter et al., 2014; Yoo et al., 2011].

Consumption of plant material, e.g., grains and vegetables either as roots or above ground plant parts such as leaves or stems, function as a source of PFAS for both humans and animals.

Bio-accumulation and Bio-magnification (tropic magnification)

Under REACH, C11-C14 PFCAs and C6-PFSA have been shown to fulfil the vB-criterion and C8-C10-PFCA the B criterion.

Studies with mammalian species show that PFASs are readily absorbed and distributed across various tissues and that some PFAS (particularly the long-chain PFAS) have long half-lives in organisms, especially in humans where half-lives are of the order of years. Studies show that PFAS binding to albumin and transporter proteins efficiently distributes PFASs into different tissues, and enhances passage across both brain and placental barriers, with transfer to neonates via breast milk. Because of their hydrophobic and oleophobic properties PFAS do not follow typical accumulation patterns, like partitioning into adipose tissue, but rather bind and accumulate in protein-rich organs like liver.

PFASs accumulate more in air-breathing organisms as compared to gill breathing- organisms, because unlike the latter, air-breathers cannot readily eliminate PFAS by passive diffusion. Thus, established methods of bio-accumulation testing in aquatic organisms do not function adequately as methodology for PFAS bio-accumulation assessments in air-breathing species such as man, Unfortunately, laboratory bio-accumulation data are very limited for air-breathers.

Short-chain PFASs are more readily excreted by urinary excretion in air-breathing organisms and tend to be less bio-accumulative, while bio-accumulation potential usually increases with perfluoroalkyl chain length. In general, BCFs and BAFs of PFASs with 8 or more carbons increase uniformly with increasing number of carbons in the alkyl chain, with highest bio-accumulation potential seen for compounds with 12 to 14 carbon-chain length.

Due to these properties, many PFASs accumulate in air-breathers, and long- chain PFASs bio-magnify in marine and fresh-water food webs, reaching high levels in top predators including humans and vulnerable species. This increase in contamination seen as one ascends the food chain is known as trophic magnification and is well established for aquatic species and predators that feed off them. It is noted that consequently this may negatively affect the recommendations related to consumption of meat and/or entrails of certain animals. A a top marine predator guillemot eggs are particularly high in PFAS.Field studies on long- and short-chain PFASs that can be analytically distinguished demonstrate that PFAS

(primarily PFBA, PFBS, PFHpA, PFHxA, PFHxS, PFOS, FOSA, 6:2 FTOH, F-53B, 6:2 Cl-PFESA, TFA, and C9-C11 PFCAs) are found globally throughout the environment in mammals, birds, fish and other vertebrates. In conclusion, and considering the increasing lines of evidence from modelling, laboratory and monitoring studies, there is a justifiable rising level of concern for a subset of PFAS being bio-accumulative while large uncertainties remain for the majority of compounds due to lack of data.

Effects on human health

A vast amount of literature has been published on the health effects of PFAS, especially for PFOA and PFOS. In humans, many perfluoroalkyl acids (PFAA) are readily absorbed by inhalation or ingestion orally, while less is known regarding absorption after dermal exposure. Many PFAA bind to proteins and are thus distributed to protein-rich tissues including liver, kidneys, and blood. Estimated human elimination half-lives for PFAAs range from a few days (PFBA) and months (PFHxA, PFBS) to a few (2-8) years (PFOA, PFNA, PFDA, PFHxS, PFOS), or to >10 years for PFUnDA. Half-lives are much shorter in rodents than in humans and differences in half-lives between sexes is often observed. Consequently, the observed toxicity in rodents underestimates the toxicity to humans. PFAA are mainly excreted via urine and faeces and thus are released to the environment. PFAA have a marked potential for bio-accumulation in humans as shown by the long half-lives and protein-binding.

The European Food Standards Agency (EFSA) extensively reviewed the epidemiological evidence for association between PFAS exposure and adverse effects in humans [EFSA, 2018; EFSA, 2020]. EFSA concluded that increased serum levels of various PFCA and PFSA provoked a reduction in the immune response to vaccination [Grandjean, 2012], increased propensity of infections, increased serum cholesterol, increased serum alanine transferase (ALT) and reduced birth weight. The association with immune effects was considered the most sensitive endpoint in humans (supported by data from experimental animals) and based on this EFSA has established a Tolerable Weekly Intake (TWI) of 4.4 ng/kg body weight/week for the sum of PFOA, PFOS, PFNA and PFHxS [EFSA, 2020].

Experimental animal studies across different groups of PFAS demonstrate that liver, kidney, thyroid, the immune system, and reproduction are major targets for PFAAs’ toxicity. In rat studies, the most consistent effects included enlarged liver, hepatocellular hypertrophy, increased serum ALT, increased kidney weight, reprotoxicity, effects on the lymph system, and decreased serum thyroid hormone levels. In particular liver effects have been observed for most PFAA for which animal studies are available. For PFOS, PFOA, PFNA, and PFDA and their salts this has resulted in harmonized classifications for carcinogenicity (Carc. 2), reproductive toxicity (Repr. 1B), lactation effects (Lact.) and specific target organ toxicity – repeated exposure (STOT RE 1, except for PFDA).

Cumulative effects of co-occurring PFAS

Many different PFAS co-occur in the environment, drinking water, food, and in human blood. Many PFAS exhibit similar effects, such as effects on the liver, kidney, thyroid, serum lipids, and immune system. Accordingly, an assessment of hazards and risks taking into account such combined exposure would reflect exposure conditions more realistically than single compound assessments.
Due to the immense number of PFAS and the lack of toxicological data for the vast majority of them, a combined assessment for all PFASs is unattainable. It is emphasized at this point that combined exposure to different PFASs affecting the same target organs may result in combined more than additive effects, i.e., synergism, making the exceeding of thresholds or limit values more likely than for assessment for individual substances on their own.

CONCLUSION

PFAS are very Persistent (vP) and many are also very Bioaccumulative (vB). Long-range transport processes (LRTP) results in planetary contamination including remote regions such as the Arctic.
Cousins et al. have recently introduced the concept of having already exceeded the ‘planetary boundary’ indicating that global environmental concentrations for PFAS already exceed tolerable sustainable levels [Cousins et al., 2022]. This should be treated as a warning against continuing use and release of PFAS to the environment, especially from dispersive applications such as AFFF firefighting foam.

The permanent presence of PFAS in human blood indicates the level of continued exposure of the general population. PFAS are present in drinking water and in food stocks. Hundreds of scientific studies have highlighted the long-term toxicity of PFAS, effecting the liver, kidneys, thyroid and immune system. The ubiquitous presence of PFAS in human blood and other species worldwide highlights the dangers associated with continued manufacturing and use in industrial and consumer products of extremely persistent organic pollutants which are totally anthropogenic in origin, not occurring naturally.

This schema summarizes all possibilities for PFAS to contaminate the environment and living beings including humans.

References

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Bakhshoodeh, R., and Santos, R.M. (2022) Comparative bibliometric trends of microplastics and perfluoroalkyl and polyfluoroalkyl substances: how these hot environmental remediation research topics developed over time. RSC Advances 12, 4973-4987.

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Grandjean, P., Andersen, E.W., Budtz-Jørgensen, E., Nielsen, F., Mølbak, K., Weihe, P., and Heilmann, C. (2012) Serum vaccine antibody concentrations in children exposed to perfluorinated compounds. JAMA 307(4), 391-7.

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Our sister company 3F MEXICO were present at the professional show EXPO FIRE in Mexico City on the 27th and 28th of August 2024.
The event was a great success and our sales team presented our catalogue of products to more than 250 companies. Some specific products, such as our Fluoro-Free foam FREEGEN, the manikins from RUTH LEE and our automatic systems of extinction KIZENITH for kitchen fires, raised a large interest.

In Part 2 of this series of articles we dealt with Class A foams and the chemistry of legacy Class B AFFF products manufactured using the Simons process of electrochemical fluorination (ECF). In this part current AFFF formulations using fluorotelomers are discussed, which have been manufactured by manufacturers like DuPont, Dynax, Ciba Geigy, Elf Atochem, Daikin, Asahi Glass, Clariant, etc.

Fluoro-telomerisation:

By contrast with the Simons ECF process which produces a mixture of branched and linear isomers with odd and even carbon chain length, fluoro-telomerisation yields almost exclusively linear even-numbered carbon chains (Vyas et al 2007 [3], determined by the starting telogen, i.e. perfluoroethyl iodide (C2F5I) or perfluorobutyl iodide (C4F9I), that is containing carbon chains N, N+2, N+4, N+6, etc.

Telomerisation involves the free radical addition of tetrafluoroethylene (CF2=CF2), the taxogen, to an alkyl iodide, the telogen, such a perfluorobutyl iodide (C4F9I) as shown below. The perfluorinated chain is then terminated with a dimethylene group, -CH2-CH2-, characteristic of end-product fluorotelomers.

Source: Buck et al (2011)

The starting material is the perfluoroalkyl iodide, whereas the reactive end-product fluorotelomer iodide is used to manufacture a range of end products, e.g., fluorotelomer alcohols, thiols, sulfonic acids and sulfonamides.

Understanding chain length distribution synthesized during telomerisation to yield fluorotelomer iodide is important. Telomerisation produces a homologous series of products with chain lengths consisting of evenly spaced perfluorocarbon units, for example, 4:2, 6:2, 8:2, 10;2, 12:2, 14:2, etc. (N:2 indicates N perfluorinated carbons attached to a non-fluorinated two-carbon unit -(CH2)2-. This is then purified by fractional distillation yielding a fraction containing the shorter chain lengths, i.e., C4-C10 mainly consisting of C6/C8, which has been used mainly for firefighting foams, and longer chain lengths >C8 used for fabric, textile, leather and paper treatments. Other structural variants on the telomer process have occasionally been used by individual manufacturers, including the use of a three carbon spacer, -(CH2)3-, instead of a two carbon unit.

Post the 2010-2015 PFOA Stewardship Program considerable efforts by the fluorochemical industry have managed to reduce the 8:2 fluorotelomer content of the precursor used for firefighting foams to less than 25ppb, as this can act as a precursor for PFOA through breakdown. Early products used to make the fluorosurfactants for formulating firefighting foams were actually a mixture of mainly C6/C8 perfluorinated chain lengths, i.e., 6:2 and 8:2. Modern fluorotelomer foams are now predominantly 6;2 and 4:2 and referred to in the industry as ‘’pure C6’’.

Unfortunately, but predictably, replacement of C6/C8 formulations with ’pure’ C6 fluorotelomers resulted in loss of foam performance which in turn required the use of higher fluorosurfactant concentrations, itself undesirable from an environmental point of view.

Compositions of six foams ~2005-2010. Data from Backe, Day & Field 2013

Fluorotelomer Intermediate Homologue Distributions

Source : DuPont

Perfluoro compounds are used in firefighting foam to lower surface tension enabling film-formation on many hydrocarbon fuels except those shorter than iso-octane such as hexane or pentane; to provide excellent heat and chemical resistance; to increase hydrocarbon repellency and thus to resist to solvent contamination or ‘f’uel pickup’’; to provide effective vapour suppression.
Manufacturers offer a range of perfluorochemicals, most of them being fluorosurfactants. These surfactants are a combination of a hydrophobic and oleophobic perfluorinated tail and a polar head group giving functionality, enabling dispersion or solubilisation of the products in the foam concentrate. One of the most popular and efficient products was probably the C8:2 perfluorinated betaine surfactant together with its C6:2 homologue.

The starting material is the perfluoroalkyl iodide, whereas the reactive end-product fluorotelomer iodide is used to manufacture a range of end products, e.g., fluorotelomer alcohols, thiols, sulfonic acids and sulfonamides.

Class B Fluorine-Free Foams (F3) for liquid hydrocarbons and polar solvents

The development of fluorine-free foams (F3) was started in the late 1990s by Ted Schaefer working for 3M Australia. By the early 2000s the first operational fluorine-free firefighting foam, called RF-3 and RF-6 for Rehealing foam 3% and 6% became available. Queensland Fire Service went fluorine-free as early as 2003. Over the next decade or so fluorine-free foam technology greatly improved to the point that today F3 products are available on the market achieving or even in some cases exceeding AFFF performance, whilst offering better value for money. Early developments included Solberg Scandinavian buying the RF patents from 3M as well as Ted Schaefer’s expertise in 2007, as well as the development of F3 by Thierry Bluteau in 2002, then working for Bio-Ex France. In the late 2000s, Gary McDowall (3F Ltd, UK) also developed F3 products. Later on, 3F Ltd offered new F3 solvent-free, i.e., glycol free, thus greatly reducing the BOD-COD problem by around 40-60%. Other major manufacturers followed suite and today F3 firefighting foams are widely available on the market, with many major organisations in civilian and military aviation, oil and gas and petrochemical industries, as well as large municipal fire departments transitioning from fluorine-containing AFFF to fluorine-free F3 foams.

The transition has taken nearly 10-15 years, mainly due to built-in conservatism in many fire departments, but also because of the costs involved which include modifying or cleaning existing equipment, as well as the proper and expensive disposal of existing legacy stocks of AFFF. Another driving force, especially in the US, has been the increasing financial and legal exposure of continuing to use products which give rise to persistent and widespread environmental contamination.

The environmentally sustainable destruction of legacy AFFF stocks, often involving huge volumes of concentrate running to millions of litres, requires destruction methods that are highly efficient (> 99.999% DRE), capable of handling solid and liquid charges, do not further contaminate the environment, and are financially feasible. Methods that are currently available will be discussed in a further article.

Apart from using fluorocompounds for their exceptional physicochemical properties, firefighting foam contains a range of other chemicals which are necessary to achieve the extinction.

The main components found in firefighting foam with or without fluorosurfactants or fluoropolymers include the following:

Foaming agents:

(a)Some fluorosurfactants like PFOS and PFHxS and their functionalised derivatives, or fluorotelomer compounds such as 1157 (perfluoroalkyl betaine) or 1183 (perfluoroalkyl aminoxide) have been used occasionally to boost foam volume in AFFF foams.
(b)r A large range of hydrocarbon surfactants are widely used by manufacturers in all types of synthetic foams: AFFF, AFFF-AR, High Expansion, Class A and F3.
Synthetic surfactants: are made from hydrocarbon chain precursors (e.g., CH3(CH2)n-produced by the petrochemical industry from mineral oil and/or animal and plant fatty acids, which are then functionalized with a polar head-group to obtain the desired surfactant property, for example, octyl sulfonate, CH3(CH2)7SO3-, or dodecyl sulfate, CH3(CH2)11SO4-.

(c) Protein polymer: obtained from the hydrolysis of slaughterhouse waste ‘‘horn and hoof’’, this old-fashioned and polluting process consists of heating the raw material in highly alkaline media. The keratin is degraded into small protein fragments, followed by neutralisation and stabilisation. The concentrated end-product can be contaminated with haemoglobin from residual blood giving it a very characteristic dark brown colour. Under operational conditions protein foams are characteristically dark brown in colour with a highly distinctive smell especially when applied to a fire.

Foam stabilisers: most of them are glycol ethers. The most used are butyl glycol, butyl carbitol and hexylene glycol, and more recently ethyl or butyl propylene glycols. We can find too lauryl alcohol.

Anti-freeze agents: monoethylene glycol, (CH2OH)2, and mono-propylene glycol, CH2(CH2OH)2, are widely used, but manufacturers also use sodium chloride, urea, etc, in some formulations.

The glycols and glycol ethers present in foam formulations are at relatively high concentrations – typically 10-20% – and are the major contributors to the BOD/COD value.

Other additives: in this category formulators use preservatives, anti-corrosion products, buffers to stabilise foam pH, and chelating agents for ions that would degrade foam performance, all at levels below 1%.

Natural polymers: carbohydrate xanthan gum is a very common natural polymer used to give alcohol-resistance to the foam. Applied to a burning fuel surface, the polymer precipitates and chars forming a barrier which resists and prevents contamination of the foam blanket by fuel – ‘’fuel pickup’’. Other polymers and gums are also used, such as celluloses, alginates, guar, locust bean, or carrageenan.

The tables below summarise the main properties of principal ingredients used in formulations.

Currently, there are at least 12 different types or foam on the market, some of which have declined in the volume used over recent years.

Different users have different hazards associated with specific risks. In selecting the correct foam, it is important to do a suitable and sufficient assessment of these specific risks, ensuring that the foam chosen is ‘fit-for-purpose’, and then go through the following steps during procurement and operational use:

(a) list the equipment: whether this is fixed or mobile, i.e., tank farm, monitors or fire appliances;

(b) check the correct induction rate, e.g., 1%, 3% or 6%, for use;

(c) ensure that the application rate is suitable;

(d) determine the length of time that the foam should be applied, and the foam        blanket stability and when re-application is necessary;

(e) determine the availability of possible support from external sources, i.e,. reinforcement;

(f) be aware of the manufacturer’s warranty and specified operating conditions for the foam;

(g) consider local environmental regulations – both current and any likely

3F is a responsible manufacturer and will be pleased to assist any of its customers in the assessment of risks and selection of an appropriate foam and associated equipment.

To be continued in Part 4.

References

Benskin J.P., De Silva A.O., Martin J.W. (2010) Isomer Profiling of Perfluorinated Substances as a Tool for Source Tracking: A Review of Early Findings and Future Applications. Rev. Environ. Contam. Toxicol.:111-160.

Buck, R.C., Franklin, J., Berger, U., Conder, J.M., Cousins, I.T., de Voogt, P., Jensen, A.A., Kannan, K., Mabury, S.A., and van Leeuwen, S.P.J. (2011) Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins. Integr. Environ. Assess. Manag. 7(4), 513-541.

D’Agostino, L.A, and Mabury, S.A. (2014) Identification of Novel Fluorinated Surfactants in Aqueous Film Forming Foams and Commercial Surfactant Concentrates. Environ. Sci. Technol. 48(1):121-9.

Moe, M.K., Huber, S., Svensen, J., Hagenaars, A,. Pabon, M., Trümper, M., Berger, U., Knapen, D., and Herzke, D. (2012) The structure of the fire fighting foam surfactant Forafac®1157 and its biological and photolytic transformation products. Chemosphere 89(7), 869-875.

Naile, J., Garrison, A.W., Avants, J.K., and Washington, J.W. Isomers/Enatiomers of Perfluorcarboxylic Acids: Method Development and Detection in Environmental Samples. Chemosphere 44, 1722-1728.

Sasaki, T., Egami, A., Yajima, T., Uekusa, H., and Sato, H. (2018) Unusual Molecular and Supramolecular Strcuturs of Chiral Low Molecular Weight Organogelators with Long Perfluoroalkyl Chains. Crystal Growth and Design 18(7) 4200-4205.

In this part we deal with the chemistry involved in formulating Class A foams for carbonaceous fuels, and legacy Class B AFFF foams based on PFOS chemistry for liquid hydrocarbon and polar solvent fires.

In Part 1 of this series of articles we saw that AFFF firefighting foams contain various perfluoroalkyl substances (PFAS); however, firefighting foam is only one of many applications.
PFAS have been used for decades in more than 200 other industrial and domestic applications, such as food packaging, leather and textile treatment, carpet and clothing anti-stain protection, detergents, water-proofing and oil-proofing, paints and varnishes, printing inks, chromium plating, outdoor and protective clothing (PPE) for the emergency services and military. These perfluorinated substances are widely used as they offer a combination of unique properties, including the ability to repel water (hydrophobicity), the ability to repel oils (oleophobicity), the ability to reduce the surface tension of aqueous solutions to less than 20 dyne/cm and with it acting as detergents, emulsifiers, wetting agents, and dispersants.

The OECD (2021) has recently clarified the definition of what constitutes a PFAS, whilst acknowledging that given by Buck et al (2011), as follows:

“PFASs are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e. with a few noted exceptions, any chemical with at least a perfluorinated methyl group (–CF3) or a perfluorinated methylene group (–CF2–) is a PFAS.”

More than 800 products currently available in the marketplace have been identified, but the true list of PFAS used in commerce and industry is likely to be 10,000 or more; the UN Stockholm Convention has listed 4,700 substances related to PFOA alone. PFAS started to be manufactured in large quantities in the early 50’s. All of them are anthropogenic created by humans using chemical synthesis. They do not exist naturally. Their extremely stable and chemically resistant perfluorinated end-products of breakdown in the environment have long been identified as ‘forever chemicals’, for example by scientists and journalists such as Rebecca Renner [“Growing Concern Over Perfluorinated Chemicals” (2001) Environ. Sci. Technol. 35(7) 154A-160A; “The long and the short of perfluorinated replacements” (2006) Environ. Sci. Technol. 40(1) 12-13] or Sharon Lerner writing in the Intercept [“Toxic Chemicals Discovered in Hundreds of Products” Sharon Lerner (The Intercept December 2020)].

It must be stressed that although still commonly and inaccurately referred to as ‘emerging contaminants’, PFAS have truly emerged as contaminants of concern for at least 10 years and should no longer be described as ‘emerging’. On the other hand, the technology of how to deal with PFAS waste is currently still emerging and developing.

Firefighting foams are classified either as Class A suitable for carbonaceous fuels such as wood, paper or vegetation, acting as wetting agents improving the penetration of water into deep seated fires and do not contain fluorosurfactants, only hydrocarbon surfactants; or, on the other hand, Class B foams are specifically formulated for liquid hydrocarbons such as gasoline and polar solvents such as ethanol. Modern Class B foams may either contain fluorsurfactants and be capable of film-formation at the air-fuel interface (AFFF), or completely fluorine-free, F3 foams, specially formulated containing only hydrocarbon surfactants. Interestingly Class B fluorine-free foams (F3) can be used effectively for both Class A and Class B fires unlike AFFF,

Class A foams for carbonaceous fuels

Class A firefighting foams are used extensively worldwide, especially in Australia, America and Southern Europe, for incidents involving carbonaceous fuels, e.g., structural house fires, plastic and tyre waste, as well as grassland and wildland or bush fires. Ted Schaefer then working for
3M Australia in the late 1980s developed one of the first effective Class A foams, “3M Fire-Brake BFFF”, recognised in 2001 by the Australian Academy of Technological Sciences and Engineering as one of the top 100 Australian inventions of the 20th century.
Class A foams behave very differently to fluorosurfactant-containing AFFFs, as they are specifically formulated to penetrate carbonaceous fuel effectively, such as compacted vegetation, paper or wood, using specialised hydrocarbon surfactants, not unrelated to kitchen washing-up liquid. Fluorosurfactant AFFFs, designed for surface application to liquid hydrocarbon or polar solvent fires, are nowhere nearly as efficient at penetrating such deep-seated fires and claims by some in the industry that their AFFF products can be used as dual Class A / Class B foams is frankly misleading.

Mister H: Penetration by Class A                          Mister F: Failure to penetrate by Class B AFFF

(Bluteau 2007)

Class B AFFF foams for liquid hydrocarbons and polar solvents

The first report of an aqueous film-forming foam (AFFF), called LightWater®, by R.L. Tuve et al of the Naval Research Laboratory and the 3M Company March 1964 of a foam capable of vapour suppression and film forming on the surface with low flash point flammable fuels such as gasoline, showed that it was 1200% more effective than standard protein foams under identical conditions.
The compounds tested in foam formulations were in the general class of perfluorosulfonic acid derivatives, some being quaternary salts, others being alcohols, esters, anionic salts of substituted sulfonamido carboxylic acids, etc. All of these water soluble, high molecular weight fluorocarbons shown dramatic surface tension depression of water to below 20 dynes/cm. In general they are insensitive to electrolytes and show surface activity when dissolved in organic solvents.
The first Patent for an AFFF was granted to Richard Tuve and Edwin Jablonski in June 1966 [1], representing a new era in firefighting foams which was to last for the next 30-40 years until the 3M Company Minnesota withdrew from PFOS-based chemistry altogether in May 2000.

Information from the patent literature gives a fascinating insight into the derivatives used in these early AFFFs. Derivatives of perfluorooctane sulfonamide (PFOSA) and perfluorooctane carboxylic acid (PFOA) were used. As reported in the 1966 patent these early formulations include the quaternary ammonium salts of PFOS and PFOA amido derivatives:

C8F17-SO2NH2-(CH3)3N(CH3)3+I-

C7F15-CONH-(CH3)3N(CH3)3+I-

an amphoteric amino betaine derivative of PFOA

C₇F₁₅-CONH-(CH₂)₃–N⁺(CH₃)₂-CH₂-CH₂-COO^–

and the potassium salt of a PFOS sulphonamide derivative

C₈F₁₇SO₂N(C₂H₅)-CH₂COOK

The potassium salt of PFOS in the form of surfactant FC-95 was also used in early foams.
Interestingly it was some 50 years later that Barzen-Hanson et al in 2017 [2] from Jennifer Field’s group at Oregon State University identified a vast range of other derivatives, or their breakdown products, involving 40 different classes in legacy AFFFs.

Electrochemical Fluorination (ECF) – the Simons Process

The 3M Company announced in May 2000 that it was phasing out fluorosurfactant production based on PFOS chemistry and withdrawing entirely from the fluorinated AFFF firefighting foam market marking an end to the availability of Light Water™ and Light Water™ ATC™ formulations (3M Company (2000)). Other products using PFOS included ScotchGuard™ stain and water repellent treatments. Production of PFOS by the 3M Company is thought to have ceased entirely around 2002, being replaced by the shorter chain compound PFBS, although PFOS and PFHxS production is thought to have continued in China and India.
Until 2000 PFOS had been manufactured using the Simons electrochemical fluorination (ECF) process (3M Company, 1999; Ignat’ev et al , 2009; Sartori and Ignat’ev, 1998). This process involves replacing the hydrogen atoms of octyl sulfonate using hydrogen fluoride electrolytically in order to generate perfluorooctane sulfonyl fluoride, PFOSF.

C₈H₁₇SO₃H + HF ==>> C₈F₁₇(C=O)F

PFOSF is highly reactive acyl fluoride and is the starting material for preparing PFOS derivataives such as the sulfonamide PFOSA or N-ethyl-PFOSA, for example:

C₈F₁₇(C=O)F + C₂H₅NH₂ ==>> C₈F₁₇(C=O)-NH-C₂H₅

PFOSF production using electro-chemical fluorination (ECF) was, and remains, an inherently ‘dirty’ process resulting in a wide range of structural isomers, both straight chain and branched with CF-CF3 and C-(CF3)2 side chains, as well as odd and even chain length homologues such as C4 PFBS, C6 PFHxS and C7 PFHpS. As a result, technical grade PFOS was always and continues to be contaminated with a significant percentage of PFHxS. In addition, the perfluoroalkyl chains of both PFOS and PFHxS can form left- or right-handed helices resulting in pseudo-racemates that have been detected in human sera (Wang et al, 2011; Naile et al , 2016; Sasaki et al , 2018). Quoting from the ECHA (13 June 2019) PFHxS restriction proposal:

“…Sources indicate that when manufacturing perfluorinated compounds, a mixture of compounds of varying chain- length is usually formed, with typical amounts of PFHxS formed when manufacturing PFOS being between 4 and 14% ( from (BiPRO, 2018) citing (Ren, 2016). These numbers are supported by measurements of PFHxS in commercial PFOS-products, namely 3.5%–9.8% in 3M’s FC-95 (from (BiPRO, 2018) citing 3M (2015) and 11.2 % – 14.2% in three products from China (Jiang et al, 2015). BiPRO also note, however, that the amount of the C6-component may be reducedby purification at different stages of the production line….”

The significance of the relatively high levels of the C6 homologue perfluorohexane sulfonic acid, PFHxS, in these AFFF formulations is that PFHxS is more toxic and bioaccumulative than PFOS, has a longer biological half-life in humans, and has also been list in the Annexes of the UN Stockholm Convention for restriction. Unfortunately, some manufacturers especially in Asia have used PFHxS as a ‘regrettable substitution’ for PFOS.

The use of ECF to produce perfluorinated sulfonic and carboxylic acids, such as PFOS and PFOA and their derivatives, has been summarised by Buck et al [2011], as shown below.

source: Buck et al (2011)

To be continued as Part3.

References

Barzen-Hanson, K.A., Roberts, S.C., Choyke, S., Oetjen, K., McAlees, A., Riddell, N., McCrindle, R., Ferguson, P.L., Higgins, C.P., and Field, J.A.. (2017) “Discovery of 40 Classes of Per- and Polyfluoroalkyl Substances in Historical Aqueous Film-Forming Foams (AFFFs) and AFFF-Impacted Groundwater” Environ, Sci. Technol. 51, 2047-2057.

Benskin J.P., De Silva A.O., Martin J.W. (2010) Isomer Profiling of Perfluorinated Substances as a Tool for Source Tracking: A Review of Early Findings and Future Applications. Rev. Environ. Contam. Toxicol.:111-160.

Buck, R.C., Franklin, J., Berger, U., Conder, J.M., Cousins, I.T., de Voogt, P., Jensen, A.A., Kannan, K., Mabury, S.A., and van Leeuwen, S.P.J. (2011)  Perfluoroalkyl and polyfluoroalkyl substances in the environment: terminology, classification, and origins. Integr. Environ. Assess. Manag. 7(4), 513-541.

Ignat’ev, N.V., Willner, W., and Sartori, P. (2009)  Electrochemical fluorination (Simons process) – A powerful tool for the preparation of new conducting salts, ionic liquids and strong Brǿnsted acids. J. Fluorine Chem. 130(12), 1183-1191.

Naile, J., Garrison, A.W., Avants, J.K., and Washington, J.W. Isomers/Enatiomers of Perfluorcarboxylic Acids: Method Development and Detection in Environmental Samples. Chemosphere 44, 1722-1728.

OECD (2021), Reconciling Terminology of the Universe of Per- and Polyfluoroalkyl Substances:

Recommendations and Practical Guidance, OECD Series on Risk Management, No. 61, OECD

Publishing, Paris.

Sartori, P. and Ignat’ev, N.V. (1988) The actual state of our knowledge about mechanism of electrochemical fluorination in anhydrous hydrogen fluoride. J. Fluorine Chem. 87(2(, 157-162.

Sasaki, T., Egami, A., Yajima, T., Uekusa, H., and Sato, H. (2018) Unusual Molecular and Supramolecular Structures of Chiral Low Molecular Weight Organogelators with Long Perfluoroalkyl Chains. Crystal Growth and Design 18(7) 4200-4205.

Tuve, R.L. amd Jablonksi, E.J. (1966) US 3,258,423 Patent June 28, 1966 “Method Of Extinguishing Liquid Hydrocarbon Fires”, assignors to the United States of America as represented by the Secretary of the Navy. Filed Sept. 4, 1963, Ser. No. 306,665.

Vyas, S.M., Kania-Korwel, I., Lehmler, H.J. (2007) Differences in isomer composition of perfluorooctanoylsulfonyl (PFOS) derivatives. J. Environ. Sci. Health and Toxic Hazard Substance Environ. Eng. 42, 249-255.

Wang,  Y., Beeson, S., Benskin, J.P., De Silva, A.O., Genuis, S.J., and Martin J.W. (2011) Enantiomer Fractions of Chiral Perfluoroctanesulfonate (PFOS) in Human Sera. Environ. Sci. Technol. 45(20) 8907-8914.

Modern chemistry has created many hundreds of thousands of chemical compounds, which we encounter as part of our daily lives. Indeed, it would be very hard to spend a day without being in contact with a class of molecules – perfluoroalkyl substances or PFAS – which have been commercially exploited since the end of WWII over the last 75 years.

Even if we could qualify chemistry as a miracle of science, it is worth knowing that chemistry has been approached by the Egyptian 3000 years BC, and was later on studied by the Ancient Greeks which described the combination of the 5 elements: earth, air, fire, water and ether. This theory was largely accepted for more than 1000 years.

The basis of the modern chemistry, as we now understand it, was established over the last three hundred years. The nature of the atom, the identification of atomic compounds, the first modern synthesis was achieved.

In 1906, Frédéric Henri Moissan (1852-1907), a French chemist working in Paris at the École Supérieure de Pharmacie, isolated for the first-time elemental fluorine gas, F2, a discovery for which he was awarded the Nobel Prize in Chemistry in 1906. Hydrogen fluoride obtained from fluorspar had been identified by the renowned Swedish chemist Karl Wilhelm Scheele some years earlier.

The post war years after WWI In the mid 1930s, were the heyday the German chemical industry, especially as regards new synthetic dyes. Fluorine chemistry started to have a commercial role – a red dye Naphthol AS, used as the official red colour the Nazi flag, and Indanthrene Blue used as a component of ‘Flieger Grau’ or Pilot Grey, the blue-grey colour of Luftwaffe uniforms, both contained a fluorinated methyl group, CF3, which helped prevent fading. Carothers working for DuPont produced the first industrial wholly synthetic fabric, the polymer Nylon. From this point chemists have never stopped to inventing new compounds!

When we think about chemicals, it is important to realise that many, if not most of the synthetic compounds now commercially available are produced by the petrochemical industry. Since the invention of the internal combustion engine, petrol (gasoline) and petroleum products have been become increasingly important around in for many human activities but are associated with a high fire risk.
The nature of this risk highlighted the necessity of addressing these often-catastrophic fires. In the early 40’s, protein foam made from ‘horn and hoof’, a slaughterhouse waste, was developed to control Class B hydrocarbon fires, e.g., those involving oil, gasoline, aircraft fuel and solvents.
In 1949, the 3M Company Minnesota industrialized the Simons electrochemical fluorination (ECF) process for making perfluoro-compounds (PFC) such as perfluorinated amines, carboxylic and sulphonic acids in which the hydrogens of the alkyl carbon chain had been totally replace by fluorine. Joseph Simons had discovered the ECF process whilst working at Pennsylvania State College in the 1930s but was unable to publish his work until after WWII because fluorine chemistry was essential for uranium purification as part of the Manhattan Project.

In 1953 the structure of Scotchgard was accidentally discovered by Patsy Sherman and Sam Smith working for the 3M Company whilst working on a rubber for jet fuel lines. Three years later in 1956, the 3M Company launched Scotchguard on the market. This fabric, textile and leather treatment is based on a PFOS-derivative containing N-ethyl-PFOSA and gives water, oil, and other liquids and stain-protection to the treated fibre.
Interestingly, N-ethyl-PFOSA known as Sulfluramid, was originally developed to kill ants, cockroaches and termites, and is still used to this day as the insecticide sulfluramid against leaf-cutting ants in Brazil. The lithium salt of PFOS was developed to kill wasps and hornets but is highly toxic to honey bees.

PFOS, perfluoro-octane sulphonic acid, and its derivatives subsequently become crucial for the development of Class B aqueous film-forming foams (AFFFs) effective against liquid hydrocarbon and solvent fires.

Figure 1. The structure of PFOS, perfluoro-octane sulphonic acid.

During the 1960s the US Department of the Navy Naval Research Laboratory in collaboration with the 3M Company began developing PFOS-based firefighting foams. A patent for AFFF firefighting foam was awarded in June 1996 for extinguishing liquid hydrocarbon fires.

In the late 60’s, a series of major fuel fires happen on board US Navy ships causing extensive loss of life and damage:
(i) 1966: USS Oriskany – fire kills 44 sailors.
(ii) 1968: USS Forrestal – whilst on active service in the Gulf of Tonkin during the Vietnam War, malfunction and accidental firing of a fighter Zuni rocket on the flight deck of this super-carrier led to a catastrophic aviation fuel fire claiming the lives of 134 crew, injuring many more, destroying nearly 50 aircraft, doing $72 million worth of damage, and leaving the vessel unfit for active service.

(iii) 1969: USS Enterprise – a shipboard fire kills 28 sailors.

These major fires prompt the US Department of the Navy to mandate the use of the recently developed AFFF firefighting foam, which the 3M Company was manufacturing for the US military.

Perfluorocompounds had been successfully used to create AFFF, and 3M’s PFOS-based LightWater® and alcohol-resistant ATC® brands became the staple for liquid hydrocarbon fuel fires from the 1970s until May 2000 when the Company announced that it was phasing out PFOS-based chemistry on environmental grounds. AFFF had indeed conquered the world of firefighting and was seen for decades as the ultimate answer to extinguishing large hydrocarbon (oil and gasoline) fires both for military and civilian use especially by the aviation and petrochemical industries.

In the 70’s, an alternative technology was developed based on the telomerization process. This technology provided an alternative to the ECF process and introduced a new class perfluorochemicals on the market. Whereas the ECF process produced mainly PFOS contaminated with odd and even numbered homologues of PFOS such as PFHxS (~5-8 % w/w), perfluorohexane sulphonic acid, as well as branched chain isomers, telomerisation produced only even number linear alkyl carbon chains. The characteristic of fluorotelomer derivates is a perfluoroalkyl moiety linked by a dimethylene group -CH2-CH2- to a functional group which could be negatively (anionic), positively (cationic) or both negatively and positively charged (amphoteric).

Most modern fluorotelomer-based AFFF firefighting foams, known as ‘pure C6 foams’, are based on derivatives of 6:2 fluororelomer sulphonic acid (6:2FTS), or a thioether analogue, containing a C6 perfluoroakyl chain linked through -(CH2)2- to a charged functional group. 6:2FTS contains a C8 chain and its structure is shown below. Its similarity to PFOS is clear but the CH2 groups cause it to behave very differently in terms of its PBT profile. All perfluoroalkyl moieties or their breakdown products are extremely environmentally persistent (vP), but with differing bioaccumulation or toxic potential.

Figure 2. Structure of 6:2FTS

Early fluorotelomer foams, however, contained both 6:2FTS and often substantial amounts of 8:2FTS derivatives. This was a problem as the 8:2FTS could be degraded to a stable end product perfluoroctanoic acid or PFOA which had substantial toxicity. This problem has now been essentially resolved as a result of the industry PFOA Stewardship Program 2010-2015, with residual PFOA or its precursors reduced to less than 25 parts perbillion (ppb).

Figure 3. 8:2FTS breakdown to PFOA

From the 1970s to the late 1990s, many manufacturers of firefighting foam appeared in the market, developing and offering a wide range of different foams for end-users. These included Class B AFFF, AFFF-AR (alcohol resistant), film-forming-protein (FFFP) and fluoro-protein (FP) foams. Class A foams specifically intended for solid carbonaceous fires such as structural building or wildland (bush) fires were also developed in this period.

On 16 May 2000 the 3M Company abruptly announced the phasing-out of its activity in PFOS-based chemistry for producing fluorochemicals, affecting not only firefighting foams but also a wide range of domestic and commercial products. This announcement was justified on company responsibility for environment, as it was confirmed that the C8 perfluoroalkyl substances (PFAS) made using ECF technology posed a threat to the environment, with pollution that had spread worldwide affecting a wide range of environmental compartments as well as biota including man.
Over the next 2-3 years, the company had stopped all activities involving PFOS-based chemistry, with a total withdrawal from the firefighting foam market, replacing it with mitigated success by a shorter chain PFBS-based (perfluorobutyl sulphonate) chemistry. However, some production of PFOS and PFHxS derivatives using the ECF process did continue in both China and India.
With 3M’s phase-out of PFOS-chemistry and withdrawal from the firefighting foam market, other major manufacturers of PFAS fluorochemicals and firefighting foam stressed that they considered fluorotelomer chemistry was ’safe’ and indeed environmentally friendly as it had nothing to do with ECF chemistry and products could not contain either PFOS or PFOA. The firefighting foam market transitioned to AFFF products based on fluorotelomers over the next few years 2000-2010.

From 2002 onwards a lively and sometimes acrimonious debate took place between manufacturers of PFAS and AFFF – under the auspices of a trade association, the Fire Fighting Foam Coalition (FFFC), funded mainly by the fluorochemical industry – and independent manufacturers especially of nascent fluorine-free foams (F3), regulators and scientific experts from academia. This discussion gave rise to a series of international seminars, conferences as well as hundreds of publications in the peer-reviewed literature about the environmental consequences of substituting fluorotelomers for PFOS-based products. At this time the main international forum for discussing developments in firefighting foam technology turned out to be the Reebok series of foam conferences, held in Manchester and Bolton in the UK, 2002, 2004, 2007, 2009 and 2013.

Starting as early as 2002 a number of the smaller independent foam manufacturers started to offer first generation experimental Class B liquid hydrocarbon fluorine-free foams (F3) as more environmentally sustainable alternatives to PFAS -containing foams. During the following 10 years the debate raged on driven by published scientific studies which concluded that telomer chemistry posed a threat to the environment. Early telomer formulation were mixtures of 6:2 and 8:2 derivatives. The 8:2 material was shown to be a potential precursor for the generation of environmentally extremely persistent PFOA (perfluorooctanoic acid or C8) through breakdown, subsequently associated with long-term health effects. At the time this was vigorously contested by representatives advocating the fluorochemical industry attending Reebok conferences.
However, as a result of pressure from the US EPA many large feedstock manufacturers adopted the PFOA Stewardship Program 2010-2015 aimed at reducing the use of PFOA or its precursors. Improvements in purifying the fluorotelomer derivatives resulted in a reduction of PFOA related material to less than 25 ppb providing so-called ‘pure C6’ fluorotelomer derivatives. The Stewardship Program led to a change in foam formulations formerly containing C6/C8 fluorotelomers to a so-called ‘drop in’ replacement containing predominantly C6 fluorotelomer.
Unfortunately, this change was not as simple as it was supposed to be and foam manufacturers had to reformulate and increase the total fluorochemical content to achieve a similar performance compared with previous C6/C8 formulations. Unfortunately, end-users were not even made aware of this change!

Around the same time, scientific studies accumulated evidence that even hyper-pure C6 was NOT a suitable alternative, but a ‘regrettable substitution’ and the debate went to another level. 2015 marked a sea-change in the PFAS debate. The toxicity of PFOA was no longer denied by the fluorochemical industry or regulators and the issue was brought to the attention of the public by scientific journalists.

A series of public statements signed by scientists worldwide – the Helsingǿr Statement 2014, the Madrid Statement 2014 and the Zürich Statement 2018 – raised concerns about the continuing use of PFAS and as major planetary pollutants and their long-term impact on the environment. A major publication in 2020 raised the issue that all PFAS should be treated as a chemical class because of their common environmental problems rather than individual chemicals.

The United Nations Stockholm Convention and their Persistent Organic Pollutants Review Committee (POPRC) has added PFOS, PFHxS and PFOA to the appropriate Annexes banning or restricting use (2018-2022).

Countries such as Germany and Norway, or individual states such Queensland in Australia, have been at the forefront in regulating the use of PFAS, especially for highly dispersive use such as firefighting foams.

Some countries are not waiting for UN decisions to regulate the use of PFAS. In Europe, PFOS has been prohibited since 2011 and PFOA since 2018; current discussions aim to stop the use of all PFAS with C4 to C20 carbons completely with a deadline of 2025, in anticipation of these restrictions many industries are moving to fluorine-free technology. In the USA, change is being driven mainly by the cost of litigation with thousands of cases against the fluorochemical industry including foam manufacturers in the pipeline.

To be continued in Part 2

Dr Thierry BLUTEAU
Managing Director
3F Americas – Panamá

Dr. Thierry BLUTEAU, French, studied at University of Paris XI, where he achieved a Master in Biochemistry and a PhD in Organic Chemistry.

In 1983, He is nominated as Professor of Biology at French Lycée in Montevideo in Uruguay for two years.

He starts to work in firefighting industry in 1992, where he is Technical Manager in Croda Fire Fighting Department.

6 years later, he funds the company Bio-EX, where he stands as Site Manager. He creates a range of firefighting foams and additives, and develops a wide network of international distributors, with presence in Asia, Australia, Africa and Latino America.`

In 2012, he keeps developing new foams independently in collaboration with LEIA Laboratories, and achieves the creation of two lines of innovative products : the firdt line is Smart Foam, foam products with no solvents and green profile. In 2020, a full line of FREGEN F3 is launched, fluoro-free products to be discovered on our website www.3fff.co.uk

Still active at R&D department in LEIA, he manages also our subsidiary 3F Américas in Panama City.

Dr. Roger A. Klein trained as a medical doctor and as a PhD physical chemist at the University of Cambridge. His academic research interests have covered tropical diseases, fundamental drug research, and more recently theoretical quantum chemistry (IUPAC Task Group on redefining hydrogen bonding) He has nearly 50 years experience advising and working with the Fire Service both in the UK and internationally, in areas that include hazardous materials (Hazmat and CBNRE) and decontamination issues, personal protective equipment (PPE), risk assessment and management, incident command and control, and the impact of fire service operations on the environment, having acted as Principal Scientific Adviser and Radiation Protection Adviser to Cambridgeshire Fire & Rescue Service until 2000. In the late 1990s he was asked by HM Fire Services Inspectorate to produce the first draft of UK guidance on risk assessment and management for the Emergency Services, which later became part of the Fire Service Manual. In 2002 he was involved in the McKinsey report on New York Fire Department (FDNY) operations at the 9/11 WTC incident in New York.

Following on from the 3M Company’s announcement on 16 May 2000 that it was withdrawing from PFOS-based chemistry he became heavily involved in the environmental chemistry of perfluorochemicals, especially as it affected the environment and human health through widespread contamination. In particular, he was concerned with the environmental impact of the dispersive use of firefighting foams, especially fluorosurfactant containing AFFF, and the transition to fluorine-free (F3) Class B foams. He has published extensively in the technical literature and co-organised a series of international seminars on the environmental impact of firefighting foams held at the Reebok Centre, Bolton, UK, in August 2002, December 2004, September 2007, July 2009 and March 2013, as well as the 1st Australian National Forum on Firefighting Foam held in Adelaide in 2011. More recently he has acted in an advisory capacity as a technical advisor to the Environment, Natural Resources and Rural Development Committee (ENRRDC) of the Parliament of Victoria (Australia) as part of the Inquiry into the legacy PFC contamination at the CFA Training College Fiskville, as well as accompanying the Committee on a study trip to Germany in December 2015.

He was also heavily involved in assisting the Queensland Government Department of Environment and Science in their development of a fire fighting foam management policy, including helping to co-organize a major conference held by the Department in Brisbane during February 2017. More recently he has been involved in presenting the case for fluorine-free firefighting (F3) foams as viable alternatives to AFFF as well as environmental and health issues concerning PFOS, PFOA and PFHxS to the UN Stockholm Convention Persistent Organic Pollutants Review Committee (POPRC-14) which met at the UN FAO Headquarters in Rome 17-21 September 2018, the ninth Convention of the Parties to the Stockholm Convention (COP-9) in Geneva 29 April-4 May 2019, and POPRC-15 also at FAO Headquarters in Rome 1-4 October 2019; acting as coordinator for the IPEN F3 Panel which produced a series of White Papers for the Committee and COP-9, which are now referenced by regulatory bodies. Formerly of the Universities of Cambridge and Bonn, and recently affiliated as a theoretical chemist to the Department of Chemistry, University of Wisconsin, Madison, since 2009 he has been Affiliated Research Faculty at the Christian Regenhard Center for Emergency Response Studies (RaCERS), John Jay College of Criminal Justice, CUNY New York.

In summary, since 2000 when the 3M Company announced withdrawing all PFOS-based chemistry, Roger Klein has been heavily involved in advising fire services, airports and industry, as well as collaborating with environmental regulators at national and international level, especially in Australasia (e.g., Australia, New Zealand, Singapore) and Northern Europe, in the control and remediation of PFAS environmental contamination. He assisted in the development of the 2016 Queensland foam management policy, now regarded as best-practice worldwide, and gave expert evidence to the Victorian Parliament’s Fiskville Inquiry 2015. He was also on the Advisory Board of a clinical study in Australia aimed at reducing blood PFAS levels in previously exposed firefighters, with the results published in April 2022 in the Journal of the American Medical Association (JAMA). He was previously a Member of the UK Institution of Fire Engineers, a Chartered Chemist and a Chartered Scientist; he is currently both a Fellow of the Royal Society of Chemistry and a Fellow of the International Union of Pure and Applied Chemistry (IUPAC); he now works as an independent scientific consultant.

Contact details:
Dr. Roger A. Klein, tel: +44 1223 306 846 mob: +44 07555 545 070 email: rogeraklein@yahoo.co.uk

3F dedicates its activity around the proposal of safe and efficient solutions to control and extinguish fires. Our role is not only to manufacture and supply firefighting foams, but to inform our customers about the past, actual and future of the foams regarding the risks, the technology and the regulation.
To bring more awareness on the market, 3F decided to publish on its website a serie of articles to review the foam facts, from AFFF to F3.

About the authors:
Dr Thierry Bluteau: Leia Laboratories, UK. PhD Organic Chemistry.
See profile in the next article
Dr Roger A. Klein: Independent Consultant UK, PhD Physical Chemistry.
See profile in the next article

3F enlarges its international network and offers now a direct sales service in Mexico. 3F MEXICO is located in Querétaro where it maintains a foam stock for emergencies and immediate delivery. From Querétaro 3F MEXICO offers its products and services to all its customers in the Republic.

3F is happy to announce that our BV certificate has been renewed for 5 years.  The list of approved products includes our F3 FREEGENs and FREEDOL, our AFFF range of CHEMEX, FLUOEX and FREESOLV and 3 protein references FP397, PROSEAL 3 and 6.

3F will be pleased to inform you in detail for your requirements to satisfy and supply foam for your shipment activities.