Fluorosurfactants used in firefighting foams, whether produced by the legacy ECF process using PFOS chemistry or by current fluorotelomerisation technology, degrade to give environmentally persistent sulphonated fluorinated degradation products. These products, PFOS and fluorotelomer sulphonate 6:2 FtS respectively, are found at high concentrations in groundwater at old training sites. Fluorosurfactant-containing foams include AFFF, FFFP and FP, together with their AR variants.

PFOS is known to be persistent, bioaccumulative and toxic (ie, it has a highly unfavourable PBT profile).  On the other hand there is currently little information in the peer-reviewed scientific literature regarding the bioaccumulative potential and toxicity of the 6:2 fluorotelomer sulphonate, although its extremely persistent nature is clear and accepted. Reports from the fluorotelomer industry at meetings have suggested its toxicity and bioaccumulation (actually biopersistence which is not the same thing) in limited test species are much less than for PFOS or PFOA. Remember, however, that one cannot necessarily transfer directly the interpretation of data from a particular test species to man.

This was the situation until the Norwegian State Pollution Control Agency (SFT) published an extremely important report (TA 2444/2009) on 3rd February 2009 which showed (i) that the fluorotelomer sulphonate 6:2 FtS is bioaccumulated by earthworms to a similar extent as PFOS and PFOA, (ii) that the predicted no-effect concentrations (PNEC) values for PFOS, PFOA and 6:2 FtS were similar within a factor of two, (iii) that local soil concentrations at sites that had used firefighting foams exceeded the PNEC, meaning that soil organisms were at risk, and (iv) shore-line sea snails had high levels of 6:2 FtS.

What are the environmental issues involved in using fluorosurfactant fire fighting foams operationally? All fluorosurfactants produce highly stable, environmentally persistent fluorinated degradation products, which can be toxic and bioaccumulative to varying degrees. The combination of persistence, bioaccumulative potential and toxicity is known as the substance’s PBT profile. The Norwegian report has completely changed the basis of the argument about the PBT profile for the fluorotelomer sulphonate 6:2 FtS. We have now to consider that 6:2 FtS, the degradation product of fluorotelomer firefighting foams, is persistent, bioaccumulative and toxic in certain species such as the earthworm, rather than just persistent, with these parameters in the same ball-park as for PFOS and PFOA.
Why are earthworms important? Their essential ecologiocal role as conditioners of the soil was pointed out for the first time in Charles Darwin’s book The Formation of Vegetable Mould, through the Action of Worms, with Observations on Their Habits, published by John Murray in 1881 and said to have outsold even his better known On The Origin of Species! Earthworms can be considered close to the bottom of the food-chain. Earthworm predators include many birds, fish, moles, shrews, hedgehogs, foxes, toads, snakes, beetles, leeches and slugs. Higher predator levels including man then eat birds and fish. As one passes up the food-chain each species will show differing bioaccumulative and toxicity profiles. This results in bio-magnification. For example, if the earthworm has a bioaccumulation factor (BAF) of N1, is eaten by a bird with a BAF of N2, which in turn is eaten by an animal with a BAF of N3, then the overall bio-magnification factor is simply (N1 x N2 x N3).

Firefighting operations almost always represent a balance between extinguishing fire, saving human life or property or otherwise resolving the incident, for example in the case of a hazardous materials spill, and the impact of these operations on the environment. Two different aspects of operational procedures need to be assessed both strategically and tactically for the risk these pose to the environment. First, what effects, potential or immediate, do normal firefighting procedures and extinguishing agents have on the environment; and secondly, at incidents involving hazardous materials (HazMat), what procedures can be used to mitigate damage caused by release of toxic materials either directly or as part of fire-water run-off.

If an extinguishing agent is judged harmful to the environment, is there a replacement or alternative technology available with similar or at least acceptable performance characteristics? This is the crux of the matter. And in practical terms the answer may have to be the result of a cost-benefit analysis. Is the environmental advantage gained by using a replacement offset by an unacceptable reduction in operational capability, or can this reduction in turn be eliminated through improved operational procedures? What are the costs of disposing of legacy stocks by high temperature incineration?

Halons are probably the classic example of extinguishing agents with a serious and unacceptable environmental impact, which nonetheless offsets the relatively poor firefighting performance of substitutes. Work which resulted in the 1995 Nobel Prize in Chemistry for Crutzen, Molina and Rowland, led to the banning of certain halons through the 1987 Montreal Protocol. Recent data indicate that atmospheric ozone depletion stopped by 1994 (2002, World Meteorological Organization, Global Ozone Research and Monitoring Project Report No. 47, WMO, Geneva, 2003), showing that concerted international effort can remedy or even reverse environmental damage, leading Kofi Annan to call it "perhaps the single most successful international agreement to date”.

Halon replacement highlights a problem which is relevant to the current discussion of fluorosurfactant-containing firefighting foams (which include AFFF, FFFP and FP and AR foams) versus fluorine-free alternatives. Whereas there are still legitimate concerns about the efficiency of halon substitutes, similar critical concerns about fluorine-free foams now seem unfounded. Class B foam concentrates are available currently that are completely fluorosurfactant-free, are approved to EN 1568 and ICAO, satisfy the petrochemical industry standard LASTFIRE for both freshwater and seawater, and can be used efficiently on both non-polar and polar fuels (AR-type foams).

Unfortunately because polyfluorinated materials are so environmentally persistent, continued release into soil and groundwater will result in increasing concentrations as time passes resulting ultimately in the predicted no-effect concentration (PNEC) being exceeded, thus putting organisms at risk.




The SFT study of fire training facilities in Norway confirms the findings of previous studies that the likely ultimate biodegradation products of the fluorochemicals used in currently manufactured AFFF agents are persistent, but are not considered to be significant environmental toxins.



A different perspective

Tom Cortina of the Fire Fighting Foam Coalition puts forward an alternative view on the Norwegian State Pollution Control Agency’s report on polyfluorinated organic compounds.

The low bioaccumulation values developed in this study reinforce previous assertions of the general safety of these products. Because these studies were done at fire training areas where foams were released uncontrolled numerous times over many years, the findings should not be used to assess the impact of a one-time use of a firefighting foam to extinguish a fire, which would result in significantly smaller contaminant concentrations.
Current accepted practice is to use fluorine-free training foams whenever possible as well as to collect and treat foam discharges when fluorine-containing foams are used for training or testing. The three main fluorochemicals found in the SFT study – PFOS, PFOA, and 6:2 FTS – have been found previously in groundwater studies from fire training facilities in the United States (1). PFOS and PFOA were likely contaminants and/or biodegradation products of the ECF-based fluorosurfactants contained in AFFF agents primarily manufactured by 3M prior to 2002. 6:2 FTS is a likely contaminant and/or biodegradation product of the fluorotelomer-based surfactants contained in currently manufactured AFFF agents (manufactured since the 1970s). Neither of these compounds (PFOS or 6:2 FTS) was used directly “as is” in the AFFF agents, as was cited incorrectly in the SFT study.

As noted above they are contaminants and/or biodegradation products of the more complex fluorosurfactants that are the key functional ingredients in AFFF. Of note in the SFT study is that concentrations for all perfluorochemicals (PFCs) other than PFOS were below their limit of quantitation in all “background” soils. Therefore concern regarding potential impact on soil dwelling organisms applies only to the immediate area surrounding sites where these repeated releases occurred.

The SFT study does confirm previously reported data that 6:2 FTS is neither bioaccumulative nor biopersistent. The bioaccumulation factor (BAF) values for 6:2 FTS in earthworms from the SFT report and in rainbow trout from previous studies (2) are 100-1,000 times lower than EU regulatory criteria for bioaccumulation.

The BAF values were slightly higher for 6:2 FTS than for PFOS and PFOA in the SFT study. For this reason we would expect advocates of alternative foams to argue that 6:2 FTS has similar environmental properties to PFOS and therefore the use of fluorotelomer-based foams should be limited. We would argue that the SFT study results do not change the basic conclusion from a broad range of existing data that 6:2 FTS is not similar to PFOS in either its physical or ecotoxicological properties (3, 4, 5, 6). Recent studies on AFFF fluorotelomer-based surfactants likely to break down to 6:2 FTS show it to be generally low in acute, sub-chronic, and aquatic toxicity, and neither a genetic nor developmental toxicant.

Both the AFFF surfactant and 6:2 FTS were significantly lower than PFOS when tested in biopersistence screening studies that provide a relative measure of biouptake and clearance (Figure 1) (7). The body of available data on the C6-based fluorotelomer surfactants used in AFFF agents provides strong evidence of the product’s safety for its intended use in Class B fires. On the other hand, many global environmental authorities have strictly regulated the use of PFOS due to its documented PBT properties.
In the European Union existing stocks of PFOS-based foams must be removed from service by June 27, 2011. PFOA is not likely to have come from fluorotelomer-based AFFF in any significant amounts. The fluorotelomer-based surfactants used in AFFF agents are not made with PFOA and PFOA is not used in the manufacturing process. Current unintended trace quantities of PFOA in fluorotelomer-based AFFF will be virtually eliminated under the EPA PFOA global stewardship program.

Under the program telomer producers have committed to 95 per cent reductions of PFOA, PFOA precursors, and related higher homologue chemicals by year end 2010 and are working toward the elimination of these chemicals from both plant emissions and finished products by year end 2015.  Fluorotelomer-based AFFF agents are the most effective agents currently available to fight flammable liquid fires (Class B) in military, industrial, and municipal settings. They neither contain nor break down into PFOS and are not likely to be significant sources of PFCAs. They do contain fluorosurfactants that are persistent, but are not generally considered to be significant environmental toxins.
FFFC members who make fluorotelomer-based AFFF agents and fluorosurfactants are in position to meet the goals of the EPA global stewardship program years ahead of the target date with a new family of fluorosurfactants that provide the same fire protection characteristics with reduced environmental impacts.

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