A different perspective
Published: 02 April, 2009
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.
