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B-1 Understanding of the Problem Firefighting foam used for extinguishing aircraft fires has been described as being a stable mass of small air-filled bubbles, which have a lower specific gravity than that of hydrocarbon fuels or water (FAA, 2004). In airport operations in North America, AFFF is used as a fire-extinguishing agent to suppress Class B fires: i.e., fires of flammable and combustible liquids such as crude oil, gasoline and fuel oils. AFFF exhibits unique properties that make it very effective as a fire- extinguishing agent, but can be potentially problematic relative to human health and the environment. Many historical AFFF formulations contained PFOS as the predominant active ingredient. Due to concerns associated with PFOSâs ubiquity and persistence in the environment, alterna- tive formulations containing fluorochemicals with a perfluorinated eight-carbon (C8) âtailâ have been used. Similar concerns (i.e., the breakdown of these long chained fluorotelomers to PFOA, which, like PFOS, has been shown to be very persistent in the environment) caused manufac- turers to look for other alternate formulations that included fluorinated chemicals with shorter chain lengths, such as C6-based fluorotelomers. Alternatives Due to the environmental concerns associated with PFOS, the United Nations Environment Programme (UNEP) (2011) referenced a PFOS alternative as: âWhen compared to PFOS, either reduces the potential for harm to human health or the environment or has not been shown to be a potential persistent organic pollutant itself.â Two guiding documents on the identification and assessment of PFOS alternatives were prepared and released by UNEP under the Stockholm Convention (2011): â¢ Draft guidance on alternatives to perfluorooctane sulfonic acid and its derivatives (UNEP/POPS/ POPRC.6/13/Add.3/Rev.1), which presents information on alternatives to PFOS and its deriv- atives. It also includes a breakdown of the uses of PFOS (e.g., coating, metal plating, firefighting foams) and indicates where alternatives have been suggested, are available, or have already been introduced to markets. The intent of this document was to enhance the capacity to tran- sition to phase out of PFOS. â¢ Technical paper on the identification and assessment of alternatives to the use of perfluorooctane sulfonic acid in open applications (UNEP/POPS/POPRC.8/INF/17.3) prepared for use by the Persistent Organic Pollutants Review Committee to develop recommendations on alternatives to PFOS in open applications. Alternatives suggested by UNEP are in no way exhaustive. Challenges continue to exist today in that there is often more information on PFOS-based AFFF than on non-PFOS based alternatives. A p p e n d i x B AFFF Alternatives
B-2 Use and potential impacts of AFFF Containing pFASs at Airports Information on alternatives may also be protected by trade secrets or is not peer-reviewed (UNEP 2011). This document looks specifically at the evolution from the PFOS-based AFFF, provides alternatives to AFFF (and PFOS-based AFFF), and outlines some advantages and dis- advantages, as suggested from a variety of sources, associated with each. Types of Firefighting Foams Firefighting foams that are commonly used range in their fluorocarbon surfactant content. Fluorine based foams differ in their content of fluorocarbon surfactants (as shown on Figure B-1) making different types of foam agents vary in their performance with regard to knockdown, heat resistance, fuel tolerance and vapor suppression. Table B-1 provides further detail on the different types of firefighting foams used to combat Class B fires. Alternatives History AFFF was developed in the 1960s for use in aviation, marine and shallow pit fires (UNEP 2010). Fluorochemicals in early AFFF formulations were the result of one of two processes, electro- chemical fluorination or telomerization. The electrochemical fluorination process was domi- nated by 3M, a major manufacturer of firefighting foam, with AFFF containing fluorochemicals synthesized by electrochemical fluorination accounting for 75% of the total AFFF stockpiled on US military bases (Place et al. 2012). The remaining stockpiled AFFF in the US contains fluoro- chemicals produced by telomerization. In 2002, 3M voluntarily removed an entire class of AFFF which contained and/or degraded into PFOS due to human health and environmental concerns. Regulations in numerous jurisdic- tions followed, placing restrictions on or banning the production and/or use of AFFF containing PFOS and/or PFOS precursors and/or other PFASs. Regulations in the US, Canada, European Union (EU), Australia and Japan currently ban all new production of PFOS-based products. In the US, Australia and Japan, these regulations do not currently restrict the use of existing stocks of PFOS-based foam. In the EU and Canada, existing stocks of PFOS-based foam were removed Figure B-1. Relationship of different types of foam agents with respect to fluorocarbon surfactant content, film formation capabilities, and dry powder compatibility. Source: Scheffey and Wright, 1994. Protein Foam Fluoroprotein Foam FFFP AFFF No Fluorocarbon surfactants Present Increasing Amounts of Fluorocarbon surfactants Present No Aqueous Film Formed; No Dry Powder Compatibility No Aqueous Film Formed; Dry Powder Compatibility Aqueous Film May Form A Dry Powder Compatibility Aqueous Film Formed Dry Powder Compatibility
Table B-1. Types of firefighting foams for Class B fires. Fluorine-Free Foams (F3) Protein Foam (PF) Fluoroprotein Foam (FP) Film Forming Fluoro-Protein (FFFP) Aqueous Film Forming Foam (AFFF) Alcohol-Resistant AFFF (AR-AFFF) Type Synthetic Protein Based Protein Based Protein Based Synthetic Synthetic Description â¢ Formulated without the use of fluorochemicals. â¢ Mechanical foam produced by proportioning foam concentrate with water at specific rations and using and discharging the resulting solution through an aspirating device. â¢ Manufactured from protein foam concentrates with added fluorocarbon surfactants. â¢ Based on protein foam formulations but are produced by increasing the quality and quantity of fluorocarbon surfactants. â¢ Synthetically formed by combining fluorine-free hydrocarbon foaming compounds with highly fluorinated surfactants. â¢ Uses plain AFFF concentrate as a base with the addition of a high molecular weight polymer to protect the foam blanket from being destroyed by a polar solvent. Use(s) â¢ Hydrocarbon fires. â¢ Aircraft rescue training foam. â¢ Hydrocarbon fires. â¢ Hydrocarbon fires. â¢ Hydrocarbon storage tank firefighting. â¢ Hydrocarbon fires. â¢ Hydrocarbon fires. â¢ Aircraft rescue. â¢ Used by city and industrial fire departments due to the effectiveness on both hydrocarbons and polar solvents. Characteristics â¢ Re-healing for burn back resistance. â¢ Good heat resistance. â¢ Do not break down to PFOS or PFOA. â¢ Does not form an aqueous film. â¢ Acts to exclude the air from the fuel vapors to prevent the creation of a combustible mixture. â¢ Relatively slow moving due to its stability when used to cover the surface of a flammable liquid. â¢ Require gentle foam application to avoid contamination if plunged directly onto the fuel surface. â¢ Does not form an aqueous film. â¢ Provides for vapor suppression and reduced fuel pick up. â¢ More resistant to fuel contamination/pickup. â¢ More mobile foam blanket when discharged onto the flammable liquid. â¢ Does not form an aqueous film. â¢ Ability to form a vapor sealing film similar to AFFF due to the higher concentrations of fluorochemicals than FP. â¢ Has the quick knockdown of AFFF with the added burn back resistance of standard fluoroprotein foam. â¢ Does not have knockdown as rapid as AFFF when used on a spill fire. â¢ Forms an aqueous film on the surface of a flammable liquid. â¢ Creates a barrier to exclude air or oxygen, and is capable of suppressing the evolution of fuel vapors. â¢ Addition of the polymer allows the foams to not be destroyed by polar solvents. â¢ Forms a membrane to separate the polar solvent from the foam blanket. (continued on next page)
Fluorine-Free Foams (F3) Protein Foam (PF) Fluoroprotein Foam (FP) Film Forming Fluoro-Protein (FFFP) Aqueous Film Forming Foam (AFFF) Alcohol-Resistant AFFF (AR-AFFF) Materials â¢ Water-soluble non- fluorinated polymer additives. â¢ Hydrocarbon surfactants. â¢ Hydrolyzed protein (i.e., hoof and horn meal) â¢ Foam stabilizers. â¢ Preservatives (to prevent bacterial decomposition and corrosion). â¢ Protein Foam. â¢ Fluorocarbon surfactants. â¢ Protein Foam. â¢ Increased quantity of fluorocarbon surfactants. â¢ Synthetic foaming agents (hydrocarbon surfactants). â¢ Solvents (i.e., viscosity leveler) â¢ Fluorocarbon surfactants. â¢ Small amount of salts. â¢ Foam stabilizers. â¢ Similar inputs to AFFF concentrate. â¢ Polysaccharide polymer. Environmental Considerations â¢ Considered to be biodegradable, low in toxicity, and can be treated in sewage treatment plants. â¢ Considered to be biodegradable and low in toxicity. â¢ Contains stable, environmentally persistent fluorinated degradation products. â¢ May require pre- treatment prior to standard wastewater treatment plants. â¢ Contains stable, environmentally persistent fluorinated degradation products. â¢ May require pre- treatment prior to standard wastewater treatment plants. â¢ Contains stable, environmentally persistent fluorinated degradation products. â¢ May require pre- treatment prior to standard wastewater treatment plants. â¢ Contains stable, environmentally persistent fluorinated degradation products. â¢ Requires pre-treatment prior to standard wastewater treatment plants. North American Standards â¢ UL 162 (Type 3 application), Standard for Safety for Foam Equipment and Liquid Concentrates. â¢ UL 162 (Type 3 application), Standard for Safety for Foam Equipment and Liquid Concentrates. â¢ UL 162 (Type 3 application), Standard for Safety for Foam Equipment and Liquid Concentrates. â¢ UL 162 (Type 3 application), Standard for Safety for Foam Equipment and Liquid Concentrates. â¢ CAN/ULC-S563 â¢ Mil-F-24385F â¢ CAN/ULC-S560 â¢ UL 162 (Type 3 application), Standard for Safety for Foam Equipment and Liquid Concentrates. â¢ CAN/ULC-S560 Application Technique â¢ Aspirating Device. â¢ Non-Aspirating Device. â¢ Sub-surface Injection Method. â¢ Must always be used with an air aspirating type discharge device. â¢ Must always be used with an air aspirating type discharge device. â¢ Air-aspirating or Non Air-aspirating nozzles. â¢ Does not provide expansion ratios as good as AFFF with a non-aspirating nozzle. â¢ Air-aspirating or Non Air-aspirating nozzles â¢ Air-aspirating or Non Air-aspirating nozzles. â¢ When used on an alcohol fire, an air- aspirating nozzle will provide better performance. Application Rate (gpm/sq.ft)1 .16 .16 .16 .10 .10 .10 1 http://www.chemguard.com/about-us/documents-library/foam-info/general.htm Table B-1. (Continued).
AFFF Alternatives B-5 from service in 2011 and 2013, respectively. Production and sale of PFOS-based AFFF in China has continued. In the early 2000s, following 3Mâs decision, the US EPA indicated that some early alternatives to PFOS-based AFFF can break down into PFOA or other perfluorocarboxylic acids (PFCAs) which, like PFOS, have been observed to be persistent in the environment. As a result, in 2006, the US EPA introduced a voluntary directive through the global 2010/2015 PFOA Stewardship Program which called for a 95 percent reduction of plant emissions and product content of PFOA, PFOA precursors, and related homologue materials by 2010, and a 100 percent reduc- tion by 2015. This global stewardship program has been adopted by other countries including Canada. Since 2006, both the US and Canada have taken steps to phase out the production and use of C8-based fluorotelomers. This has also contributed to a shift by AFFF manufacturers toward using shorter chain (i.e., PFCAs â¤ C6, having six or less carbon molecules) fluorinated chemicals. The 2010/2015 PFOA Stewardship Program is voluntary, and there are no restrictions banning the use of C8-based fluorotelomers. The implementation of regulations brought about substantial research and development to find substitutes to PFOS-based AFFF. The following sections identify alternatives to PFOS-based AFFF and AFFF that can break down into other PFASs. Fluorine Based Foam Agents Description The FAA identifies the following fluorinated agents for airport firefighting involving hydro- carbon fuels: â¢ Aqueous Film-Forming Foam (AFFF); â¢ Fluoroprotein Foam (FP); and, â¢ Film-Forming Fluoroprotein Foam (FFFP). Similarly, Transport Canada recognizes AFFF and FFFP foams to be the principal extinguishing agents for airports. What gives these fluorine based foams their function and properties are the fluorocarbon sur- factants. Fluorocarbon surfactants are not naturally occurring; rather, they are man-made chemi- cals that are used in firefighting due to their ability to reduce surface tension and form a film on top of lighter fuel (Sontake and Waugh, 2014). Since production of PFOS-based AFFF ceased, most modern AFFF (except some produced in China and India) contains fluorocarbon surfac- tants produced by telomerization. These are referred to as fluorotelomers. Fluorotelomers do not break down into PFOS and do not contain any chemicals currently considered to be persistent, bioaccumulative, and toxic (Melkote et al. 2012). Although currently thought to be better practice than using PFOS-based AFFF, there is still some uncertainty with respect to potential environmental impacts associated with other types of PFASs found in fluorotelomer based foams. Early alternatives to PFOS-based AFFF that contained longer chain (C8-based) fluorotelomers are on the path towards being phased out by producers due to their potentially hazardous and long-range transport properties. This âphase-outâ has created a shift towards shorter chain C6, C4 and C3-based perfluoroalkylated chemicals, which are perceived to be less problematic. The most common and most widely used are C6-based fluorotelomers. The reformulated C6-based fluorotelomers are used in AFFF, FFFP, and FP foams. The predominant breakdown product from the C6-based fluorotelomers is referred to as the 6:2 fluorotelomer sulfonate (6:2 FtS) (Cortina and Korzeniowski, 2008). A broad range of existing data suggest that 6:2 FTS is not similar to PFOS in either its physical or eco-toxicological prop- erties (Cortina 2010). 6:2 FTS does, however, have the potential, depending on environmental
B-6 Use and potential impacts of AFFF Containing pFASs at Airports conditions, to eventually degrade to PFHxA (perfluorohexane), PFPeA (perfluoropentanoic acid) and 5:3 fluorotelomer acid. Benefits The benefits presented in the literature and by product manufacturers on the use of fluorine based foams, specifically fluorotelomer-based foams, include: Strong PerformanceâIn addition to stability, a key factor in the performance of firefighting foams containing fluorocarbon surfactants is their extremely low surface tension, which has been shown to not be matched with other surfactants apart from PFOS itself (UNEP 2011). It is this sta- bility that creates rapid surface migration to contribute to high-speed coating processes, beneficial in the event of a fire that involves hydrocarbons. Fluorocarbon surfactants in firefighting foams contribute to the strong performance in quickly and effectively extinguishing fires resulting from highly combustible and flammable materials as they provide rapid extinguishment, burnback resistance, and protection against vapor release (FFFC 2014). ComplianceâIn the US, the MIL-SPEC (MIL-F-24385) specifications are known to be the most stringent standards for firefighting foams. Only fluorotelomer-based AFFF foam agents extinguished gasoline and heptane fires in less than 30 seconds, passing the test to qualify for the MIL-SPEC specification. In the US, the FAA requires all US airports to carry AFFF agents that have met the MIL-SPEC specifications. In Canada, it is required that AFFF meet the ULC Standard, CAN/ULC-S560. There are many fluorotelomer based AFFF products that meet this standard for use at airports in both the US and Canada. Low Hazard Profile (based on current data)âFluorotelomer based foams do not break down into PFOS (perfluorooctance sulfonate) or homologues of PFOS, nor do they break down into any chemicals that are currently listed as persistent organic pollutants (POPs) under the Stockholm Convention (FFFC 2014). Recent studies of fluorotelomers that break down into 6:2 FTS show it to have low acute, sub-chronic and aquatic toxicity, negative genetic and developmental toxicol- ogy, not to be bio-accumulative according to regulatory criteria, and to be significantly lower than PFOS in biopersistence (Seow 2013). A pilot study determined that since the phase-out of PFOS based materials in 2002, there has been a 60% decline in PFOS concentrations in serum samples collected from the Red Cross in 2006 in comparison to 2000â2001 data (Olsen et al. 2008). This is consistent with the timeline of phase-out and the half-life of PFOS. Disadvantages The disadvantages presented in the literature and by product manufacturers on the use of fluorine-based foams include: Environmental PersistenceâWhile fluorotelomers are low in biopersistance, they can be considered as environmentally persistent. All fluorinated materials are highly persistent in the environment due to their perfluorinated chains that degrade very slowly, if at all, under environ- mental conditions (Blum et al., 2015). Measurements made at former US military firefighting foam training sites found that 6:2 FTS has an environmental half-life of at least a decade (Seow, 2013). In addition, according to the information provided by Germany in 2011 to UNEP, due to the very limited ability of the C6-based perfluroalkylates bodies to adsorb, it is difficult to remove these chemicals from water (UNEP 2011). More recently, the Madrid Statement on Poly-and Per- fluoroalkyl Substances (2015) has come forward to suggest that the use of the entire class of PFAS (including the short chain alternatives) should be avoided due to their environmental persistence. Use of the short-chain alternatives may not reduce the amount of PFAS in the environment, and the environmental impacts may be compounded by use in larger quantities required to provide the same performance (Blum et al. 2015).
AFFF Alternatives B-7 Limited DataâThere are limited independent pieces of research or studies on the environ- mental and human health impacts of AFFF formulated with fluorotelomers, in comparison to the research done for foams that use PFOS and PFOA. In addition, there is little publicly avail- able information on the chemical structures, properties, uses and toxicological profiles of these fluorotelomer based alternatives. As is suggested in Place et al. (2012), further research studying the fate of the fluorochemicals during biodegradation is needed as the environmental behavior and toxicity of individual fluorinated surfactants is still unknown (Place et al. 2012). Products There are a number of AFFF, FFFP, and FP products that are available today that use fluoro- chemicals, particularly C6-based fluorotelomers as inputs. These firefighting foams are formu- lated using their own blends or use inputs from other manufacturers (e.g., Chemours, Dynax). Inputs currently on the market include: â¢ ForafacÂ® products, with 65â95% C6 fluorinated amphoteric telomers based on perfluorohexyl ethyl sulfonamideâProduced by Chemours (Dupont). â¢ Novecâ¢ 1230 Fire Protection Fluid containing dodecafluoro-2-methylpentan-3-oneâ Produced by 3M. â¢ Dynax DX1025 â blend of C6-based fluorocarbon surfactants â Produced by Dynax America Corporation. Fluorine-Free Firefighting Foams Description Fluorine-free firefighting foams, sometimes referred to as âF3s,â are formulated without the use of fluorochemicals. To be considered fluorine-free, these foams must not contain either fluo- rocarbon surfactants or fluoropolymers. They instead contain water-soluble non-fluorinated polymer additives and increased levels of hydrocarbon detergents (Seow 2013). In general, the approach to reformulating foams to be fluorine free has been to increase hydrocarbon surfactant levels to compensate for the removal of fluorine (Melkote et al. 2012). Free of fluorochemicals, fluorine-free foams do not degrade into PFOS or PFOA and as such these foams are considered to be more environmentally friendly. In Norway, for example, Avinor phased out the use of AFFF containing fluorine and fluorocarbon surfactants in 2012. The fluorine- free foam used in Avinor meets the International Civil Aviation Organization standards (ICAO level B) on fire-extinguishing performance, meeting both safety and environmental requirements. The use of fluorine-free foams has been suggested as an alternative for use as training foams and as fluids/methods for system and equipment testing. It has been noted however that some foam concentrates that degrade rapidly and completely in the environment, such as Class A and fluorine-free Class B foams containing only hydrocarbon surfactants, are likely to be more acutely toxic to aquatic organisms than Class B AFFF foams con- taining fluorocarbon surfactants and hydrocarbon surfactants, which degrade more slowly and incompletely because of their organo-fluorine content. Fluorine-free foams also fail to provide the same firefighting performance as the fluorinated alternatives. Benefits The advantages presented in the literature and by product manufacturers on the use of fluorine- free foams include: Less Environmentally PersistentâFree of fluorochemicals, fluorine-free foams cannot break down to PFOS or PFOA. Bioaccumulation and persistence are also unlikely to be significant unless
B-8 Use and potential impacts of AFFF Containing pFASs at Airports unusual additives are present (Seow 2013). Some fluorine-free foam products are also described as being substantially biodegradable. TrainingâFluorine-free foams can play an important role in training exercises where con- trols can be put in place to reduce environmental risks. These foams can mimic the induction performance of fluorinated foams. Disadvantages The disadvantages presented in the literature and by product manufacturers on the use of fluorine-free foams include: Decrease in PerformanceâFluorine-free foams have been shown to not have the same perfor- mance as their fluorinated counterparts. They are currently not able to provide the same level of fire suppression capability, flexibility, applicability, and scope of usage as AFFF firefighting foams (Industrial Fire Journal, 2013). An analysis of the performance of two available fluorine-free foams found that they would need to be replenished three times more often than AFFF to provide the same level of fire protection (Schaefer et al. 2008). In the same analysis, it was found that some fluorine-free foams offered little or no performance for the suppression of flammable vapors. Limitations in the effectiveness of fluorine-free foams are in large part due to the oil loving properties of the hydrocarbon surfactants. Lab experiments by Dynax show that a commercial fluorine-free foam becomes flammable and degrades when contaminated with fuel in contrast to commercial fluorocarbon surfactant-based foams that do not become flammable or degrade with fuel contamination (Jho 2013). This is observed due to the oleophilicity (fuel attraction) of hydrocarbon surfactants in fluorine-free foams. Increase in Short-Term ToxicityâIn order to achieve the properties for AFFF, particularly the low surface tension, many fluorine-free foams rely on increasing the hydrocarbon surfactant levels to compensate for the removal of fluorine. While many fluorine-free foams are neither biopersistent nor bioaccumulative, the increase in hydrocarbons can cause foams to exhibit extremely high aquatic toxicity, greater than what is observed with AFFF (Melkote et al. 2012). Higher Biochemical Oxygen DemandâFluorine-free foams containing hydrocarbon surfac- tants will emulsify with oil based fuels in an aquatic environment. This creates higher biochemical oxygen demands due to the increase in required oxygen needed to degrade the foam. An increase in required oxygen reduces available oxygen for organisms in the aquatic environment. Higher CostsâIt has been difficult for fluorine-free foams to gain a firm foothold in the market, partly because of established supplier relationships with manufacturers of C6-based fluorotelomers (UNEP 2011). In the United Kingdom, for example, it was shown that the fluorine-free alternatives to firefighting foams are 5â10% more expensive than fluorocarbon surfactant-based foams. It has been suggested, however, that as the market size for fluorine-free alternatives increases the price will fall (UNEP 2011). Products Fluorine-free foams have been developed by most foam manufacturers as alternatives to AFFF and are being used for some applications in Europe and Australia, particularly in environmen- tally sensitive areas. These products use inputs that include: â¢ Silicone-based surfactants; â¢ Hydrocarbon-based surfactants; â¢ Synthetic detergent foams; and, â¢ Protein-based foams. As of late, these foams are used more for training purposes than for emergency response.
AFFF Alternatives B-9 Conclusion There are commercially produced alternative foam types to AFFF. Most of these alterna- tive foam types contain PFASs (with the exception of the fluorine-free foams). However, all available firefighting foam alternatives exhibit properties that have the potential to impact the environment and/or human health, whether they are fluorotelomer-based or fluorine-free. Recognizing the importance of efficacy and safety in fire protection, these foams will continue to be used. Therefore, it is important to consider preventative approaches and best manage- ment practices that limit the discharge off firefighting foams to the environment and protect the individuals using these foams. References 1. Blum, A., Balan, S. A., Scheringer, M., Trier, X., Goldenman, G., Cousins, I. T., & Peaslee, G. (2015). The Madrid statement on poly-and perfluoroalkyl substances (PFASs). Environmental health perspectives, 123(5), A107-A111. Accessed online at: http://ehp.niehs.nih.gov/1509934/ 2. Cortina, T., & Korzeniowski, S. (2008). AFFF industry in position to exceed environmental goals. Asia Pacific Fire June, 18â22. Accessed online at: www.fffc.org/images/APFarticle08.pdf 3. Cortina, T. May 2010. The Phaseout that Didnât Happen. International Fire Protection. Accessed online at: http://www.fffc.org/journal.php 4. Jho, C. (2013) Interactions of Firefighting Foam with Hydrocarbon Fuel. Reebok Foam Seminar, Bolton, UK. Presentation. March 18â19, 2013. Accessed online at: http://www.dynaxcorp.com/dynax-resources/ presentations.html 5. Place, B. J., and Field, J. A. (2012). Identification of novel fluorochemicals in aqueous film-forming foams used by the US military. Environmental Science & Technology 46.13: 7120â7127. Accessed online at: http://pubs. acs.org/doi/abs/10.1021/es301465n 6. Scheffey, J. L., & Wright, J. A. (1994). Analysis of Test Criteria for Specifying Foam Firefighting Agents for Aircraft Rescue and Firefighting. HUGHES ASSOCIATES INC COLUMBIA MD. Chicago. Accessed online at: oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier 7. Schaefer, T. H., Dlugogorski, B. Z., & Kennedy, E. M. (2008). Sealability properties of fluorine-free firefighting foams (FfreeF). Fire technology, 44(3), 297â309. 8. Seow, J., and Australia, C. W. (2013). Firefighting Foams with Perfluorochemicals-Environmental Review. Hemming Information Services. 9. Sheinson, R. S., Williams, B. A., Green, C., Fleming, J. W., Anleitner, R., Ayersa, S., . . . & Barylski, D. (2002). The future of aqueous film forming foam (AFFF): performance parameters and requirements. National Institute of Standards and Technology (US Dept. of Commerce). 10. Sontake, A and Wagh, S. (2014). The Phase-out of Perfluorooctane Sulfonate (PFOS) and the Global Future of Film Forming Foam (AFFF), Innovations in Firefighting Foam. Chemical Engineering and Science. Accessed online at: http://pubs.sciepub.com/ces/2/1/3/ 11. Melkoke, R, Wang Liangzhen and Nicolas Robinet. Next Generation Fluorine-Free Fighting Foams. Accessed online at: www.nfpa.org/~/media/files/research/. . ./22melkoterobinetwang-presentation.pdf 12. Olsen, G. W., Mair, D. C., Church, T. R., Ellefson, M. E., Reagen, W. K., Boyd, T. M., & Butenhoff, J. L. (2008). Decline in perfluorooctanesulfonate and other polyfluoroalkyl chemicals in American Red Cross adult blood donors, 2000â2006. Environmental Science & Technology, 42(13), 4989â4995. Chicago. Accessed online at: http://pubs.acs.org/doi/abs/10.1021/es800071x 13. Persistent Organic Pollutants Review Committee. Technical Paper on the Identification and Assessment of Alternatives to the Use of Perfluorooctane Sulfonic Acid, Its Salts, Perfluorooctane Sulfonyl Fluoride and Their Related Chemicals in Open Applications (UNEP/POPS/POPRC. 8/INF/17 Rev. 1).Accessed online at: http://chm.pops.int/TheConvention/POPsReviewCommittee/Meetings/POPRC7/POPRC7Followup/ Requestsforinformation/RequestsforcommentsbyPOPRC7IWGs/PFOSinopenapplicationsRequestfor comments/tabid/2736/Default.aspx 14. Qualified Products Database. MIL-F-24385F (1)âFire Extinguishing Agent, Aqueous Film-Forming Foam (AFFF) Liquid Concentrate, for Fresh and Sea Water (2015): http://qpldocs.dla.mil/search/parts.aspx?qpl=1910 15. Williams, B., Murray, T., Butterworth, C., Burger, Z., Sheinson, R., Fleming, J., & Farley, J. (2011, March). Extinguishment and Burnback tests of fluorinated and fluorine-free firefighting foams with and without film for- mation. Suppression, Detection, and Signaling Research and Applications-A Technical Working Conference (SUPDET 2011). Accessed online: www.nfpa.org/~/media/Files/proceedings/supdet11williamspaper.pdf