PFAS such as PFOA and PFOS have been used to manufacture a variety of industrial, commercial, and military products, including (through 2001) PFOS-based fluorochemical surfactants used in AFFF, which is used to extinguish flammable liquid (e.g., hydrocarbon) fires. Environmental releases of AFFF have occurred from tank and supply line leaks, use of aircraft hangar fire suppression systems, and from firefighting training activities. Due to their chemical structure, PFAS are very stable in the environment and are resistant to biodegradation, photo-oxidation, direct photolysis, and hydrolysis. PFOA, PFOS, and other select PFAS have attracted increased regulatory scrutiny because of their resistance to degradation, ability to bioaccumulate, and growing evidence of toxicity to ecological receptors.
SERDP is actively engaged in research to develop tools to assess PFAS ecological risks. Completed and on-going projects include developing TRVs for a range of freshwater and on land receptors, as well as the compilation of TRVs from the scientific literature into tools that can be used for ecological risk assessments (see PFAS Ecotoxicity Risks: How SERDP is Closing the Knowledge Gaps). PFAS bioaccumulation, biomagnification, and toxicity to marine receptors remains an important information gap. On-going research under SERDP will provide some data, but in addition to PFOA and PFOS, there remains a need for uptake and toxicity data for readily bioaccumulable compounds such as perfluorohexane sulfonic acid (PFHxS), perfluorohexanoic acid (PFHXA), and perfluorobutanoic acid (PFBA ), 6:2 fluorotelomer sulfonate (FTS), 8:2 FTS and other PFAS in marine aquatic environments. These compounds are frequently detected as mixtures in the environment and are of increasing interest to regulators.