AFFF is a water-based foam used by the Department of Defense (DoD) since the 1970s for fire suppression in ships, shore-fixed systems, aircraft hangers, and to extinguish liquid fuel fires. Until production ceased in 2002, the DoD used AFFF mixtures containing significant quantities of the PFAS perfluorooctane sulfonate (PFOS) and related perfluoroalkyl sulfonates such as perfluorohexane sulfonate (PFHxS), although the DoD continued to use PFOS-containing AFFF stocks for some time after production stopped. The DoD’s legacy use of AFFF also included various fluorotelomer-based formulations, but the majority of DoD’s environmental liability likely results from the use of PFOS-based AFFF formulations.

PFAS are anthropogenic chemicals and do not occur naturally in the environment. Due to their unique chemical structure, PFAS are very stable in the environment and are relatively resistant to biodegradation, photooxidation, direct photolysis, and hydrolysis. Some PFAS, however, notably the polyfluoroalkyls, can be degraded in the environment, in some cases producing perfluoroalkyls, including perfluorooctanoic acid (PFOA). PFAS tend to bioaccumulate, and laboratory studies have shown that these compounds can have adverse health effects. The potential magnitude of the DoD’s PFAS liabilities will require a sustained effort to identify the best technologies to characterize, treat, and manage PFAS-impacted sites.

Since FY 2011, SERDP and ESTCP have addressed the issue of PFAS by both developing new PFAS-free firefighting formulations and by improving our management of PFAS in the environment. An overview of these investments is shown below.