Legacy class B liquid fuel fire extinguishing agents (i.e., aqueous film-forming foam [AFFF]) contain per- and polyfluoroalkyl substances (PFAS). Some PFAS are found to bioaccumulate in the liver and other tissues and are poorly excreted in animals and humans. The replacement of PFAS in products has largely been focused on reducing persistence to reduce exposure and thus risk. Many of the constituents in PFAS-free firefighting formulations (F3) are well-studied solvents and surfactants; however, study of the entire mixture toxicity can better inform understanding of direct F3-level hazards.

This project evaluated the toxicity of six candidate F3 products versus a PFAS‐containing product. Products were assessed via literature review of ingredients disclosed on safety data sheets, estimation techniques (i.e., models), and incorporation of testing data with whole products (i.e., in vitro and in vivo tests [acute, 28-day, and combined repeated-dose toxicity and reproductive/developmental screenings with laboratory mice]).

F3s ingredients have a lower likelihood of environmental persistence and bioaccumulation compared to the ingredients in AFFF.

The overarching observation in in vivo tests was that mammalian toxicity of F3s may be equivalent to or less than the reference AFFF. In the acute toxicity tests, no mortality was observed following single oral exposures. In the 28-day toxicity tests, the endpoint that allowed for the best cross-product comparison was liver weight. Whereas the PFAS-containing reference AFFF induced increased liver weights, the F3s were linked to either decreased or unaffected relative liver weights. In general, liver weight changes are not considered for ecological risk assessments, although they are important for other risk assessments.

In the combined repeat-dose toxicity and reproductive/developmental screenings, the endpoint that allowed for the best cross-product comparison was body weight. Whereas the PFAS-containing reference product impacted the body weight of adult female mice and did not impact the bodyweight of offspring (either sex), all F3 tested impacted body weights of adult female mice and their offspring to varying degrees. Importantly, F3s were not linked to any of the reproductive or developmental effects commonly seen with individual PFAS exposures at the occupationally relevant concentrations tested. 

Results from the whole-product toxicity tests were consistent with studies of well-characterized ingredients of the products, which are also common ingredients of many household and consumer products. Namely, F3s were not linked to any of the reproductive or developmental effects commonly seen with individual PFAS. Decision makers can use the information from this project, other projects, and cost–benefit, sustainability, or life‐cycle analyses to make a data‐driven decision for the adoption of F3s. Successful implementation of this research holds profound implications for improving the management of PFAS, directly addressing mission readiness by safeguarding the warfighter and communities. (Project Completion - 2025)

East, A.G., A.M. Narizzano, L.A. Holden, M.A. Bazar, M.E. Bohannon. D. Pervitsky, V.H. Adams, N.R. Reinke, and M.J. Quinn, Jr. 2023. Comparative Toxicity of Seven Aqueous Film Forming Foams to In Vitro Systems and Mus. Environmental Toxicology & Chemistry, 42(11):2364-2374. doi.org/10.1002/etc.5714.

Holden, L.A., A.G. East, A.M. Narizzano, and M.J. Quinn, Jr. 2023. Toxicology Assessment for Six Per- and Polyfluoroalkyl (PFAS)-Free Aqueous Film Forming Foam (AFFF) Products. Integrated Environmental Assessment Management, 19(6):1609-1618. doi.org/10.1002/ieam.4750.