Aqueous film-forming foam (AFFF) products have been linked to accumulation of per- and polyfluoroalkyl substances (PFAS) in soil invertebrates and terrestrial plants. Alternative PFAS-free firefighting formulations (F3) are being developed as replacement products. This project evaluated the relative, chronic toxicity of candidate F3s and a legacy AFFF in soil invertebrate and terrestrial plant species.

This Project Involves Toxicity Tests that Evaluate Reproduction and Growth with a Variety of Soil Invertebrates and Terrestrial Plants.

This project was undertaken to investigate the toxicity of candidate F3 products versus a reference AFFF product in soil invertebrates (earthworm, potworm, and collembola) and terrestrial plants (ryegrass, alfalfa, and barnyard grass). Standardized toxicity tests assessing reproduction or growth endpoints were conducted. Then, toxicity benchmarks were used to calculate scientifically defensible soil invertebrate- and plant-based soil ecotoxicological risk factors.

The F3 products tested showed relatively low overall toxicity based on median effective concentration values. Several F3 products were similarly toxic to the soil invertebrate and plant species tested compared to PFAS-containing reference product. Because soil invertebrates and terrestrial plants were exposed to whole products (i.e., mixtures of chemicals), exposure estimates and the toxicity benchmarks determined in this project were based on calculated values, which introduces some uncertainty for decision makers. The F3 products assessed were mixtures of multiple ingredients, some of which were proprietary and many of which are well studied, used in consumer and household products, and generally considered safe. 

Taken together with data from another SERDP project (ER20-1531) which indicates rapid biodegradation of F3 ingredients, replacement products may present less overall risk to soil invertebrates and terrestrial plants than PFAS-containing, legacy AFFF. 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 - 2024)