Comparative toxicity of seven aqueous film forming foams (AFFFs) to in vitro systems and Mus.

The comparative toxicity of six per- and polyfluoroalkyl substance (PFAS)-free and one PFAS-containing aqueous film forming foam (AFFF) were evaluated in an outbred mouse species as well as several in vitro assays. The in vivo toxicological profile of PFAS-free AFFFs in short-term, high concentration exposures is different than a PFAS-containing AFFF. The PFAS-containing reference product induced increased liver weights, while the PFAS-free AFFFs were linked to either decreased or unaffected relative liver weights. The in vitro toxicological profile across PFAS-free AFFFs was uniform except in the Microtox assay where thresholds were variable and spanned several orders of magnitude. This direct comparison of products through short-term toxicity tests and in vitro screenings represents early data to support evaluation of potential regrettable substitutions when selecting alternative PFAS-free AFFFs. Further work in diverse taxa (e.g., aquatic organisms, terrestrial invertebrates, birds) and mammalian studies capturing sensitive life stages will refine and expand this dataset across a range of risk-relevant toxicological endpoints.