Sublethal Toxicity of Fluorine-Free Firefighting Foams in Soil Invertebrate Caenorhabditis elegans

Fluorinated aqueous film-forming foams (AFFFs) presenting human health and environmental concerns will be replaced imminently with fluorine (F)-free foams by the U.S. Department of Defense and other organizations. However, the environmental impacts of F-free foams are still unclear. Thus, ecotoxicity assessment is urgently needed to avoid replacement regret. In this study, we used model organism Caenorhabditis elegans to evaluate sublethal toxicity of six F-free AFFF alternatives and a current short-chain AFFF in soil invertebrates. We developed a rapid counting and measuring method for assessing sublethal toxicity in C. elegans. All tested formulations showed adverse impacts on the growth of C. elegans at concentrations lower than or close to the practical application concentration in the field. Also, five of six F-free alternatives caused reduced reproduction in C. elegans. Analysis of the chemical composition of the formulations indicated that the types and concentrations of surfactants may be linked to the observed toxicity. Formulations containing higher concentrations of hydrocarbon surfactants were more toxic than other formulations to C. elegans. This study provides ecotoxicological data that, combined with data from all related ongoing research, should be used in decision making regarding recommendations for manufacturing and use of candidate F-free foams.