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.