Deterministic risk assessment of firefighting water additives to aquatic organisms
By S Graetz, M Ji, S Hunter, P K Sibley, and R S Prosser
September 8, 2020
Past firefighting water additives were found to contain perfluorinated compounds that could persist in the environment resulting in potential adverse effects to biota. Since this revelation, manufacturers have introduced alternative firefighting water additives that are fluorine free, but few studies have investigated the fate and effects in the environment of these new additives. Firefighting water additives could enter aquatic ecosystems through run-off, leaching or direct application. Therefore, there is a need to investigate the potential effect that firefighting water additives could have on aquatic biota. This study investigated the toxicity of six firefighting water additives: Eco-Gel™, Thermo-Gel™, FireAde™, Fire-Brake™, Novacool Foam™, and F-500™ to aquatic biota. The toxicities of firefighting water additives to Lemna minor (duckweed), Daphnia magna (water flea), Hexagenia spp. larvae (mayfly), Lampsilis fasciola (wavy-rayed lampmussel) and Oncorhynchus mykiss (rainbow trout) were investigated through acute and chronic static and semi-static tests to estimate LC50 values for survival and EC50 values for immobility and/or reproduction endpoints. A large variation in toxicities among the firefighting water additives and among the test species was observed. Based on a worst-case exposure scenario of direct application, several firefighting water additives were found to pose a hazard to aquatic organisms. An exposure rate representative of a direct overhead application by a water bomber during a forest fire was used in the hazard assessment. For example, the hazard quotients determined for the D. magna acute toxicity tests ranged from 0.20 for Eco-Gel to 317 for F-500 in the forest pool (15 cm) scenario. This study presents the first deterministic risk assessment of firefighting water additives in aquatic ecosystems.