Ecological Effects of Fire Retardant Chemicals and Fire Suppressant Foams

Accidental spills of fire-fighting chemicals in streams could cause substantial fish kills depending on the stream size and flow rate. For example, the retardant Fire-Trol GTS-R is prepared for field use by mixing 1.66 pounds per gallon of water to produce 1.1 gallons of slurry, which is equivalent to 198,930 mg/liter. Comparing the concentration of FT GTS-R field mixture to the acute toxicity values for the most sensitive life stage for rainbow trout gives a ratio of 853 in soft water and 1474 in hard water.

Applying a safety factor of 100 to this ratio suggests a dilution of 85, 300 in soft water and 147,400 in hard water is needed to lower the chemical concentration in a receiving water to limit adverse effects, i.e., fish kill, in a stream. For rainbow trout, other dilution factors would be 52,100 for Fire-Trol LCG-R, 85,600 for Phos-Chek D75-F, 71,400 for Phos-Chek WD-881, and 50,000 for Silv-ex. Fire-fighting chemicals are very toxic in aquatic environments and fire control managers need to consider protection of aquatic resources, especially if endangered species are present.