Abstract:
Laboratory studies were conducted to determine the acute toxicity of three
ammonia-based fire retardants (Fire-Trol LCA-F, Fire-Trol LCM-R, and Phos-Chek
259F), five surfactant-based fire-suppressant foams (FireFoam 103B, FireFoam
104, Fire Quench, ForExpan S, and Pyrocap B-136), three nitrogenous chemicals
(ammonia, nitrate, and nitrite) and two anionic surfactants (linear
alkylbenzene sulfonate
... [LAS] and sodium dodecyl sulfate [SDS]) to juvenile
rainbow trout Oncorhynchus mykiss in soft water. The descending rank order of
toxicity (96-h concentration lethal to 50% of test organisms [96-h LC50]) for
the fire retardants was as follows: Phos-Chek 259F (168 mg/L) > Fire-Trol LCA-F
(942 mg/L) = Fire-Trol LCM-R (1,141 mg/L). The descending rank order of
toxicity for the foams was as follows: FireFoam 103B (12.2 mg/L) = FireFoam 104
(13.0 mg/L) > ForExpan S (21.8 mg/L) > Fire Quench (39.0 mg/L) > Pyrocap B-136
(156 mg/L). Except for Pyrocap B-136, the foams were more toxic than the fire
retardants. Un-ionized ammonia (NH3; 0.125 mg/L as N) was about six times more
toxic than nitrite (0.79 mg/L NO2-N) and about 13,300 times more toxic than
nitrate (1,658 mg/L NO3-N). Linear alkylbenzene sulfonate (5.0 mg/L) was about
five times more toxic than SDS (24.9 mg/L). Estimated total ammonia and NH3
concentrations at the 96-h LC50s of the fire retardants indicated that ammonia
was the primary toxic component in these formulations. Based on estimated
anionic surfactant concentrations at the 96-h LC50s of the foams and reference
surfactants, LAS was intermediate in toxicity and SDS was less toxic to rainbow
trout when compared with the foams. Comparisons of recommended application
concentrations to the test results indicate that accidental inputs of these
chemicals into streams require substantial dilutions (100-1,750-fold) to reach
concentrations nonlethal to rainbow trout. 
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