Acute Toxicity of Fire-Retardant and Foam-Suppressant Chemicals to Hyalella azteca (Saussure)

Table 2

Table 2. Summary of the ammonia characteristics of five fire-retardant chemicals used in tests with adult Hyallela azteca exposed in American Society for Testing and Materials soft and hard waters. A regression equation was fitted for each chemical tested using the total ammonia as nitrogen (NH₃-N) concentrations determined at test initiation (n = 4). Each regression model was used to predict initial NH₃-N (mg/L) in the 96-h mean lethal concentration (LC50).

Chemical	Water Type	Regression Equation^a	96-Hour LC50 (mg/L)	Predicted Total Ammonia (NH₃-N, mg/L)	Un-ionized Ammonia (mg/L)^b
Fire-Trol GTS-R	Soft	NH₃-N = -0.386 + 0.197*LC50	127	24.63	0.13-0.79
		Adj R² = 1.0000
	Hard	NH₃-N = -1.834 + 0.215*LC50	363	76.21	0.53-2.40
		Adj R² = 0.9999
Fire-Trol LCG-R	Soft	NH₃-N = -0.366 + 0.107*LC50	73	7.44	0.02-0.08
		Adj R² = 0.9999
	Hard	NH₃-N = -1.291 + 0.108*LC50	535	56.49	0.24-1.09
		Adj R² = 0.9996
Phos-Chek D75-F	Soft	NH₃-N = -0.382 + 0.197*LC50	53	10.06	0.09-0.25
		Adj R² = 1.0000
	Hard	NH₃-N = 5.257 + 0.192*LC50	394	80.90	0.38-1.01
		Adj R² = 0.9971
Phos-Chek WD-881	Soft	NH₃-N = 0.0597 + -0.000151*LC50	10	0.06	0.00
		Adj R² = -0.2944
	Hard	NH₃-N = 0.0418 + -0.000141*LC50	22	0.04	0.00
		Adj R² = -0.2072
Silv-Ex	Soft	NH₃-N = 0.0230 + 0.00784*LC50	24	0.21	0.00-0.01
		Adj R² = 0.9995
	Hard	NH₃-N = 0.0270 + 0.00719*LC50	27	0.22	0.00-0.02
		Adj R² = 1.0000
^aNH₃-N = total ammonia as nitrogen (mg/L) used as the dependent variable in the regression model; LC50 = 96-h LC50 (mg/L) used as the independent variable in the regression model; adjusted R² = 1 - (1 - R²)(n - 1/d.f. error). ^bUn-ionized ammonia = total ammonia, as determined at test initiation and adjusted for temperature and pH.

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