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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

Key values for assessment come from the OECD 209 guideline study. As Benzotriazole is acting as nitrification inhibitor the effect concentration EC50 based on the results from the inhibition of the total respiration was selected. Since no EC10 could be calculated from these results, the EC10 was estimated from the results of the Pre Test.

Key value for chemical safety assessment

EC50 for microorganisms:
940 mg/L
EC10 or NOEC for microorganisms:
1 mg/L

Additional information

Besides both included studies several further studies with Benzotriazole, Tolyltriazole as well as different commercially available aircraft deicing fluids (ADF) using Microtox test system (Vibrio fischeri) are available (Cancilla, 1997; Cancilla, 2003; Cornell, 2000; Pillard, 2001) were reviewed. The results are summarized below.


Microtox EC50 (15 min) [mg/L]



4.25 (95% CI 4.18-4.35)

Cancilla, 2003


21 (95% CI 9.0-47)

Pillard, 2001


8.7 (95% CI 8.2-9.2)

1:1 mixture of 4-MBT and 5-MBT

7.3 (95% CI 6.9-7.7)


41.65 ± 11.01

Cancilla, 1997


5.91 ± 1.11

different ADFs with tolyltriazole


Cornell, 2000


Based on these observations the three Triazoles can be sorted by decreasing toxicity to Vibrio fischeri (Benzotriazole < 4-methylbenzotriazole < 5-methylbenzotriazole) showing a moderate acute toxicity, in general.


Cancilla DA et al. (1997) Isolation and characterization of Microtox-active components from aircraft de-icing/anti-icing fluids, Environ Toxicol Chem, 16, 3, 430-434.

Cancilla DA et al. (2003) Studies of the environmental fate and effect of aircraft deicing fluids: Detection of 5-methyl-1H-benzotriazole in the fathead minnow (Pimphales Promelas), Environ Toxicol Chem, 22, 1, 134-140.

Cornell JS et al. (2000) Comparative measures of the toxicity of component chemicals in aircraft deicing fluid, Environ Toxicol Chem, 19, 6, 1465-1472.

Pillard DA et al. (2001) Toxicity of Benzotriazole and Benzotriazole derivatives to three aquatic species, Wat Res, 35, 2, 557-560.