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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Link to relevant study record(s)

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 the two OECD studies reported, further studies with Benzotriazole are available in the public domain.

Cancilla et al. investigated the effects of BTA in a Microtox test showing an EC50 of 41.65 mg/L. Furthermore, Li et al examined the inhibition of nitrification in an ISO 9506 guideline test with return activated sludge. After 270 minutes an effect concentration of 1.99 mg/L was observed.

Inglezakis et al (2017) reported on the inhibition of several polar and non-polar organic substances. For the testing activated sludge from a local STP was used. The inhibition was examined by measuring the oxygen demand at increasing concentrations of the substances. Based on the results an EC50 of ca. 600 mg/L can be estimated for 1H-Benzotriazole.

Lakhey et al (2019) investigated the toxoicity of BTA towards the anaerobic ammonium oxidation process. In batch experiments with anammox biomass from a granular sludge bed reactor the bacteria were incubated for about 12 hours. Based on the findings an IC50 of 19.6 mg/L for BTA was calculated.

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.
Inglezakis et al. (2017), Inhibitory effects of polar and non-polar organic substances on activated sludge activity, Desalination and Water Treatment 91 (2017) 185–191.
Lakhey et al (2019), Toxicity of azoles towards the anaerobic ammonium oxidation (anammox) process, J Chem Technol Biotechnol 2020;95:1057–1063