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Ecotoxicological information

Toxicity to soil microorganisms

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Description of key information

The key values were observed in an OECD guideline 216 study. Both values are based on observations on the nitrate formation rate after 28 days of incubation.

Key value for chemical safety assessment

Short-term EC50 for soil microorganisms:
15.4 mg/kg soil dw
Long-term EC10 or NOEC for soil microorganisms:
8.1 mg/kg soil dw

Additional information

Available information on inhibition of nitrification in topsoil samples indicated a strong inhibitory potential of Benzotriazole. In observations with 45 heterocyclic N compounds in three different soils significant inhibition of nitrification (35, 55, and 81 %) at 12 µg Benzotriazole /g soil was found (McCarty et al., 1989). By comparing the different molecular structures the three vicinal Nitrogen atoms in the triazole ring have been suspected as responsible fragment for the inhibitory effect. These findings are in a similar range to the current OECD guideline study and confirm the overall picture of toxicity to soil microorganisms.


McCarty GW, Bremmer JM (1989) Inhibition of nitrification in soil by heterocyclic nitrogen compounds, Biol Fertil Soils, 8:204-211.