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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

 Algae appear to be of lower sensitivity to the toxicity of ammonia compared to other aquatic organisms including fish, consistent with the fact that ammonia represents a nitrogen source for algae.  An EC50 of 2700 mg/L is calculated for Chlorella vulgaris.

Key value for chemical safety assessment

EC50 for freshwater algae:
2 700 mg/L

Additional information

The effect of ammonia concentration on growth and physiology of a unicellular green alga, Chlorella vulgaris, was studied by Tam & Wong (1996). Algal growth was accompanied by a decrease in nitrogen content in the medium, indicating that nitrogen removal was due to algal uptake and assimilation. Results demonstrate that C. vulgaris can tolerate high concentrations of ammonia. The 18 day EC50 was calculated to be 2700 mg/L. Algae appear to be of lower sensitivity to the toxicity of ammonia compared to other aquatic organisms including fish, consistent with the fact that ammonia represents a nitrogen source for algae, which is required for growth.