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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Slight toxic effects reported in two studies were caused by the low pH-value. Replicates with the test item concentration of 100 mg/L adjusted to pH 7.9 showed no toxic effects. The pH neutralization reflects the actually existing environmental conditions in the buffered aquatic systems. Therefore it can be concluded that the test item has no effect on algae.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

In one key-study, the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus over the period of 72 hours. The nominal EC50-values with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 69.7 (69.0 – 70.1) and 55.8 (50.2 – 89.5) mg test item/L, respectively. The nominal NOEC-values for inhibition of growth rate and yield after 72 hours were 50.0 and 25.0 mg test item/L, respectively.

 

Toxic effects were caused by the low pH-value. Replicates with the test item concentration of 100 mg/L adjusted to pH 7.9 showed no toxic effects.

All effect values given are based on nominal test item concentrations.

 

A second key study found that the72-Hour ErC50 for the test item to freshwater green alga Desmedesmus subspicatus based on nominal concentration was > 100 mg/L. The 72 -Hour NOEC Growth rate and yield were 100 mg/L.

 

In the supporting study it could be shown, that the low pH values had an effect on the growth-rate of the algae. The 72 -Hour ErC50 for the test item to Scenedesmus subspicatus based on nominal concentration was 79.8 mg/L. At the highest test concentration (100 mg/L) a pH of 5.6 at the Beginning and pH of 5.4 at the end of the 72 -h test period was observed. Therefore it can not be excluded that these pH values had an influence on the result.

 

Therefore it can be concluded that the test item has no effect on algae. The pH neutralization reflects the actually existing environmental conditions in the buffered aquatic systems.