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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In this study the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus after 72 hours with the following effect values (nominal test item concentrations). The NOEC-values for both inhibition of growth rate and yield after 72 hours were 32.0 mg/L. The LOEC-values for both inhibition of growth rate and yield after 72 hours were 100 mg/L. The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) with 95 % confidence intervals after 72 hours were 47.8 (34.5 – 78.5) and 44.2 (32.8 – 84.4) mg/L, respectively. At the highest test concentration no inhibition of the growth rate and a lower inhibition of yield was observed when tested at a pH-value of 8.04. Therefore, it is considered that the pH value has a major influence on the inhibiting effect of the test item. The pH neutralization also reflects the actually existing environmental conditions in the buffered aquatic systems. Based on the pH-neutralized concentration the NOEC-values for both the inhibition of the growth rate and the inhibition of the yield after 72 hours were < 100 mg/L. The EC50-values for the inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 100 mg/L and ≤ 100 mg/L. All effect levels are given based on nominal concentrations of the test item.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

In this study the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus after 72 hours with the following effect values (nominal test item concentrations). The NOEC-values for both inhibition of growth rate and yield after 72 hours were 32.0 mg/L. The LOEC-values for both inhibition of growth rate and yield after 72 hours were 100 mg/L. The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) with 95 % confidence intervals after 72 hours were 47.8 (34.5 – 78.5) and 44.2 (32.8 – 84.4) mg/L, respectively. At the highest test concentration no inhibition of the growth rate and a lower inhibition of yield was observed when tested at a pH-value of 8.04. Therefore, it is considered that the pH value has a major influence on the inhibiting effect of the test item. The pH neutralization also reflects the actually existing environmental conditions in the buffered aquatic systems. Based on the pH-neutralized concentration the NOEC-values for both the inhibition of the growth rate and the inhibition of the yield after 72 hours were < 100 mg/L. The EC50-values for the inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 100 mg/L and ≤ 100 mg/L. All effect levels are given based on nominal concentrations of the test item.