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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The substance was tested for toxicity towards algal growth yielding an ErC50 (72 h) > 41.7 mg/L (Bayer AG, 1999b).

Key value for chemical safety assessment

EC50 for freshwater algae:
41.7 mg/L
EC10 or NOEC for freshwater algae:
12.8 mg/L

Additional information

According to the Guidance Document R.7b (ECHA, 2008), the control samples should show an exponential growth over the entire test duration. That requirement is not fulfilled by the present study as the growth of the control slowed down after 48 h. Despite that drawback the study was used for the hazard assessment due the following facts:

The growth curves for samples with nominal concentrations of 12.5 mg/L, 25 mg/L as well as 50 mg/L are nearly identical to that of the control, whereas the algal growth is obviously hampered at a nominal concentration of 100 mg/L. Accordingly, adverse effect of the substance towards growth of green algae can be excluded at concentrations below 50 mg/L (nominal).

As the test item concentration decreased over the test duration, a nominal concentration of 50 mg/L is related to a measured concentration of 41.7 mg/L (arithmetic mean value). Finally, adverse effects of the substance towards aquatic algae are preferably characterised by an ECr50 > 41.7 mg/L.