Registration Dossier
Registration Dossier
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EC number: 423-300-7 | CAS number: 128554-52-9
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
The EC50 for both cell growth inhibition and growth rate reduction were beyond the range tested, i.e. greater than a nominal concentration of 100 mg/l, corresponding with an average measured concentration of 71 mg/l. The NOEC corresponded with 10 mg/l. The levels of test substance tested were far beyond the solubility of test substance in water (0.64 mg/l).
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 71 mg/L
- EC10 or NOEC for freshwater algae:
- 10 mg/L
Additional information
The test substance was assessed for toxicity to aquatic algae according to EU Method C3.
The test substance consisted of a white powder and was insoluble in water. The water solubility of the test substance at room temperature was determined to be <0.64 mg/l.
A homogeneous dispersion of the test substance above the solubility of test substance in water could still be prepared when preparation started with a stock in deionised water and the solutions were treated with ultra-sonic waves.
After a range-finding test, a final test was performed exposing exponentially growing algal culture to test substance concentrations ranging from 10 to 100 mg/l, increasing with a factor of 1.8. The initial cell density was 10E4 cells/ml. The total test period was 72 hours. Samples for analysis were taken at the start and the end of the second test and analysed for determination of Total Organic carbon (TOC).
The test substance only slightly affected cell growth of the fresh water algae species Selenastrum capricornutum at nominal concentrations of 32 mg/l and higher. This minor effect on algal growth was probably related to the fact that these test solutions were increasingly turbid and adsorbed a part of the light needed for algal growth. Further, a substantial part of the test substance consisted of undissolved particles, which might have induced physical damage to a significant fraction of the algal cells.
The EC50 for both cell growth inhibition and growth rate reduction were beyond the range tested, i.e. greater than a nominal concentration of 100 mg/l, corresponding with an average measured concentration of 71 mg/l.
The NOEC corresponded with 10 mg/l.
The levels of test substance tested were far beyond the solubility of test substance in water (0.64 mg/l).
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