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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

ErC50 (72h) >100 mg/L for green alga Desmodesmus subspicatus (OECD TG 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

One reliable study ( Harlan Laboratories Ltd - Vryenhoef, H & Mullee DM, 2010) was available which was given a Klimisch 1 score. The study was performed according to OECD TG 201 and EC Method C.3, and according to GLP principles. In this limit study, green alga Desmodesmus Subspicatus were exposed to an aqueous solution of phosphoric acid at 100 mg/L under static test conditions for 72h. The pH was adjusted to neutral (pH 7.5).

The choice for doing a limit test was based on a preliminary test in which the algae were exposed to concentrations of 0.1, 1, 10 and 100 mg/L with and without pH adjustment. When the pH was not adjusted, the ErC50 was 75 mg/L and the NOEC=10 mg/L. The pH of the 100 mg/L test solution was 3.0 while the pH of the 10 mg/L test solution was 6.3 -6.4.

When the pH was adjusted, the result obtained in the final limit test are: ErC50>100 mg/L and NOEC=100 mg/L, based on nominal concentrations. Measured test concentrations ranged from 103% to 106% of nominal at the start of the test, and from 97% to 99% after 72h.