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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Description of key information

An algal inhibition assay was conducted in accordance with GLP and OECD 201 test guideline.  A 72-h ErC50 of 0.11 mg/L was derived.

Key value for chemical safety assessment

EC50 for freshwater algae:
4.1 mg/L
EC10 or NOEC for freshwater algae:
0.11 mg/L

Additional information

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" referenced as Method C.3 of Commission Regulation (EC) No 76112009.

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to an aqueous solution of the test item at nominal concentrations of 0.10, 0.32, 1.0, 3.2, 10 and 32 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Analysis of the test preparations at 0 hours showed measured test concentrations to range from less than the limit of quantification (LOQ) of the analytical method employed (determined to be 0.046 mg/L) at 0.10 mg/L through to 28 mg/L. A decline in measured test concentrations was observed at 72 hours in the range of less than the LOQ at 0.1 0, 0.32 and 1.0 mg/L to 23 mg/L.

Analysis of test solutions prepared with the omission of algal cells at 72 hours showed measured test concentrations in the range of less than the LOQ at 0.10 and 0.32 mg/L to 24 mg/L were obtained indicating that the test item was both unstable under the conditions of the test and was adsorbing to the algal cells present.

Given this decline in measured test concentrations it was considered justifiable to base the results on the geometric mean measured test concentrations in order to give a "worst case" analysis of the data.

72 -hour ErC50 and ErC10 values of 4.1 and 0.11 mg/L respectively were determined.