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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Exposure of Pseudokirchneriella subcapitata to the test item gave EC50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Concentration was 100 mg/L loading rate WAF.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 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 761/2009.

Due to the low aqueous solubility and complex nature of the test item for the purposes of the test, the test item was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to a WAF of the test item at a single nominal loading rate of 100 mg/L (six replicate flasks) 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.

Chemical analysis of the test preparations at 0 and 72 hours showed measured test concentrations of less than the limit of quantification (LOQ) of the analytical method employed were obtained which was determined to be 0.00052 mg/L. This does not infer that no test item was in solution, just that any dissolved test item was at a concentration of less than the LOQ.

Given that toxicity cannot be attributed to a single component or mixture of components but to the test item as a whole, and the dissolved test item was below the quantifiable limit of the analytical method, the results were based on nominal loading rates only.

Exposure of Pseudokirchneriella subcapitata to the test item gave EL50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF.

It was considered unnecessary and unrealistic to test at loading rates in excess of 100 mg/L loading rate WAF.