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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

Exposure of Pseudokirchneriella subcapitatato the test item gave EL50 based on growth rate of 0.75 mg/L loading rate WAF. The No Observed Effect Loading rate was 0.32 mg/L based on growth rate (OECD 201 and EU Method C.3).

Key value for chemical safety assessment

EC50 for freshwater algae:
0.75 mg/L
EC10 or NOEC for freshwater algae:
0.32 mg/L

Additional information


A study was performed to assess the effect of the test item on the growth of the green algaPseudokirchneriella 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) 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 preliminary range-finding tests,Pseudokirchneriella subcapitatawas exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 0.10, 0.32, 1.0, 3.2 and 10 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1°C. Due to the need to test at relatively low test concentrations, the 0.10 and 0.32 mg/L loading rate WAFs were prepared as serial dilution from the 1.0 mg/L loading rate WAF.

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 and 72 hours showed measured test concentrations to range from 0.031 to 2.1 mg/L.

Given that the toxicity cannot be attributed to a single component or a mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

Exposure of Pseudokirchneriella subcapitatata the test item gave the following results:

Response Variable


(mg/L Loading Rate WAF)

95% Confidence Limits

(mg/L Loading Rate WAF)

No Observed Effect Loading Rate

(NOEL) (mg/L)

Lowest Observed Effect Loading Rate

(LOEL) (mg/L)

Growth Rate


0.63 – 0.89





0.41 – 0.50