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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

The effect of the test material on the growth of Desmodesmus subspicatus has been investigated and gave EL50 values of greater than 100 mg/L loading rate WAF.  Correspondingly the No Observed Effect Loading Rate was 100 mg/L loading rate WAF.

Key value for chemical safety assessment

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

Additional information

Introduction

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.

 

Methods

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, the green algae were exposed to a WAF of the test item, at a single loading rate of 100 mg/L (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 (+1) degrees 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.

 

Results

Exposure ofPseudokirchneriella subcapitatato the test item gave EL50 values of greater than 100 mg/L loading rate WAF. The No Observed 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. Total Organic Carbon analysis of the 100 mg/L loading rate WAF test preparation at 0 hours gave a measured concentration of 7.23 mg C/L. A decline in measured concentration was observed at 72 hours to 2.34 mg C/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.