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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Based on growth rate, the EL50 (72h) value was determined to be 14 mg/L loading rate WAF based on growth rate and the NOEC (72h) was reported as 3.2 mg/L loading rate WAF based on growth rate (OECD 201 and EU Method C.3).

Key value for chemical safety assessment

EC50 for freshwater algae:
14 mg/L
EC10 or NOEC for freshwater algae:
3.2 mg/L

Additional information

GUIDELINE

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 preliminary range-finding tests, Pseudokirchneriella subcapitata was exposed to Water Accommodated Fractions (WAFs) of the test item at nominal loading rates of 1.0, 3.2, 10, 32 and 100 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.

 

RESULTS

Total Organic Carbon (TOC) analysis of the test preparations performed at 0 and 72 hours showed measured concentrations of 3.0 to 18 mg C/L at 0 hours and 1.6 to 29 mg C/L at 72 hours. 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. 

 

CONCLUSION

Exposure of Pseudokirchneriella subcapitata to the test item gave EL50 values of 14 mg/L loading rate WAF (confidence limits 11 to 18 mg/L loading rate WAF) based on growth rate and 4.2 mg/L loading rate WAF (confidence limits 3.6 to 4.9 mg/L loading rate WAF) based on yield. The No Observed Effect Loading Rate was 3.2 mg/L loading rate WAF based on growth rate and 1.0 mg/L loading rate WAF based on yield. The Lowest Observed Effect Loading Rate was 10 mg/L based on growth rate and 3.2 mg/L based on yield.