Ethyl 2,6,6-trimethylcyclohexa-1,3-ene-1-carboxylate

Toxicity to aquatic algae and cyanobacteria

Description of key information

EC50 (aquatic algae; growth rate)= 8.9 mg/L (C.I. 7.3 - 12) , 72 hour, freshwater, OECD TG 201, Wil Research B.V. 2015
EC10 (aquatic algae; growth rate)= 1.6 mg/L (C.I. 0.99-2.1), 72 hour, freshwater, OECD 201,Wil Research B.V. 2015
NOEC (aquatic algae; growth rate)= 1.0 mg/L, 72 hour, freshwater, OECD 201, Wil Research B.V. 2015

Key value for chemical safety assessment

EC50 for freshwater algae:

8.9 mg/L

EC10 or NOEC for freshwater algae:

1.6 mg/L

Additional information

The algal growth inhibition to Pseudokirchneriella subcapitata, was carried out according to OECD 201 Freshwater Alga and Cyanobacteria, Growth Inhibition Test and EU Method C.3 guidelines. A final test was performed based on the results of a preceding combined limit/range-finding test. Six replicates of exponentially growing algal cultures were exposed to untreated control medium, while three replicates per group were exposed to 1.0, 2.2, 4.6, 10 and 22% of the SS prepared at 100 mg/L test substance. The total test period was 72 hours and the initial algal cell density was 10^4 cells/ml. Samples for analytical confirmation of actual exposure concentrations were taken at the start, after 24 and 72 hours of exposure. Because the actual concentrations decreased during the exposure, the effect parameters were expressed in terms of Time Weight Average (TWA) concentrations. The calculated TWA concentrations were 0.51, 1.0, 1.6, 3.6 and 11 mg/L for the solutions containing 1.0, 2.2, 4.6, 10 and 22% SS, respectively. The 72h-EC10 for growth rate reduction based on TWA concentrations was 1.6 mg/L. The EC50 for growth rate reduction (72h-ERC50) based on TWA concentrations was 8.9 mg/L (C.I.: 7.3 – 12 mg/L).