2-ethoxy-1,3-dimethylcyclohexane

Toxicity to aquatic algae and cyanobacteria

Description of key information

A study was performed to assess the effect of the test material on the growth of the green alga Pseudokirchneriella subcapitata. The method followed that described in the OECD TG No 201. Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to solutions of the test material at nominal concentrations of 1.0, 3.2, 10, 32 and 100% v/v saturated solution. (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. The test material solutions were prepared by a saturated solution method with the aid of propeller stirring at approximately 1500 rpm for 24 hours, any undissolved test item was removed by filtration through a 0.2 µm Sartorius Sartopore filter.

Analysis of the test preparations at 0 and 72 hours showed a very slight decline in measured test concentrations and hence it was considered appropriate to calculate the results based on the geometric mean measured test concentration only in order to give a “worst case” analysis of the data.

Exposure of Pseudokirchneriella subcapitatato the test item gave the following results based on the geometric mean of test concentrations:

Inhibition of growth rate:

ErC10 (0 - 72 h) :       4.6 mg/L

ErC50 (0 - 72 h) :       6 mg/L; 95% confidence limits 5.7 – 6.4 mg/L

NOEC:                       1.8 mg/L

Inhibition of Yield:

EyC10 (0 - 72 h) :       0.9 mg/L

EyC50 (0 - 72 h) :       3.8 mg/L; 95% confidence limits 3.1 – 4.7 mg/L

NOEC: 1.8 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

6 mg/L

EC10 or NOEC for freshwater algae:

4.6 mg/L