Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Measured data: TEGBE surrogate: 72hr EC10 (growth rate) = 613mg/l, TEGME, EC10>500mg/l.
QSAR value (EC50): 7000mg/l.

Key value for chemical safety assessment

EC50 for freshwater algae:
7 000 mg/L

Additional information

There is no measured value available for the toxicity to algae for this substance. There is however measured data for two substances either side of it in the homologous series of these triethylene glycol ethers. A full and detailed justification for a category approach for meeting the individual data requirements for glycol ethers to support read across is included as an attachment in chapter 13 to this dossier. For this specific end point, this approach shows a clear trend of decreasing toxicity to aquatic species with reducing length of the alkyl chain length of the alcohol used to produce the glycol ether. Interpolation from the results of other glycol ethers within the same homologous family of triethylene glycol ethers can be considered a valid approach to meeting the data requirements of this substance.

2-(2-(2 -methoxyyethoxy)ethoxy)ethanol (TEGME) has a measured 72hr EC0 of >500mg/l (maximum tested dose) whereas 2-(2-(2 -butoxyyethoxy)ethoxy)ethanol has a measured 72 hr EC10 of 613mg/l.. The value for 2-(2-(2-ethoxyyethoxy)ethoxy)ethanol (TEGEE) will fall somewhere in between. The predicted values for the logkow using the ECOSAR QSAR are shown below:

Substance

Measured values (mg/l)

QSAR values (mg/l)

NOEC/EC10

EC50

NOEC/EC10

EC50

TEGME

>500

1810

14066

TEGEE

993

6979

TEGBE

613

294

1688

It can be seen that the QSAR is slightly conservative. The key value for the EC50 (rounded to 2 significant figures) is taken from the QSAR, justified by the supporting experimental data from surrogate substances that suggest that the QSAR is conservative and over estimates toxicity.