2-(2-methylpropoxy)ethanol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 January 2018 to 09 February 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

yes

Remarks:

The 24h results have not been included due to a lag phase in the growth of the algae

GLP compliance:

yes (incl. QA statement)

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: dilution series
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): Substance observed to be soluble is solution.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 278/4
- Source (laboratory, culture collection): SAMS Limited
- Age of inoculum (at test initiation): Not reported
- Method of cultivation: Pre-cultures in the exponential growth phase were prepared from stock laboratory cultures by inoculating autoclaved freshwater at 120 °C for 15 minutes with nutrient medium (3N-BBM+V) 2 to 4 days before test commencement and incubated at approximately 21 ±2 °C under constant illumination as the inoculum source for subsequent toxicity tests.

ACCLIMATION
- Acclimation period: 2-4 days
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: None reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not specified

Test temperature:

21 ±2 °C

pH:

8.1 ±0.2.

Dissolved oxygen:

Not specified

Salinity:

Not specified

Conductivity:

Not specified

Nominal and measured concentrations:

Nominal concentrations: 100, 320, 1000, 3200 and 10,000 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:100 ml borosilicate glass conical flasks
- Material, size, headspace, fill volume: 50 ml of test medium
- Initial cells density: 5 x10^3-10^4 cells per millilitre
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes (conforms to OECD 201 and ISO 8692)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Purified water treated by reverse osmosis followed by electro-deionisation.

OTHER TEST CONDITIONS
- Adjustment of pH: pH of the culture medium is adjusted if required, by adding 1M HCl, or NaOH to give a pH of 8.1 ± 0.2.
-Photoeperiod: Constant
- Light intensity and quality: 4440 to 8880 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations:] haemocytometer, Sedgewick-Rafter chamber, or Fluorometer measurements.

TEST CONCENTRATIONS
Range finding study
- Test concentrations: 1,10,100 and 1000 mg/l
- Results used to determine the conditions for the definitive study: 72h EC50 >1,000

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 920 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2 090 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

320 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): None reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.661 to 1.719 mg/l

Reported statistics and error estimates:

The result is based on nominal concentrations and was calculated by non-linear regression within the CETIS (V1.8) suite of statistical analysis.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour EC50 was 1920 mg/L and the 72-hour NOEC 320 mg/L. Based on the results of the test the substance did not meet the criteria for classification as acutely toxic to the aquatic environment according to Regulation (EC) N° 1272/2008.

Executive summary:

The short-term toxicity of 2-(2-methylpropoxy)ethanol to algae ( Pseudokirchneriella subcapitata) was determined by a GLP compliant study performed according to OECD 201 test guideline.

A range finding study was first performed to determine the concentrations to be used in the definitive test. The 72H EC50 of the range finding test was >1000 mg/L and as a result the following concentration range were used in the definitive study: 100, 320, 1000, 3200 and 10,000 mg/L. Three replicates were prepared for each test concentration and 6 replicates for the control. Potassium dichromate was used as a reference substance and the results of this test were vaild. The 72h EC50 for 2-(2-methylpropoxy)ethanol as determined by the definitive test was 1920 mg/L and the 72h NOEC was 320 mg/L. As the EC50 value is >1 mg/L the substance does not meet the criteria for classification as acutely toxic to the aquatic environment according to Regulation (EC) N ° 1272/2008.

Description of key information

The short-term toxicity of 2-(2-methylpropoxy)ethanol to algae ( Pseudokirchneriella subcapitata) was determined by a GLP compliant study performed according to OECD 201 test guideline.

Pseudokirchneriella subcapitata was exposed to the following concentrations: 100, 320, 1000, 3200 and 10,000 mg/L. The 72h EC50 as determined by the definitive test was 1920 mg/L and the 72h NOEC was 320 mg/L. As the EC50 value is > 1 mg/L the substance can be regarded as not acutely toxic to the aquatic environemnt in accordance with CLP Regulation (EC) No 1272/2008.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 920 mg/L