1-[(2-hydroxyethyl)thio]propan-2-ol

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:

From 11 September 2017 to 29 September 2017

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 growth rates were not used in the calculation of results.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

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):
- Method of cultivation: culture 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
- Culturing media and conditions: 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 to 24 °C

pH:

8.1 ±0.2. Not increased during the test by more than 1.5 relative to the pH of the growth medium.

Dissolved oxygen:

Not specified

Salinity:

Not specified

Conductivity:

Not specified

Nominal and measured concentrations:

Nominal concentrations: 1, 10, 100, and 1000 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: borosilicate glass crystallising dishes
- Material, size, headspace, fill volume: 100 mL
- Type of flow-through: static
- Initial cells density: initial cell density of approximately 5 x10^3-10^4 cells per millilitre
- No. of vessels per concentration (replicates): three
- No. of vessels per control (replicates): six

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used: As specified in OECD 201

OTHER TEST CONDITIONS
- Light intensity and quality: Between 5470 and 5490 lx

TEST CONCENTRATIONS
- Test concentrations: 1, 10, 100 and 1,000 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

5 600 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
- Unusual cell shape: None reported
- Colour differences: None reported
- Flocculation: None reported
- Adherence to test vessels: None reported
- Aggregation of algal cells: None reported
- Any stimulation of growth found in any treatment: None reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None reported
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 1.42 mg/L

Reported statistics and error estimates:

Results for both range-finding and definitive tests were calculated by Linear Interpolation within the CETIS suite of statistical analysis.

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour EC50 was >10,000 mg/L and the 72-hour NOEC 5,600 mg/L. The substance did not meet the criteria for classification as toxic to the aquatic environment according to Regulation (EC) N° 1272/2008.

Executive summary:

The short-term toxicity of 1-[(2-hydroxyethyl)thio]propan-2-ol to algae was determined during a GLP-compliant study performed according to the OECD Testing Guideline 201.

The species was Pseudokirchneriella subcapitata.

A range-finding test was performed to determine the concentrations to be used during the definitive test. As a result of this range-finding test, concentrations of 1,000, 1,800, 3,200, 5,600 and 10,000 mg/L were used during the definitive test.

The 72-hour EC50 was >10,000 mg/L and the 72-hour NOEC 5,600 mg/L. The substance did not meet the criteria for classification as toxic to the aquatic environment according to Regulation (EC) N° 1272/2008.

Description of key information

The short-term toxicity of 1-[(2-hydroxyethyl)thio]propan-2-ol to algae was determined during a GLP-compliant study performed according to the OECD Testing Guideline 201.

The species was Pseudokirchneriella subcapitata.

A range-finding test was performed to determine the concentrations to be used during the definitive test. As a result of this range-finding test, concentrations of 1,000, 1,800, 3,200, 5,600 and 10,000 mg/L were used during the definitive test.

The 72-hour EC50 was >10,000 mg/L and the 72-hour NOEC 5,600 mg/L. As a conclusion the test substance was not considered to be toxic to aquatic algae and cyanobacteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

10 000 mg/L