Oxazolidine, 3-butyl-2-(1-ethylpentyl)-

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 2005-07-11 to 2005-07-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted 1981

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

adopted 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: The concentration and stability of the test material in the test preparations were verified by chemical analysis at 0 and 72 hours. A volume of test sample was eluted through the cartridge. The test material was eluted from the cartridge with acetonitrile and prepared for subsequent GC-FID analysis.

Vehicle:

no

Details on test solutions:

For the purpose of the definitive test, the test material was dissolved directly in culture medium with the aid of prolonged stirring.
An amount of test material (1100 mg) was dispersed in 11 litres of culture medium and stirred using a propeller stirrer at approximately 1500 rpm for 24 hours to give the required test concentration of 100 mg/L. A series of dilutions was made from this solution to give further stock solutions of 32, 10, 3.2 and 1.0 mg/L. An aliquot (900 mL) of each of the stock solutions was separately inoculated with algal suspension (4.5 mL) to give the required test concentrations of 1.0, 3.2, 10, 32 and 100 mg/L.
The stock solutions and each of the prepared concentrations were inverted several times to ensure adequate mixing and homogeneity.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus (new name: Desmodesmus subspicatus)
- Strain: CCAP 276/20
- Source: Culture Collection of Algae and Protozoa (CCAP)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 1 °C

pH:

Control: 7.3
1.0 mg/L: 7.3
3.2 mg/L: 7.4
10 mg/L: 8.5
32 mg/L: 9.2
100 mg/L: 9.6

Nominal and measured concentrations:

Nominal concentrations: 1.0, 3.2, 10, 32 and 100 mg/L.
Due to the rapid hydrolysis of the test item, steady measured concentrations of the test item were not achievable. The hydrolysis products could not be detected by the analytical method due to possible but unconfirmed adsorption to surfaces.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml glass conical flasks
- Initial cells density: 1x 10E4 cells per mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: approx. 7000 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: Cell densities were determined using a Coulter® Multisizer Particle Counter

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.10, 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

5.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% confidence limits: 4.8 - 6.5 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence limits: 9.7 - 15 mg/L

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Due to the rapid hydrolysis of the test item, steady measured concentrations of the test item were not achievable. The hydrolysis products could not be detected by the analytical method due to possible but unconfirmed adsorption to surfaces.

Reported statistics and error estimates:

Statistical analysis of the area under the growth curve data was carried out for the control and all test concentrations using one way analysis of variance incorporating Bartlett's test for homogeneity of variance and Dunnett's multiple comparison procedure for comparing several treatments with a control.

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test material on the growth of Scenedesmus subspicatus has been investigated over a 72-hour period and gave an ErC50 (0 - 72 h) value of 12 mg/L; 95 % confidence limits 9.7-15 mg/L. The No Observed Effect Concentration at 72 hours was 1.0 mg/L.

Executive summary:

A study was performed to assess the effect of the test material on the growth of the green alga Scenedesmus subspicatus, according to OECD Guideline No 201 and the EU Method C.3. Following a preliminary range-finding test, Scenedesmus subspicatus was exposed to an aqueous solution of the test material at concentrations of 1.0, 3.2, 10, 32 and 100 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Exposure of Scenedesmus subspicatus to the test material gave an ErC50 (0 - 72 h) value of 12 mg/L; 95% confidence limits 9.7 - 15 mg/L.

The No Observed Effect Concentration was 1.0 mg/L.

All reported biological results are related to the nominal concentrations. Due to the rapid hydrolysis of the test item, steady measured concentrations of the test item were not achievable. The hydrolysis products could not be detected by the analytical method due to possible but unconfirmed adsorption to surfaces.

Description of key information

The effect of the test material on the growth of Scenedesmus subspicatus has been investigated over a 72-hour period and gave an ErC50 (0 - 72 h) value of 12 mg/L; 95 % confidence limits 9.7-15 mg/L. The No Observed Effect Concentration at 72 hours was 1.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

12 mg/L

EC10 or NOEC for freshwater algae:

1 mg/L

Additional information

A study was performed to assess the effect of the test material on the growth of the green alga Scenedesmus subspicatus, according to OECD Guideline No 201 and the EU Method C.3. Following a preliminary range-finding test, Scenedesmus subspicatus was exposed to an aqueous solution of the test material at concentrations of 1.0, 3.2, 10, 32 and 100 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1°C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.

Exposure of Scenedesmus subspicatus to the test material gave an ErC50 (0 - 72 h) value of 12 mg/L; 95 % confidence limits 9.7 - 15 mg/L.

The No Observed Effect Concentration was 1.0 mg/L. All reported biological results are related to the nominal concentrations.

Due to the rapid hydrolysis of the test item, steady measured concentrations of the test item were not achievable. The hydrolysis products could not be detected by the analytical method due to possible but unconfirmed adsorption to surfaces.