Ethylene carbonate

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:

2015-07-17 to 2015-08-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method:
* range-finding test: A sample of each test concentration was taken for chemical analysis at 0 and 72 hours in order to determine the stability of the test item under test conditions.
* definitive test: Samples were taken from the control and the 100 mg/L test group from the bulk test preparation at 0 hours and from the pooled replicates at 72 hours for quantitative analysis. Dumplicate samples were taken at 0 and 72 hours and stored frozen for further analysis if necessary.
- Sample storage conditions before analysis: all samples are kept stored frozen prior to analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
* Range-finding test: The test item was dissolved directly in culture medium. Prior to use the test item was heated to 50°C in order to melt. A nominal amount of test item (50 mg) was dissolved in culture medium and the volume adjusted to 500 mL to give a 100 mg/L stock solution from which a series of dilutions was made to give further stock solutions of 10, 1.0 and 0.10 mg/L. An aliquot (450 mL) of each of the stock solutions was separately inoculated with algal suspension (3.5 mL) to give the required test concentrations of 0.10, 1.0, 10 and 100 mg/L. The stock solutions and each of the prepared concentrations were inverted several times to ensure adequate mixing and homogeneity.
- Controls: yes, the control group was maintained under identical conditions but not exposed to the test item.
* Definitve test: a nominla amount of test item (100 mg) was dissolved in culture medium and the volume adjusted to 1 liter to give a 100 mg/L stock solution. This stock solution was inoculated with algal suspension (8.8 mL) to give the required concentration of 100 mg/L. Stock solutionb and the prepared concentration were inverted several times to ensure adequate mixing and homogeneity.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: - Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland
- Method of cultivation: The master cultures were maintained in the laboratory under constant aeration and constant illumination at 21 ± 1 °C.

ACCLIMATION
- Acclimation period: no data
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

not reported

Test temperature:

24± 1°C

pH:

* Control: pH increased from pH 7.9 at 0 hours to pH 8.3 at 72 hours.
* Definitive test: 8.0 - 8.3

Dissolved oxygen:

not reported

Salinity:

not relevant

Nominal and measured concentrations:

* Range-finding test: 99 to 106% of nominal concentrations (100 mg/L)
* Definitive test: 86 to 88% of nominal concentrations (100 mg/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass conical flasks
- Type (delete if not applicable): plugged with polyurethane foam
- Material, size, headspace, fill volume: 250 mL glass conical flasks containing 100 mL of test preparation .
- Initial cells density: 5000 algal cells/mL test medium
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, according to guidelines (OECD 201)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: the culture medium was prepared using reverse osmosis purified deionized water
- Culture medium different from test medium: no difference
- Intervals of water quality measurement: 72h

OTHER TEST CONDITIONS
- Sterile test conditions: no information
- Adjustment of pH: adjusted to 7.5 with 0.1 N NaOH or HCl
- Photoperiod: continuously illuminated
- Light intensity and quality: mean value of about 7000 lux achieved by white lighting (380-730 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: Multisize particle counter ( Coulter)
- Effect parameters calculated: specific growth rate, yield data

TEST CONCENTRATIONS
- Spacing factor for test concentrations: none (limit test)
- Range finding study:
- Test concentrations: 0.1, 1.0, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 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
- Effect concentrations exceeding solubility of substance in test medium: no remarkable observations. The test media of all test concentrations remained clear throughout the entire test period.
- The 72-h EC50 (biomass) = 28 mg/L (95% CL 22-36 mg/L)
- The 72-h EC10 (biomass) = 11 mg/L (95% CL 6-15 mg/L)
- The 72-h EC10 (growth rate) = 24 mg/L (95% CL 7-36 mg/L)
- The 72-h EC90 (biomass) = 69 mg/L (95% CL 50-121 mgL)
- The 72-h EC90 (growth rate) = 133 mg/L (95% CL 80-902 mg/L)
- The 72-h NOEC (growth rate and biomass) = 10 mg/L

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: (growth rate) 1.0 mg/L (95% CL 0.90-1.2 mg/L)

Reported statistics and error estimates:

A student's t-test incorporating Bertlett's test for homogeneity of variance was carried out on the growth rate and yield data.

Validity criteria fulfilled:

yes

Conclusions:

A 72-h growth inhibition test with the unicellular green algae Pseudokirchneriella subcapitata was performed according to the OECD 201 guideline. The 72-h NOEC was determined to be 100 mg ethylene carbonate/L (nominal). The 72-h EC50 (growth rate) was determined to be > 100 mg ethylene carbonate/L. The results of the test can be considered reliable without restriction.

Description of key information

A Klimisch 1 study (Vryenhoef, 2015) on ethylene carbonate reported an unbounded 72-h ErC50  value of > 100 mg/L and a NOErC of 100 mg/L. 

Additional information

The recently performed acute study of Vryenhoef (2015) was used as key study. The study was performed following the OECD 201 guideline. Following a range-finder study, the algae were exposed to a single test concentration of 100 mg/L. Analysis of the test preparations showed that the measured test concentration was near the nominal concentrations (<20% differences), so results were based on nominal test concentrations only.

The test resulted in a unbounded 72-h ErC50 > 100 mg/L for the algae Pseudokirchnerella subcapitata. No effects were observed at the highest concentration tested. The 72-h NOErC was determined to be 100 mg/L.