2-Propenoic acid, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl ester

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:

04 MARCH 2019 to 06 MARCH 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Testing Guideline No. 201 Freshwater Alga and Cyanobacteria, Growth Inhibition Test (adopted 23 March 2006) (Annex 5 corrected 28 July 2011).

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 23 March 2006, Annex 5 corrected 28 July 2011

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Sample Fortification
1 mL aliquots of OECD media were measured into glass vials and fortified at
appropriate nominal concentrations. An example of the range used is as follows:
1 x control
F 0.05 μg/mL: Add 50 μL of 1.0 μg/mL solution
F 1.0 μg/mL: Add 100 μL of 10 μg/mL solution
F 60 μg/mL: Add 60μl of 1000 μg/mL solution
After fortification the samples were treated as described in the ‘Sample Preparation’
section below.
Sample Preparation
1. Aliquots of media (1 mL) were measured into appropriate glass vials.
2. These samples were then fortified as required and 4 mL of acetone added
before the vials were capped
3. The vials were then shaken to mix well
4. The samples in the vials were then diluted as necessary with diluent (acetone:
OECD medium 4:1 v:v).
5. The samples were then thoroughly mixed before analysis
6. A portion of the solution was then transferred into a suitable vial for GC/MS
analysis.

Vehicle:

no

Details on test solutions:

The dilution media used was alga nutrient medium (EC medium = OECD TG 201
medium according to Annex 3 of the OECD test guideline).

Preparation of Test Medium
A 38.4 mg/L and 12.0 mg/L solution were prepared by adding 38.37 and 12.04 mg of test substance to 1000 mL of OECD medium. The solution was then sonicated for ca 5 minutes to aid dissolution.

The control treatment was prepared with OECD medium only.

Following preparation, all the test solutions were checked for the tyndall effect usinga Hach 2100 N turbidity meter. The turbidity meter confirmed that there was no dispersed test substance present, as these were similar to the control and below a nephelometric turbidity units (NTU) value of 1.

Test organisms (species):

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

Details on test organisms:

The test organism, Raphidocelis subcapitata (Strain 278/4; formerly known as
Pseudokirchneriella subcapitata (P. subcapitata used throughout the report)), was originally obtained from the Culture Collection of Algae and Protozoa (CCAP), Oban, UK and is a representative species of the freshwater aquatic phytoplankton. This species is recommended for testing in accordance with the OECD regulatory guidelines.
Prior to testing, duplicate starter cultures were prepared and incubated under test
conditions to obtain sufficient algal cells in exponential growth and to achieve a starting alga cell density of 1 x 104 cells/mL.
Positive control tests are conducted periodically to assess the performance of the test species.

Test type:

static

Water media type:

freshwater

Remarks:

The dilution media used was alga nutrient medium (EC medium = OECD TG 201 medium according to Annex 3 of the OECD test guideline will be referred to as OECD media in the report).

Limit test:

no

Total exposure duration:

72 h

Hardness:

See Table 1

Test temperature:

See Table 1

pH:

See Table 1

Conductivity:

See Table 1

Nominal and measured concentrations:

See Table 2

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Erlenmeyer flasks (nominal volume 250 mL) plugged withfoam bung, 100 ml fill volume
- Initial cells density: 1 x 104 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate 22 JANUARY 2019 - 25 JANUARY 2019

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.66 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Confidence limits: 2.57-4.44

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.35 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.83 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Remarks on result:

other: Confidence Limit: 1.23-2.24

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.627 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

yield

Details on results:

The algae cells in the inoculum at the start of the test and in the control and test
vessels at the end of the test were observed using a microscope. The observations
results are presented in the table 3.

Results with reference substance (positive control):

EC50 (mg/L): 1.3
NOEC (mg/L): 1.0
- Results with reference substance valid: YES

Reported statistics and error estimates:

The toxicity results are expressed in terms of the non-inoculated geometric mean
measured concentrations. The no observed effect concentrations were determined using the following statistical tests:
The 24 and 72 hour average specific growth rate (μ) time intervals were
analysed using a Dunnett multiple comparison test, as the data indicated a
parametric and non-monotonic trend.
The 48 hour average specific growth rate (μ) time interval was analysed using
a Williams multiple comparison test, as the data indicated a monotonic and
parametric trend.
The 72 hour final yield time interval was analysed using a Dunn/Bonferroni-
Holm test, as the data indicated a non-monotonic and non-parametric trend.
Linear interpolation analysis was performed in order to estimate EC10, EC20 and EC50 values for the 72 hour final yield and the 0-24, 0-48, 0-72, 24-48 and 48-72 hour average specific growth rate (μ) time intervals. Where possible, 95% confidence limits were calculated for the EC10, EC20 and EC50 values. Outliers were assessed using Grubbs extreme value. No outliers were excluded from the results, as the outliers identified during the statistical analysis were not considered to be biologically significant.
To distinguish between ECx values, estimated using areas under the growth curve,
final yield and growth rates, the symbols EyCx and ErCx were used, respectively.

 

Table 3: Algae observations in the incolum at the start and the end of the test.

Algae Culture		0 hours	appear healthy
Control	Control
0.384	0.305		Green, sickle shaped
1.20	1.16
3.84	3.06		Green/yellow, some sickle/deformed in shape
		72 hours
				Green/yellow, very few
12.0	11.5			cells, sickle/deformed in
				shape
				Green/yellow, very, very
38.4	31.3			few cells, sickle/deformed
				in shape

Validity criteria fulfilled:

yes

Remarks:

Controll cell density increase: 111 Coefficient of variation of average grorth rate 4.99% Mean Coeff. of variation for section by section specific growth rates: 32.7%

Conclusions:

The effects of the test item on the growth of the unicellular green alga, Pseudokirchneriella subcapitata at exponential growth phase were determined during a 72-hour growth inhibition test conducted in accordance with OECD Chemicals Testing Guideline No. 201 Freshwater Alga and Cyanobacteria, Growth Inhibition Test (adopted 23 March 2006) (Annex 5 corrected 28 July 2011).

The 72-hour EyC50 and ErC50 values based on geometric mean measured concentrations were both estimated to be 1.83 and 3.66 mg/L.

The 72-hour NOEC values for 72 hour yield and growth rates based on geometric mean measured concentrations were both estimated to be 3.06 and 1.16 mg/L.

All validity criteria were met; therefore, the test was considered valid.

Description of key information

One study with green algae was conducted.
The key study is an OECD 201 guideline compliant study conducted with Pseudikirchneriella subcapitata over 72 hours. 
Test concentrations of 0.384, 1.2, 3.84, 12 and 38.4 mg/L were investigated for effects on growth rate and yield inhibition under static conditions. 
The test concentration were analytical verified and in the range of 80% to 120% of nominal. 
After 72 hours the EC50 values for inhibition of growth rate and yield were 3.66 and 1.83 mg/L, respectively. 
The EC10 values for inhibition of growth rate and yield were 1.35 and 0.627 mg/L, respectively. All validity criteria were met.

 

Key value for chemical safety assessment

EC50 for freshwater algae:

3.66 mg/L

EC10 or NOEC for freshwater algae:

1.16 mg/L