Lauric acid, monoester with propane-1,2-diol

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:

10 November 2016 to 19 January 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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Physical state/Appearance: Clear colorless liquid
Batch: 1023R25811
Purity: 99.5%
Expiry Date: 14 September 2019
Storage Conditions: Room temperature in the dark

Analytical monitoring:

yes

Remarks:

gas chromatography

Details on sampling:

The test samples were thawed with the aid of a water bath. The test samples (200 mL) plus 60 g of sodium chloride were extracted directly with 20 mL of hexane in the same bottle. An aliquot of the hexane layer was taken for analysis.

Vehicle:

no

Details on test solutions:

A nominal amount of test item was dispersed in culture medium with the aid of propeller stirring. After 24 hours the stirring was stopped and any undissolved test item was removed by filtration through a 0.2 µm filter (first approximate 2 liters discarded in order to precondition
the filter) to give a 100% v/v saturated solution.
The concentration and stability of the test item in the test preparations were verified by chemical analysis at 0, 24, 48 and 72 hours.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Method of cultivation: flask under constant agitation by orbital shaker, constant aeration and constant illumination

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 1 °C

pH:

7.7 - 8.4

Nominal and measured concentrations:

6.25, 12.5, 25, 50 and 100% v/v saturated solution.

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks
- Type: closed
- Material, size, headspace, fill volume: 250 mL glass conical flasks
- Aeration: continuous
- Initial cells density: 5.00 x 103 cells/mL
- No. of vessels per concentration (replicates): 5.00 x 103 cells/mL
- No. of vessels per control (replicates): 5.00 x 103 cells/mL

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes
- Photoperiod: continuous
- Light intensity and quality:7000 lux warm white lighting (380 – 730 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0.10, 1.0, 10 and 100% v/v saturated solution
- Results used to determine the conditions for the definitive study: The results showed no effect on growth at the test concentrations of 0.10, 1.0 and 10% v/v saturated solution. However, growth was observed to be reduced at 100% v/v saturated solution.
Based on this information test concentrations of 6.25, 12.5, 25, 50 and 100% v/v saturated solution were selected for the definitive test.

Reference substance (positive control):

yes

Remarks:

The positive control was conducted between 28 November 2016 and 01 December 2016.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.068 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.033 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.047 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.051 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.033 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.047 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

biomass

Details on results:

All test and control cultures were inspected microscopically at 72 hours. After 72 hours there were no abnormalities detected in the control or test cultures at 0.033 and 0.047 mg/L, no intact cells were observed to be present in the test cultures at 0.060, 0.077 and 0.94 mg/L

Results with reference substance (positive control):

ErC50 (0 – 72 h) : 1.4 mg/L; 95% confidence limits 1.2 – 1.5 mg/L
EyC50 (0 – 72 h) : 0.60 mg/L; 95% confidence limits 0.52 – 0.69 mg/L
The results from the positive control with potassium dichromate were within the normal ranges for this reference item.

Reported statistics and error estimates:

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 was carried out on the growth rate and yield data after 72 hours for the control and all test concentrations to determine any statistically significant differences between the test and control groups.

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test item on the growth of Pseudokirchneriella subcapitata has been investigated over a 72-Hour period and based on the geometric mean measured test concentrations:
Growth rate:
- EC50 = 0.068 mg/L ; 95% Confidence Limits = 0.064 - 0.072 mg/L
- No Observed Effect Concentration (NOEC) = 0.033 mg/L
- Lowest Observed Effect Concentration (LOEC) = 0.047 mg/L
Yield:
- EC50 = 0.051 mg/L ; 95% Confidence Limits = 0.049 - 0.054 mg/L
- No Observed Effect Concentration (NOEC) = 0.033 mg/L
- Lowest Observed Effect Concentration (LOEC) = 0.047 mg/L

Description of key information

Toxicity to Pseudokirchneriella subcapitata over a 72-Hour period:

Growth rate:

- EC50 = 0.068 mg/L ; 95% Confidence Limits = 0.064 - 0.072 mg/L

- No Observed Effect Concentration (NOEC) = 0.033 mg/L

- Lowest Observed Effect Concentration (LOEC) = 0.047 mg/L

Yield:

- EC50 = 0.051 mg/L ; 95% Confidence Limits = 0.049 - 0.054 mg/L

- No Observed Effect Concentration (NOEC) = 0.033 mg/L

- Lowest Observed Effect Concentration (LOEC) = 0.047 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

0.068 mg/L

EC10 or NOEC for freshwater algae:

0.033 mg/L