Sodium 2-stearoyllactate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 Apr - 13 May 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted March 23, 2006, corrected July 28, 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz; Wiesbaden; Germany

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 2-stearoyllactate

EC Number:

246-929-7

EC Name:

Sodium 2-stearoyllactate

Cas Number:

25383-99-7

Molecular formula:

This reference substance is a UVCB of the NCS type. It is a complex mixture of compounds and therefore molecular formula, molecular weight, SMILES, InChI and structural formula cannot be given.

IUPAC Name:

sodium 2-hydroxy-2-methyl-3-oxoicosanoate

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Control and highest test item concentration (samples were taken from all test item concentrations but analytical measurements were performed only with the highest test item concentration)
- Sampling method: Duplicate samples from test media of all test concentrations and the controls were taken at test start. At test end (after 72 h) samples were taken in duplicate by pooling the content of the test beakers of all replicates for each treatment. Analytical measurements were performed for the highest test item concentration only, since no effects were observed up to the highest test item concentration.
- Sample storage conditions before analysis: All samples were stored in a freezer (≤ -20 °C), protected from light until analysis was performed. Afterwards the samples were again stored deep frozen and will be kept stored up to the date of the final report.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A supersaturated stock solution of nominal 100 mg test item/L was prepared by suspending 52.0 mg test item in 520 mL test water for preparing the test concentrations. The stock suspension was stirred for 2 hours at room temperature at approximately 100 rpm with subsequent ultrasonic treatment for 15 minutes to dissolve as much test item as possible. Then, non-dissolved fractions of the test item were separated from the test medium by membrane filtration (0.45 µm cellulose acetate filter). The solution with dissolved test item was used as the test medium of the highest test concentration and to prepare the desired 1:3, 1:9, 1:27 and 1:81 dilutions.
- Controls: Medium without test item

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: No. 61.81 SAG
- Source: Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen, Göttingen, Germany
- Age of inoculum (at test initiation): 3 day old pre-culture

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same as test conditions
- Any deformed or abnormal cells observed: Not observed

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

0.24 mmol/L (= 24 mg/L) as CaCO3

Test temperature:

22 - 23 °C

pH:

8.1 - 9.4 (Control)
7.6 - 9.9 (Test item concentrations)

Nominal and measured concentrations:

Nominal: Control, 1.23, 3.70, 11.1, 33.3 and 100 (corresponding to 0.0455 mg/L based on geometric mean measured concentration)

Details on test conditions:

TEST SYSTEM
Test vessel:
- Type: open (loosely covered with watch glass)
- Material, size, headspace, fill volume: glass, Erlenmeyer flasks of 50 mL volume with nominal 50 mL of test medium
- Aeration: No aeration
- Initial cells density: 0.5 x 10E+04 cells/mL
- Control end cells density: 120.769 cells [10000/mL]
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Analytical grade salts were added in deionised water.
- Culture medium different from test medium: No
- Intervals of water quality measurement: daily

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous
- Light intensity and quality: 5263 lux (4840 to 5590 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The cell density on each observation time was determined by spectrophotometric measurement. The algal cell densities were calculated by subtracting the absorption of the blanks, from each of the measured absorption of the test media (with algae).

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.0
Range finding study: non-GLP, not reported

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

yield

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

yield

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.045 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

yield

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.045 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

yield

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.045 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks:

and yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): No abnormalities were observed

Results with reference substance (positive control):

72-hour EC50: 0.858 mg/L

Reported statistics and error estimates:

Based on the calculated cell densities, the 72 hours ErL50 and the 72 hour EyL50 could not be calculated by a statistical analysis due to the lack of effects and were therefore determined directly from the raw data.
For the determination of the 72 hour LOEL and the 72 hour NOEC, the calculated growth rates and yields at each test concentration were tested for significant differences compared to the control values by Dunnett's t-test.
The software used to perform the statistical analysis was ToxRat Professional, Version 3.3.0, ToxRatSolutions GmbH.

Any other information on results incl. tables

Biological Results

Table 1: Growth Rates µ and Percentage Inhibition of µ during the Test Period

Nominal loading rate	Growth rates µ [1/day] and % inhibition of µ
	0 - 24 hours		0 - 48 hours		0 - 72 hours
[mg test item/L]	µ	%	µ	%	µ	%
Control	2.027	-	1.937	-	1.825	-
1.23	2.043	-0.8	1.934	0.2	1.785	2.2
3.70	2.070	-2.1	1.972	-1.8	1.814	0.6
11.1	2.043	-0.8	1.964	-1.4	1.847	-1.2
33.3	2.097	-3.5	1.983	-2.4	1.841	-0.9
100	2.150	-6.1	2.147	-10.8	1.808	1.0

negative values in ‘% inhibition’ indicate an increase in growth relative to that of the control
No statistically significant difference (tested with Williams t-test (24 and 48 h) and Dunnett's t-test (72h),a = 0.05, one-sided smaller)

Analytical Results

Table 2: Summary of Analytical Results

 

Sample Description	Concentration nominal	fresh (0h)		aged (24h)		aged (48h)		aged (72h)		Geometric mean² Concentration
[mg test item/L]	[mg test item/L]1	Concentration calculated [mg test item/L]1	n	Concentration calculated [mg test item/L]1	n	Concentration calculated [mg test item/L]1	n	Concentration calculated [mg test item/L]1	n	%	[mg test item/L]1
Control	0	n.a.	2	n.a.	2	n.a.	2	n.a.	2	n.a.	n.a.
1:81 dilution of filtrate	1.23	n.m.	-	n.m.	-	n.m.	-	n.m.	-	n.a.	n.a.
1:27 dilution of filtrate	3.70	n.m.	-	n.m.	-	n.m.	-	n.m.	-	n.a.	n.a.
1:9 dilution of filtrate	11.1	n.m.	-	n.m.	-	n.m.	-	n.m.	-	n.a.	n.a.
1:3 dilution of filtrate	33.3	n.m	-	n.m	-	n.m	-	n.m	-	n.a.	n.a.
Filtrate of 100 mg test item/L	100	1.296	2	0.829	2	<LOD	2	<LOQ	2	0.05	0.0455

1 mean value of all measured samples per sampling date

2 Geometric mean calculated according to OECD Guidance Document No. 23, Annex 2 (2000)

Italic: Regarding these concentrations no biological effects were observed and only filtrate of 100 mg test item/L was analysed.

 

For values <LOQ, half the LOQ and for values <LOD, the LOD was used for calculating geometric mean concentrations according to OECD Guidance Document No. 23; LOD: Limit of Detection = 0.001 mg test item/L; LOQ: Limit of Quantification = 0.02 mg test item/L; n: number of analysed samples; n.a.: not applicable; ; n.m.: not measured because concentrations were below the NOEC determined in this test

Table 1: Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	241.5	Yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	12%	Yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	3%	Yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.