Sodium 2-(1-carboxylatoethoxy)-1-methyl-2-oxoethyl laurate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019-11-19 to 2020-09-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

adopted 13 h April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Test item name: Sodium lauroyl lactylate
- Product name: Esterlac SLL Balance+
- Batch No.: PG20192001
- Purity: 100 % (UVCB substance)
- Appearance: golden-yellow, solid, very viscous

Analytical monitoring:

yes

Details on sampling:

The concentrations of C12-1 lactylate and C12-2 lactylate in the aqueous solutions were measured during the study at the start of the test, at media renewal at 24 hours and at test end. Samples of aged solutions were taken from one representative replicate at media renewal and test end.

Vehicle:

yes

Remarks:

acetone for coating of mixing vessel surfaces; completely evaporated before addition of test media

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Each test solution was prepared individually. In a first step, for each test concentration an acetonic application solution was prepared by dissolving an appropriate amount of test item in acetone. Afterwards, the acetonic application solutions were used to prepare the test solutions by applying 0.5 mL of the respective acetonic application solution into a glass bottle. After complete evaporation of acetone, the glass bottles were filled with 500 mL deionized water, ultra-sonicated for 10 minutes and then stirred for 1 hour. After stirring, the test solutions still showed undissolved test material. The two highest test concentrations were turbid and wax-like particles were observed at the surface and in the solutions. Therefore, all test solutions were filtered using a 0.22 µm PES bottle top filter to remove the undissolved test material left in the test solutions. Since no acetone was left in the glass bottles, no solvent control was necessary. The control medium was treated the same way as test solutions with dilution water only. Test and control solutions were freshly prepared prior medium renewal.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: not specified
- Source: German Federal Environment Agency, Institut für Wasser-, Boden- und Lufthygiene. Specimens were bred in the laboratory of the Fraunhofer IME.
- Age of parental stock: at least 3 weeks
- Age of test organisms: 4-24 hours old
- Feeding during test: None
- Food type: algal suspension (Desmodesmus subspicatus) and ArtemioFluid (JBL).
- Amount: Algae growing in the log-phase were centrifuged and the pellet was re-suspended in a few mL of medium. 30 mL of this suspension was given to 1 L of Daphnia medium.
- Frequency: The water was changed three times a week.

ACCLIMATION
- Acclimation period: same as test

Test type:

semi-static

Water media type:

freshwater

Remarks:

Cu-reduced drinking water

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Observations at 24 and 48 hours

Hardness:

Hardness was below the recommended range (> 140 mg/L as CaCO3). Therefore, the Cu-reduced dilution water is enriched with an appropriate amount of CaCl2 to increase the hardness, resulting in values of about 250–350 mg CaCO3/L.

Test temperature:

18.7–21.9 °C (mean 20.2 °C)

pH:

7.59–8.19

Dissolved oxygen:

5.01–8.43 mg/L

Salinity:

Not applicable

Conductivity:

Not reported

Nominal and measured concentrations:

Nominal: 0, 1.94, 4.27, 9.39, 20.7, 45.5 and 100 mg/L
Geometric mean measured concentrations of fresh and aged test solutions: 0, 1.02, 3.15, 7.63, 20.9, 45.3 and 96.4 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL glass beakers
- Type: closed. The numbers of immobile animals were visually determined daily and dead specimens were removed. Immobility was determined according to OECD guideline 202.
- Aeration: None
- Renewal rate of test solution (frequency/flow rate): 24 hours
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM/WATER PARAMETERS
- Source/preparation of dilution water: Purified, Cu-reduced drinking water was used as holding- and dilution water. The purification includes filtration with activated charcoal and aeration. To avoid copper contamination, plastic water pipes are used for the testing facilities.
The following water chemistry data are recorded regularly in the testing facility and are reported: pH, conductivity, dissolved oxygen content, content of nitrate, nitrite, ammonium, phosphate, calcium, magnesium, total hardness, alkalinity, DOC content (or NPOC, as appropriate), content of metals (cadmium, chrome, copper, iron, lead, manganese, nickel and zinc).

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light/8 hours dark
- Light intensity: 888–918 Ix (corresponding to 11.8–12.2 µE/(m² × s))

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The numbers of immobile animals were visually determined daily and dead specimens were removed. Immobility was determined according to OECD guideline 202. The animals were considered to be immobile when they were not able to swim within 15 seconds after gentle agitation of the test vessels. Any abnormalities in appearance and behaviour were also recorded. Evaluation and statistics were applied to the 48 h results.

VEHICLE CONTROL PERFORMED: No

Reference substance (positive control):

yes

Remarks:

K2Cr2O7 to check the sensitivity of the test clone checked twice a year in a non-GLP test

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

44.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

20.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

45.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

At test end (48 h), all daphnids seemed to be slightly discoloured in the control and in all test concentrations. No other significant signs of disease, stress or abnormal behaviour were observed in any replicate. For detailed results see table 1 in box " Any other information on results incl. tables".

Results with reference substance (positive control):

The latest 24 h-EC50 (December 2019) for potassium dichromate (K2Cr2O7) was 1.267 mg/L (95% confidence limits: 1.056–1.609 mg/L).

Reported statistics and error estimates:

EC50 and 95 % confidence intervals estimated using Probit-analysis assuming log-normal distribution.
NOEC and LOEC determined using appropriate statistical methods (e.g. Fisher’s Exact Binomial Test for quantal response).
The computer program ToxRat was used for statistical evaluations.

Analytical results

The concentrations of the test item in the aqueous test solution were assessed by analysis of the C12-1 lactylate and the C12-2 lactylate at the start of the test, at media renewal after 24 hours, and at test end. A LC-MS/MS system (LOQ = 0.01 mg/L) was used for measurements.

Concentrations of freshly prepared test media showed recovery rates between 98.8 and 120 % of nominal. Concentrations in aged test media showed recovery rates between 13.8 and 103 % of nominal and between 13.9 and 96.3 % of initial concentrations. The evaluation of effects was based on the geometric mean measured concentrations of 1.02, 3.15, 7.63, 20.9, 45.3 and 96.4 mg test item/L, corresponding to 52.6, 73.7, 81.2, 101, 99.5, and 96.4 % of nominal. Background concentrations in control media were below the LOQ of 0.01 mg/L.

Biological results

Table 1. Mobile and immobile daphnids after 48 h and per treatment level after 48 hours

Mean measured concentration based on geometric mean (mg/L)	Total introduced	Mobile	Immobile	% Immobility
Control	20	18	2	10.0
1.02	18	2	0	10.0
3.15	20	14	6	30.0
7.63	20	19	1	5.0
20.9	20	17	3	15.0
45.3	20	12	8	40.0
96.4	20	2	18	90.0

 

Validity criteria fulfilled:

yes

Remarks:

Validity criteria of the guideline are fulfilled: Mortality in controls ≤10 %, dissolved oxygen conc. at the end of the aging period (48 h) > 3 mg/L in control and test vessels.

Conclusions:

The test item sodium lauroyl lactylate showed toxic effects on Daphnia magna in a 48-h immobilization test conducted according to OECD test guideline 202. The EC50 was calculated to be 44.4 mg/L based on geometric mean measured concentrations. The NOEC was determined to 20.9 mg/L and the LOEC was identified at 45.3 mg/L.

Executive summary:

The 48-hr acute toxicity of sodium lauroyl lactylate (SLL) to Daphnia magna was studied under semi-static conditions. Test organisms were exposed to control and test chemical at measured) concentrations of 1.02, 3.15, 7.63, 20.9, 45.3 and 96.4 mg/L for 48 hours.  Mortality/immobilisation and sublethal effects were observed daily.  The 48-hour EC₅₀ was 44.4 mg/L. The 48-hr NOEC based on immobilisation was 20.9 mg/L. The sublethal effects included were slight discolouration in both treatments and control, thus most likely not test item related.

Based on the results of this study, SLL would not be classified as toxic to Daphnia magna in accordance with the classification system of the CLP Regulation.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Results synopsis

Test organism age (e.g. 1st instar): < 24 h

Test type: Static renewal

EC₅₀:  44.4 mg/L (95 % C.I. not determinable); Probit slope: 1.31

NOEC: 20.9 mg/L

Endpoint(s) effected: Mobility

Description of key information

The 48-h semi-static acute toxicity test with sodium lauroyl lactylate (SLL) in Daphnia magna was conducted according to OECD test guideline 202. The EC₅₀ (mobility) was calculated to be 44.4 mg/L based on geometric mean measured concentrations. The NOEC was determined to be 20.9 mg/L and the LOEC was identified at 45.3 mg/L.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Following Regulation (EC) 1272/2008, no classification for acute toxicity is warranted. As the substance is readily biodegradable, classification for chronic toxicity is not warranted.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

44.4 mg/L