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

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 14.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

10.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

other: yield

Remarks on result:

other: 95 % CI = 8.95–12.9 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

8.06 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: 95 % CI = 6.39–10.2 mg/L

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 4.92 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

11.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 4.92 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

6.01 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

Due to the low inhibition of 7.7 and 4.9 % at 4.95 and 6.01 mg/L, the NOEC was set to this concentration since effects below 10% compared to control are generally not considered to be ecotoxicologically relevant.

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 4.92 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (total fraction)

Basis for effect:

other: yield

Details on results:

- Exponential growth in the control (for algal test): Yes
- Observation of abnormalities (for algal test): No abnormalities observed.
- Any stimulation of growth found in any treatment: No

Results with reference substance (positive control):

The sensitivity of the test organism is routinely checked using 3,5-dichlorophenol as primary standard following internal SOPs in a non-GLP test twice a year. The nominal growth rate ErC50 value of 2.90 mg/L (9 5% CI = 2.66–3.16 mg/L, December 2017) is in good agreement with the results of an international ring test with an ErC50 of 3.38 ± 1.30 mg/L.

Reported statistics and error estimates:

See reported effect concentrations.

Analytical results

The test item was quantified by LC-MS/MS measurements in samples of freshly prepared test solutions and controls prior to adding into the test vessels at test initiation. At the end of the test, samples were taken from two representative test replicates per treatment level and control. The level of quantification (LOQ) was determined to be 6.0 µg/L.

At the start of the exposure, the recoveries of the measured concentrations were in the range of 9.4 and 17.2 % of the loading. At the end of the test, the concentrations were between 9.7 and 14.2 % of the loading. The test item concentrations decreased by more than 20 % during the test period, except for the second and third concentration.

The test was evaluated using the geometric mean of the measured concentrations. The mean measured concentrations in increasing order were 4.92, 6.01, 7.39, 11.1 and 14.4 mg test item/L.

Effects on growth rate and yield

Growth rate

There was a slight concentration-dependent effect on the growth rate of the algae up to 16.8 % inhibition at the highest test concentration of 14.4 mg/L, resulting in an (unbounded) E_rC₅₀ of > 14.4 mg test item/L. The inhibition of 7.7 and 4.9 % compared to the control at the two lowest test concentrations was significantly different from the control, respectively. However, effects below 10 % inhibition compared to the control are generally not considered to be ecotoxicologically relevant. The statistically significant effects are a result of the low variability between the replicates. Therefore, the NOEC for growth rate was set to 6.01 mg test item/L.

Yield

There were significant, concentration-dependent effects on yield up to 60.7 % inhibition compared to the control at the highest test concentration of 14.4 mg/L during the growth test. Due to the inhibition above 50 % an E_yC₅₀ value of 10.4 mg/L could be calculated.

Other observations

Microscopic observation of the cell cultures

Date	Observations
Test start, day 0	Inoculum culture: normal appearance of intact cells
Test end, day 3	–
Control	Normal appearance of intact cells, almost no cell debris
4.92 mg/L	Normal appearance of cells, lower cell density than control
6.01 mg/L	–
7.39 mg/L	Decreasing cell density and increasing amount of cell debris with increasing test concentrations.
11.1 mg/L	–
14.1 mg/L	–

 

Validity criteria fulfilled:

yes

Remarks:

Mean growth rate of 1.839/d; Mean coefficient of variation (CV) for section-by-section specific growth rates (days 0-1, 1-2, 2-3) in the control cultures was 14.2 %; mean coefficient of variation of growth rates in replicate control cultures was 1.4%.

Conclusions:

The 72-h ErC50 for inhibition of the growth rate of Raphidocelis subcapitata was > 14.4 mg test item/L based on geometric mean measured concentrations. The NOEC for growht rate was 6.01 mg/L (mean measured).

Executive summary:

In a 72-hour acute toxicity study, cultures of Raphidocelis subcapitata were exposed to sodium isostearoyl lactylate (ISL) at geometric mean measured concentrations of 4.92, 6.01, 7.39, 11.1 and 14.4 mg test item/L under static conditions in accordance with OECD guideline 201. The NOEC and EC₅₀ values based on growth rate were 6.01 and > 14.4 mg/L, respectively.

The microscopic examination of the shape of the algal cells after 72 hours of test duration did not show any abnormalities.

This toxicity study is classified as acceptable and satisfies the guideline requirements for algae growth inhibition study according to OECD guideline 201.

Following Regulation (EC) 1272/2008, the EC50 of ISL does not fulfil any classification criteria for aquatic toxicity.

Results synopsis

Test organism: Raphidocelis subcapitata

Test type: Static

Effect levels:

72 hr E_rC₁₀: 8.06 mg/L (95 % CI = 6.39–10.2 mg/L)

72 hr E_rC₅₀: > 14.4 mg/L

72 hr NOEC: 6.01 mg/L

72 hr LOEC: 11.1 mg/L

Endpoint(s) effected: growth rate

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).

Description of key information

To evaluate the toxicity of sodium lauroyl lactylate (SLL) to aquatic algae and cyanobacteria information on sodium isostearoyl lactylate (ISL) is available by way of read-across.

In a 72-hour acute toxicity study reported by Wenzel (2018), cultures of Raphidocelis subcapitata were exposed to sodium isostearoyl lactylate (ISL) at geometric mean measured concentrations of 4.92, 6.01, 7.39, 11.1 and 14.4 mg test item/L under static conditions in accordance with OECD guideline 201. The NOEC and EC₅₀ values based on growth rate were 8.06 and > 14.4 mg/L, respectively.

The microscopic examination of the shape of the algal cells after 72 hours of test duration did not show any abnormalities.

This toxicity study is classified as acceptable and satisfies the guideline requirements for algae growth inhibition study according to OECD guideline 201.

Following Regulation (EC) 1272/2008, the EC₅₀ of ISL does not fulfil any classification criteria for aquatic toxicity.

This information is used in a read-across approach in the assessment of the target substance sodium lauroyl lactylate (SLL).

Endpoints obtained for ISL need to be corrected stoichiometrically. The correction factor is 0.813, obtained from the molecular weight ratio of SLL and ISL of 366.4249/450.584. Accordingly, algal toxicity endpoints converted to SLL are:

E_rC₅₀ > 11.7 mg/L

E_rC₁₀ = 6.55 mg/L

The E_rC₅₀ is reported as an unbounded value but will will be taken forward to the risk assessment in terms of a point estimate, thus representing a conservative worst-case.

Key value for chemical safety assessment

EC50 for freshwater algae:

11.7 mg/L

EC10 or NOEC for freshwater algae:

6.55 mg/L

Additional information

This information is used in a read-across approach in the assessment of the target substance.

For justification of read-across please refer to the attached read-across report (see IUCLID section 13).