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

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

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

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

The EC50 for the reference item was found to be 19.5 mg/L and is therefore within the accepted range of the OECD 209 guideline of 2 to 25 mg/L

Table 1. Mean inhibition (%) of the respiration rate by the test item

Test item concentration [mg TI/L]
10 mg/l	100 mg/L	1000 mg/L
-5.30%	-18.30%	-358.90%

TI = Test item; No significant difference when compared with control (P < 0.05).

Considering the observed stimulation of microbial respiration hence the absence of an adverse effect up to the limit concentration, EC-values are reported as EC10 ≥ 1000 mg/L, EC20 ≥ 1000 mg/L, EC50 ≥ 1000 mg/L, and EC80 ≥ 1000 mg/L, respectively (nominal concentrations).

A significant abiotic oxygen demand by the test item was not observed during the 3 h test period.

The test is considered valid, as:

- with 38 mg O2/g activated sludge (dry weight of suspended solids) in an hour, the oxygen uptake rate in blank controls was ≥ 20 mg O2/g in an hour,

- with 8 %, the coefficient of variation of oxygen uptake rate in control replicates is ≤ 30 %,

- with 19.5 mg/L, the EC50 (3 hours) of the reference substance 3,5-dichlorophenol is in the accepted range of 2 to 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

There was no significant inhibition of bacterial respiration by the test item up to and including a nominal concentration of 1000 mg per liter. An activated sludge respiration inhibition test according to OECD 209 resulted in an EC50 > 1000 mg/L and a NOEC ≥ 1000 mg/L.

Executive summary:

To investigate potential harmful effects of the test item Sodium-Isostearoyl-Lactylate on microorganisms, an activated sludge respiration inhibition test was performed according to OECD 209 and under GLP.

A definitive test with the nominal test concentrations of 10, 100, and1000 mg /L was performed. The pH in the test vessels was 7.5 ± 0.5. No inhibition was observed in the test vessels up to and including a nominal concentration of 1000 mg/L test concentration (-358.9 to -5.3%)

The respiration rates in the test vessels were not significantly lower than the respiration rate of the controls (Williams' Multiple Sequential t-test).

The results are therefore:

EC50 > 1000 mg/L

NOEC ≥ 1000 mg/L

The test is considered valid, as:

- with 38 mg O2/g activated sludge (dry weight of suspended solids) in an hour, the oxygen uptake rate in blank controls was ≥ 20 mg O2/g in an hour,

- with 8 %, the coefficient of variation of oxygen uptake rate in control replicates is ≤ 30 %,

- with 19.5 mg/L, the EC50 (3 hours) of the reference substance 3,5-dichlorophenol is in the accepted range of 2 to 25 mg/L.

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 microorganisms read-across from sodium isostearoyl lactylate (ISL) was applied.

There was no significant inhibition of bacterial respiration by the test item ISL up to and including a nominal concentration of 1000 mg per litre. An activated sludge respiration inhibition test according to OECD 209 resulted in an EC₅₀ > 1000 mg/L and a NOEC ≥ 1000 mg/L. No toxic effects of ISL on STPs were identified. This information is used in a read-across approach in the assessment of the target substance sodium lauroyl lactylate (SLL).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 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).