L-Glutamic acid, N-coco acyl derivs., disodium salts

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions (test substance concentration not analytically verified)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Direct addition by initial weight into the test flasks. The testsubstance was weighed in the required amounts for the test concentrations directly to the test vessels.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: Activated sludge from the municipal wastewater treatment plant of Mannheim, Germany was collected on 05 Jun 2012 from the aeration tank of the plant.
- Preparation of inoculum for exposure: The activated sludge suspension was sieved with a fine woven mesh (mesh size about 1 mm). The suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water. The suspension was adjusted to 3 g/L dry matter.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20.8 - 21.3 °C

pH:

7.1 - 7.4 (at the start)
7.7 - 8.0 (after incubation time)

Dissolved oxygen:

> 2 mg/L (during aeration)
> 7 mg/L (immediately before measurement)

Nominal and measured concentrations:

Nominal concentration: 118, 236, 472, 943 and 1887 mg/L (based on test substance)
Nominal concentration: 62.5, 125, 250, 500 and 1000 mg/L (based on active matter)

Details on test conditions:

TEST SYSTEM
- Test vessel: beakers
- Material: glass: Size: 1 L; Fill volume: 500 mL
- No. of vessels per concentration: 2
- No. of vessels per control: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water
- Culture medium different from test medium: 16 mL/test vessel of 100-fold concentrated OECD medium
- Intervals of water quality measurement: The pH was measured at the beginning and at the end of the test. Oxygen concentration was measured during aeration and immediately before measurement.

OTHER TEST CONDITIONS
- Adjustment of pH: yes

EFFECT PARAMETERS MEASURED: Oxygen consumption was measured for a period of 8 - 10 minutes after a incubation time of 3 h.

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 = 7 mg/L
- Other: The reference substance shows an EC50 in the range of 2 - 25 mg/L in 3 h. This indicates that the microorganisms are responding normally to toxicant stress.

Validity criteria fulfilled:

yes

Description of key information

EC10 (3h) > 1000 mg/L (nominal, based on active matter) for activated sludge (OECD 209)

Additional information

One study investigating the toxicity of l-Glutamic acid, N-coco acyl derivs., disodium salts (CAS No. 68187-30-4) to aquatic microorganisms is available. The study was performed according to GLP and OECD guideline 209 using non-adapted activated sludge as inoculum (BASF, 2012). Nominal concentrations between 118 and 1887 mg/L were tested, which correspond to test concentrations of 62.5 to 1000 mg/L based on active matter. No respiration inhibition compared to the control was observed in any treatment. Thus, a 3h-EC10 (based on active matter) is determined to be > 1000 mg/L.