Glycine, N-methyl-, N-coco acyl derivs., sodium 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:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Version / remarks:

Apr 1984

Deviations:

yes

Remarks:

test temperatures (22.5 - 24.5 °C) were above the recommended 20 ± 2 °C. It was concluded that this did not affect the reliability and quality of this study, since respiration was normal and all other criteria were met.

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umweltschutz und Gewerbeaufsicht, Mainz, Germany

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: For the first control replicate, 16 mL nutrient medium was mixed with 284 mL drinking water. Then, 200 mL inoculum was added and the solution was aerated. 5 minutes later, the second control replicate was prepared in the same way. Another 5 minutes later, the reference replicate was prepared by mixing 16 mL nutrient medium with 1.25 mL stock solution, filled up to 300 mL with drinking water and then aerated. All other reference, test and control replicates were prepared in this same way with 5 min intervals. After 3 h the contents of the first vessel was transferred to a 250 mL narrow neck glass bottle and respiration activity was measured by continuous measurement of the oxygen concentration during 5 min. The subsequent vessels were all measured in the same way, in 5 min intervals.
- Controls: nutrient medium, drinking water and inoculum without test substance

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Sewage Treatment Plant Neustadt/W., Germany
- Preparation of inoculum for exposure: The sludge was filtered and resuspended in drinking water. The dry weight was determined by drying an aliquot of 5 mL at 105 °C and weighing of the residue afterwards.
- Pretreatment: The sludge was diluted with drinking water to a dry weight of 4.0 g ± 0.4 g/L and was aerated until use in the test. Before test start the pH was measured and, if necessary, adjusted to 6.0 - 8.0.
- Initial biomass concentration: 1592 mg suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

22.5 - 24.5 °C

pH:

7.4

Conductivity:

249 µS/cm

Nominal and measured concentrations:

nominal: control and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: beakers (800 - 1000 mL); for O2 measurements: narrow mouth bottles (250 mL) with flat bottom
- size, headspace, fill volume: Test volume: 500 mL
- Aeration: yes, continuously
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 3.98 g/L suspended solids
- Nutrients provided for bacteria: culture medium 32 mL/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: drinking water; total hardness: 0.943 mmol/L

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Details on termination of incubation: After 3 h the content of the vessel was filled into a 250 mL narrow mouth bottle and the respiration was determined by continuous measurement of the O2 concentration in 5 minute intervals.

EFFECT PARAMETERS MEASURED:
- O2 consumption: about 5 minutes after 3 h incubation

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 1, 10, 100 and 1000 mg/L
- Results used to determine the conditions for the definitive study: Yes, the preliminary test showed an inhibition of 8% at the maximum, nominal test concentration of 1000 mg/L and no inhibition at the lower test concentrations.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

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

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

Remarks on result:

other:

Remarks:

In the study report a NOEC of 100 mg/L is reported. But as the main test was conducted as limit test with a test concentration of 1000 mg/L only this effect concentration could be used for the evaluation of the NOEC.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: range finder: EC50 = 6.2 mg/L, 95% confidence interval = 4.5 - 7.9 mg/L; main test: EC50 = 7 mg/L, 95% confidence interval = 4.7 - 9.6 mg/L

Reported statistics and error estimates:

Oxygen uptake was calculated from a linear regression of the O2 values for the respective test vessel.

Table 1. Oxygen uptake.

Nr.	Sample name	Nominal concentration [mg/L)	O2 consumption [mg/L*min]	Mean O2 consumption [mg/L*min]	Mean O2 consumption [mg/L*h]
1	Control	0	0.6419*	0.5921	35.526
2		0	0.5921
3	Reference	2.5	0.3646	0.37685	22.611
4		2.5	0.3891
5		5	0.3449	0.3584	21.504
6		5	0.3719
7		10	0.2335	0.23955	14.373
8		10	0.2456
9		20	0.1497	0.1515	9.09
10		20	0.1533
11		40	0.0881	0.0875	5.25
12		40	0.0869
13	Control	0	0.5359
14		0	0.5166
25	Control	0	0.5789	0.5814	34.884
26		0	0.5839
27	Test item	1001	0.4725	0.47795	28.677
28		1001	0.4834
29	Control	0	0.5945	0.5907	35.442
30		0	0.5869

*the first measurement was omitted from analysis because it is likely an error of measurement.

 

Table 2. Inhibition.

Sample name	Concentration [mg/L]	Inhibition [%]
Reference	2.5	33
Reference	5	36
Reference	10	57
Reference	20	73
Reference	40	84
Test item	1001	19

 

Description of key information

EC50 (3 h) > 1000 mg/L (nominal, OECD 209, activated sludge)

Additional information

One GLP-study according to OECD 209 investigating the toxicity of Glycine, N-methyl-, N-coco acyl derivatives, sodium salts (CAS 61791-59-1) to microorganisms is available. In a limit test activated sludge from a local, municipal STP treating predominantly domestic waste water was exposed to a nominal concentration of 1000 mg/L test substance for 3 h. The test concentration was previously established by a range-finding test with nominal concentrations ranging from 1 - 1000 mg/L (1, 10, 100 and 1000 mg/L). Before the test the activated sludge was washed, filtered and resuspended and the dry weight of suspended solids was determined. For the test the activated sludge was adjusted to a concentration of 1592 mg suspended solids/L in synthetic sewage feed. After 3 h exposure the respiration rate of the activated sludge was measured continuously for 5 min.

In the preliminary range-finding test, test concentrations below 1000 mg/L (nominal) did not affect the respiration of the activated sludge. In the definitive test the limit test concentration of 1000 mg/L (nominal) showed an inhibition of respiration of 19 %. The EC50 (3 h) was > 1000 mg/L (nominal).