Carbamic acid,N,N'-[1,3-phenylenebis[methyleneiminocarbonylimino(methyl-3,1-phenylene)]]bis-di-C11-14-isoalkylesters, C13-rich

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

yes

Remarks:

100 – 102 % of the values stated in the study plan. As the loads were slightly higher and no inhibition of oxygen consumption of the treated sludge was detected The nutrient solution was prepared with pure CaCl2 and not with CaCl2*2H2O

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant D-67435 NW-Lachen-Speyerdorf and aerated during transport. Upon arrival in the test facility, the sludge was filtrated, washed with tap water and resuspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 ml /L synthetic sewage feed.

Test type:

not specified

Water media type:

freshwater

Total exposure duration:

3 h

Test temperature:

20.8 – 22.4 °C

pH:

7-7.5

Details on test conditions:

Duration three hours
Replicates one replicate/treatment (positive control, test item lower
concentrations)
five replicates for test item treatment 1000 mg/L (nominal)
Control two replicates before and two after measuring positive
control and test item, respectively
Water tap water
Aeration purified air, using Pasteur pipettes,
flow approx. 0.75 L/min.
Feeding nutrient solution, 16 mL/vessel
Temperature 20.8 – 22.4 °C

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (CAS 591-35-5) was used as positive control. A stock solution in deionised water containing 500 mg/L (nominal) was freshly prepared for each experiment.

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:

growth inhibition

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:

growth inhibition

Details on results:

O2-Consumption, Inhibition Main Study
The values of the O2 consumption (which is a measure for the viability of the bacteria) of controls, test item and positive control and the calculated inhibition are presented in the following table. The measured pH at the end of the test is also stated.
Table 7.5-c O2-Consumption, Inhibition Main Study
Vessel
No.
Content Concentration
in mg/L
O2 consumption
in
mg/(L*min.)
O2 consumption
in
mg/(L*h)
Inhibition
in %
pH
1 Control 0 0.7317 43.899 0 7.6
2 Control 0 0.7255 43.528 0 7.6
3 Positive Control 5 0.5258 31.550 30.2 7.8
4 Positive Control 10 0.2852 17.115 62.1 7.7
5 Positive Control 20 0.1234 7.402 83.6 7.7
6 Positive Control 40 0.0677 4.059 91.0 7.8
7 Control 0 0.7684 46.106 0 7.6
8 Control 0 0.7423 44.541 0 7.6
9 Test Item 1000.4 0.7405 44.432 1.7 7.6
10 Test Item 1001.0 0.7543 45.256 -0.1 7.6
11 Test Item 1000.0 0.7723 46.335 -2.5 7.5
12 Test Item 1000.8 0.7687 46.122 -2.0 7.6
13 Test Item 1000.2 0.7788 46.727 -3.4 7.6
14 Test Item 100.4 0.7655 45.929 -1.6 7.5
15 Test Item 10.2 0.7801 46.805 -3.6 7.5
16 Test Item 1.0 0.7562 45.372 -0.4 7.6
17 Control 0 0.7870 47.222 0 7.6
18 Control 0 0.7649 45.893 0 7.5

Results with reference substance (positive control):

3 Positive Control 5 0.5258 31.550 30.2 7.8
4 Positive Control 10 0.2852 17.115 62.1 7.7
5 Positive Control 20 0.1234 7.402 83.6 7.7
6 Positive Control 40 0.0677 4.059 91.0 7.8

Validity criteria fulfilled:

yes

Conclusions:

One experiment was performed.
All validity criteria were met. For the estimation of the EC50 of the positive control, the fit showed good statistical correspondence of the data with the dose-response-equation. The positive control gave an EC50 of 7.9 mg/L which lies within the recommended range of 2 – 25 mg/L. The coefficient of variation of oxygen uptake rate in control replicates was below 30 % at the end of the test. The oxygen uptake rate of the blank controls was above 20 mg O2 per gram activated sludge. No significant inhibition in all treatments was observed; therefore, no additional experiment had to be performed No observations were made which might cause doubts concerning the validity of the study outcome. The result of the test can be considered valid.

Executive summary:

The test item was tested using five concentrations (ranging from 1001 to 1 mg/L). Duration of the test was three hours. Activated sludge was used as inoculum. It was taken from a

domestic sewage treatment plant and washed before usage. The dry matter was determined as 2.92 g suspended solids/L, giving a concentration of 1.46 g suspended solids/L in the test. 3,5-Dichloro-phenole was used as positive control. Four concentrations were tested; an EC50 of 7.9 mg/L (95% confidence interval: 3.5 – 12 mg/L) was determined, which lies within the range of 2 – 25 mg/L. Because no significant inhibition was observed, no additional experiment had to be performed. The following results for the test item Addukt TI 65 - MXDA were determined:

3h NOEC ≥ 1000 mg/L

3h EC10 > 1000 mg/L

3h EC50 > 1000 mg/L

Description of key information

no significant inhibition was observed

The following results for the test item Addukt TI 65 - MXDA were determined:

3h NOEC ≥ 1000 mg/L

3h EC10 > 1000 mg/L

3h EC50 > 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L