N-(2-carboxyethyl)-N-octyl-β-alanine

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23-04-2012 - 25-04-2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Test performed under GLP according guidelines, all quality criteria were met

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:

Sodium capryliminodipropionate and 3,5-dichlorophenol was added to the incubation vessels using a stock solution of approximately 1.0 g/L. The stock solution of sodium capryliminodipropionate was prepared by dissolving 0.92 g sodium capryliminodipropionate in 920 mL deionized water.

pH stock solution sodium capryliminodipropionate = 9.5

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Unadapted secondary activated sludge was obtained (24-04-2012) from the WWTP Nieuwgraaf in Duiven. The WWTP Duiven is an activated sludge plant treating predominantly domestic wastewater. Prior to use the activated sludge was homogenized with a syringe. The dry weight of the homogenized activated sludge was determined and subsequently concentrated by settlement to the required dry weight concentration. The dry weight of the activated sludge in the incubation vessels was 1.5 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

Temperature varied from 19.8 to 20.5°C.

pH:

The pH of the reaction mixtures after the incubation period ranged from 7.2 to 7.3.

Dissolved oxygen:

aerobic during test

Details on test conditions:

-The test was performed in 300 ml Erlenmeyers.
-The homogenized activated sludge was incubated in a shaking water bath (100 rpm, 20°C) for 3 hours with various concentrations of the test
compound and synthetic sewage.
-Synthetic sewage was added to the activated sludge (1.6 ml on a total volume of 50 ml).
Synthetic sewage contained per liter: 16 g peptone
11 g meat extract
3 g urea
0.7 g NaCl
0.3 g CaCl2
0.2 g MgSO4.7H2O
2.8 g K2HPO4
-Different concentrations (spaced by a factor two) of test compound and reference compound where added using stock solutions both of
1.0 g/l
-Tap-water was used to fill up the total test volume to 50 ml.
- The dry weight concentration of the activated sludge in the test was 1.5 g/l
-Controls without test substance (or reference compound) are measured at the beginning and at the end of the test
-The inhibitory effect of the test substance/reference compound is expressed as a percentage of the mean of the two control respiration rates.
-An abiotic control was not performed because neither reduction of oxygen by the test substance nor formation of oxygen due to chemical breakdown of the test substance is expected.
-No specific analyses were performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 640 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: equivalent to 246.4 mg a.i./L

Details on results:

Test conditions
The pH of the reaction mixtures after the incubation period ranged from 7.2 to 7.3. Temperature varied from 19.8 to 20.5°C. These conditions allow respiration of the activated sludge used.

Validity of the test
The validity of the test is demonstrated by three criteria. First, the coefficient of variation of the replicates of the control oxygen uptake rates was 10%, which fulfils the maximum prescribed variation of <30%. Secondly, the prescribed average oxygen uptake rate of > 20 mg O2/g dry weight/hour for the control measurements was achieved (30 mg O2/g dry weight/hour). The third criterion was met as shown by the EC50 of the reference compound of 15 mg/L, which is within the prescribed range of 2 to 25 mg/L.

Activated sludge respiration inhibition test
The inhibitory effect of sodium capryliminodipropionate at a particular concentration is expressed as a percentage of the two controls. From the results EC values were calculated. The EC50 of sodium capryliminodipropionate for activated sludge after 3 hours contact time is >640 mg/L. Inhibition of the activated sludge respiration by sodium capryliminodipropionate does not follow a classical dose-response curve and varied from 11% to 19% over the measured concentration range.

Results with reference substance (positive control):

The EC50 of the reference compound was 15 mg/L at a contact time of 3 hours, respectively. These EC50 values is within the prescribed range of 2 to 25 mg/L.

Validity criteria fulfilled:

yes

Remarks:

see "details on results"

Conclusions:

The test is valid as shown by the EC50 of the reference compound 3,5- dichlorophenol (15 mg/L), the coefficient of variation of the replicates of the control oxygen uptake rates (10%) and the average oxygen uptake rate for the control replicates (30 mg O2/g dry weight/hour). The toxicity of sodium capryliminodipropionate to activated sludge was determined at a contact time of 3 hours, using various concentrations of the test substance. The inhibitory effect of sodium capryliminodipropionate at a particular concentration is expressed as a percentage of the two controls. From the results EC values were calculated. The EC50 of sodium c pryliminodipropionate for activated sludge after 3 hours contact time is >640 mg/L. Inhibition of the activated sludge respiration by sodium capryliminodipropionate does not follow a classical dose-response curve and varied from 11% to 19% over the measured concentration range (Figure 2). Sodium capryliminodipropionate is therefore considered not harmful to activated sludge.

Executive summary:

In order to predict effects of chemicals in the environment and in biological waste water treatment plants, an activated sludge respiration inhibition test was performed. The toxicity to activated sludge was determined in accordance with OECD Test Guideline 209, and in compliance with the OECD principles of Good Laboratory Practice. The test is valid as shown by the EC50 of the reference compound 3,5 -dichlorophenol (15 mg/L), the coefficient of variation of the replicates of the control oxygen uptake rates (10%) and the average oxygen uptake rate for the control replicates (29 mg O2/g dry weight/hour). The toxicity of sodium capryliminodipropionate to activated sludge was determined at a contact time of 3 hours, using various concentrations of the test substance. The inhibitory effect of sodium capryliminodipropionate at a particular concentration is expressed as a percentage of the two controls. From the results EC values were calculated. The EC50 of sodium capryliminodipropionate for activated sludge after 3 hours contact time is >640 mg/L. Inhibition of the activated sludge respiration by sodium capryliminodipropionate does not follow a classical dose-response curve and varied from 11% to 19% over the measured concentration range (Figure 2). Sodium capryliminodipropionate is therefore considered not harmful to activated sludge.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Justification for type of information:

See read-across justification attached in Section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 640 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: equivalent to 246.4 mg a.i./L

Description of key information

Exposure of activated sludge to an analogue test item gave EC50 (3 h) > 246.4 mg a.i./L. No effect on microbial respiration was observed at the highest test concentration (OECD 209).

Additional information

In order to predict effects of chemicals in the environment and in biological waste water treatment plants, an activated sludge respiration inhibition test was performed. The toxicity of an analogue test item to activated sludge was determined in accordance with OECD Test Guideline 209, and in compliance with the OECD principles of Good Laboratory Practice.

 

Test validity was shown by the EC50 of the reference compound 3,5 -dichlorophenol (15 mg/L), the coefficient of variation of the replicates of the control oxygen uptake rates (10%) and the average oxygen uptake rate for the control replicates (29 mg O2/g dry weight/hour). The toxicity of sodium capryliminodipropionate to activated sludge was determined at a contact time of 3 hours, using various concentrations of the test substance. The inhibitory effect of sodium capryliminodipropionate at a particular concentration was expressed as a percentage of the two controls. From the results EC values were calculated.

 

The EC50 of sodium capryliminodipropionate for activated sludge after 3 hours contact time was determined to be >640 mg/L (equivalent to 246.4 mg a.i./L. Inhibition of the activated sludge respiration by sodium capryliminodipropionate did not follow a classical dose-response curve and varied from 11% to 19% over the measured concentration range. Sodium capryliminodipropionate was therefore considered not harmful to activated sludge.