Benzamide, N-[[4-[(cyclopropylamino)carbonyl]phenyl]sulfonyl]-2-methoxy-

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

Study period:

07 - 11 Aug 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Commission Directive 88/302/EEC; Official Journal of the EG L 133 Part C. 11 (1988)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Type of application: direct weighing
- Controls: Two controls without test item are included in the test design, one at the start and the other at the end of the test series. One physico-chemical oxygen consumption control (10000 mg/L) was performed.
- Test concentration separation factor: 10
- Other relevant information: The test item has been added to about 130 mL deionized water and stirred overnight before testing (equilibration phase).

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Culture type: Mixed population of aquatic microorganisms (activated sludge)
- Name and location of sewage treatment plant where inoculum was collected: Municipal STP Cologne-Stammheim (aeration tank of a domestic sewage treatment plant).
- Pretreatment: Aeration of the activated sludge, daily fed with synthetic medium
- pH of the suspension before application: 7.2

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21.1 - 22.6 °C

pH:

6.8 - 7.7

Nominal and measured concentrations:

Nominal test concentrations (mg/L) : 0 (Control), 100, 1000, 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Aeration: yes, permanent aeration
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 1
- Sludge concentration: 840.0 mg/L suspended solids
- Nutrients provided for bacteria: A synthetic sewage feed was made by dissolving the following amounts of substance in 1 litre of water.
16.0 g peptone
11.0 g meat extract
3.0 g urea
0.7 g NaCl
0.4 g CaCl2 • 2H2O
0.2 g MgSO4 • 7H2O
2.8 g K2HPO4

EFFECT PARAMETERS MEASURED: respiration rate

Reference substance (positive control):

yes

Remarks:

3.5- Dichlorophenol; Test concentration: 5, 10 and 20 mg/L

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:

respiration rate

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

AE 0001789 showed 13.0 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L.

The EC50 is higher than 10000 mg/L. The effect value related to nominal concentration, since no analytical monitoring was performed.

 

 

 

Table 1: Respiratory rate of the test item and the controls

Test concentration [mg/1]	Respiratory rate test item [mg/1 • h]	Phys.-chem. O2 consumption [mg/1 • h]	Respiratory rate - phys.-chem. O2 consumption [mg/1 • h]	Inhibition [%]
100	39.0	*0.0	39.0	0.0
1000	39.0	*0.0	39.0	0.0
10000	30.0	0.0	30.0	13.0
Control, mean	34.5
Control 1	36.0
Control 2	33.0

Test concentrations are given as nominal concentrations and have not been confirmed by analytical methods.

* The physico-chemical oxygen consumption has been determined at 10000 mg/L test item concentration. As no physico-chemical oxygen consumption was observed at that test item concentration this observation also holds true for the lower test item concentrations.

 

 

 

Table 2: Validity criteria for OECD 209

Criterion from the guideline	Outcome	Validity criterion fulfilled
The blank controls (without the test substance or reference substance) oxygen uptake rate should not be less than 20 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour.	The mean oxygen uptake rate of the blank controls was 41.1 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour.	yes
The coefficient of variation of oxygen uptake rate in control replicates should not be more than 30% at the end of definitive test.	The coefficient of variation of oxygen uptake rate in control replicates was 6.1% at the end of definitive test.	yes

 

Validity criteria fulfilled:

yes

Remarks:

See Table 2 in "Any other information on results incl. tables".

Description of key information

EC50 (3 h) > 10000 mg/L (nominal, activated sludge, OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:

10 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

The respiration inhibition of the test item was tested in a respiration inhibition test using activated sludge fed with synthetic sewage (OECD 209, M-276100-01-1). Only a moderate inhibition of 13% compared to the control was observed at the highest test item concentration of nominal 10000 mg/L. Thus, a 3 h EC50 for the test substance was reported as >10000 mg/L.