Acetamide, N-(4-fluorophenyl)-2-hydroxy-N-(1-methylethyl)-

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:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

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

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Type: mixed population of aquatic microorganisms (activated sludge)
- Origin: laboratory scale sewage treatment unit
- Pre-Treatment: None

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Nominal and measured concentrations:

560, 1000, 1800, 3200 and 5600 mg/L (nominal)

Details on test conditions:

- Test item concentration/s: 560, 1000, 1800, 3200 and 5600 mg/L
- Test item concentration in physico-chemical oxygen consumption control: 10000 mg/L
The test item concentrations were not confirmed by analytical methods, they were based on nominal concentrations.
- Method of application: direct weighings
- Test concentration of the activated sludge: 435 mg/L
- Test temperature: 20 ± 2°C
- Incubation time: 3 hours with permanent aeration

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 760 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

EC50 of the reference compound 3,5-Dichlorophenol is in the range 5 – 30 mg/L (13 mg/L).

Inhibition

concentrations [mg/L]	respiration rate [mg/L*h]	inhibition [%]
5600	4.3	80.9
3200	6.0	73.3
1800	11.1	50.7
1000	16.5	26.7
560	18.0	20.0
control	22.5

Validity criteria fulfilled:

yes

Conclusions:

A 3h-EC50 of 1760 mg/L was determined for the test substance towards microorganisms.

Executive summary:

A study was conducted to assess the toxicity of the test substance to bacteria in accordance with ISO 8192 ”Activated sludge respiration inhibition” (1986). This test method is equal to OECD Guideline 209 (1984).

The activated sludge was exposed to the test substance at different concentrations (560, 1000, 1800, 3200 and 5600 mg/L).The respiration rate of each mixture was determined after aeration periods of 3 hours.

A 3h-EC50 of 1760 mg/L was determined for the test substance towards microorganisms. The effect value related to nominal concentration, since no analytical monitoring was performed.

For the reference compound 3,5-Dichlorophenol an EC50 of 13 mg/L was determined.

Description of key information

A study was conducted to assess the toxicity of the test substance to bacteria in accordance with ISO 8192 ”Activated sludge respiration inhibition” (1986). This test method is equal to OECD Guideline 209 (1984).

The activated sludge was exposed to the test substance at different concentrations (560, 1000, 1800, 3200 and 5600 mg/L).The respiration rate of each mixture was determined after aeration periods of 3 hours.

A 3h-EC50 of 1760 mg/L was determined for the test substance towards microorganisms.The effect value related to nominal concentration, since no analytical monitoring was performed.

Key value for chemical safety assessment

EC50 for microorganisms:

1 760 mg/L