[No public or meaningful name is available]

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)

Principles of method if other than guideline:

This test method is equal to OECD Guideline 209 (1984).

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

TEST ORGANISM:
- mixed population of aquatic microorganisms, origin of an aeration tank of a domestic sewage treatment plant (Municipal STP Cologne-Stammheim, Germany)
- pretreatment: aeration at 20 °C +/- 2 °C, daily feed with synthetic medium
- pH of the suspension before application: 7.6
- pH of the synthetic sewage feed : 7.5 ± 0.5
- test concentration of the activated sludge: 800 mg/l suspended solids

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

No data

Test temperature:

19.1 °C (concerning the highest concentration of 1000 mg/l)

pH:

pH: 7.7 (concerning the highest concentration of 1000 mg/l)

Dissolved oxygen:

oxygen (mg/l): O2-start 6.3; O2-end 3.9 (concerning the highest concentration of 1000 mg/l)

Salinity:

No data

Details on test conditions:

TEST CONDITIONS:
- type of application: direct weighing
- temperature: 20 +/- 2 °C
- stirring period before start of incubation time: 16 h
- test concentration: 3 (10, 100, 1000 mg/l)
- test parameter: respiration rate
- aeration: permanent

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol, concentration (5, 10, 20 mg/l), purity 97 %

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: probit analysis

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

Remarks:

respiration rate

Remarks on result:

other: probit analysis

Details on results:

Test concentrations are given as nominal concentrations and were not confirmed by analytical methods. The physico-chemical oxygen consumption has been determined at 1000 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.

Results with reference substance (positive control):

EC50 of the reference substance 3.5 -dichlorophenol is in the range 5 – 10 mg/L

Validity criteria fulfilled:

yes

Conclusions:

In a study, the substance showed 2.0 % respiration inhibition of activated sludge at the highest test item concentration of 1000 mg/l according to the OECD guideline 209 (Currenta, 2009). An EC10 and an EC50 of >1000 mg/l were obtained in this tes

Executive summary:

In a study, the substance showed 2.0 % respiration inhibition of activated sludge at the highest test item concentration of 1000 mg/l according to the OECD guideline 209 (Currenta, 2009). An EC10 and an EC50 of >1000 mg/l were obtained in this test.

Description of key information

In a study, the substance showed 2.0 % respiration inhibition of activated sludge at the highest test item concentration of 1000 mg/l according to the OECD guideline 209 (Currenta, 2009). An EC10 and an EC50 of >1000 mg/l were obtained in this test.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L