2,2,6,6-tetramethylpiperidin-4-ol

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:

1988-11-07

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non GLP-Guideline study.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

EEC L 133, p. 118-122 (30. May 1988)

Principles of method if other than guideline:

Instead of a centrifuged sludge a settled sludge was used.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Inoculum: 1.6 g/L activated sludge collected from STP of CH-4153 Reinach
- Preparation of inoculum: according to the guideline (sludge was separated by settling instead of centrifugation)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20±2°C

Nominal and measured concentrations:

Reference substance: 32, 10 and 3.2 mg/l
Test substance: 100, 32, 10, 3.2, 1 and 0 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 250 ml BOD flasks with gas inlet
- Aeration: yes
- No. of vessels per concentration (replicates): 1
- No. of vessels per blank control (replicates): 2
- No. of vessels per reference control (replicates): 3 (1/conc.)


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: mineral medium according to guideline

OTHER TEST CONDITIONS
- Adjustment of pH: not during test

EFFECT PARAMETERS MEASURED
- oxygen consumption

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 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.:

> 100 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):

IC50 = 14 mg/L

highest inhibition observed was 16% at 100 mg/L test concentration

Validity criteria fulfilled:

yes

Description of key information

The key study shows a EC 50 of > 100 mg/ and an EC 20 of >100 mg/L based on the nominal loading rate. No analytical monitoring was carried out. 

The highes inhibition with 16% was observed at 100 mg/L. The EC10 is within the range from 32 mg/L to 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L