Disodium [4-hydroxy-3-[(2-hydroxy-4-nitrophenyl)azo]naphthalene-1-sulphonato(3-)][1-[(2-hydroxy-4-nitrophenyl)azo]-2-naphtholato(2-)]chromate(2-)

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:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

- Preparation of the inoculum : higher sludge weight after the washing procedure, - 4 instead of 5 test concentrations and - T° 22.4 °C instead of 20+/-2 °C

Qualifier:

according to guideline

Guideline:

other: EEC Method 87/302, L 133/118 -122 "Activated Sludge, Respiration Inhibition Test", (Edition : 30.05.1988)

Deviations:

yes

Remarks:

- Preparation of the inoculum : higher sludge weight after the washing procedure, - 4 instead of 5 test concentrations and - T° 22.4 °C instead of 20+/-2 °C

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Code number: FAT-20011/D
Batch-Nr: 61
Purity: ca 52.5 %
Appearance: solid
Solubility: miscible
Storage: room temperature
Expiration date: 07/99

Analytical monitoring:

no

Vehicle:

yes

Remarks:

deionized water

Details on test solutions:

Stock solutions: 500 mg/l test substance / reference substance in deionized water.

Test organisms (species):

other: Activated sludge of a communal sewage treatment plant (ARA-Pro Rheno Basel)

Details on inoculum:

- Pretreatment: 3 times washing with tap water and addition of synthetic sewage (a day before the main test).
- Sludge dry weight: 1.50 g/l

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

22.4 °C

pH:

7.3 before the test beginning.

Nominal and measured concentrations:

Test concnetrations (nominal concentrations)
- 320,100, 32 and 10 mg/l of the test substance.
- 320, 10 and 10 mg/l for the reference substance.

Details on test conditions:

Experimental conditions
- Sludge dry weight: 1.50 g/l
- Test volume: 100 ml
- Test duration: 3 hours
- Estimation technique: O2 - consumption, measured with an oxygen sensitive electrode system : OXI DIGI 530 (SAV : 00 109)
- Aeration: 0.1 - 0.2 l/min by pasteur-pipette
- pH of sludge: 7.3 before the test beginning

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (Merck 821768)

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 320 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:

other: IC20

Effect conc.:

110 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 (3 h) of the reference substance 3,5-Dichlorophenol: 12 mg/l

Validity criteria fulfilled:

yes

Conclusions:

The IC50 (3 h) of FAT 20011/D was >320 mg/l

Executive summary:

The toxicity of FAT 20011/D to activated sludge was determined in a 3-hour respiration inhibition test according to the EEC Method No. L 133/118 -122 and to the OECD Guideline No. 209. The test was performed in compliance with the Good Laboratory Practice (GLP) Regulations of Switzerland.

 

The test substance concentrations tested were 320,100, 32 and 10 mg/L. The reference substance, 3,5-Dichlorophenol was tested in concentrations of 32,10 and 3.2 mg/L.

 

Results:

IC50 (3 h) of the test substance FAT 20011/D: >320 mg/L

IC20 (3 h) of the test substance FAT 20011/D: 110 mg/L

IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 12 mg/L

Description of key information

The toxicity of FAT 20011/D to activated sludge was determined in a 3-hour respiration inhibition test conducted according to the EEC Method No. L 133/118 -122 and the OECD Guideline 209, in compliance with GLP. The test substance concentrations tested were 320,100, 32 and 10 mg/L. Based on the findings of the study, the IC50 of FAT 20011/D was determined to be >320 mg/L.

The above outcome was further supported by the results of supporting studies conducted in 1982 (FAT 20011/C) and 1976 (FAT 20011/B), where IC50s were reported as 100 and >320 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

320 mg/L