Sodium 2-[[2-amino-8-hydroxy-6-[(methylanilino)sulphonyl]-1-naphthyl]azo]-5-(chloroacetamido)benzenesulphonate

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:

1 November 1995 to 8 November 1995

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:

1) Preparation of the inoculum : higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines). 2) 4 instead of 5 test concentrations.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: 1.56
- Expiration date of the lot/batch: June 2000

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 8°C (light protected)
- Solubility of the test substance in the solvent/dispersant/vehicle/test medium: > 1 g/l [in water]

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: 320, 100, 32 and 10 mg/l of the test substance.
32, 10 and 3.2 mg/l of the reference substance.

Vehicle:

no

Details on test solutions:

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

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Method of cultivation: Activated sludge of a communal sewage treatment plant (ARA-Pro Rheno Basel), collected on November 7, 1995.
- Pretreatment: 3 times washing with tap water and addition of synthetic sewage feed (a day before the main test).
- Initial biomass concentration: 1.56 g/l

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Test terminated after 3 h

Hardness:

No data

Test temperature:

20 + 2 °C

pH:

7.7 before the test beginning

Dissolved oxygen:

No data

Salinity:

No data

Nominal and measured concentrations:

320, 100, 32 and 10 mg/l of the test substance

Details on test conditions:

TEST SYSTEM
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 100 ml
- Aeration: 0.1 - 0.2 l/min by Pasteur-pipette
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates):2
- Biomass loading rate: 1.56 g/L

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):

TEST CONCENTRATIONS
- Test concentrations: 320, 100, 32 and 10 mg/l of the test substance
- Results used to determine the conditions for the definitive study: O2 - consumption

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol for synthesis (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

Results with reference substance (positive control):

The IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 9 mg/l

Validity criteria fulfilled:

yes

Conclusions:

IC50 (3 h) of FAT 20075/B >320 mg/l.

Executive summary:

The toxicity of FAT 20075/B to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209 and as per GLP. This study was carried out for determination of the test substance concentration, which reduces the respiration of activated sludge by 50 % (IC50 value). Activated sludge of a communal sewage treatment plant (ARA-Pro Rheno Basel), collected on November 7, 1995 was used to carry out this study. A sludge was pretreated by washing with tap water thrice and addition of synthetic sewage feed a day before the main test. 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. Based on the test results, IC₅₀ (3 h) of FAT 20075/B > 320 mg/l while IC₅₀ (3 h) of the reference substance 3,5-Dichlorophenol: 9 mg/l.

Description of key information

The toxicity of FAT 20075/B to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209 and as per GLP. This study was carried out for determination of the test substance concentration, which reduces the respiration of activated sludge by 50 % (IC50 value). Activated sludge of a communal sewage treatment plant (ARA-Pro Rheno Basel), collected on November 7, 1995 was used to carry out this study. A sludge was pretreated by washing with tap water thrice and addition of synthetic sewage feed a day before the main test. 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. Based on the test results, IC₅₀(3 h) of FAT 20075/B > 320 mg/l while IC₅₀(3 h) of the reference substance 3,5-Dichlorophenol: 9 mg/l. In another supporting study (1975), the IC₅₀ for FAT 20075/A was also found to be >300 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

320 mg/L