Disodium 2-[[5-carbamoyl-1-ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridyl]azo]-4-[[4-[(2-chloro-5-sulphonatophenyl)amino]-6-fluoro-1,3,5-triazin-2-yl]amino]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:

02 December 1992 to 01 January 1993

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

Version / remarks:

April 4, 1984 (Edition : Paris, 1993).

Deviations:

yes

Remarks:

1) Deionised water instead of distilled water; 2) Preparation of the inoculum: higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines); 3) 4 instead of 5 test concentrations.

GLP compliance:

yes

Specific details on test material used for the study:

Code number: FAT - 40138/D
Batch-Nr.: 275605.26
Purity: 79 %
Appearance: solid
Solubility: 100 g/l [in water]
Storage: room temperature
Expiration date: July, 1993

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Communal sewage treatment plant (ARA-Pro Rheno Basel)
- Pretreatment: 3 times washing with tap water and addition of synthetic sewage (a day before the main test)

Test type:

static

Water media type:

not specified

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21.9 °C

pH:

6.8 before the test beginning (Sludge)
7.2 - 7.8 (after 3 h)

Dissolved oxygen:

0.95 - 1.03 mg O2 pro min/l

Nominal and measured concentrations:

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

Details on test conditions:

TEST MEDIUM / WATER PARAMETERS
Sludge dry weight: 1.50 g/l
Test volume: 100 ml
Test duration: 3 h
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: 6.8 before the test beginning

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

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

Details on results:

The % inhibition observed was 0, 2, 4 and 5 % for 320, 100, 32 and 10 mg/L, respectively.

Results with reference substance (positive control):

The IC50 (3 h) of the reference substance 3,5-Dichlorophenol : 7.5 mg/l

Validity criteria fulfilled:

yes

Conclusions:

IC50 (3 h) of FAT 40138/D was determined to be >320 mg/l.

Executive summary:

The toxicity of FAT 40138/D to activated sludge was determined in a 3-h respiration inhibition test according to OECD Guideline 209, in compliance with GLP. The test substance concentrations tested were 320, 100, 32 and 10 mg/l. Exposure was carried out for 3 hours. The % inhibition observed was 0, 2, 4 and 5% for 320, 100, 32 and 10 mg/L respectively. Hence, IC50 (3 h) of FAT 40138/D was determined to be >320 mg/l.

Description of key information

IC50 (3 h) of test substance was determined to be >320 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

320 mg/L

Additional information

The toxicity potential of FAT 40138 to microorganisms was assessed on the basis of three available studies. In a key study, the toxicity of FAT 40138/D to activated sludge was determined in a 3-h respiration inhibition test according to OECD Guideline 209, in compliance with GLP. The test substance concentrations tested were 320, 100, 32 and 10 mg/l. Exposure was carried out for 3 hours. The % inhibition observed was 0, 2, 4 and 5 % for 320, 100, 32 and 10 mg/L, respectively. Hence, IC50 (3 h) of FAT 40138/D was determined to be >320 mg/l. In two other supporting studies, 21-day IC50 for FAT 40138 was calculated to be >300 mg/L.