Reaction mass of 5-[{4-[Benzyl(methyl)amino]phenyl}diazenyl]-1,4-dimethyl-4H-1,2,4-triazol-1-ium bromide and 3-[{4-[Benzyl(methyl)amino]phenyl}diazenyl]-1,4-dimethyl-4H-1,2,4-triazol-1-ium bromide

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:

Study initiation date - 02 November 1993; Experiment start and date - 10 November 1993; Study completion date - 19 November 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

Deviations:

yes

Remarks:

-Deionised water instead of dest. water for the stock solution. -Preparation of the inoculum : higher sludge weight after the washing procedure (Sludge concentrations in the test according to the guidelines). - 4 instead of 5 test concentrations

GLP compliance:

yes

Specific details on test material used for the study:

- Code number: FAT 31016/P
- EN-Nr.: 414154.32
- Purity: 95 %
- Appearance: solid
- Solubility: 40 g/L (in water)
- Storage: room temperature
- Expiration date: 07/98

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Organism: Activated sludge of a communal sewage treatment plant (ARA-Birsig Therwil)
- Sludge pretreatment: 3 times washing with tap water and addition of synthetic sewage (a day before the main test)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21.5 °C

pH:

7.8 - 8.0

Dissolved oxygen:

O2-consumption (in cm) 10 mg/l: 3.9, 32 mg/l: 2.4, 100 mg/l 0.7 and 320 mg/l: 0.4

Nominal and measured concentrations:

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

Details on test conditions:

- Temperature: 21.5 °C
- Sludge dry weight: 1.50 g/l
- Test volume: 100 ml
- Test duration: 3h
- 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: 7.9 before the test beginning

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

21 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

The IC50 (3 h) of the reference substance 3,5-Dichlorophenol: 8.0 mg/l

Table: % inhibition observed for test concentrations

Test substance (mg/l)	% inhibition
320	93.02
100	84.88
32	61.63
10	29.07

Validity criteria fulfilled:

yes

Conclusions:

The IC50 (3 h) of the test substance FAT 31016/P was determined to be 21 mg/l.

Executive summary:

The toxicity of FAT 31016/P to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209, and to the EEC Method No. L 133/118. 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 % inhibitions observed at test concentrations 320, 100, 32 and 10 mg/l were 93.02, 84.88, 61.63 and 29.07, respectively. Hence, the IC50 (3 h) of the test substance FAT 31016/P was determined to be 21 mg/l.

Description of key information

The IC50 (3 h) of the test substance FAT - 31016/P was determined to be 21 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

21 mg/L

Additional information

The toxicity of FAT - 31016/P to activated sludge was determined in a 3-hours respiration inhibition test according to the OECD Guideline No. 209, and to the EEC Method No. L 133/118. 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 % inhibitions observed at test concentrations 320, 100, 32 and 10 mg/l were 93.02, 84.88, 61.63 and 29.07, respectively. Hence, the IC50 (3 h) of the test substance FAT - 31016/P was determined to be 21 mg/l. In another study, the toxicity of FAT 31016/C was to be 50 mg O2/g