Sodium 4-[[4-[(4-hydroxy-2-methylphenyl)azo]phenyl]amino]-3-nitrobenzenesulphonate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Dec 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

4 instead of 5 concentrations tested

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 4-[[4-[(4-hydroxy-2-methylphenyl)azo]phenyl]amino]-3-nitrobenzenesulphonate

EC Number:

274-950-1

EC Name:

Sodium 4-[[4-[(4-hydroxy-2-methylphenyl)azo]phenyl]amino]-3-nitrobenzenesulphonate

Cas Number:

70865-20-2

Molecular formula:

C19H16N4O6S.Na

IUPAC Name:

sodium 4-[[4-[(4-hydroxy-2-methylphenyl)azo]phenyl]amino]-3-nitrobenzenesulphonate

Test material form:

solid: particulate/powder

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

500 mg/L test substance prepared with deionised water to get a stock solution. Stock solution treated for 10 min. in ultrasonic bath for dissolving.
Test concentrations prepared by dilution with test medium (synthetic sewage feed): 10, 32, 100 and 320 mg/L

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: ARA pro Rheno Basel, collected on 12 Dec 1995
- Pretreatment: 3 times washed with tap water and addition of synthetic sewage feed one day before the main test

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

180 min

Test conditions

Test temperature:

18 - 22°C

pH:

8.0 (beginning)

Nominal and measured concentrations:

10, 32, 100, 320 mg/L

Details on test conditions:

TEST SYSTEM
- Aeration: 0.1 - 0.2 L/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 1.56 g/L
- Nutrients provided for bacteria: peptone, meat extract, urea (provided through synthetic sewage feed medium)

EFFECT PARAMETERS MEASURED: respiration inhibition

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Key result

Duration:

180 min

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:

- Blank controls oxygen uptake rate: 0.80 mg O2/min
- Coefficient of variation of oxygen uptake rate in control replicates: 0%

Results with reference substance (positive control):

180 min-IC50: 14 mg/L corresponding to normal sensitivity

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test item has a 180-min IC50 >320 mg/L based on respiration inhibtion. The substance is not expected to be inhibitory in wastewater treatment plants when released at expectedly much lower concentrations.