3,3'-[ethylenebis[(3-sulpho-p-phenylene)azo]]bis[5-amino-4-hydroxynaphthalene-2,7-disulphonic acid] hexasodium salt AND 3,3'-[ethylenebis[(3-sulpho-p-phenylene)azo]]bis[5-amino-4-hydroxynaphthalene-2,7-disulphonic] acid, compound with 2,2',2''-nitrilotriethanol (1:6)

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:

10 October 2005 to 15 November 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: test according to the guideline under GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

500.1 mg test susbtance was added to 284 mL tap water and stirred for 20 minutes. Therafter 200 mL activated sludge and 16 mL synthetic waste water were added to reach a concentration of 1000 mg/L.
synthetic waste water according to OECD 209:
- peptone 16 g
- meat extract (or a comparable vegetable extract) 11 g
- urea 3 g
- sodium chloride (NaCl) 0.7 g
- calcium chloride dihydrate (CaC12, 2H2O) 0.4 g
- magnesium sulphate heptahydrate (MgSO4, 7H2O) 0.2 g
- anhydrous potassium monohdydrogen phosphate (K2HPO4) 2. 8g
- distilled or deionized water to 1 litre

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of inoculum/activated sludge: waste water treatment plant ARA Ergolz II, Fuellinsdorf, Switzerland
- Storage length: 3 days (fed with synthetic waste water (50 mg/L))
- Sorage condition: aerated at room temperature
- Preparation of inoculum for exposure: washed twice with tap water, supernatant decanted, homogenized and dried
- Pretreatment: none
- Concentration of sludge at start of the test: 4 g dry weight/L (1.6 g dry material/L)
- Water filtered: no
- pH: adjusted form 8.6 to 7.1 with diluted sulfuric acid

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Post exposure observation period:

measurement of respiratory rate over 10-15 minutes without aeration under continuous stirring

Test temperature:

20 °C

pH:

7.6-8.4

Dissolved oxygen:

8.4-8.6 mg/L

Nominal and measured concentrations:

nominal 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 2000 mL glass
- Fill volume: 1000 mL
- number of vessels : 1 for test substance, 2 for inoculum control; 1 per concentration for positive controls
- Aeration: yes
- Stirring: continuously

EFFECT PARAMETERS MEASURED : respiration rate (dissolved oxygen concentration) over 10-15 minutes after 3 h exposure period with oxygen electrode

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol at 5, 16 and 50 mg/L

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

inhibition was 0.4% compared to inoculum controls

Results with reference substance (positive control):

EC50 19 mg/L (probit analysis)

Reported statistics and error estimates:

NA

Validity criteria fulfilled:

yes

Conclusions:

The NOEC is ≥ 1000 mg/L

Executive summary:

In a limit test according to OECD 209, 1000 mg/L of the substance did not lead to inhibition of the respiratory activity of activated sludge. The NOEC is ≥ 1000 mg/L.

Description of key information

In a limit test according to OECD 209, 1000 mg/L of the substance did not lead to inhibition of the respiratory activity of activated sludge. The NOEC is ≥ 1000 mg/L (RCC 2005)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L