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)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 September 2005 to 18 October 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guideline study under GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Qualifier:

according to guideline

Guideline:

EU Method C.9 (Biodegradation: Zahn-Wellens Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: waste water treatment plant ARA Ergolz II, Fuellinsdorf, Switzerland
- Storage length: not indicated
- 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: 4 g dry weight/L
- Water filtered: no
- Ratio inoculum/test substance (as DOC): 3:1

Duration of test (contact time):

28 d

Initial conc.:

280 mg/L

Based on:

test mat.

Initial conc.:

ca. 100 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: accoding to the guideline
- Test temperature: 21-25 °C
- pH: 6.5-7.6 (measured at start and before each sampling)
- pH adjusted: if necessary to pH 7.1 to 7.9 (both in test substance vessels and controls)
- Aeration of dilution water: yes
- Suspended solids concentration: not determined
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2000 mL Erlenmeyer with 1000 mL testsolution (water and evaporation losses were compensated if necessary)
- Number of culture flasks/concentration: 2 for test substance, 2 for inoculum controls, 2 for reference controls, 1 toxicity control, 1 sterility control
- Method used to create aerobic conditions: not fully closed vessels and continuously stirring with magnetic stirrer
- Oxygen concentration: 6.7-8.9 mg/L (measured at start and before each sampling)
- Measuring equipment: TOC-analyzer

SAMPLING
- Sampling frequency: after 3 hours and on day 3, 7, 10, 14, 21 and 28
- Sampling method: no details
- Sterility check if applicable: included
- Sample storage before analysis: analysed immediately

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: 1
- Toxicity control: 1

Reference substance:

diethylene glycol

Test performance:

All values are corrected for the degradation measured in inoculum controls.

Key result

Parameter:

% degradation (DOC removal)

Value:

12

Sampling time:

3 d

Key result

Parameter:

% degradation (DOC removal)

Value:

>= 50 - <= 53

Sampling time:

7 d

Remarks on result:

other: from day 7 to 28

Details on results:

Toxicity controls 74% degradation within 14 days (based on DOC of 190.3 mg/L 49% test substance and 51% reference substance)
No degrdation in abiotic controls
No DOC removal during the first 3 hours of the test --> indicative for no adsorption

Results with reference substance:

The degradation of the reference substance was 100% after 7 days.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The substance is inherently biodegrdable

Executive summary:

In a Zahn-Wellens/EMPA test a biodegradation of 53% was observed for the substance (initial concentration 280 mg/L).No toxicity was towards micto organism was found. As the degradation is > 35% the substance is considered inherently biodegradable.

Description of key information

In a Zahn-Wellens/EMPA test (RCC 2005) a biodegradation of 53% was observed for the substance (initial concentration 280 mg/L).No toxicity was towards micro-organisms was found. As the degradation is > 35% the substance is considered inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

In addition in a limited reported Zahn-Wellens test (BASF 1988) the substance degraded up to 60%, which confirms the finding that the substance is inherently biodegradable.