Disodium [3-[4,5-dihydro-4-[(2-hydroxy-5-nitrophenyl)azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulphonato(3-)][1-[[2-hydroxy-5-(phenylazo)phenyl]azo]-2-naphtholato(2-)]chromate(2-)

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

Activeted sludge of communal sewage treatment plant - Ara Reinach collected on 02.08.94

Duration of test (contact time):

28 d

Initial conc.:

150 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- water/nutrient: according to the specifications of the OECD guideline
- test temperature: 22.0 ± 3 °C
- lighting: indirect daylight
- sludge concentration: 530 mg/l

Reference substance:

diethylene glycol

Parameter:

% degradation (DOC removal)

Value:

6.6

Sampling time:

28 d

Details on results:

The test substance biodegradation after 28 days, corrected by the blank control, is 6.6 % (average of two tests running in parallel).
Adsorption after 3h: 7.5 %

Results with reference substance:

The biodegradation of the reference substance corrected by the blank control and measured as DOC is 99.5 % at 8th day (average of two tests running in parallel).

Interpretation of results:

not inherently biodegradable

Conclusions:

Biodegradation after 28 days was 6.6 %

Executive summary:

Biodegradation test was carried out according to OECD guideline 302B. The biodegradation value is 6.6 % after 28 days (average of two tests running in parallel).

Description of key information

The biodegradation value is 6.6 % after 28 days. 

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Three different tests are available to evaluate the biodegradability potential in water of the substance: one regarding the inherent biodegradability and two regarding the biochemical and/or chemical oxygen demand.

The inherent biodegradability test was carried out according to the OECD Guideline 302B. The biodegradation value is 6.6 % after 28 days.

Two studies on BOD5 and COD are available for this substance, therefore they have been used together with the previous test as supporting studies in order to exclude a rapidly biodegradation of the substance, in fact, according to the ECHA "Guidance on information requirements and chemical safety assessment - Chapter R.7b: Endpoint specific guidance" (May 2008 version 1.1), if the BOD5:COD ratio is lower than 0.5, it can be expected that the substance is not readily biodegradable; if the ratio between BOD5 and COD is more than 0.5 there is an indication of ready biodegradation.

In the first one, COD was measured according to DIN 38409 - H 41-1 method (1980) corresponding to EEC Directive 92 / 69 / C.6. (1992). The value found is 1243 mg O2/g.

In the second one, BOD5 was measured according to ISO 5815 second edition 1989 -08 -01 (E) corresponding to 92/96/EEC C.5. The BOD5 value found is 5 mg O2/g.

Other indications regarding the biodegradation profile in water are available only in a summary of results of different tests performed with an other formulation. As the reliability cannot be assigned (no many details are reported in the summary) and the complete study reports cannot be recovered , the values are not considered for the assessment of the substance. The values are:

- Biodegradation after 28 d: 26.9%

- COD: 540 mg O2/g

- BOD5: 98 mg O2/g