Disodium [6-[(2-anilino-1-naphthyl)azo]-2,4-dinitrophenolato(2-)][3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]naphthalene-1-sulphonato(3-)]chromate(2-)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

From January 05th to February 02nd, 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

Details on read-across are available in section 13.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1981

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source: sludge of a biological sewage treatment plant (ARA-Therwil), collected on 04.01.94.

Duration of test (contact time):

28 d

Initial conc.:

150 mg/L

Based on:

DOC

Initial conc.:

445 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: according to the specification of the EEC L133, Volume 31 resp. OECD Method 302B.
- Test temperature: 22 ± 3 °C
- Continuous darkness: no; indirect daylight.
- Sludge concentration: 1040 mg/l

Reference substance:

diethylene glycol

Parameter:

% degradation (DOC removal)

Value:

29.2

Sampling time:

3 h

Parameter:

% degradation (DOC removal)

Value:

26.8

Sampling time:

28 d

Details on results:

The bioelimination measured as DOC after 28 days and corrected by blank control resulted to be 26.8 % (average of 2 tests running in parallel).
Adsorption after 3 hours: 29.2 %.

Results with reference substance:

Bioelimination, corrected by blank control and measured as DOC (mg/l) resulted to be 98.8 % at the 16th day.

After	Reference substance DOC (mg/l)	Reference substance control DOC (mg/l)	Reduction %	Substance DOC (mg/l)	Substance blank DOC (mg/l)	Reduction %
0h	157.1	6.4	3.6	136.3	6.4	14.8
3h	156.7	5.2	3.1	113.1	5.2	29.2
2d	154.5	6.9	5.6	99.6	6.9	39.2
5d	143.5	11.5	15.6	99.8	11.5	42.1
7d	137.5	12.8	20.3	105.2	12.8	39.4
9d	73.4	10.6	59.8	108.5	10.6	35.8
12d	7.9	5.5	98.5	112	5.5	30.2
13d	7	5.1	98.8	-	-	-
14d	8.3	4	97.3	112.6	4	28.8
15d	7.7	5.2	98.4	-	-	-
16d	6.1	4.2	98.8	111	4.2	30
19d	-	-	-	112.3	3.4	28.6
21d	-	-	-	116.9	4.5	26.3
23d	-	-	-	117.3	3.6	25.4
26d	-	-	-	113.8	3.4	27.6
28d	-	-	-	115.3	3.7	26.8

Mean values of the double determination

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Test item resulted to be not biodegradable under the test conditions.

Executive summary:

The inherent biodegradability of test item was determined in a 28 days Zahn-Wellens Test, according to OECD guideline 302B (1981) and the EEC-Directive, L133Volume 31, May 88. The test was performed in compliance with GLP Regulations of Switzerland.

The test substance was tested in concentration of 150 mg DOC/l. The reference substance diethylenglycol was also tested in a concentration of 150 mg DOC/l.

The bioelimination measured as DOC after 28 days corrected by the blank control resulted to be 26.8 % (average of 2 tests running in parallel). The DOC removal after 3 hours resulted to be 29.2 %.

The bioelimination of the reference substance after 16 days resulted of 98.8 %

Conclusion

The test item resulted to be not biodegradable under the test conditions.

Description of key information

Neither readily nor inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

There are no information about the biodegradability potential of Acid Black 222, thus the available information on the structural analogous Similar Substance 01 have been taken into consideration; the read across approach can be considered as appropriate and suitable to assess the property under investigation. Details are available in IUCLID section 13.

The biodegradability of Similar Substance 01 was investigated following testing procedures outlined into OECD guideline 302B. The test item resulted to be mainly eliminated during the first 3 hours, when 29.2 % of the initial DOC was removed; after 28 days, mean bioelimination resulted to be 26.8 %. Thus, the substance can be considered as neither readily nor inherently biodegradable (Mätzler, 1994).

A second test, conducted on the Similar Susbtance 01, is available. The inherent biodegradability of test item was determined in a 28 days Zahn-Wellens Test, according to the OECD 302B. The test was penformed with adapted sludge (adaptation 28 days) because of the unusual result of the first test with non-adapted sludge. Bioelimination, measured as DOC after 28 days and corrected by blank control, resulted to be 69 % (average of 2 measurements). The DOC removal after 3 hours resulted to be 26 % and the removal after 4 days was of 62.5 % (Frey, 1985).

The curve shape, in this second experiment, shows that the substance was removed in the first days of experiment; after 4 days, a flatten of the curve seems to occur. The behavoiur described in consistent with the above mentioned test outcomes and with the behaviour expected for the substance, based on the physicochemical properties. In conclusion, the substance can be considered as neither readily, nor inherently biodegradable.