Reaction mass of [5-methyl-2-[[4-(4-methylanilino)-9,10-dioxo-1-anthryl]amino]phenyl]sulfonyloxypotassium and [5-methyl-2-[[4-(4-methyl-2-potassiooxysulfonyl-anilino)-9,10-dioxo-1-anthryl]amino]phenyl]sulfonyloxypotassium

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 15 January to 17 February, 1991

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:

The read across approach is detailed into the document attached to the IUCLID 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)

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Inoculum: a mixed population of activated sewage sludge microorganisms.
- Source: the aeration stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
- Preparation: the activated sludge was washed by repeatedly settling and resuspending with the test water.
- Amount: usage rate equivalent to 0.75 g dry weight/I.

Duration of test (contact time):

28 d

Initial conc.:

255 mg/L

Based on:

test mat.

Remarks:

(=100 ppm C)

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Test temperature: 22 ± 1 °C
- Continuous darkness: yes; the test was conducted in darkness.
- Agitation: by magnetic stirrers and compressed air via narrow bore glass tubes.
- pH: pH values did not drop below 5.3 in any culture vessel during the course of the study and were adiusted to pH 7.3 daily.
- Dissolved oxygen: dissolved oxygen levels remained at approximately 7.8 mgO2/l or above in all cultures at all times.

SAMPLING
- Sampling preparation: losses by evaporation were made good by the addition of de-ionised water immediately prior to sampling.
- Sampling amount: 20 ml samples were withdrawn from each vessel and filtered through 0.45 um disposable filters; the first 10 ml was discarted.

Reference substance:

diethylene glycol

Remarks:

220 mg/l (= 100 ppm C)

Parameter:

% degradation (DOC removal)

Value:

18

Sampling time:

28 d

Details on results:

Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

Results with reference substance:

The Standard Substance, diethylene glycol, attained 93 % degradation within 8 days and 100 % degradation by day 27, thereby confirming the suitability of the inoculum and culture conditions.

Details on test results

Day	DOC* value mg/l (Mean of 2 Assays)		% biodegradation
	Test item	Reference	Test item	Reference
0 Hours	130	88	0	0
3 Hours	130	88	0	0
1	130	91	0	<3>
2	132	94	<2>	<6>
3	132	93	<2>	<5>
6	131	74	<1>	17
8	126	6	3	93
10	130	5	0	95
14	116	2	11	97
16	117	1	10	99
21	115	3	11	96
23	114	3	12	96
27	108	0	17	100
28	107	0	18	100

<increase>

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

Executive summary:

The biodegradability of test item, exposed to activated sludge, was investigated under aerobic static conditions. The assessment was performed in accordance with Zahn-Wellens test method.

Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

The Standard Substance, diethylene glycol, attained 93 % degradation within 8 days and 100 % degradation by day 27, thereby confirming the suitability of the inoculum and culture conditions.

Conclusion

Based on the test results, the substance resulted to be not biodegradable under the test conditions, since less than 20 % degradation was attained after 28 days of contact time.

Description of key information

neither readily nor inherently biodegradable

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

Acid Green 025 is a diaminoanthraquinones, with external sulfate groups. The substance is not expected to be readly biodegradable because of its chemical structure and its specific function. Commonly, dyes undergo a primary transformation, i.e. discolourization due to the interrupting the conjugation; nevertheless, the degradation process involves more steps and take more time.

Because there is no experimental information about the biodegradability potential of Acid Green 025, the available information on the structural analogues Similar Substance 01 and Similar Substance 02 has been taken into consideration; the read across approach can be considered as appropriate and suitable to assess the property under investigation (details about the approach are reported into the IUCLID section 13).

The biodegradability of Similar Substance 01 was investigated under aerobic static conditions, in accordance with Zahn-Wellens test method. Test item attained 18 % degradation within 28 days and cannot, therefore, be considered as inherently biodegradable.

The Standard Substance, diethylene glycol, attained 93 % degradation within 8 days and 100 % degradation by day 27, thereby confirming the suitability of the inoculum and culture conditions.

Also the biodegradability potential of the Similar Substance 01 was investigated according to the Zahn-Wellens/EMPA Test method. Test item attined between 4 and 16 % degradation, based on DOC removal, within 28 days, thus it cannot be considered as inherently biodegradable.