Disodium 7-[[2-(acetylamino)-4-[(5-chloro-2,6-difluoro-4-pyrimidinyl)amino]phenyl]azo]naphthalene-1,3-disulphonate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Study period:

From October 31st to November 28th, 1996

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 301 E (Ready biodegradability: Modified OECD Screening Test)

Version / remarks:

adopted July 17, 1992

Qualifier:

according to guideline

Guideline:

EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)

Version / remarks:

December 1992

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Type: Microorganisms from a domestic waste water treatment plant.
- Source: ARA Ergolz ll, Füllinsdorf / Switzerland.
- Pretreatment: the activated sludge was washed three times with tap water and an amount corresponding to 4 g dry material (± 10 %) per litre was mixed with Sörensen buffer solution pH 7 and was then aerated until use.
- Preparation of the inoculum: in amount of 0.5 ml sludge (filtered through cotton wool) was added to 1000 ml test medium (with the exception of the abiotic control).

Duration of test (contact time):

28 d

Initial conc.:

32.9 - 34.1 mg/L

Based on:

DOC

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: 50 ml Erlenmeyer flasks, cleaned with alcoholic hydrochloric acid, rinsed with bidistilled water and dried. The test vessels were filled with about 30 ml of test medium, or test medium containing test article and/or reference compound.
- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature: 21 - 22 °C
- Continuous darkness: the test vessels were protected from light by means of a loose cover with aluminium foil.
- Agitatin: shaking water bath.

MEDIUM
The test medium (30 ml per flask) was prepared according to the OECD Guideline No. 301E.

CONTROL AND BLANK SYSTEM
- Inoculum blank: untreated test medium was inoculated and used as the control.
- Abiotic sterile control: the concentration of the test article in sterile filtered test medium (0.45 µm filtered) was 100 mg/I, corresponding to an actual amount of 33.8 mg DOC/l.
- Toxicity control: the concentrations of the test article and the reference compound Aniline in the test medium were 50 and 25 mg/I, respectively, corresponding to a total actual amount of 34.8 mg DOC/l. A theoretical amount of 19.4 mg DOC/I originated from Aniline.

SAMPLING
- Sampling frequency: samples were taken on day 0 (treatment day), 7, 14, 21, 27 and 28 of the incubation period.
- Sampling method: per sampling interval, two flasks of the samples containing the test article or reference compound and one flask of the inoculum blank, the toxicity control and the abiotic control were taken and analyzed for DOC in triplicate.
- Other: water evaporation losses were compensated by adding bidistilled water at the respective sampling intervals.

Reference substance:

aniline

Parameter:

% degradation (DOC removal)

Value:

-4 - 3

Sampling time:

28 d

Details on results:

In the test flasks containing the test article and inoculum (test set no. 1 and 2), the mean concentrations of DOC (Dissolved Organic Carbon) varied from 32.8 to 34.7 mg/l over the exposure period of 28 days and were practically equat to the initial mean DOC concentration of 33.5 mg/l measured on day-0. Expressed as percentage DOC-removal, very low values in the range from -4 to 3 % were noted.
Therefore, the test item was found to be practically non-biodegradable under the test conditions over the 28-day exposure period to activated sludge from a domestic waste water treatment plant.

ABIOTIC CONTROL
ln the abiotic control (test set no. 6) containing the test article and sterile medium, the DOC concentrations varied from 31.9 to 34.3 mg/l over the exposure period of 28 days and were practically equalto the initial DOC concentration of 33.8 mg/l measured on day d. Therefore, no abiotic degradation occurred.

DEGRADATION IN THE TOXICITY CONTROL
ln the toxicity control (test set no. 7) containing the test article (44.3 % as DOC), the reference compound (55.7 % as DOC) and inoculum, the initial DOC concentration of 34.8 mg/l measured on day-0 decreased by 52.0 % to 16.7 mg/l within 28 days of exposure. This indicates nearly complete biodegradation of the reference compound Aniline in the presence of test article, and that the non-biodegradability of test item is not the result of a toxic effect on the microorganisms.
ln other words, 50.3 % degradation (based on DOC measured on day-0) occurred within 14 days of exposure; thus, according to the test guidelines the test article can be assumed to not be inhibitory because degradation was higher than 35 % within 14 days.

Results with reference substance:

ln the procedure controls (test set no. 3 and 4) containing the reference compound Aniline and inoculum, Aniline was readily biodegraded by an average of 99 % within 14 days of exposure, and was fully biodegraded (102 %) by the end of the test (day 28).

	mg DOC/l*, after x days
	0	7	14	21	27	28
Blank	0.5	0.7	0	0	0.4	0.3
Test article and inoculum	33.4	35.3	34.3	33.6	33.3	31.7
Test article and inoculum	34.6	35.4	33.3	33.2	33.9	34.5
Mean test article and inoculum, corrected for blank	33.5	34.7	33.8	33.4	33.2	32.8
Aniline and inoculum	16.9	12.7	0.1	0.2	0.5	0.1
Aniline and inoculum	18.1	14.1	0.3	0.0	0.5	-0.1
Mean aniline and inoculum, corrected for blank	17.0	12.7	0.2	0.1	0.1	-0.3
Sterile mineral nutrient solution with test article	33.8	34.3	32.1	33.1	31.9	32.4
Test article (50 mg/l), Aniline (25 mg/l) and inoculum	35.3	18.0	17.3	17.7	18.4	17
Test article, Aniline and inoculum, corrected for blank	34.8	17.3	17.3	17.7	18.0	16.7

* Values given represent mean of three determinations.

Interpretation of results:

not readily biodegradable

Conclusions:

Non readily biodegradable (DOC removal (28d): -4 - 3 %)

Executive summary:

Test item was investigated for the ready biodegradability in the "28-Day Modified OECD Screening Test". In the test flasks containing the test article and inoculum (test set no. 1 and 2) the mean concentrations of DOC (Dissolved Organic Sarbon) varied from 32.8 to 34.7 mg/l over the exposure period of 28 days and were practically equal to the initial mean DOC concentration of 33.5 mg/l measured on day-0. Expressed as percentage DOC-removal, very low values in the range from -4 to 3 % were noted over the 28-day exposure period. Therefore, test item was found to be practically nonbiodegradable in the "Modified OECD Screening Test".

In the abiotic control (test set no. 6) containing the test article and sterile medium, the DOC concentrations varied from 31.9 to 34.3 mg/l over the exposure period of 28 days and were practically equalto the initial DOC concentration of 33.8 mg/l measured on day-0. Therefore, no abiotic degradation occurred.

In the procedure controls (test set no. 3 and 4) containing the reference compound Aniline and inoculum, Aniline was readily biodegraded by an average of 99 % within 14 days of exposure, and was fully biodegraded (102 %) by the end of the test (day-28); thus confirming suitability of the activated sludge.

In the toxicity control (test set no. 7) containing the test article (44.3 % as DOC), the reference compound (55.7 % as DOC) and inoculum, the initial DOC concentration of 34.8 mg/l measured on day-0 decreased by 52.0 % to 16.7 mg/l withln 28 days of exposure. This indicates nearly complete biodegradation of the reference compound Aniline in the presence of test article, and that the non-biodegradability of test item is not the result of a toxic etfect on the microorganisms. In other words, 50.3 % degradation (based on DOC measured on day-0) occurred within 14 days of exposure; thus, according to the test guidelines the test article can be assumed to not be inhibitory because degradation was > 35 % within 14 days.

Conclusion

Non readily biodegradable (DOC removal (28d): -4 - 3 %)

Description of key information

Non readily biodegradable (DOC removal (28d): -4 - 3 %)

Additional information

There is no information about the biodegradability potential of Reactive Yellow 215, 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 about the approach are reported into the IUCLID section 13).

Similar Substance 01 was investigated for the ready biodegradability in the "28-Day Modified OECD Screening Test". In the test flasks containing the test article and inoculum (test set no. 1 and 2) the mean concentrations of DOC (Dissolved Organic Sarbon) varied from 32.8 to 34.7 mg/l over the exposure period of 28 days and were practically equal to the initial mean DOC concentration of 33.5 mg/l measured on day-0. Expressed as percentage DOC-removal, very low values in the range from -4 to 3 % were noted over the 28-day exposure period. Therefore, test item was found to be practically nonbiodegradable in the "Modified OECD Screening Test".

In the abiotic control (test set no. 6) containing the test article and sterile medium, the DOC concentrations varied from 31.9 to 34.3 mg/l over the exposure period of 28 days and were practically equalto the initial DOC concentration of 33.8 mg/l measured on day-0. Therefore, no abiotic degradation occurred.

In the procedure controls (test set no. 3 and 4) containing the reference compound Aniline and inoculum, Aniline was readily biodegraded by an average of 99 % within 14 days of exposure, and was fully biodegraded (102 %) by the end of the test (day-28); thus confirming suitability of the activated sludge.

In the toxicity control (test set no. 7) containing the test article (44.3 % as DOC), the reference compound (55.7 % as DOC) and inoculum, the initial DOC concentration of 34.8 mg/l measured on day-0 decreased by 52.0 % to 16.7 mg/l withln 28 days of exposure. This indicates nearly complete biodegradation of the reference compound Aniline in the presence of test article, and that the non-biodegradability of test item is not the result of a toxic etfect on the microorganisms. In other words, 50.3 % degradation (based on DOC measured on day-0) occurred within 14 days of exposure; thus, according to the test guidelines the test article can be assumed to not be inhibitory because degradation was > 35 % within 14 days.