m,m'-[carbonylbis[imino(3-methoxy-p-phenylene)azo]]bis(benzenesulphonic) acid, compound with 2,2'-iminodiethanol (1:2)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready 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:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

TEST ORGANIMS:
Type: mixed population of aquatic microorganisms (activated sludge)
Origin: aeration tank of a wastewater plant treating predominantly domestic sewage (Wupper area water authority, WWTP Odenthal)
Date of collection: 2017-03-06
Concentration of inoculum: 30 mg/L suspended solids

PRE-TREATMENT OF THE INOCULUM:
− Before use, the inoculum was stored for two days at room temperature under continuous stirring with aeration
− The sludge was washed twice by adding mineral medium and centrifuging for 10 min at 2000 rpm and 20 °C and decanting off the supernatant
− An aliquot of the wet sludge was dried in order to determine the wet weight / dry weight ratio of the sludge and to prepare a stock suspension (activated sludge) of 3 g dw/L
− The calculated amount of sludge, needed to achieve 300 mL of this stock suspension, was dissolved in mineral medium and then filled up to a defined end volume

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

PRE-TREATMENT OF THE TEST SUBSTANCE
- 27.9 mg test item = 25 mg active ingredient of the test item were weighed out, added to the test flasks and filled with 200 mL of mineral medium
- Volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg active ingredient/L

PRE-TREATMENT OF THE REFERENCE COMPOUND (Sodium Benzoate)
- 25 mg of the reference compound were weighed out, added to the test flasks and filled with 200 mL of mineral medium
- Volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg reference compound/L

PRE-TREATMENT OF THE TOXICITY CONTROL
- 27.9 mg test item = 25 mg active ingredient of the test item and 25 mg of the reference compound were weighed out, added to the test flasks and filled with 200 mL of mineral medium
- Volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg active ingredient and reference compound/L

EXPOSURE CONDITIONS
- Test volume: 250 mL
- Test apparatus: OxiTopControl System (WTW)
- Mixing: 1 magnetic stirrer per test vessel
- Incubation time: 28 days
- Incubation temperature: 22 ± 1 °C
- Test temperature: 22 ± 1 °C
- pH: 7.2 - 8.0
- Continuous darkness

SAMPLING
- Sampling frequency: The BOD (in mg O2/L) was measured daily

NUMBER OF DETERMINATIONS
- Determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate

Reference substance:

benzoic acid, sodium salt

Remarks:

(Acros Organics) Purity: 99.9 %, Batch-no.: A0357641

Key result

Parameter:

% degradation (O2 consumption)

Value:

36

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

26

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

35

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

36

Sampling time:

21 d

Details on results:

The toxicity control exhibited degradation rates > 25 % within 14 days.

Results with reference substance:

The reference compound sodium benzoate showed 86 % degradation after 14 days.

Validity criteria fulfilled:

yes

Remarks:

biodegradation of reference compound >= 60 % within 14 days; toxicity control exhibited de gradation rates > 25 % within 14 days; Replicates difference < 20 %; Oxygen uptake of the inoculum blank was <= 60 mg/L; no pH influence

Interpretation of results:

not readily biodegradable

Conclusions:

With a degradation of 36 % within 28 days Bayscript Yellow GGN has to be classified as not readily biodegradable.

Executive summary:

The study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4 -D "Manometric Respirometry Test (2008)". This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992). A suspension of the test substance in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation of Bayscript Yellow GGN was followed by continuous automated BOD determinations. The 28-day degradation was 36 % while a biodegradation of 86 % was observed for the positive control (with reference substance sodium benzoate). In conclusion Bayscript Yellow GGN is not readily biodegradable under test conditions.

The degradation rate of the test item was set in relation to its experimentally determined COD. As the COD implicitly covers the oxygen demand for the nitrification process, there was no need to take additional correction measures into account.

Description of key information

The study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4 -D "Manometric Respirometry Test (2008)". This test method is in all essential parts identical with OECD Guideline 301 F (adopted July 1992). A suspension of the test substance in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation of Bayscript Yellow GGN was followed by continuous automated BOD determinations. The 28-day degradation was 36 % while a biodegradation of 86 % was observed for the positive control (with reference substance sodium benzoate). In conclusion Bayscript Yellow GGN is not readily biodegradable under test conditions.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The degradation rate of the test item was set in relation to its experimentally determined COD. As the COD implicitly covers the oxygen demand for the nitrification process, there was no need to take additional correction measures into account.