Octasodium 2,2'-[1,4-phenylenebis[imino(6-chloro-1,3,5-triazine-4,2-diyl)imino(1-hydroxy-3,6-disulphonatonaphthalene-2,8-diyl)azo]]bisnaphthalene-1,5-disulphonate

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)

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 (adaptation not specified)

Details on inoculum:

- 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: 2017-07-24
- Concentration of inoculum: 30 mg/L suspended solids

Pre-treatment of the inoculum
− Before use, the inoculum was stored for three 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:

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 design: test item, 3 replicates; inoculum blank, 3 replicates; reference compound, 2 replicates; Toxicity control, 1 replicate
- pH-value after 28 d: 7.4 - 8.1
- darkness

Pre-treatment of test item
- 32.3 mg = 25 mg (active ingredient) of the test item were weighed out and added to the test flasks, 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 of the test item/L

Pre-treatment of the reference compound
- 25 mg of the reference compound were weighed out and added to the test flasks, 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
- 25 mg of the active ingredient (= 32.3 mg of the test item) and 25 mg of the reference compound were weighed out and added to the test flasks, filled with 200 mL of mineral medium
- the flask volume was made up to 250 mL with mineral medium containing the inoculum to give a test concentration of 100 mg active ingredient of the test item and 100 mg of the reference compound/L

Reference substance:

benzoic acid, sodium salt

Remarks:

Acros Organics, purity 99.9 %, batch-no. A0357641

Parameter:

% degradation (O2 consumption)

Value:

6

Sampling time:

28 d

Results with reference substance:

The reference compound sodium benzoate showed 91 % degradation after 14 days.

Validity criteria fulfilled:

yes

Remarks:

biodegration of reference compound ≥ 60 % in 14 d; degradation of toxicity control > 25 % in 14 d; biodegradation in parallels with test item did not differ >20 %, oxygen uptake of inoculum blank ≤ 60 mg/L

Interpretation of results:

not readily biodegradable

Conclusions:

Within 28 days, a degradation rate of 6 % was determined for the active ingredient of Reactive Red 141. Therefore, it (active ingredient) is considered to be "Not Readily Biodegradable".

Executive summary:

A study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D “Manometric Respirometry Test“(2008), which is in all essential parts identical with OECD Guideline 301 F (adopted July 1992), to assess the ready biodegradability of Reactive Red 141.

A suspension of 100 mg of the active ingredient Reactive Red 141 in a mineral medium was inoculated and incubated for 28 d in the dark under aerobic conditions. During this period, degradation was followed by continuous automated BOD determinations.

The endogenous activity of the inoculum was checked running parallel blanks with inoculum but without test item. A reference compound (sodium benzoate) was run in parallel to check the operation of the procedures. A toxicity control (test item and reference compound mixed, one replicate) was run in parallel, to ensure that the chosen concentration of the test item was not inhibitory to microorganisms.

Because of the nature of biodegradation and of the mixed bacterial populations used as inoculum, determinations of test item and inoculum blank were carried out in triplicate and of reference compound in duplicate. At the end of incubation, the pH was measured in the flasks.

Reactive Red 141 (active ingredient) showed 6 % degradation after 28 days. Therefore, Reactive Red 141 (active ingredient) is considered to be “Not Readily Biodegradable“.

The reference compound sodium benzoate showed 91 % degradation after 14 days.

The test item is an N-containing substance. Therefore, the concentration of nitrite and nitrate was determined at the start of the test. The oxygen consumed by nitrification was not determined after 28 days, because poor degradation of the test item was observed.

Description of key information

A study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.4-D “Manometric Respirometry Test“(2008), which is in all essential parts identical with OECD Guideline 301 F (adopted July 1992), to assess the ready biodegradability of Reactive Red 141.

A suspension of 100 mg of the active ingredient Reactive Red 141 in a mineral medium was inoculated and incubated for 28 d in the dark under aerobic conditions. Reactive Red 141 (active ingredient) showed 6 % degradation after 28 days. Therefore, Reactive Red 141 (active ingredient) is considered to be “Not Readily Biodegradable“.

The reference compound sodium benzoate showed 91 % degradation after 14 days.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed