9,10-Anthracenedione, 1,4-diamino-, N,N'-mixed 2-ethylhexyl and 3-[(2-ethylhexyl)oxy]propyl and 3-methoxypropyl derivs.

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

Study period:

13 Feb 2018 - 06 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

No further details specified in the study report.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Source of inoculum/activated slude: Aerobic activated sludge, microorganisms from a domestic waste water treatment plance supplied by the sewage treament plant, Bensheim, Germany.

Conditioning:
- The aerobic activated sludge used for this study was deposited for 15 mins, washed by centrifugation and the supernatant liquid phase was decanted.
-The solid material was re-suspended in test water and centrifuged again. This process was repeated 3 times.
-An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight calculated.
-Calculated aliquots of the washed sludge suspension corresponding to 3.5g dry material per L were mixed with test water and aerated for 2 days. This suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial conc.:

101.8 mg/L

Based on:

test mat.

Remarks:

corresponding to an oxygen demand of about 258.5 mg/L (ThODNH4) and 276.9 mg/L (ThODNO3)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS:
- Test Temperature: 22 ± 1°C
- Light conditions: darkness
- pH value of test solutions: 7.4 - 7.5 (measured at start of test and pH adjusted to 7.5).
7.3-7.7 (measured at day 29)

TEST WATER:
Analytical grade salts were added to pure water to prepare the following stock solutions:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl filled up with pure water to 1000 mL volume; The pH-value was 7.4.
b) 11.25 g MgSO4 x 7 H2O filled up with pure water to 500 mL volume
c) 18.2 g CaCl2 x 2 H2O filled up with pure water to 500 mL volume
d) 0.125 g FeCl3 x 6 H2O filled up with pure water to 500 mL volume (with one drop of concentrated HCl per litre to avoid precipitation.
50 mL of stock solution a) and 5 mL of the stock solutions b) to d) were combined and filled up to a final volume of 5000 mL with pure water.
The reconstituted test water was adjusted with 1N NaOH to pH 7.4.

TEST ITEM PREPARATION:
The amounts of test items and reference items were weighed directly into test flasks. No emulsifiers or solvents were used. Each flask was made up to a final volume of 244mL with the prepared test water. The list of samples is as follows, with 2 flasks of each:
Solvent Red Blue 79 (Test substance + inoculum)
CONTROLS:
Inoculum control: (inoculum only)
Procedure control: (sodium benzoate reference item + inoculum)
Abiotic control: Test substance + poisoned with CuS04 solution 1g/L
Toxicity Control: Test substance + Reference item + inoculum
The exact preparations are given in Table 1.

MEASUREMENTS:
Measurements were taken daily for 28 days. The change of pressure in the test flasks was measured by means of a manometric method. The amount of oxygen consumed by the activated sludge was calculated from the pressure decrease.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 3

Sampling time:

28 d

Details on results:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.
Solvent Blue 79B never reached a biodegradation of 10% or higher during the incubation time of 28 days. The mean biodegradation at test end after 28 days was 3% (ThODNH4, ThODNO3).

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 87% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

In the toxicity control containing both the test item and the reference item sodium benzoate, 35% biodegradation was noted within 14 days and 39% after 28 days of incubation (based on ThODNH4, 34% and 378% respectively based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.
Solvent Blue 79B never reached a biodegradation of 10% or higher during the incubation time of 28 days. The mean biodegradation at test end after 28 days was 3% (ThODNH4, ThODNO3).

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 87% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

In the toxicity control containing both, the test item and the reference item sodium benzoate, 35% biodegradation was noted within 14 days and 39% after 28 days of incubation (based on ThODNH4, 34% and 37% respectively based on ThONO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Executive summary:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.

Solvent Blue 79B never reached a biodegradation of 10% or higher during the incubation time of 28 days. The mean biodegradation at test end after 28 days was 3% (ThOD_NH4,ThOD_NO3).

Therefore, Solvent Blue 79B is considered to be not readily biodegradable based on ThOD_NH4/ThOD_NO3.

The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 87% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

In the toxicity control containing both, the test item and the reference item sodium benzoate,  38% biodegradation was noted within 14 days and 39% after 28 days of incubation (based on ThODNH4, 34% and 37% respectively based on ThONO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Description of key information

The degradation rate of Solvent Blue 79B was <10% after a test duration of 28 days in a manometric respirometry test

Therefore, Solvent Red Blue 79B is considered to be not readily biodegradable based on ThODNH4/ThODNO3.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater