Tribenzylamine

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:

2020-10-28 to 2020-11-25

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:

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:

May 30, 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Bensheim, Germany.
- Sludge preparation: The aerobic activated sludge used for this study was deposited for 30 min, washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated overnight. This suspension was used for the experiment.
- Concentration of sludge: 3.5 g dry material per litre; final sludge concentration in test flasks: 28.7 mg sludge/L
- Water filtered: yes, ultrapure water was used to prepare test water

Duration of test (contact time):

28 d

Initial conc.:

102.3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
Analytical grade salts were added to ultrapure 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
In order to avoid precipitation of iron hydroxide in the stock solution d), one drop of concentrated HCl per litre was added before storage. 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 ultrapure water. The pH was adjusted to pH 7.6 with 1M HCl solution.
- Solubilising agent: silicone oil AR 20 at a concentration of about 1 % of the final flask volume
- Test temperature: 22°C ± 1°C
- pH: 7.6 (measured at the start of the test), 7.5 (measured at the end of the test)
- pH adjusted: yes
- Aeration of dilution water: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: test flasks containing a volume of approximately 500 mL
- Number of culture flasks/concentration: 2 for test item and inoculum control, 1 for procedure, abiotic and toxicity control
- Method used to create aerobic conditions: continuous stirring
- Measuring equipment: The change of pressure in the test flasks was measured by means of a manometric method (BSB-Sensomat-System©). The temperature was recorded by means of the automated software AMR Wincontrol©.
- Test performed in closed vessels due to significant volatility of test substance: closed vessel was used to measure O2 consumption based on pressure.
- Test performed in open system: no

SAMPLING
- Sampling frequency: daily record of measurement
- Sampling method: no sampling as the change of pressure in the test flasks was measured by means of a manometric method

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 flasks
- Abiotic sterile control: yes, 1 flask
- Toxicity control: yes, 1 flask

STATISTICAL METHODS: Not performed

Reference substance:

benzoic acid, sodium salt

Test performance:

The reference item sodium benzoate was sufficiently degraded to 84 % after 14 days and to 86 % after 28 days of incubation. The percentage biodegradation of the reference item confirmed the suitability of the used aerobic activated sludge inoculum.
In the toxicity control containing both, the test item and the reference item sodium benzoate, 30 % (ThODNH4) biodegradation was noted within 14 days and 34 % (ThODNH4) biodegradation after 28 days of incubation (28 % and 32 % 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.
The oxygen demand in the abiotic control was 0 mg/L during the test duration.

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

The test item never reached a degradation of 10 % during the incubation period of 28 days; therefore the 10 day window criterion was not passed. The mean biodegradation at test end after 28 days was 0 % (ThODNH4 and ThODNO3).

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 84 % after 14 days and to 86 % after 28 days of incubation.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Executive summary:

The test item was investigated for its ready biodegradability in a manometric respirometry test over a period of 28 days using aerobic activated sludge. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Test item was used at a concentration of 102.3 mg/L corresponding to an oxygen demand of about 290.3 mg/L (ThODNH4) and 313.1 mg/L (ThODNO3). Sodium benzoate was used at a concentration of 101.6 mg/L corresponding to an oxygen demand of about 169.3 mg/L (ThODNH4). The test was conducted at 22°C ± 1°C in darkness. Nitrogen is part of the molecular structure of the test item; therefore the evaluation of biodegradation was based on ThODNH4 and ThODNO3. 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. The reference item sodium benzoate was sufficiently degraded to 84 % after 14 days and to 86 % 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, 30 % (ThODNH4) biodegradation was noted within 14 days and 34 % (ThODNH4) biodegradation after 28 days of incubation (28 % and 32 % 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. The test item never reached a mean biodegradation of 10 % (ThODNH4, ThODNO3). The mean biodegradation at test end after 28 days was 0 % (ThODNH4, ThODNO3). Therefore, the test item is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Description of key information

The test item is considered to be not readily biodegradable based on ThODNH4 and ThODNO3 (reference 5.2-1).

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Ready Biodegradability: Manometric Respirometry Test

In the key study the test item was investigated for its ready biodegradability in a manometric respirometry test over a period of 28 days using aerobic activated sludge. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. Test item was used at a concentration of 102.3 mg/L corresponding to an oxygen demand of about 290.3 mg/L (ThODNH4) and 313.1 mg/L (ThODNO3). Sodium benzoate was used at a concentration of 101.6 mg/L corresponding to an oxygen demand of about 169.3 mg/L (ThODNH4). The test was conducted at 22°C ± 1°C in darkness. Nitrogen is part of the molecular structure of the test item; therefore the evaluation of biodegradation was based on ThODNH4 and ThODNO3. 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. The reference item sodium benzoate was sufficiently degraded to 84 % after 14 days and to 86 % 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, 30 % (ThODNH4) biodegradation was noted within 14 days and 34 % (ThODNH4) biodegradation after 28 days of incubation (28 % and 32 % 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. The test item never reached a mean biodegradation of 10 % (ThODNH4, ThODNO3). The mean biodegradation at test end after 28 days was 0 % (ThODNH4, ThODNO3). Therefore, the test item is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Furthermore, supporting data from a QSAR prediction is available:

Using BIOWIN v4.1 as part of EPISuite v4.11 the test substance is determined to be not readily biodegradable. The substance is within the applicability domain of the model. Thus the estimation is accurate.

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction model

The prediction model was descriped using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.