2,4,6-trimethylpyridine

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:

Experimental Starting Date: January 03, 2020
Experimental Completion Date: January 31, 2020

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)

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

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 Rossdorf, Germany.

- Preparation of inoculum for exposure:
The aerobic activated sludge used for this study was deposited for 15 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:
final sludge concentration in test flasks: 28.7 mg sludge/L
- Water:
Reconstituted Test Water was prepared by adding analytical grade salts to ultrapure water.

Duration of test (contact time):

28 d

Initial conc.:

102 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
Reconstituted Test Water: 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 7.5 with 1M HCl solution.

- Test temperature: 22°C ± 1°C
- pH: 7.7 to 7.8 (measured at the start of the test), 7.7 to 8.0 (measured at the end of the test)

- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500 mL culture flasks
- Number of culture flasks/concentration: 2
- Measuring equipment: The change of pressure in the test flasks was measured by means of a manometric method (BSB/BOD-Sensor-System).
- Details of trap for CO2: Potassium hydroxide solution (45%)

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks
- Abiotic sterile control: 1 flask, poisoned with CuSO4 (5mL)
- Toxicity control: 1 flask (reference item 24.9 mg sodium benzoate, 25.2 mg test item)
- Other: procedure control, 1 flask, with reference item sodium benzoate (25.1 mg per flask)

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Details on results:

Percentage Biodegradation: Nitrogen is part of the molecular structure of the test item; therefore nitrification (ThODNO3) was considered for the evaluation of the 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.
The test item never reached 10% biodegradation. The mean biodegradation percentage at the end of the 28-day exposure period was 3% (ThODNO3). If no nitrification is considered, the mean biodegradation was 3% (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was not fulfilled.
Conclusion: The degradation rate of 2,4,6-Collidine never reached 60%.
Therefore, 2,4,6-Collidine is considered to be not readily biodegradable.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 77% after 14 days and to 79% after 28 days of incubation.

For details on the results, please refer to the attached document.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

2,4,6-Collidine is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Executive summary:

The purpose of this study was to determine the ready biodegradability of the test item 2,4,6-Collidine. The test item was exposed to aerobic activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. 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. Aerobic activated sludge from a domestic waste water treatment plant was used in this study. A manometric Test System with a BSB/BOD-Sensor-System and flasks containing a volume of approximately 500 mL were used. The test flasks were incubated at 22°C ± 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BODSensor-System. The test flasks were closed gas-tight by a measuring head. Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel. Nitrogen is part of the molecular structure of the test item; therefore nitrification (ThODNO3) was considered for the evaluation of the 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. The test item never reached 10% biodegradation. The mean biodegradation percentage at the end of the 28-day exposure period was 3% (ThODNO3). If no nitrification is considered, the mean biodegradation was 3% (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was not fulfilled. Therefore, 2,4,6-Collidine is considered to be not readily biodegradable. The reference item sodium benzoate was sufficiently degraded to 77% after 14 days and to 79% after 28 days of incubation.

Description of key information

The test item was found to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Biodegradation in water

The purpose of this study (OECD 301F) was to determine the ready biodegradability of the test item 2,4,6-Collidine. The test item was exposed to aerobic activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. 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. Aerobic activated sludge from a domestic waste water treatment plant was used in this study. A manometric Test System with a BSB/BOD-Sensor-System and flasks containing a volume of approximately 500 mL were used. The test flasks were incubated at 22°C ± 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BODSensor-System. The test flasks were closed gas-tight by a measuring head. Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel. Nitrogen is part of the molecular structure of the test item; therefore nitrification (ThODNO3) was considered for the evaluation of the 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. The test item never reached 10% biodegradation. The mean biodegradation percentage at the end of the 28-day exposure period was 3% (ThODNO3). If no nitrification is considered, the mean biodegradation was 3% (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was not fulfilled. Therefore, 2,4,6-Collidine is considered to be not readily biodegradable. The reference item sodium benzoate was sufficiently degraded to 77% after 14 days and to 79% after 28 days of incubation.