2(1H)-Pyridinone, 4-amino-5-methyl-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018 - 02 - 23 - 2018 - 05 - 18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-amino-5-methyl-1,2-dihydropyridin-2-one

EC Number:

682-818-3

Cas Number:

95306-64-2

Molecular formula:

C6 H8 N2 O

IUPAC Name:

4-amino-5-methyl-1,2-dihydropyridin-2-one

Test material form:

solid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Species/Origin: Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Bensheim, Germany.
Conditioning: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted after 15 minutes of deposition. 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 (see 6.5) and aerated for 2 days. This suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Test Design:
The test item 4-Amino-5-methylpyridinon was investigated for its ready biodegradability in a manometric respirometry test over a period of 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.
Endpoints:
Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.
Test Item Loading Rate (initial concentration in medium C0):
101.4 mg/L corresponding to an oxygen demand of about 156.9 mg/L (ThODNH4) and 261.6 mg/L
(ThODNO3)
Reference Item:
Sodium Benzoate
Reference Item Loading Rate:
103.7 mg/L corresponding to an oxygen demand of about 172.7 mg/L (ThODNH4)
Test Conditions:
22°C ± 1°C, darkness

Test Units
Type and Size:
Manometric Test System with test flasks containing a volume of approximately 500 mL.
Apparatus: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany
Principle:
The test flasks prepared according paragraph 6.6 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/BOD-Sensor-System, Aqualytic Dortmund, Germany. 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.
Identification: Each test unit was uniquely identified with the study number, treatment and replicate number.

Preparation of Test Flasks:
The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogeneous solution of the test item.
The expiry date of the reference item refers to the storage in the container. At test start (weighing of test item and reference item), the reference item was durable. The reference item expired not until it was in test solution.
Incubation:
The closed test flasks were incubated in a climatised chamber under continuous stirring. The consumption of oxygen was determined by measuring the change of pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.
Test Duration:
28 days

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

The mean biodegradation of 4-Amino-5-methylpyridinon never reached 10%. The mean biodegradation at test end after 28 days was 0% (ThODNH4, ThODNO3).
Therefore, 4-Amino-5-methylpyridinon is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Details on results:

Biodegradation of Test Item
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 mean biodegradation of 4-Amino-5-methylpyridinon never reached 10%. The mean biodegradation at test end after 28 days was 0% (ThODNH4, ThODNO3).
Therefore, 4-Amino-5-methylpyridinon is considered to be not readily biodegradable based on ThODNH4 and ThODNO3.

Conclusion:
The degradation rate of 4-Amino-5-methylpyridinon never reached 10%.
Therefore, 4-Amino-5-methylpyridinon is considered to be not readily biodegradable.

Biodegradation in the Toxicity Control
Percentage Biodegradation:
In the toxicity control containing both, the test item and the reference item sodium benzoate, 44% (ThODNH4) biodegradation was noted within 14 days and 46% (ThODNH4) biodegradation after 28 days of incubation (34% and 35% based on ThODNO3).

Conclusion:
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.

Abiotic Control
Oxygen Demand:
The oxygen demand in the abiotic control was 0 mg/L during the test duration

BOD5 / COD results

Results with reference substance:

Biodegradation of Reference Item Sodium Benzoate
Percentage Biodegradation:
The reference item sodium benzoate was sufficiently degraded to 81% after 14 days and to 87% after 28 days of incubation.
Conclusion: The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Any other information on results incl. tables

Cumulative Biochemical Oxygen Demand (mg O2/L) in Test Flasks during the Test period of 28 days

Time	Flask No.
(days)	1	2	3	4	5	6	7
1	5	5	5	5	65	0	70
2	5	5	5	5	90	0	90
3	10	10	10	10	120	0	120
4	10	10	10	10	130	0	130
5	10	10	10	10	140	0	140
6	15	15	15	15	145	0	145
7	15	15	15	15	150	0	150
8	15	15	15	15	150	0	155
9	15	15	15	15	155	0	160
10	15	15	15	15	155	0	160
11	20	20	20	20	160	0	165
12	20	20	20	20	160	0	165
13	20	20	20	20	160	0	165
14	20	20	20	20	160	0	165
15	20	20	20	20	165	0	170
16	20	20	20	20	165	0	170
17	20	20	20	20	165	0	170
18	20	20	20	20	165	0	170
19	20	20	20	20	165	0	170
20	20	20	20	20	165	0	170
21	20	20	20	20	165	0	170
22	20	20	20	20	165	0	170
23	20	20	20	20	165	0	170
24	20	20	20	20	165	0	170
25	20	20	20	20	170	0	170
26	20	20	20	20	170	0	170
27	20	20	20	20	170	0	170
28	20	20	20	20	170	0	170

Flasks 1 and 2: 4-Amino-5-methylpyridinon

Flasks 3 and 4: inoculum control

Flask5: reference(procedure control)

Flask 6: abiotic control

Flask 7: toxicity control

Percentage Biodegradation of the Test Item, of Sodium Benzoate and of the Toxicity Control based on ThODNH4

Time	Percentage Biodegradation^1
(Days)	4-Amino-5-methylpyridinon^1		Sodium Benzoate^2	Toxicity control^1, 2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	0	0	35	20
2	0	0	49	26
3	0	0	64	34
4	0	0	69	37
5	0	0	75	40
6	0	0	75	40
7	0	0	78	41
8	0	0	78	43
9	0	0	81	44
10	0	0	81	44
11	0	0	81	44
12	0	0	81	44
13	0	0	81	44
14	0	0	81	44
15	0	0	84	46
16	0	0	84	46
17	0	0	84	46
18	0	0	84	46
19	0	0	84	46
20	0	0	84	46
21	0	0	84	46
22	0	0	84	46
23	0	0	84	46
24	0	0	84	46
25	0	0	87	46
26	0	0	87	46
27	0	0	87	46
28	0	0	87	46

1ThOD_NH4of 4-Amino-5-methylpyridinon: 1.547 mg O₂/mg test item
2ThOD_NH4of sodium benzoate: 1.666 mg O₂/mg reference item

Percentage Biodegradation of Test Item and of the Toxicity Control based on ThODNO3 and of Sodium Benzoate based on ThODNH4

Time	Percentage Biodegradation^1
(Days)	4-Amino-5-methylpyridinon^1		Sodium Benzoate^2	Toxicity control^1, 2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	0	0	35	15
2	0	0	49	20
3	0	0	64	26
4	0	0	69	28
5	0	0	75	30
6	0	0	75	30
7	0	0	78	31
8	0	0	78	33
9	0	0	81	34
10	0	0	81	34
11	0	0	81	34
12	0	0	81	34
13	0	0	81	34
14	0	0	81	34
15	0	0	84	35
16	0	0	84	35
17	0	0	84	35
18	0	0	84	35
19	0	0	84	35
20	0	0	84	35
21	0	0	84	35
22	0	0	84	35
23	0	0	84	35
24	0	0	84	35
25	0	0	87	35
26	0	0	87	35
27	0	0	87	35
28	0	0	87	35

1ThOD_NO3of 4-Amino-5-methylpyridinon: 2.579 mg O₂/mg test item
2 ThOD_NH4of sodium benzoate: 1.666 mg O₂/mg reference item

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation rate of 4-Amino-5-methylpyridinon never reached 10%.
Therefore, 4-Amino-5-methylpyridinon is considered to be not readily biodegradable.

Executive summary:

Summary
Title:	4-Amino-5-methylpyridinon: Ready Biodegradability in a Manometric Respirometry Test
Guidelines:	This study was designed to comply with the following methods: -     Commission Regulation 440/2008/EC, Method C.4-D of: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008) -     OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted
Material and Methods:
Test Item:	4-Amino-5-methylpyridinon; Batch No.: BXR7SWA
Test Species:	Aerobic activated sludge (microorganisms from a domestic waste­water treatment plant) was supplied by the sewage treatment plant of Bensheim,.
Test Design:	The test item 4-Amino-5-methylpyridinon was investigated for its ready biodegradability in a manometric respirometry test over a period of 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.
Endpoints:	Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.
Test Item Loading Rate (initial concentration in medium C0):	101.4 mg/L corresponding to an oxygen demand of about 156.9 mg/L (ThODNH4) and 261.6 mg/L (ThODNO3)
Reference Item:	Sodium Benzoate
Reference Item Loading Rate:	103.7 mg/L corresponding to an oxygen demand of about 172.7 mg/L (ThODNH4)
Test Conditions:	22°C ± 1°C, darkness
Results:
Biodegradation of 4-Amino-5-methylpyridinon:	Nitrogen is part of the molecular structure of the test item; therefore the evaluation of biodegradation has to be based on ThODNH4and 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 mean biodegradation of 4-Amino-5-methylpyridinon never reached 10%. The mean biodegradation at test end after 28 days was 0% (ThODNH4, ThODNO3). Therefore, 4-Amino-5-methylpyridinon is considered to be not readily biodegradable based on ThODNH4and ThODNO3.
Biodegradation of Sodium Benzoate:	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.
Biodegradation of the Toxicity Control:	In the toxicity control containing both, the test item and the reference item sodium benzoate, 44% (ThODNH4) biodegradation was noted within 14 days and 46% (ThODNH4) biodegradation after 28 days of incubation (34% and 35% 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. .