Propionamide

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:

2019-03-15 to 2019-04-15

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:

July 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

May 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: 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: 3.5 g dry material per litre

Duration of test (contact time):

28 d

Initial conc.:

103.1 mg/L

Based on:

test mat.

Remarks:

corresponding to an oxygen demand of about 157.9 mg/L (ThODNH4) and 248.2 mg/L (ThODNO3)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Reconstituted water according to guideline using pure water and analytical grade salts
- Additional substrate: No
- Test temperature: 22 °C ± 1 °C
- pH: 7.6 (measured at the start of the test); 6.6 to 6.7 (measured at the end of the test)
- pH adjusted: No
- Aeration of dilution water: No
- Continuous darkness: Yes

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flasks containing a volume of approximately 500 mL; closed test flasks were incubated in a climatised chamber under continuous stirring
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: Inoculum aerated
- Measuring equipment: BSB/BOD-Sensor-System
- Test performed in closed vessels due to significant volatility of test substance: Closed gas-tight by a measuring head
- CO2 trap: Potassium hydroxide (45 %)

SAMPLING
- Sampling method: The change of pressure in the test flasks was measured by means of a manometric method (BSB/BOD-Sensor-System). Nitrate and Nitrite determination was done using a AA3 Continuous Flow Analyzer and equipment.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Procedure control: Yes
- Abiotic sterile control: Yes
- Toxicity control: Yes; containing both, the test item and the reference item sodium benzoate.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

None

Test performance:

VALIDITY CRITERIA OF THE STUDY
Inoculum Control:
The oxygen demand of the inoculum control (medium and inoculum) was 15 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline.

pH-Value:
The pH-value of the test item flasks at the end of the test was 6.6 to 6.7 and therefore within the range of pH 6.0 to 8.5 as required by the test guideline.

Reference Item:
The percentage degradation of the reference item should reach the level for ready biodegradability (>60 %) within 14 days as required by the test guideline. The reference item sodium benzoate was degraded to more than 60 % after 5 days of incubation.

Test Item:
The difference of duplicate values for the degradation of the test item at the plateau, at the end of the test and at the end of the 10-day window was less than 20 %. The differences of duplicate values at the end of the 10 day window and at the end of the test at day 28 were 11 %.
The validity criterion was fulfilled.

Toxicity Control:
If in a toxicity test, containing both the test item and a reference item less than 25 % biodegradation (based on total ThOD) occurred within 14 days, the test item can be assumed to be inhibitory. The biodegradation was 59 % (ThODNO3) at day 14; the test item was not inhibitory.

Key result

Parameter:

% degradation (O2 consumption)

Value:

91

Sampling time:

28 d

Remarks on result:

other: after correction for nitrification

Details on results:

The 10-day windows began on day 3 after application, the mean value was calculated to be 36 % biodegradation (ThODNO3). Therefore, the end of the 10-day window was day 13. After correction for the mean biochemical oxygen demand of the inoculum controls the mean biodegradation percentage based on ThODNO3 at the end of the 10-day window was 84 %; the criterion of the 10 day window was passed. The mean biodegradation percentage at the end of the 28-day exposure period and after correction for nitrification was 91 % (ThODNO3).
If no nitrification is considered, the mean biodegradation was 143 % (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was fulfilled on day 13.
The nitrate concentration in the controls after 28 days of incubation was 1.56 mg/L (mean). The nitrate concentration in the test item treated vessels was 20.17 mg/L (mean). Therefore, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 89 % after 28 days.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 89 % after 14 days and to 99 % after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

Table 1: Cumulative Biochemical Oxygen Demand (mg O2/L) in Test Flasks during the Test Period of 28 Days

Time (day)	Flask No.
	1	2	3	4	5	6	7
1	5	5	0	0	50	0	60
2	10	10	5	5	75	0	195
3	95	95	5	5	90	0	230
4	110	120	5	10	105	0	250
5	125	135	5	10	120	0	250
6	140	150	5	10	130	0	255
7	160	170	5	10	135	0	255
8	175	185	10	15	140	0	260
9	190	210	10	15	145	0	260
10	200	215	10	15	150	0	260
11	205	220	10	15	155	0	260
12	210	225	10	15	160	0	260
13	210	230	10	15	160	0	260
14	215	230	10	15	165	0	260
15	215	235	10	15	170	0	260
16	220	235	10	15	170	0	260
17	220	235	10	15	170	0	260
18	220	235	10	15	175	0	260
19	220	240	10	15	175	0	260
20	220	240	10	15	175	0	260
21	220	245	10	15	180	0	260
22	225	245	15	15	180	0	260
23	225	245	15	15	180	0	260
24	225	245	15	15	180	0	260
25	225	245	15	15	180	0	260
26	225	245	15	15	180	0	260
27	225	250	15	15	185	0	260
28	230	250	15	15	185	0	260

Flasks 1 and 2: Test item;

Flask 3 and 4: inocumum control;

Flask 5: reference (procedure control);

Flask 6: abiotic control;

Flask 7: Toxicity control

 

Table 2: Percentage Biodegradation of Test Item, of Sodium Benzoate and of the Toxicity Control based on ThODNH4

Time (Days)	Percentage Biodegradation
	Test item^1		Sodium Benzoate^2	Toxicity control^1,2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	3	3	29	18
2	3	3	41	58
3	57	57	50	69
4	65	71	57	74
5	75	80	66	74
6	84	90	71	76
7	97	102	74	76
8	104	109	74	76
9	113	124	77	76
10	119	127	80	76
11	123	131	83	76
12	126	134	86	76
13	126	137	86	76
14	129	137	89	76
15	129	140	92	76
16	132	140	92	76
17	132	140	92	76
18	132	140	95	76
19	132	143	95	76
20	132	143	95	76
21	132	146	98	76
22	134	145	96	75
23	134	145	96	75
24	134	145	96	75
25	134	145	96	75
26	134	145	96	75
27	134	148	99	75
28	137	148	99	75

 ¹ThODNH4 of test item: 1.532 mg O2/mg test item

² ThODNH4 of sodium benzoate: 1.666 mg O2/mg reference item

 

Table 3: Percentage Biodegradation of Test Item and of the Toxicity Control based on ThODNO3 and of Sodium Benzoate based on ThODNH4

Time (Days)	Percentage Biodegradation
	Test item^1		Sodium Benzoate^2	Toxicity control^1,2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	2	2	29	14
2	2	2	41	46
3	36	36	50	54
4	42	45	57	58
5	48	51	66	58
6	54	57	71	59
7	62	65	74	59
8	66	69	74	59
9	72	79	77	59
10	76	81	80	59
11	78	83	83	59
12	80	85	86	59
13	80	87	86	59
14	82	87	89	59
15	82	89	92	59
16	84	89	92	59
17	84	89	92	59
18	84	89	95	59
19	84	91	95	59
20	84	91	95	59
21	84	93	98	59
22	85	92	96	59
23	85	92	96	59
24	85	92	96	59
25	85	92	96	59
26	85	92	96	59
27	85	94	99	59
28	87	94	99	59

 ¹ThODNO3 of test item: 2.408 mg O2/mg test item

²ThODNH4 of sodium benzoate: 1.666 mg O2/mg reference item

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In a Manometric Respirometry Test according to OECD guideline 301 F and EU Method C.4-D the test item was determined to be readily biodegradable within the 10-day-window and after 28 days (91 % based on ThODNO3 and 143 % based on ThODNH4)

Executive summary:

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test according to OECD guideline 301 F and EU Method C.4- D over a period of 28 days.

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. Simultaneously, a procedure control (containing the reference item sodium benzoate, 1 replicate), a blank control (containing test medium and inoculum, 2 replicates) and a toxicity control (containing both the test item and the reference item, 1 replicate) and an abiotic control (poisoned with CuSO4) were performed. In result the reference item, sodium benzoate, was sufficiently degraded to 89 % after 14 days and to 99 % after 28 days of incubation, thus confirming the suitability of the used aerobic activated sludge inoculum. The oxygen demand of the inoculum control (medium and inoculum) was 15 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline. 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. Thus, there was no need to correct the degradation of the test item and toxicity control.
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 10-day windows began on day 3 after application, the mean value was calculated to be 36 % biodegradation (ThODNO3). Therefore, the end of the 10-day window was day 13. After correction for the mean biochemical oxygen demand of the inoculum controls the mean biodegradation percentage based on ThODNO3 at the end of the 10-day window was 84 %; the criterion of the 10 day window was passed. The mean biodegradation percentage at the end of the 28-day exposure period and after correction for nitrification was 91 % (ThODNO3). If no nitrification is considered, the mean biodegradation was 143 % (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was fulfilled on day 13. The nitrate concentration in the controls after 28 days of incubation was 1.56 mg/L (mean). The nitrate concentration in the test item treated vessels was 20.17 mg/L (mean). Therefore, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 89 % after 28 days.
In conclusion, the degradation rate of the test item, reached 60 % within the 10-day window and after 28 days. Therefore, the test item is considered to be readily biodegradable.

Description of key information

In a Manometric Respirometry Test according to OECD guideline 301 F and EU Method C.4-D the test item was determined to be readily biodegradable within the 10-day-window and after 28 days (91 % based on ThODNO3 and 143 % based on ThODNH4; reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test according to OECD guideline 301 F and EU Method C.4- D over a period of 28 days.

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. Simultaneously, a procedure control (containing the reference item sodium benzoate, 1 replicate), a blank control (containing test medium and inoculum, 2 replicates) and a toxicity control (containing both the test item and the reference item, 1 replicate) and an abiotic control (poisoned with CuSO4) were performed. In result the reference item, sodium benzoate, was sufficiently degraded to 89 % after 14 days and to 99 % after 28 days of incubation, thus confirming the suitability of the used aerobic activated sludge inoculum. The oxygen demand of the inoculum control (medium and inoculum) was 15 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline. 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. Thus, there was no need to correct the degradation of the test item and toxicity control.
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 10-day windows began on day 3 after application, the mean value was calculated to be 36 % biodegradation (ThODNO3). Therefore, the end of the 10-day window was day 13. After correction for the mean biochemical oxygen demand of the inoculum controls the mean biodegradation percentage based on ThODNO3 at the end of the 10-day window was 84 %; the criterion of the 10 day window was passed. The mean biodegradation percentage at the end of the 28-day exposure period and after correction for nitrification was 91 % (ThODNO3). If no nitrification is considered, the mean biodegradation was 143 % (ThODNH4) after 28 days of incubation. The criterion of the 10 day window was fulfilled on day 13. The nitrate concentration in the controls after 28 days of incubation was 1.56 mg/L (mean). The nitrate concentration in the test item treated vessels was 20.17 mg/L (mean). Therefore, a nitrification occurred. In the case of a nitrification, or transformation of ammonium to nitrate the degradation of the test item was 89 % after 28 days.
In conclusion, the degradation rate of the test item reached 60 % within the 10-day window and after 28 days. Therefore, the test item is considered to be readily biodegradable.