1,3-dimethylimidazolidin-2-one

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study carried out in compliance with an internationally recognised guideline

Qualifier:

according to guideline

Guideline:

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

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: Worlingworth STW, sludge sieved (1 mm2)
- Laboratory culture: left to stand for 30 minutes, supernatant removed and remaining sludge aerated until required
- Storage conditions: not specified
- Storage length: not specified
- Preparation of inoculum for exposure: The solids content of the sludge was determined by filtering the sludge through pre-weighed filters, then drying and re-weighing the filters. The appropriate volume of inoculum was added to the control and test vessels to give a final suspended solids concentration of 30 mg/L.
- Initial cell/biomass concentration: 30 mg/L.
- Concentration of sludge:
- Water filtered: yes. Tap water softened and treated by reverse osmosis; nominal resistivity, >= 18 MegOhm.cm.

Duration of test (contact time):

28 d

Initial conc.:

81.5 other: mg/100 mL

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: standard mineral salts medium
- Additional substrate: none
- Solubilising agent: not used
- Test temperature: 21.1 to 22.4°C
- pH: 7.45 and 7.48 at the start of the test and 7.15 and 7.57 at the end.
- pH adjusted: no
- Aeration of dilution water:
- Suspended solids concentration: 30 mg/mL
- Continuous darkness: not specified


TEST SYSTEM
- Culturing apparatus: glass culture bottle
- Number of culture flasks: two for control and main test, one for reference and nitrification inhibition tests
- Method used to create aerobic conditions: magnetic stirrer set to produce a vortex in each test mixture
- Measuring equipment: automated respirometer and associated software
- Details of trap for CO2 and volatile organics if used: 5 mL of 2M potassium hydroxide
-

SAMPLING
- Sampling frequency: daily
- Sampling method: each bottle was fitted with an electrolytic cell assembly (containing the electrolyte, 1M copper sulfate solution, and the CO2 absorber,5 mL of 2M potassium hydroxide) and connected to a respirometer
- Sterility check if applicable: not applicable
- Sample storage before analysis: not applicable


CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated mineral salts medium alone

- Toxicity control: test substance and reference substance (both at 50 mgO2/L) in order to assess the potential inhibitory effects of the test substance on the microbial inoculum.

- Other: As the test substance contained nitrogen, two further mixtures (one blank-control and one mixture containing the test substance) contained an inhibitor of nitrification, allylthiourea (ATU) at, 1.16 g/L. The results of the additional cultures were used to consider the impact of nitrification in the test.

STATISTICAL METHODS: not applicable

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

19 d

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

20 d

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

4

Sampling time:

23 d

Parameter:

% degradation (O2 consumption)

Value:

5

Sampling time:

27 d

Results with reference substance:

The reference substance achieved 62% of the ThOD after 3 days of incubation. The reference substance in the presence of DMI achieved 65% of the ThOD after 3 days of incubation. Levels of oxygen consumption by the controls after 28 days were acceptable for the assay system. These results confirmed that DMI was not inhibitory to the activity of the microbial inoculum and that the test was valid.

Day	% Biodegradation
	DMI (50 mgO2/L)			DMI (50 mgO2/L) in the presence of ATU	Sodium Benzoate (50 mgO2/L)	Sodium benzoate(50 mgO2/L) in the inhibition mixture
	Test 1	Test 2	Mean
1	0	0	0	0	49	49
2	0	0	0	1	55	57
3	0	0	0	1	62	65
4	0	0	0	1	68	-
5	0	0	0	1	73	-
6	0	0	0	1	77	-
7	0	0	0	1	80	-
8	0	0	0	1	81	-
9	0	0	0	1	83	-
10	0	0	0	1	84	-
11	0	0	0	1	86	-
12	0	0	0	2	87	-
13	0	0	0	2	88	-
14	0	0	0	2	88	-
15	0	0	0	1	90	-
16	0	0	0	1	91	-
17	0	0	0	1	92	-
18	0	0	0	2	93	-
19	0	1	1	2	94	-
20	0	3	2	2	95	-
21	0	5	3	3	96	-
22	1	6	3	4	97	-
23	1	7	4	4	97	-
24	1	7	4	4	98	-
25	1	7	4	4	99	-
26	1	8	4	4	100	-
27	1	8	5	4	100	-
28	1	8	5	4	101	-
The data presented were calculated using unrounded values stored in the computer database. Minor numerical differences may be observed if rounded values are used to calculate the data. This minor discrepancy is not considered to be significant.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test substance was not considered to be readily biodegradable under the conditions of this test

Description of key information

The substance is not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

In a test carried out in accordance with OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test), the test substance showed 5% degradation in 28 days and therefore cannot be considered readily biodegradable.