1-methylimidazole

Biodegradation in water: screening tests

Description of key information

Not readily biodegradable (according to OECD criteria) but inherently biodegradable after a prolonged test duration.

Additional information

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and, therefore, the endpoint(s) sufficiently covered and suitable for risk assessment.

 

Assessment:

The biodegradability of 1-methylimidazole (CAS 616-47-7) is assessed based on experimental and estimated data.

 

Experimental data:

- In a GLP compliant CO2/DOC-combination test performed according to International Standard ISO 9439 (Annex D) the biodegradation was studied under enhanced test conditions applying a prolonged test duration of 60 days (BASF SE, 2011; report no. 29G0492/11G077). Non-adapted domestic activated sludge was used as inoculum. Based on CO2-production, an elimination of 18% was observed after 28 d of exposure. The substance revealed a long lag-phase within the test up to approx. 24 days. After 35 d, degradation was > 60%. The final degradation value was 79% after 60 d. However, elimination based on DOC was higher than based on CO2 evolution. After 28 d the DOC removal was 46% (35 d: 98%). Therefore, 1-methylimidazole was found to be not readily biodegradable according to OECD criteria but inherently biodegradable after prolonged test duration.

- Furthermore, the substance turned out to be not readily biodegradable (according to OECD criteria) in a GLP guideline study according to OECD 301 F. The oxygen consumption was measured to be in the range of 0 to 10 % after 28 days (BASF AG, 2000; report no. 00/0336/26/1). The inoculum was a mixture of municipal and industrial activated sludge (1:1).

 - Additionally, in a GLP study conducted according to OECD Guideline 310 the required pass level for ready biodegradability was not reached. 2 ±2% TIC/TOC (mean ±SD) based on the mean value of the maximum level of degradation observed at the end of the test. No ten-day window was observed during the study. Therefore, 1 -methylimidazole was not readily biodegradable under the conditions of this test over the

28-day exposure to domestic non-adapted activated sludge.

(Q)SAR data:

To support the experimaental data the (Q)SAR model of OASIS CATALOGIC v5.14.1.5, 301C v11.16 was applied; the substance was within the parametric and the metabolic domain of the model, but not entirely within the structural domain (the substance is to 67% within the structural fragments domain, 33% of fragments are not present in the set of training chemicals).

- CATALOGIC 301C v11.16 predicted a degradation of 10% after 28 d, based on O2 consumption.

 

Predicted metabolites:

Table: QSAR prediction for CAS 616-47-7 (1-methylimidazole) using CATALOGIC 301C v11.16 (OASIS CATALOGIC v5.14.1.5; metabolites with a quantity > 0.001 mol/mol parent after 28 d are highlighted by grey background and bold type; metabolite no: according to (Q)SAR model Catalogic v11.16)

#	Metabolite (No)	Smiles	CAS-#	Name	Quantity (mol/mol parent)	LogKow	BOD prediction (% after 28 d)	PBT-Assessment (ECHA (disseminated substances)
parent	1	CN1C=CN=C1	616-47-7	1-Methylimidazole	0.6153	0.6059	10	not PBT / vPvB
1	3	CN1C=NCC1=O	184590-87-2	1H-Imidazol-5-ol, 1-methyl-	0.1689	-0.7281	3	not listed
2	9	CN(CO)C=N	-	-	0.1055	-1.6131	26	not listed
3	7	CN1CC(=O)N=C1	184590-85-0	1H-Imidazol-4-ol, 1-methyl-	0.02631	-1.3631	37	not listed
4	23	OCN1C=CN=C1	51505-76-1	1H-Imidazol-1-ylmethanol	0.0259	-0.3095	10	not listed
5	4	OCN1C=NCC1=O	-	-	0.01283	-2.1929	2	not listed
6	16	CN	74-89-5	Methanamine	0.004689	-0.6385	64	not PBT / vPvB
7	22	N=CNCO	-	N-(Hydroxymethyl)imidoformamid	0.002048	-1.8243	86	not listed
8	19	CNC=N	57500-38-6	Methanimidamide, N-methyl-	0.002048	-0.3595	78	not listed
9	13	CNCO	3400-38-2	(Methylamino)methanol	0.002048	-1.6374	77	not listed
10	25	CN1CNC=C1	-	-	0.0007803	-1.2939	71	n.a.
11	26	CN(C=C=O)C=N	-	-	0.0007803	-1.582	86	n.a.
12	5	OCNC=NCC(O)=O	-	-	0.0001228	-3.2227	77	n.a.
13	2	CN1C=NC=C1O	-	-	0	0.8757	3	n.a.
14	6	CN1C=C(O)N=C1	-	-	0	0.8757	37	n.a.
15	18	NCO	-	-	0	-2.1033	100	n.a.
16	21	C=N	-	-	0	0.7191	100	n.a.
17	20	NC=N	-	-	0	-0.8254	100	n.a.
18	14	OC=O	-	-	0	-0.4605	100	n.a.
19	10	N=C=O	-	-	0	0.239	100	n.a.
20	17	C=O	-	-	0	0.35	100	n.a.
21	24	OCN1C=NC=C1O	-	-	0	-0.0397	2	n.a.
22	8	CN(CO)C=NC(O)=O	-	-	0	-2.3026	26	n.a.

 

 

n.a.– not assessed. Metabolites with a quantity < 0.001 mol/mol parent after 28 d are not considered being relevant for the PBT/vPvB assessment and, therefore their PBT/vPvB status was not assessed.

 

Overall predicted metabolites: 22 metabolites

9 metabolites: quantity > 0.001; thereof: 4 readily biodegradable (BOD > 60%). 9 metabolites have a log Kow < 3 indicating no significant accumulation in organisms.

 

 

Conclusion:

Based on the available experimental and estimated results, 1-methylimidazole (CAS 616-47-7) is assessed to be not readily biodegradable (according to OECD criteria) but inherently biodegradable after a prolonged test duration.