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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

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

Key value for chemical safety assessment

Additional information

The biodegradability of 1-methylimidazole (CAS 616-47-7) is assessed based on a weight-of-evidence approach including 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).

 

- In addition, a non-GLP batch test according to OECD 302B was performed to determine the inherent biodegradability of the substance (BASF AG, 1980; entry no. 929). As inoculum industrial activated sludge was used. After 18 d of incubation, the removal was 2%.

 

(Q)SAR data:

Two (Q)SAR models of OASIS CATALOGIC v5.11.19 were applied; the substance was within the parametric and the metabolic domain of both models, but not within the structural domain:

- CATALOGIC Kinetic 301B v.02.09 predicted a degradation of 0.77% after 28 d, based on CO2 evolution.

- CATALOGIC 301C v.09.13 predicted a degradation of 16% after 28 d, based on O2 consumption.

 

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.