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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The substance has been found to be neither readily nor inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The two studies for ready biodegradability and one study for the inherent biodegradability are available.

In an OECD 301E study conducted under GLP, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, CAS 6674-22-2) was found to be 2% degraded after 31 days. These measurements were based DOC removal (BASF AG, 1990, Rep. no.: 01.90/0184). Effluent from laboratory wastewater treatment plants fed with municipal sewage was used as inoculum.

This result is also supported by a ready biodegradability study cited by the Japanese National Institute of Technology and Evaluation (NITE, 2013). The test was conducted according to OECD guideline 301 C (MITI Japan, 2013). The exposure time was 28 days. 0 % degradation of was found concerning TOC removal and 1 % concerning oxygen consumption (BOD / ThOD) was observed. Though no detailed test report is available, all tests from the Japanese authorities are performed according to an OECD guideline and GLP incl. analytics.

According to the (Q)SAR model 301C v09.13 (OASIS Catalogic v5.11.19; BASF SE, 2017) the substance was also not readily biodegradable (0.1% TOC removal). The substance was within the applicability domain of the model.

The (Q)SAR model BIOWIN v4.10 (EPI Suite v4.11; BASF SE, 2017) predicted DBU to be not readily biodegradable (based on BIOWIN 3 and 5). Only models BIOWIN 1, 2 and 6 resulted in fast biodegradability for DBU. The substance is within the applicability domain of all submodels.

In an inherent biodegradability test according to OECD 302B (Zahn-Wellens), the substance was degraded to 19% after 28 days based on DOC (BASF AG, 1990, Rep. no.: 01.90/0184). The 7-day window criterion was not fulfilled and the log phase was longer than 3 days (21 days). Therefore, the substance cannot be considered to be inherently biodegradable.

In conclusion, DBU is neither readily nor inherently biodegradable.