Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The results of the QSAR predictions for the butenes category indicate that it is expected to degrade rapidly, with an estimated half life of 2.8 days. These results  indicate that they would not meet the criteria for persistent in the PBT assessment and do not indicate the potential for long term effects in the environment for the classification and labelling assessment.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

As the butenes are gases at standard temperature and pressure, conducting a standard ready biodegradability test is technically difficult,and based on exposure estimates the test may not be relevant. Therefore, the use of a QSAR to predict the biodegradability of the butene category members is an appropriate technique to use a part of a weight of evidence approach. The use of BioHCwin and Biowin is appropriate for the butenes as these compounds clearly fall within the applicability domains of these models as all substructures in butenes category are included in the models. The results from both QSAR indicate that butenes are expected to biodegrade rapidly.

In addition, various researchers have isolated microorganisms that are capable of metabolising but-1-ene (e.g. Hou et al. 1983). Although this study does not follow standard guidelines for ready biodegradability tests they do demonstrate that microorganisms can biodegrade butenes in aerobic conditions. This review adds to the weight of evidence that members of the butenes category can be expected to biodegrade if released to the environment.