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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Results from all predictions using BIOWIN   showed the substances except isobutane to be  readily biodegradable.  Isobutane, although not readily biodegradable was shown to biodegrade.  Therefore streams within this Category  are expected to degrade rapidly.

Key value for chemical safety assessment

Additional information

As the member streams within this Category 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 this Category is an appropriate technique to use as part of a weight of evidence approach. But-1 -ene, Isobutene and Butane were all shown to be readily biodegradable. Isobutane was deemed not readily biodegradable due to having a Biowin5 (MITI Linear model) of 0.4898 and Biowin 7 (anaerobic linear) of 0.4315. However Biowin 2 (non-linear model), Biowin 3 (ultimate biodegradation time) and Biowin 6 (MITI non-linear model) were all above the readily biodegradable threshold for the PBT Assessment. Based on weight of evidence it is considered that this Category would be classed as readily biodegradable.