Registration Dossier
Registration Dossier
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EC number: 295-405-4 | CAS number: 92045-23-3 A complex combination of hydrocarbons produced by the distillation of the products of a steam cracking process. It consists predominantly of hydrocarbons having a carbon number of C4, predominantly 1-butene and 2-butene, containing also butane and isobutene and boiling in the range of approximately minus 12°C to 5°C (10.4°F to 41°F).
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key 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 for this endpoint.
As the category is made up of C4 hydrocarbons, representative hydrocarbon C4 substances butane (CAS no. 106-97-8), isobutane (CAS No. 75-28-5), isobutene (CAS No. 115 -11 -7) and but-1 -ene (CAS No. 106-98-9) have been used as read-across. 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.
Based on the available data, it is considered that this Category would be classed as readily biodegradable.
Key value for chemical safety assessment
- Biodegradation in water:
- readily biodegradable
Additional information
But-1-ene, Isobutene and Butane were all shown to be readily biodegradable. Isobutane was deemed not readily biodegradable due to having a Biowin 5 (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 screening criteria for Persistence in the PBTAssessment. In addition, asecond model (BioHCWin v1.01) predicts that isobutene, but-1-ene, isobutane and butane will biodegrade rapidly with a half life of between 1.9 and 3.5 days.
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