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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Biodegradation rates between 0 - 0.7 % were determined in reliable studies conducted on constituents of GLS-Silane according to appropriate test protocols (OECD 310/301D), and in compliance with GLP. 

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

GLS-Silane is a UVCB comprised of 4 silanes and 4 hydrocarbons. Dichloro(methyl)silane is the most prevalent substance and accounts for >20-<40% w/w of GLS-Silane. Chloro(dimethyl)silane and trichlorosilane make up >10-<20% and >5 -<15% of GLS-Silane respectively.  The silane constituents of GLS-Silane are not biodegradable in water and comprise about 75% of the GLS-Silane. Therefore, GLS-Silane is not predicted to be biodegradable in water. Hydrolysis is expected to be the predominant breakdown pathway for these constituents.No hydrolysis study is available for the GLS-Silane. However, a reliable study equivalent to OECD 111 is available for dichloro(dimethyl)silane. This substance is fully hydrolyzed within a few minutes at pH 4, 7 and 9 and 1.5°C. This is also the case for other chlorosilanes for which measured data are available.


Chlorosilanes in general exhibit rapid hydrolysis due to the size of the silica atom and the nature of the bond. Therefore, the environmental fate properties of the silanols will be discussed as exposure to the environment to the hydrolysis products rather than the parent substance.The environmental properties of HCL will not be discussed as it will be buffered to various extents, dependent on the buffering capacity of different compartments in the environment. The predicted environmental concentrations of HCL indicate that the buffering capacity of the environment is sufficient. At pH 7 it is found as water and the chloride ion, which do not need to be further discussed.

Tetramethylsilane comprises >10 - < 30% of the GLS-Silane and does not undergo hydrolysis. The 4 hydrocarbons (isobutane, butane, chloromethane, and 2 -methylbutane) account for the remaining 0 -16% of GLS-Silane with 2-methylbutane being the predominant hydrocarbon at >3 - <10% w/w. Isobutane, butane, and chloromethane are liquified gases.

As GLS-Silane contains consitutents that hydrolyse to non-biodegradable molecules, it is regarded as being non-biodegradable.