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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Biodegradation in water, screening tests: No significant biodegradation expected.

Key value for chemical safety assessment

Additional information

A reliable study conducted according to an appropriate test protocol (OECD 310), and in compliance with GLP is available for trimethylsilanol, which is a close structural analogue of methylsilanetriol. This is selected as the key study.

Reaction mass of potassium methylsiliconate is a multi-constituent substance containing methylsilanetriolate, dimers and trimers of methylsilanetriolate, and potassium hydroxide. The substance hydrolyses quickly in contact with water resulting in an aqueous alkaline solution. As the pH is lowered, polymerisation occurs. Under comparable conditions of concentration and pH methylsilanetriolate is equivalent to the parent acid, methylsilanetriol. The dimers and trimers (and any higher molecular weight oligomers and polymers formed) are expected to be less biodegradable than the monomer. Therefore, read-across from trimethylsilanol, which is a close structural analogue of methylsilanetriol, is appropriate.

The use of such read-across is supported by evidence that within a category of small molecule silicon-dominated organosilicon compounds, without reactive functional groups in the side chain, there is no evidence of any significant biodegradation in ready biodegradation tests (Wilmot and Fisk (2013), Biodegradation: Main analogue group, PFA.300.005.007).