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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: 89% in 28d (EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)). The hydrolysis product vinylsilanetriol is not expected to biodegrade to any significant extent.

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Additional information

Two reliable ready-biodegradation studies are available. The most recent study, conducted according to EU method C4-A, is selected as the key study, and gives a biodegradation result of 89% in 28 days, meeting the 10-day window. The supporting study, conducted according to OECD method 301 B, gives biodegradation rates of 88% (9.93 mg/l initial test substance concentration) and 62% (20 mg/l initial test substance concentration) in 29 days. The 10 day window was met at the lower test concentration but not at the higher test concentration.

Tris(2-methoxyethoxy)vinylsilane hydrolyses rapidly (half-life62 min at pH 7 and 25°C) to vinylsilanetriol and 2 -methoxyethanol. The results from the biodegradation studies are likely to represent biodegradation of 2-methoxyethanol, which is expected to biodegrade rapidly, and makes constitutes 9 out of the 11 carbons in the parent molecule, rather than ofvinylsilanetriol, which is not expected to biodegrade to any significant extent.

This 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 (Data gap filling report for ready biodegradability of silicon-dominated substances PFA.151.004.022A).