Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Abiotic degradation

Trimethoxy(octyl)silane is expected to hydrolyse rapidly (half-life at 20-25°C approximately 4 h at pH 7, 0.2 at pH 4 and 0.1 at pH 9; see Section 4.1.1.1). A half-life of 1.3 days for reaction with hydroxyl radicals in air has been calculated for trimethoxy(octyl)silane.

The hydrolysis products are expected to be octylsilanetriol and methanol. A half-life of 0.8 days for reaction with hydroxyl radicals in air has been calculated for octylsilanetriol.

Biotic degradation

Based on read-across from an analogous substance, no significant biodegradation of the silanol hydrolysis product, octylsilanetriol, is expected.

The chemical safety assessment indicates that it is not necessary to obtain further information on biodegradation via simulation tests in water, sediment or soil.

Table 4.1.5 Degradation rates

Degradation rate in water:

Hydrolysis half-life: approximately 4 h at 20-25°C (predicted). No significant biodegradation expected for the silanol hydrolysis product.

Degradation rate in sediment:

Hydrolysis may occur (hydrolysis half-life in water approximately 4 h at 20-25°C (predicted)). No significant biodegradation expected for the silanol hydrolysis product.

Degradation rate in soil:

Hydrolysis may occur (hydrolysis half-life in water approximately 4 h at 20-25°C (predicted)). No significant biodegradation expected for the silanol hydrolysis product.

Degradation rate in air:

Half-life for reaction with hydroxyl radicals in air of the parent substance: 1.3 days (calculated).

Half-life for reaction with hydroxyl radicals in air of silanol hydrolysis product: 0.8 days (calculated).