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Environmental fate & pathways

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The substance hydrolyses very rapidly to give silanetriol and HCl. The Si-H bonds of trichlorosilane also react in water (assumed half-life <12 hours at pH 7 and 25°C) to produce hydrogen and monosilicic acid. Both silanetriol and monosilicic acid exist only in dilute aqueous solutions and readily condense at concentrations above approximately 100-150 mg/L as SiO2 to give a dynamic equilibrium between monomer, oligomers and insoluble amorphous polysilicic acid.

These hydrolysis products are inorganic substances which enter natural biogeochemical cycles. Monosilicic acid and its condensation products are ubiquitous in the environment.

A comparison of the total flux of dissolved silica into rivers can be compared with the input from manufacture and use of trichlorosilane, and indicates that the input is considered negligible in comparison with the natural flux of silica/silicic acid in the environment.

Therefore, it is not appropriate to calculate Predicted Environmental Concentrations (PECs) for the hydrolysis product monosilicic acid.

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