Registration Dossier
Registration Dossier
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EC number: 242-560-0 | CAS number: 18765-38-3
Endpoint summary
Administrative data
Description of key information
Additional information
The substance hydrolyses to monosilicic acid and 2 -butoxyethanol with a hydrolysis half-life of less than 12 hours.Therefore, the environmental hazard assessment, including sediment and soil compartments due to water and moisture being present, is based on the properties of the hydrolysis products in accordance with REACH guidance for Chemical Safety Assessment.
Monosilicic acid is the final product of hydrolysis reactions under conditions of a hydrolysis laboratory study, and is the silicon-containing hydrolysis product relevant to conventional REACH Chemical Safety Assessment. However, other biotic or abiotic reactions may occur over longer time-scales in the environment.
At concentrations above about 100-150 mg/l (measured as SiO2 equivalents), condensation products of monosilicic acid can also form. At concentrations >100-150 mg/l of SiO2, monomeric monosilicic acid condenses into colloidal particles of polysilicic acid (silica sol) or a highly cross-linked network (silica gel). The condensation rate is dependent on temperature, concentration, and acidity/alkalinity (as in the pH) of the system. A dynamic equilibrium is established between monomeric monosilicic acid, oligomers and insoluble amorphous polysilicic acid. The composition of a solution is dependent upon conditions such as pH, temperature and the presence of ions. The term "(Poly)silicic acid" is used in this dossier to indicate a mixture of monosilicic acid, its oligomers and amorphous polysilicic acid in dynamic equilibrium.
Monosilicic acid and its condensation products are naturally occurring inorganic substances that are ubiquitous in the environment and are expected to enter natural biogeochemical cycles in the environment. Monosilicic acid, oligomeric and polysilicic acids are therefore not expected to be harmful to organisms present in the environment, as confirmed by the available data. Therefore, it is not appropriate to calculate Predicted Environmental Concentrations (PECs) for the hydrolysis product monosilicic acid.
2 -Butoxyethanol is well-characterised in the public domain literature. 2 -Butoxyethanol does have the potential to cause harm at high dose levels and therefore the hazard assessment will be based on the properties of 2-butoxyethanol.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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