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Environmental fate & pathways

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Description of key information

The composition of the registration substance has been updated (September 2020) from multiconstituent to UVCB. The change in composition means that changes to the chemical safety assessment are required. These changes are in progress but not included in the current dossier update.

The substance as currently assessed is a complex multi-constituent substance containing four constituent groups. The constituents of the submission substance are expected to hydrolyse rapidly in contact with water to form methylsilanetriol (Silanol HP-X), 5-oxa-9-aza-1,13-disilatridecane-1,1,1,7,13,13,13-heptol (Silanol HP-Y), 3-aminopropylsilanetriol (Silanol HP-Z), ethanol and/or methanol with an expected hydrolysis half-life of less than 12 hours at pH 7 and 20-25°C. Therefore, the environmental hazard assessment, including sediment and soil compartments due to water and moisture being present, is based on the properties of the silanol hydrolysis products in accordance with REACH guidance for Chemical Safety Assessment (Chapter R.16).

 

Methylsilanetriol (Silanol HP-X), 5-oxa-9-aza-1,13-disilatridecane-1,1,1,7,13,13,13-heptol (Silanol HP-Y) and (3-aminopropyl)silanetriol (Silanol HP-Z) are the final products of hydrolysis reactions under conditions of a hydrolysis laboratory study, and are the hydrolysis product relevant to conventional REACH Chemical Safety Assessment. However, other biotic or abiotic reactions may occur over longer time-scales in the environment.

 

Reference:

ECHA (2016). REACH Guidance on Information Requirements and Chemical Safety Assessment Chapter R16: Environmental Exposure Assessment Version: 3.0. February 2016

Additional information