Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

[2-(Perfluorohexyl)ethyl]triethoxysilane will hydrolyse in water under dilute conditions, half-lives of 1.44 h at pH 4, 12.5 h at pH 7 and 5.18 h at pH 9 and 20°C to form [2-(perfluorohexyl)ethyl]silanetriol and ethanol with a hydrolysis half-life of greater than 12 hours but less than 48 hours. Therefore, the environmental hazard assessment for the aquatic compartment, including waste water treatment plant, is based on the properties of the parent substance in accordance with REACH guidance for Chemical Safety Assessment (Chapter R.16). In addition, based on the properties of the parent substance, environmental hazard assessment for the soil compartment is also performed for the parent substance. This is appropriate because the limit of solubility is extremely low and it cannot be assumed that undissolved substance present during the WWTP transit would be hydrolysed to the extent anticipated by the measured half-life. A desorption of unreacted parent substance to WWTP sludge is therefore considered to be a possibility.

Since the hydrolysis half-life of the parent substance is between 12 and 48 hours at pH 7, environmental hazard assessment for the sediment and soil compartments is also conducted for the silanol hydrolysis product.

[2-(Perfluorohexyl)ethyl]silanetriol is the final product of hydrolysis reactions under conditions of a hydrolysis laboratory study. 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