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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption/desorption:

Log Koc for parent substance = 4.7 (QSAR)

Log Koc for silanol hydrolysis product = 2.4 (predicted)

Key value for chemical safety assessment

Koc at 20 °C:
50 120

Additional information

In accordance with Section 2 of REACH Annex XI, the adsorption study does not need to be conducted because it is technically not feasible to conduct the study due to the very low water solubility (predicted water solubility value of 6.4E-06 mg/l at 20°C), which indicates that maintaining stable and measurable aqueous test concentrations will be extremely difficult.

However, the log Koc of the parent substance has been predicted to be 4.7 using a validated QSAR estimation method. The predicted result is used for assessment purposes.

In contact with water, the submission substance hydrolyses moderately to form [2-(perfluorohexyl)ethyl]silanetriol and ethanol.

For environmental exposure assessment, adsorption of [2-(perfluorohexyl)ethyl]silanetriol is predicted using the EU TGD (Technical Guidance Document) ‘non-hydrophobics’ log Kow prediction method (EC, 2003), also referred to in REACH Guidance R7a (ECHA, 2008).

Log Koc= 0.52 log Kow + 1.02

Log Koc for silanol hydrolysis product = 2.4.

[LogKoc: 4.7]