Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The distribution in a sewage treatment plant (STP) has been estimated using the SimpleTreat 3.0 model (implemented in EUSES), see table below. Due to the rapid hydrolysis of the parent substance, the distribution calculation is done for the silanol hydrolysis product

Table. Distribution modelling for STP

Assessment entities

dimethylsilanol (Intermediate HP)

dimethylsilanediol (final HP)

Release to water



Release to air



Release to sludge



Release degraded




1,1,3,3-Tetramethyldisiloxane hydrolyses very rapidly (half-life 11.3 minutes at pH 7 and 25°C) to form dimethylsilanol, which further hydrolyses to form the final hydrolysis product, dimethylsilanediol (half-life 2.5 days). Dimethylsilanediol is not expected to undergo any significant biodegradation, has low Henry’s Law constant and low log Kow/log Koc. Therefore water is the main compartment to which it is expected to partition in a sewage treatment plant.