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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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 model (implemented in EUSES 2.1.2), see table below. Due to the moderate to slow rate of hydrolysis of the parent substance, the distribution calculation is done for the registration substance and its silanol hydrolysis product.


 


The distribution in a sewage treatment plant (STP) has been estimated using the SimpleTreat model (implemented in EUSES 2.1.2), see table below. Due to the moderate to slow rate of hydrolysis of the parent substance, the is done for both the registration substance and its silanol hydrolysis product. For environmental exposure assessment, the distribution in the STP of the silanol hydrolysis product has been set to that of the parent due to the hydrolysis half-life of the substance.


 


Table. Distribution modelling for STP




































 



4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane, CAS 56706-10-6; EC No. 260-350-7



Silanol HP



 



Fraction of emission directed to water by STP



4.57



100



[%]



Fraction of emission directed to air by STP



84.42



1.73E-15



[%]



Fraction of emission directed to sludge by STP



11.01



3.25E-05



[%]



Fraction of the emission degraded in STP



0



0



[%]



 


4,4,13,13-Tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane (S2) hydrolyses at a moderate rate in contact with water to form (3-{[3-(trihydroxysilyl)propyl]disulfanyl}propyl)silanetriol and ethanol. S2 is not expected to undergo any significant biodegradation, is predicted to have very high Henry’s Law constant and high log Kow/log Koc. Therefore, air is the main compartment to which it is expected to partition in a sewage treatment plant.


 


4,4,13,13-Tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane hydrolyses to give the corresponding silanetriol and ethanol. The hydrolysis half-life is >40 hours at 20-25°C. The hydrolysis half-life is such that the initial release to the environment will be as parent substance but subsequent exposure to the hydrolysis product could also occur. It is therefore necessary to consider the environmental exposure to both the parent and hydrolysis products. As the initial release to the STP will be as parent it is relevant to use the same removal and distribution in the STP as the parent for the hydrolysis product. This assumes that the majority of the hydrolysis of the parent to the silanol occurs after the STP and ensures that the correct fractions to water and sewage sludge are estimated.