Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 208-765-4 | CAS number: 541-05-9
Biodegradation in water and sediment: simulation tests
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
The simulation test on ultimate degradation in surface water and sediment and identification of degradation products do not need to be conducted as, in accordance with Column 2 of REACH Annex IX, the chemical safety assessment according to Annex I indicates that this is not necessary
The available evidence regarding biodegradation and persistence of organosilicon compounds is summarised in an attached document (PFA, 2021f). For most organosilicon compounds, little or no degradation is observed in ready biodegradation studies once degradation of any readily biodegradable hydrolysis by-product is accounted for. This is supported by a small number of simulation studies that show limited biodegradation. Therefore, most organosilicon compounds either meet the criteria for persistence or produce transformation products that may meet the criteria for persistence based on currently available data.
The registered substance is ‘not readily biodegradable’ based on a reliable study. The registration substances hydrolyses with a half-life of 23 min at pH 7 and 25°C, to form the intermediate hydrolysis products, 1,1,3,3,5,5-hexamethyltrisiloxane-1,5-diol (CAS 3663-50-1; EC No. 222-920-3; L3-diol) and 1,1,3,3-tetramethyldisiloxane-1,3-diol (CAS 1118-15-6; EC No. 214-258-9; L2-diol). The half-life for the hydrolysis of the L3-diol and L2-diol is approximately 200 hours at pH 7 and 25°C; the final hydrolysis product is dimethylsilanediol (DMSD, CAS 1066-42-8; EC No. 213-915-7).
The exposure assessment and risk characterisation is carried out for the silanol hydrolysis products of the substance on the basis that they are not biodegradable; risk characterisation ratios are below 1. Therefore, further testing for biodegradation would not affect the outcome of the environmental risk characterisation.
Since degradation of the registration substance is expected to be principally via abiotic transformation under the aqueous conditions of a degradation simulation study, the transformation products expected in the environment are those identified in the abiotic degradation study in Section 5.1.2 of the IUCLID.
Reference:
PFA (2021f) Background to persistence assessment of organosilicon compounds, Report number: PFA.923.001.001. Report date: Feb 25, 2021
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
