Registration Dossier
Registration Dossier
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EC number: 252-558-1 | CAS number: 35435-21-3
Endpoint summary
Administrative data
Description of key information
Additional information
No terrestrial toxicity data are available for the registration substance. Testing for toxicity to soil organisms is not considered necessary because:
PNECsoil has been calculated from the aquatic data using the Equilibrium Partitioning Method. The risk characterisation ratios (RCR) based on the PNECsoil are <1.
In accordance with Column 2 of REACH Annex IX, there is no need to further investigate the effects of this substance in a terrestrial toxicity to invertebrates/higher plants study because, as indicated in guidance R.7.11.6 (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio (RCR) is below 1, and therefore the risk is already adequately controlled and further testing is not justifiable.
The silanol hydrolysis product is not readily biodegradable but has low potential for bioaccumulation and low bioavailability (based on log Kow <3 (0.9)), and there is no reason to expect any specific mechanism of toxicity beyond narcosis.
Long-term toxicity testing to aquatic invertebrates has been carried out with the registered substance as well as a structural analogue. During these tests, it is likely that organisms were exposed to the hydrolysis products of the test substance. The occurrence of more severe toxic effects in the terrestrial compartment that were not expressed in these aquatic studies (conducted at concentrations up to 100 mg/l) would be considered unlikely.
Overall it is concluded that the risk characterisation conclusion is sufficiently conservative in respect of any uncertainties and therefore further testing is not considered necessary.
Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 and Chapters 9 and 10 of the Chemical Safety Report, respectively.
Long-term aquatic toxicity tests are being conducted in accordance with ECHA Final Decision TPE-D-2114455990-41-01/F. The OECD TG 210 Fish, Early Life-Stage Toxicity test and the OECD TG 211 Daphnia Reproduction test are currently ongoing. The substance dataset and risk assessment will be updated once results of the chronic aquatic studies are available and the studies are finalised. An update is planned to be completed within three months from when the last final report is received. The draft reports are expected in January/February 2021, with the final reports following in March/April 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.
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