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EC number: 219-137-4 | CAS number: 2370-88-9
Due to the rapid hydrolysis of the substance, the chemical safely assessment is based on the silanol hydrolysis product methylsilanetriol.
Testing for long-term toxicity to fish is not considered necessary because:
The final silanol hydrolysis product, methylsilanetriol, is highly water-soluble, has low bioavailability (based on log Kow <3 (-2.4 at 20°C, QSAR)) and there is no reason to expect any specific mechanism of toxicity beyond narcosis. Therefore, the occurrence of toxic effects that were not expressed in the existing short-term aquatic studies, read across from a structural analogue with the same silanol hydrolysis product, would be considered unlikely.
Based on the short-term aquatic data set, no effects were seen in any trophic level. Long-term testing with methylsilanetriol has been carried out with Daphnia at concentrations up to 10 mg/l. No effects were observed. An algal NOEC of ≥500 mg/l has also been determined, which is equivalent to ≥264 mg/l when expressed in terms of the hydrolysis product, methylsilanetriol.
The hydrolysis product of the registration substance and the substances used for read-across are part of a class of low functionality compounds acting via a non-polar narcosis mechanism of toxicity, and as such log Kow drives toxicity. It is therefore expected that fish will not be any more sensitive than invertebrates or algae. As no long-term toxic effects were expressed in these organisms, or short-term effects in any of the test organisms, a long-term fish toxicity test is not necessary.
Aquatic PNECs have not been derived due to the high water solubility and low log Kow of the hydrolysis product of the registration substance, and absence of effects when structural analogues have been tested at high concentrations. Overall it is concluded that no hazard is identified and therefore further in vivo testing is not considered necessary or justified on ethical grounds.
Details on PNEC derivation and risk can be found in IUCLID Section 6.0 and Chapters 9 and 10 of the Chemical Safety Report, respectively.
In addition, the substance is only used in industrial settings in closed systems under controlled conditions and emissions to surface waters are unlikely. Therefore, further studies are not scientifically justified.
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.
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