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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 242-171-6 | CAS number: 18293-82-8
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
Short-term toxicity to invertebrates: 48 hr EC50 >864 mg/l (estimated from DOC measured stock solution) (highest concentration tested) (EU Method C.2 (Acute Toxicity for Daphnia)), read-across from an analogous/structurally related substance, isobutyl(trimethoxy)silane (CAS 18395-30-7). The EC50 is equivalent to >660 mg/l when expressed in terms of the silanol hydrolysis product.
Short-term toxicity to invertebrates: 48 hr EC50 295 mg/l (nominal) (EU Method C.2 (Acute Toxicity for Daphnia)), read-across from an analogous/structurally related substance, 3-chloropropyl(diethoxy)methylsilane (CAS 13501-76-3). The EC50 is equivalent to 216 mg/l when expressed in terms of the silanol hydrolysis product.
Key value for chemical safety assessment
Additional information
There are no reliable short-term invertebrate toxicity data available for isobutyl(dimethoxy)methylsilane (CAS 18293-82-8), therefore good quality data for appropriate structural analogues, isobutyl(trimethoxy)silane (CAS 18395-30-7) and 3-chloropropyl(diethoxy)methylsilane (CAS 13501-76-3), have been read across using a weight of evidence approach. The three substances have structurally similar silanol hydrolysis products, isobutyl(methyl)silanediol, (2-methylpropyl)silanetriol and (3-chloropropyl)(methyl)silanediol respectively. The other hydrolysis products are methanol for the registration substance and isobutyl(trimethoxy)silane, and ethanol for 3-chloropropyl(diethoxy)methylsilane.
A 48 h E(L)C50 value of >864 mg/l and NOEC of ≥864 mg/l (estimated from DOC measured stock solution) (highest concentration tested) have been determined for the effects of isobutyl(trimethoxy)silane (CAS 18395-30-7) on mortality of Daphnia magna. In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. The results may be expressed in terms of concentration of the hydrolysis product, (2-methylpropyl)silanetriol, by applying a molecular weight correction: (MW of silanol = 136.22 / MW of parent= 178.31) * >864 = >660 mg/l.
A 48 h E(L)C50 value of 295 mg/l and NOEC of 160 mg/l (nominal) have been determined for the effects of 3-chloropropyl(diethoxy)methylsilane (CAS 13501-76-3) on mortality of Daphnia magna. In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the hydrolysis products of the tested substance. The results may be expressed in terms of concentration of the hydrolysis product, (3-chloropropyl)(methyl)silanediol, by applying a molecular weight correction: (MW of silanol = 154.67 / MW of parent= 210.78) * 295 = 216 mg/l.
The results in terms of (2-methylpropyl)silanetriol and (3-chloropropyl)(methyl)silanediol concentration are read across to isobutyl(methyl)silanediol without further correction.
Refer to the discussion in the Section 6 endpoint summary for further discussion of the approach to chemical safety assessment for this registration substance, and justification for read-across used.
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.
