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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 241-881-3 | CAS number: 17955-88-3
Short-term toxicity to fish
Administrative data
Link to relevant study record(s)
Description of key information
Short-term toxicity to fish: 96hr LC50 >110 mg/l nominal (highest concentration tested (TSCA GUIDELINE 797.1400).
Key value for chemical safety assessment
Additional information
A 96-hour LC50 value >110 mg/l (nominal) (highest concentration tested) has been determined for the effects of 1,1,1,3,5,5,5-heptamethyl-3-octyltrisiloxane on mortality of the freshwater fish Pimephales promelas, in accordance with TSCA Guideline 797.1400.
In view of the test media preparation method/exposure regime it is likely that the test organisms were exposed predominantly to the tested substance.
Test concentrations exceeded the test substance water solubility and undissolved test material and an oily film were observed during the test. However, no adverse effects on the fish were observed, therefore the effect concentration is >LoS (limit of solubility).
Another supporting study has reported a 96-hour LC50 value of >100 mg/l (nominal) (highest concentration tested) for the same test item in a limit test on mortality of the freshwater fish Danio rerio, in accordance with guideline OECD 203.
Supporting data are also read-across from the structural analogue 3-hexyl heptamethyltrisiloxane (CAS 1873-90-1).
No effects were observed in a 96-hour study conducted with Lepomis machrochirus conducted in a saturated solution of 3-hexyl heptamethyltrisiloxane prepared at 1000 ppm. Chemical analysis determined measured concentrations in excess of the solubility limit of the substance in test media (6 μg/l (reported as 6 ppb)). It can therefore be concluded that the 96-hour EC50 value for aquatic invertebrates is >LoS of the test substance.
When the results are expressed using measured concentrations of the saturated solution, a 96-hour EC50 value of >49 μg/l can be determined for the effects of the test substance on mortality of Lepomis machrochirus, based on geometric mean measured concentrations (geometric mean concentrations calculated by the reviewer using the analytical data).
The data should be used with caution because the test solution was cloudy after mixing, settling into a clear solution with a surface film, although no effects were observed.
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.
