Registration Dossier
Registration Dossier
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EC number: 404-370-8 | CAS number: 126990-35-0 DCPMS; DYNASYLAN 9415; EURENOR 5023; SAN-30; WACKER SILAN CP2-DIMETHOXY; Z-6228
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
There are no in vivo data on the toxicokinetics of dicyclopentyl(dimethoxy)silane (CAS 126990-35-0). The following summary has therefore been prepared mainly based on validated predictions of the physicochemical properties of the substance itself and its silanol hydrolysis product. Dicyclopentyl(dimethoxy)silane is a moisture-sensitive liquid that hydrolyses in the presence of water (half-life 19 hours at pH 7; measured), generating methanol and dicyclopentylsilanediol. Human exposure can occur via the inhalation or dermal routes. Relevant inhalation exposure would be to the parent substance.
Absorption
Oral: Significant oral exposure is not expected for this substance.
Dermal: Dermal absorption is unlikely to occur as the predicted log Kow (5.5) and measured water solubility (5.32 mg/l) suggest that the rate of penetration might be limited by the rate of transfer between the stratum corneum and the dermis. Uptake into the stratum corneum is likely to be high. Once hydrolysis has occurred, dermal absorption might increase based on the predicted water solubility (2600 mg/l) and log Kow (3.1) of dicyclopentylsilanediol, which favour dermal absorption. There were no systemic effects, and therefore no evidence of dermal absorption, in the acute dermal toxicity studies.
Inhalation: The measured water solubility (5.32 mg/l) and predicted log Kow (5.5) of the parent substance are favourable for absorption from the respiratory tract epithelium by micellar solubilisation. However, the high water solubility of the hydrolysis product, dicyclopentylsilanediol (2600 mg/l) might lead to some of this hydrolysis product being retained in the mucus of the lungs. Therefore, once hydrolysis has occurred, absorption may slow down. There are no inhalation data.
Distribution
The parent substance is lipophilic, is likely to distribute into cells and the intracellular concentration might be higher than the extracellular concentration, particularly in fatty tissues. The hydrolysis product is not likely to be as widely distributed due to its higher water solubility.
Metabolism
There are no data regarding the metabolism of dicyclopentyl(dimethoxy)silane or its hydrolysis product. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolic activation for dicyclopentyl(dimethoxy)silane.
Excretion
The low molecular weight and high water solubility of the hydrolysis product, dicyclopentylsilanediol, suggest that it is likely to be effectively eliminated via the kidneys in urine. The parent substance however, is predicted to be highly lipophilic and therefore not as readily eliminated from the body.
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