Registration Dossier
Registration Dossier
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EC number: 242-053-4 | CAS number: 18169-57-8
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 trichloroisobutylsilane. The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance itself and its hydrolysis products. Trichloroisobutylsilane is a moisture-sensitive, volatile liquid that hydrolyses rapidly in contact with water (half-life <1 minute at pH 7), generating HCl and isobutylsilanetriol. Human exposure can occur via the inhalation or dermal routes. Relevant inhalation exposure would be to the hydrolysis products (hydrolysis would occur rapidly when inhaled, even if a mixture of parent and hydrolysis products were present in air). The substance would also hydrolyse rapidly in contact with moist skin. The resulting HCl hydrolysis product would be severely irritating or corrosive.
Absorption
Oral: Significant oral exposure is not expected for this corrosive substance.
Dermal: The molecular weights of the parent and hydrolysis product, isobutylsilanetriol, are not ideal for dermal absorption, but they would not preclude it. However, the water solubility (1.0E+06 mg/l) and predicted log Kow(-0.96) of the hydrolysis product suggest that dermal uptake is likely to be low. Since the other hydrolysis product, HCl is corrosive to the skin, damage to the skin might increase penetration. There are no reliable studies to check for signs of dermal toxicity.
Inhalation: The high water solubility of isobutylsilanetriol might lead to some of this hydrolysis product being retained in the mucous of the lungs. As with dermal exposure, damage to membranes caused by the corrosive nature of the HCl hydrolysis product might enhance the uptake. There are no inhalation studies to check for signs of absorption.
Distribution
All absorbed material is likely to be in the form of the hydrolysis products, isobutylsilanetriol and hydrogen chloride. With a log Kowof -0.96 and high water solubility, the isobutylsilanetriol molecule is likely to be widely distributed, but its hydrophilic nature will limit its diffusion across membranes (including the blood-brain and blood-testes barriers) and its accumulation in fatty tissues. Hydrogen and chloride ions will enter the body’s natural homeostatic processes.
Metabolism
Trichloroisobutylsilane is rapidly hydrolysed to isobutylsilanetriol and hydrogen chloride in the presence of moisture. Most if not all of this will have occurred before absorption into the body. There are no data regarding the metabolism of isobutylsilanetriol. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolic activation.
Excretion
The high water solubility of isobutylsilanetriol suggests that it is likely to be rapidly eliminated via the kidneys in urine. There is therefore no evidence to suggest that this substance will accumulate in the body.
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