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Description of key information

Key value for chemical safety assessment

Additional information

There are no in vivo data on the toxicokinetics of trichloro(phenyl)silane. The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance itself and its hydrolysis products. Trichloro(phenyl)silane is a moisture-sensitive, volatile liquid that hydrolyses rapidly in contact with water (half-life <1 minute at pH 7), generating HCl and phenylsilanetriol. 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 products do not negate the possibility of absorption across the skin, although they are not ideal. However, the very high water solubility (1E+06 mg/l) and low predicted log Kow(-0.02) of the hydrolysis product, phenylsilanetriol, suggest that it is too hydrophilic to cross the lipid rich stratum corneum. Therefore 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 phenylsilanetriol 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 reliable studies to check for signs of inhalation toxicity.

Distribution

All absorbed material is likely to be in the form of the hydrolysis products, phenylsilanetriol and HCl. The hydrophilic nature of phenylsilanetriol 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

Trichloro(phenyl)silane is rapidly hydrolysed to phenylsilanetriol and HCl 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 phenylsilanetriol. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolic activation for trichloro(phenyl)silane.

Excretion

The low molecular weight and high water solubility of phenylsilanetriol suggest 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.