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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 tris(2-methoxyethoxy)vinylsilane. The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance itself and its hydrolysis products. Tris(2-methoxyethoxy)vinylsilane is a moisture-sensitive, volatile liquid that hydrolyses in contact with water (half-life ca. 1 hour at pH 7), generating 2-methoxyethanol (ethylene glycol) and vinylsilanetriol. Human exposure can occur via the inhalation or dermal routes. Relevant inhalation and dermal exposure would be to the parent substance and hydrolysis products.

Absorption

Oral: Significant oral exposure is not expected for this substance.

Dermal: Dermal exposure would be to the parent and hydrolysis products. The molecular weights of tris(2-methoxyethoxy)vinylsilane and vinylsilanetriol are not ideal for dermal absorption, but they would not preclude it. The predicted water solubility (7.1E+4 mg/l) and predicted log Kow (0.26) of tris(2-methoxyethoxy)vinylsilane suggest that the amount of this parent substance that crosses the stratum corneum is very limited. The hydrolysis product has a high water solubility (1.0E+6 mg/l), and a log Kow of -2.0 and it is therefore not likely to be sufficiently lipophilic to cross the stratum corneum and therefore dermal absorption into the blood is likely to be low. There were no adverse systemic effects in dermal toxicity studies, and therefore no evidence of absorption.

Inhalation: The water solubility and log Kow of tris(2-methoxyethoxy)vinylsilane suggest that it will be dissolved in the mucous of the respiratory tract lining, but the log Kow is optimal for absorption, so it could be passively absorbed from the mucous. The hydrolysis product is also likely to be dissolved in mucous, but is significantly less likely to be absorbed. There are no reliable inhalation studies to check for evidence of absorption.

Distribution

The absorbed material is likely to be in the form of the parent and hydrolysis products, but overall is likely to be low. The log Kow of the parent substance means that it 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 likely to be widely distributed in the blood, but the rate at which it diffuses across membranes might limit its distribution. Toxicity studies provide evidence for distribution to the lymphoid tissue.

Metabolism

There are no data on the metabolism of tris(2-methoxyethoxy)vinylsilane. However, it will continue to hydrolyse slowly to form 2-methoxyethanol and vinylsilanetriol once absorbed into the body. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolicactivation.

Excretion

Following dermal exposure, tris(2-methoxyethoxy)vinylsilane and vinylsilanetriol are likely to be sloughed off with skin cells. The high water solubility and low molecular weights of the parent and hydrolysis products mean that, once absorbed, they are likely to be excreted by the kidneys into urine.