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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 tetramethylsilane. The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance. Tetramethylsilane is an extremely volatile liquid (predicted vapour pressure of 64,589 Pa). Human exposure can occur via the inhalation or dermal routes.

Absorption

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

Dermal: The molecular weight of tetramethylsilane would allow dermal absorption. However, the predicted water solubility (33 mg/l) and predicted log Kow(4.2) suggest that the dermal absorption will be low. The total absorption is likely to be further reduced because tetramethylsilane is a highly volatile liquid, and when applied to the skin surface the majority is expected to evaporate. There were no systemic effects in an acute dermal toxicity study and skin irritation study that could provide evidence of absorption.

Inhalation: The high volatility of tetramethylsilane suggests that most of an inhaled dose will be exhaled without crossing the respiratory tract epithelium. The water solubility and log Kow of tetramethylsilane suggest that any test substance that is available for absorption might be absorbed by micellar solubilisation. Inhalation studies show only very minor adverse effects as evidence of systemic availability. 

Distribution

Very little tetramethylsilane is likely to be systemically available. The log Kow of tetramethylsilane means that, if absorbed, it is likely to distribute into cells and the intracellular concentration might be higher than the extracellular concentration particularly in fatty tissues. Toxicity studies do not provide strong evidence for distribution as very few effects were observed.

Metabolism

There are no data on the metabolism of tetramethylsilane. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolic activation.

Excretion

Following inhalation exposure the majority of tetramethylsilane is likely to be exhaled. Some dermally applied tetramethylsilane might be sloughed off with skin cells. The water solubility and molecular weight of this substance suggest that once absorbed, they are likely to be excreted by the kidneys into urine.