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There are no in vivo data on the toxicokinetics of trichloro(octyl)silane.

The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance itself and its hydrolysis products and using this data in algorithms that are the basis of many computer-based physiologically based pharmacokinetic or toxicokinetic (PBTK) prediction models. The main input variable for the majority of these algorithms is log Kow so by using this, and other where appropriate, known or predicted physicochemical properties of trichloro(octyl)silane or its hydrolysis product, reasonable predictions or statements may be made about their potential ADME properties.

Trichloro(octyl)silane is a moisture-sensitive liquid that hydrolyses very rapidly in contact with water (half-life less than one minute at pH 7; predicted), generating hydrochloric acid and octylsilanetriol. 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 hydrochloric acid hydrolysis product would be severely irritating or corrosive.

Therefore, due to the very rapid hydrolysis of trichloro(octyl)silane, systemic exposure to this parent substance is not expected. Potential systemic exposure to the hydrolysis product, octylsilantriol is discussed below. Potential systemic exposure to the other hydrolysis product, hydrochloric acid, is not discussed.




Significant oral exposure is not expected for this corrosive substance.

However, oral exposure to humans via the environment may be relevant for the hydrolysis product, octylsilanetriol.When oral exposure takes place it is necessary to assume that except for the most extreme of insoluble substances, that uptake through intestinal walls into the blood takes place. Uptake from intestines must be assumed to be possible for all substances that have appreciable solubility in water or lipid. Other mechanisms by which substances can be absorbed in the gastrointestinal tract include the passage of small water-soluble molecules (molecular weight up to around 200) through aqueous pores or carriage of such molecules across membranes with the bulk passage of water (Renwick, 1993).

As octylsilanetriol, with a water solubility of 59000 mg/l and a molecular weight of 192.33, meets both of these criteria, should oral exposure occur it is reasonable to assume systemic exposure will occur also. 


The fat solubility and therefore potential dermal penetration of a substance can be estimated by using the water solubility and log Kow values. Substances with log Kow values between 1 and 4 favour dermal absorption (values between 2 and 3 are optimal) particularly if water solubility is high. Due to the likely very rapid hydrolysis of trichloro(octyl)silane on contact with skin, systemic exposure via this route is predicted to be minimal. However, the predicted water solubility (59000 mg/l) and predicted log Kow (1.1) of the hydrolysis product, octylsilanetriol, are favourable for absorption across the skin so systemic exposure via this route is likely. After or during deposition of a liquid on the skin, evaporation of the substance and dermal absorption occur simultaneously so the vapour pressure of a substance is also relevant. Octylsilanetriol has a very low vapour pressure so evaporation would not affect significantly the potential for dermal absorption.

Since the other hydrolysis product, hydrochloric acid is corrosive to the skin, damage to the skin might increase penetration. There are no dermal studies to check for signs of systemic availability.


There is a QSPR to estimate the blood:air partition coefficient for human subjects as published by Meulenberg and Vijverberg (2000). The resulting algorithm uses the dimensionless Henry coefficient and the octanol:air partition coefficient (Koct:air) as independent variables.

The high water solubility of the hydrolysis product, octylsilanetriol, results in a high blood:air partition coefficient so once hydrolysis has occurred, as it would be expected to in the lungs, then significant uptake would be expected into the systemic circulation. However, the high water solubility of octylsilanetriol may lead to some of it being retained in the mucus of the lungs so once hydrolysis has occurred, absorption is likely to slow down.

As with dermal exposure, damage to membranes caused by the corrosive nature of the hydrochloric acid hydrolysis product might enhance the uptake. There are no reliable studies on the hydrolysis product to check for signs of inhalation toxicity.


For blood:tissue partitioning a QSPR algorithm has been developed by DeJongh et al. (1997) in which the distribution of compounds between blood and human body tissues as a function of water and lipid content of tissues and the n-octanol:water partition coefficient (Kow) is described. For the hydrolysis product, approximately the same proportion would distribute to liver, muscle, brain and kidney, whereas distribution would be 10-fold higher to fat.

Tissue:blood partition coefficients


Log Kow
















Hydrogen and chloride ions will enter the body’s natural homeostatic processes.


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


A determinant of the extent of urinary excretion is the soluble fraction in blood. QPSRs as developed by DeJongh et al. (1997) using log Kow as an input parameter, calculate the solubility in blood based on lipid fractions in the blood assuming that human blood contains 0.7% lipids.

Using this algorithm, the soluble fraction of octylsilanetriol in blood is approximately 92% suggesting it is likely to be effectively eliminated via the kidneys in urine.



DeJongh, J., H.J. Verhaar, and J.L. Hermens, A quantitative property-property relationship (QPPR) approach to estimate in vitro tissue-blood partition coefficients of organic chemicals in rats and humans. Arch Toxicol, 1997. 72(1): p. 17-25.

Renwick A. G. (1993) Data-derived safety factors for the evaluation of food additives and environmental contaminants.Fd. Addit. Contam.10: 275-305.

Meulenberg, C.J. and H.P. Vijverberg, Empirical relations predicting human and rat tissue:air partition coefficients of volatile organic compounds. Toxicol Appl Pharmacol, 2000. 165(3): p. 206-16.