Registration Dossier

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 (3-chloropropyl)triethoxysilane. The following summary has therefore been prepared based on validated predictions of the physicochemical properties of the substance itself and its hydrolysis products. (3-chloropropyl)triethoxysilane is a moisture-sensitive, volatile liquid that hydrolyses slowly in contact with water (half-life 35 hours at pH 7), generating ethanol and 3-chloropropylsilanetriol. Human exposure can occur via the inhalation or dermal routes. Relevant inhalation and dermal exposure would be predominantly to the parent substance. The toxicokinetics of ethanol is discussed elsewhere and is not included in this summary.

Absorption

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

Dermal: Dermal exposure would be to the parent substance. The molecular weight of 3-chloropropyltriethoxysilane is not ideal for dermal absorption, but it would not preclude it. The predicted water solubility (33 mg/l) and predicted log Kow (3.4) of 3-chloropropyltriethoxysilane suggest that this parent substance has the potential to be absorbed quite effectively through the skin. There are no reliable repeated dose toxicity studies to check for signs of systemic availability. There were no signs of systemic toxicity in several skin irritation studies.

Inhalation: The water solubility and log Kow of 3-chloropropyltriethoxysilane suggest that it will be absorbed directly across the respiratory tract lining. There are no inhalation toxicity studies on 3-chloropropyltriethoxysilane to check for signs of systemic availability.

Distribution

The absorbed material is likely to be in the form of the parent substance. 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 with a log Kow of -1.1, uptake into organs and tissues will be limited by its diffusion across membranes. Reliable toxicity studies do not provide evidence for distribution to any particular organ or tissue.

Metabolism

There are no data on the metabolism of 3-chloropropyltriethoxysilane. However, it will hydrolyse gradually to form ethanol and 3-chloropropylsilanetriol once absorbed into the body. Genetic toxicity tests in vitro showed no observable differences in effects with and without metabolic activation.

Excretion

The water solubility and molecular weights of the parent and hydrolysis products (predicted water solubility of 1.0E+6 mg/l) mean that, once absorbed, they are likely to be excreted by the kidneys into urine.