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EC number: 217-983-9
CAS number: 2031-67-6
No studies are available. Based on molecular structure, molecular
weight, water solubility, and octanol-water partition coefficient it can
be expected that the submission substance is likely to be absorbed via
the inhalation route rather than the oral and dermal routes. Hydrolysis
occurs rapidly, and the physico-chemical parameters of the hydrolysis
product suggest that absorption is likely to be decreased afterwards.
However, if absorption occurs, systemic exposure is expected to both the
parent substance and the hydrolysis product. Based on the water
solubility, the registered substance and its silanol-containig
hydrolysis product are likely to be distributed in the body, and
excretion via the renal pathway can be expected. Bioaccumulation is not
There are no
studies available in which the toxicokinetic properties of
triethoxy(methyl)silane have been investigated. Therefore, the
toxicokinetic behaviour assessment of the substance and its hydrolysis
product was assessed from its physico-chemical properties and the
available toxicology studies on the substance itself.
hydrolyses in contact with water (half-life is 5.5 hour at pH 7 and
20°C), generating ethanol and methylsilanetriol. This suggests that
systemic exposure to both the parent, triethoxy(methyl)silane, and to
the hydrolysis product, methylsilanetriol, is possible. Hence, this
toxicokinetic behaviour assessment will try to predict the behaviour of
both these substances. The toxicokinetics of ethanol is discussed
elsewhere and is not included in this summary.
weight and the predicted water solubility of triethoxy(methyl)silane are
178.30 g/mol and 2900 mg/L, respectively. In contrast, the molecular
weight and predicted water solubility of the hydrolysis product,
methylsilanetriol, are 94.142 g/mol and 1E+06 mg/L, respectively. This
shows that the hydrolysis product is smaller in size and is more water
soluble and, thereby, suggests that it will have greater potential to be
absorbed through biological membranes than the parent substance.
However, the predicted log Kow values of 2.2 for the parent
substance and -2.4 for the hydrolysis product indicate that the
hydrolysis product, unlike the parent, is not lipophilic enough to
efficiently pass through biological membranes by passive diffusion.
an acute oral limit test with triethoxy(methyl)silane, there was no
mortality or marked systemic effect in rats at 2007 mg/kg bw, therefore,
showing the substance to be of low toxicity and/or having low potential
to be absorbed by the oral route. If
ingestion occurs, the hydrolysis of the parent substance in the low pH
of the stomach will be rapid, so any absorption of the parent substance
is expected to be minimal and it is more likely to be the hydrolysis
product that is absorbed.
water solubility (2900 mg/L) of the parent and the hydrolysis product
(1E+06 mg/L) suggests that both substances will readily dissolve in the
gastrointestinal fluids. Also, the low molecular weight (≤ 178 g/mol) of
the substances suggests they will have the potential to pass through
aqueous pores or be carried through the epithelial barrier by the bulk
passage of water. However, the moderate log Kow value of 2.2
for the parent versus -2.4 for the hydrolysis product suggests that the
parent substance is more likely to be absorbed by passive diffusion than
the hydrolysis product. Therefore, once hydrolysis has occurred, the
level of absorption is likely to decrease.
acute inhalation study with triethoxy(methyl)silane showed signs of
systemic toxicity; therefore,
indicating that absorption via the inhalation route is possible for the
registered substance. Also, the predicted vapour pressure of the parent
substance (100 Pa) is indicative that inhalation of the registered
substance as a vapour could occur.
moderate water solubility (2900 mg/L) and log Kow (2.2) of
the parent substance suggest that absorption from the respiratory tract
epithelium by passive diffusion is likely. However, the high water
solubility (1E+06 mg/L) and low log Kow (-2.4) of the
hydrolysis product, methylsilanetriol, suggest that it will be retained
in the mucous of the lungs. Once hydrolysis has occurred, the level of
absorption is likely to decrease. Particles deposited on the mucociliary
blanket will be elevated into the laryngeal region and ultimately be
moderate water solubility (2900 mg/L) and log Kow (2.2) of
the parent substance suggest that absorption via the dermal route is
possible. For the hydrolysis product, methylsilanetriol, the high water
solubility (1E+06 mg/L) and the low log Kow value (-2.4)
suggest that the substance may be too hydrophilic to cross the lipid
rich environment of the stratum corneum; however, the molecular weight
of less than 100 g/mol may favour some dermal uptake. QSAR-based dermal
permeability prediction (DERWIN V2.00.2009) using molecular weight, log
Kow and water solubility, calculated a dermal penetration rate of
0.00167 mg/cm²/h for triethoxy(methyl) silane and 0.01004 mg/cm²/h for
methylsilanetriol, respectively. This shows that dermal penetration of
the parent substance and of the hydrolysis product will be very low and
low, respectively. The low dermal absorption and/or toxicity potential
is also confirmed in an acute dermal limit test with triethoxy(methyl)
silane, where no mortality or marked systemic effect in rats were seen
at 2007 mg/kg bw.
For blood: tissue
partitioning a QSPR algorithm has been developed by De Jongh et al.
(1997) in which the distribution of compound 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.
Using this value for triethoxy(methyl)silane predicts that it will
distribute into the main body compartments as follows: fat >> liver >
brain > muscle > kidney with tissue: blood partition coefficients of 78
for fat and 2.8 to 1.7 for the remaining tissues. For the hydrolysis
product, distribution would be approximately equal to liver, muscle,
brain and kidney and about 800-fold lower to fat. In comparison to the
parent product, distribution would be approximately 5-fold lower into
blood partition coefficients
hydrolyses rapidly in contact with water (half-life is 5.5 hour at pH 7
and 20°C), generating ethanol and methylsilanetriol. There are no data
regarding the enzymatic metabolism of triethoxy(methyl)silane or
methylsilanetriol. Genetic toxicity tests in vitro showed no observable
difference in effects with and without metabolic activation for
low molecular weight and high water solubility of the parent and
hydrolysis product suggest that they are likely to be excreted by the
kidneys into urine.
Oral absorption – not expected for
Dermal absorption - triethoxy(methyl)silane >
Inhaled absorption – triethoxy(methyl)silane > methylsilanetriol
Distribution – triethoxy(methyl)silanefat >> liver > brain >
muscle > kidney
Distribution – methylsilanetriol kidney > muscle ≈ brain > liver > fat
Distribution triethoxy(methyl)silane 5- fold greater than
Metabolism – no data
Excretion via urine – minimal for
triethoxyl(methyl)silane, significant for methylsilanetriol
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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