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EC number: 213-650-7
CAS number: 998-30-1
No other studies are availabe.
Result: Exposure to trimethoxy(methyl)silane was not associated with reproductive toxicity. The findings support a NOAEL of 1000 mg/kg/day.
NOAEL (maternal toxicity): 50 mg/kg/day
NOAEL (reproductive toxicity): 1000 mg/kg/day
LOAEL (maternal toxicity): 250 mg/kg bw/day
The one surviving male animal exposed to 5 ppm for 9 days
was observed to have increased testes weight (absolute and relative to
body weight); the relative testes weight (as a percentage of brain
weight) for this one animal was decreased. Interpretation of these
findings must be performed with caution due to the small number of
animals (one) and its moribund condition.
In a IUCLD 2007 summary of an inhalation range-finding study
(reliability score 4) conducted using a protocol similar to OECD 412,
and to GLP, trimethoxysilane vapor at 5 ppm was lethal, with death
probably being a consequence of respiratory tract injury. Based on the
body weights, organ weights, the clinical pathology, and the necropsy
and histopathologic observations, the NOAEL for trimethoxysilane in rats
exposed for 9 days was 0.2 ppm. The reproductive toxicity NOAEL was a
cautious 1 ppm based on effects on testes weight in one surviving animal
at 5 ppm.
Result: There were no test article related effects in any of the reproductive organs at the highest concentration tested (0.51 ppm) after 90 days exposure.
In a good quality 90-day inhalation study
(reliability score 2) conducted in a study comparable to OECD 413 and
GLP, the NOAEL for trimethoxysilane was greater than 0.51 ppm (the
highest dose tested) in rats exposed six hours/day, five days/week,
followed by a four-week recovery period. There were no test
substance-related effects in any of the reproductive organs up to the
highest concentration tested.
No reproductive toxicity studies have been conducted with
trimethoxysilane; this substance is a highly reactive
toxicant, it is unlikely to reach the reproductive organs or
the embryo/fetus and result in toxicity. In repeated dose
toxicity studies, the NOAEL were identified as >0.51 ppm (after
28 or 90 days exposure) and 0.2 ppm (after 9 days exposure).
These repeated dose studies indicated that a maximum
concentration of 0.5 ppm would be required for a
reproduction study in order to avoid death or obvious
suffering due to respiratory damage. The data provided in
the repeated dose toxicity studies indicate a practical and
humane dose range for reproductive toxicity studies is below
the limit of toxicological significance. Furthermore,
trimethoxysilane is a site limited chemical intermediate
that is not transported from the site of manufacture. Trimethoxysilane is produced in closed systems that are hard
piped. Final products generally contain less than 0.001 %,
but may contain up to 0.2% trimethoxysilane.
There are no reliable studies that
investigate the potential for trimethoxysilane to cause adverse effects
on fertility; therefore a reliable oral OECD 422 study on the structural
has been used. In addition there is a 90 day rat inhalation study on trimethoxysilane
that did not show any adverse treatment-related effects on the
reproductive organs up to an exposure concentration of 2.55 mg/m³.
In the OECD 422 study male and female
rats were dosed with 50, 250, and 1000 mg/kg bw/day with
trimethoxy(methyl)silane for up to 29 and 51 days, respectively. No
mortality was observed and no difference in body weight gain was
observed within the treatment and control group animals. No effects on
the reproductive endpoints and no maternal toxicity have been observed.
Gross pathology and organ weight were not assessed in the study. In
conclusion a NOAEL of 1000 mg/kg bw was deduced for both, maternal and
In a good quality 90-day inhalation
study (reliability score 2) conducted in a study comparable to OECD 413
and in compliance with GLP, the NOAEC for trimethoxysilane was greater
than 0.51 ppm (the highest dose tested; 2.55 mg/m³) in rats exposed six
hours/day, five days/week, followed by a four-week recovery period.
There were no test substance-related effects in any of the reproductive
organs up to the highest concentration tested. The repeated dose studies
indicated that a maximum
concentration of 0.5 ppm would be required for a reproduction study
in order to avoid death or obvious suffering due to respiratory damage
(LOAEL in the range-finder was 1 ppm, based on local corrosive
Short description of key information:
No studies have been conducted with triethoxysilane for reproductive
toxicity. Since the 90 day inhalation study tested very low
concentrations of trimethoxysilane, it is appropriate to read-across
from the structural analogue, trimethoxy(methyl)silane, for which there
is an oral OECD 422 study. In this study reproductive effects were not
observed up to a dose of 1000 mg/kg bw/day.
A study similar to a OECD 414 is available for the analogue substance disodium metasilicate (CAS 6834-92-0), where the NOAEL for maternal toxicity was 12.5 mg/kg bw for maternal toxicity and 200 mg/kg bw (highest dose tested) for developmental toxicity.
TOXIC RESPONSE/EFFECTS BY DOSE LEVEL:
- Parental data and F1:
- Body weight: no treatment-related effects were observed in either
mother animals, fetuses delivered by hysterectomy or
- Fertility index:
Dose [mg/kg bw/d] pregnancies/mated female % pregnancies
0 (control) 20/26 77%
12.5 22/24 92%
50 20/31 65%
200 21/25 84%
- Duration of gestation: 18 days
- Mortality: 2/27 females administered 50 mg/kg and 2/33 females
administered 200 mg/kg died during the exposure period. In
one female of the highest dose group all fetuses died at an early stage. No parturition fatalities were observed when mothers
were allowed to deliver their young naturally.
- Gross pathology incidence and severity: observed skeletal malformations in neonates like cervical vertebrae, tail vertebrae
and vomer adhesion occurred in the controls, too, and did not show a dosage correlation. No malformations of the skeleton or
the inner organs of fetuses delivered by hysterectomy were observed; the frequency of malformations and abnormalities of theexternal integument, like opened eyes, cleft palate and exencephaly showed a slight tendency toward dose dependance, but it
was lower than in the control. No effects on main organs of both mothers and neonates as compared to controls.
- Number of corpora lutea: No significant differences between control and test groups, but actual numbers not reported.
- Organ weight changes: No treatment-related effects of organ weights of mother animals and neonates; not reported for
fetuses delivered by hysterectomy.
- Offspring toxicity F1:
- Litter size and weights: There was a dose-related, but not statistically significant decrease in litter size.
Dose [mg/kg bw/d] average no. of neonates/litter
0 (control) 14.7 +- 2.4
12.5 13.8 +- 2
50 12.9 +- 2
200 12.8 +- 2
- Post natal survival until weaning: no treatment-related effects on body weight gain.
- Effects on offspring: a dose-related, but not statistically significant decrease in embryo weight and delayed
ossification process was observed.
- Postnatal growth, growth rate: no treatment related effects
- Other observations: no treatment-related effects in the Running Test and the Rod Grasping Test.
Result: Maternal toxicity was not apparent at any dose level. NOAEL = 1000 mg/kg/day. Developmental toxicity was not apparent at any dose level.
NOAEL = 1000 mg/kg/day.
Grossly visible abnormalities, external, soft tissue and
skeletal abnormalities: None.
Litter sizes were comparable for all groups. No gross abnormalities were found for any of the pups, with the exception of a single runt in the 50
mg/kg bw/day group.
A study similar to an OECD 414 is
available for an analogue substance disodium metasilicate (CAS
6834-92-0), where the NOAEL was 12.5 mg/kg bw for maternal toxicity and
200 mg/kg bw (highest dose tested) for developmental toxicity. The NOAEL
of 12.5 for parental toxicity was probably based on the mortality of
2/27 females in the 50 mg/kg bw group. No further information is given
regarding the dead females. Thus, it can not be excluded, that
substance-related systemic parental toxicity would be observed only at
In the study by Saiwai et al. (1980),
pregnant mice were administered 12.5, 50 or 200 mg/kg bw/d sodium
metasilicate in aqueous solution from day 0 until 17/18 of gestation by
daily gavage. Among the mother animals 2 fatalities occurred both in the
50 and 200 mg/kg group (total number of animals: 33 and 27,
respectively); body and organ weights and dissection findings were not
affected. On day 18 of gestation fetuses were delivered by hysterectomy
and examined. No differences to controls were observed for the following
parameters: number of pregnancies and living or dead fetuses, body
weight and malformations of inner organs and the skeleton. 10 mother
animals were allowed to deliver their young naturally. The neonates were
observed for 30 days. Litter size and fertility index were not
significantly affected up to and including 200 mg/kg bw/d. Body weight
gain, organ weights and behavioral development did not reveal any
differences to the control. Skeletal malformations did not exhibit a
correlation with dosage. A dose-related decrease in the number of
neonates was observed, however, this was not statistically significant.
available data on reproduction and developmental toxicity of the test
substance do not meet the criteria for classification according to
Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore
conclusive but not sufficient for classification.
information is available on effects via lactation.
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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