Registration Dossier

Administrative data

Description of key information

No measured acute oral toxicity data are available for the registered substance, dimethoxymethylsilane, however, a reliable study is available for the structural analogue substance diethoxymethylsilane.
Oral (OECD TG 403): LD50: rat > 2000 mg/kg bw (female)
Inhalation (similar to OECD TG 403, limit test): LC50: rat > 4600 mg/m³
Dermal: no acute dermal data available

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
Reference
Endpoint:
acute toxicity: oral
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Sex:
female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Remarks on result:
other: no mortalities or clinical signs of toxicity observed
Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008
Conclusions:
In conclusion, under the conditions of the present study, according to OECD 423 and GLP, at the limit concentration of 2000 mg/kg bw no mortalities or clinical signs of toxicity were observed. The source test substance and thus the target substance does not need to be classified for oral toxicity. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in acute oral toxicity potential.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
discriminating dose
Value:
2 000 mg/kg bw
Quality of whole database:
The study was conducted according to an appropriate OECD test guideline, and in compliance with GLP.

Acute toxicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 Aug - 30 Dec 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
(1981)
Deviations:
yes
Remarks:
(no gross necropsy was done at the end of the observation period, no justification for the use of a whole-body inhalation system is given)
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: charles River Breeding Laboratories
- Weight at study initiation: 175 - 200 g
- Fasting period before study:
- Housing: in stainless steel wire mesh bottomed cages
- Diet: Purina rodent chow, ad libitum, except during exposure
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 30 - 50
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
clean air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel and glass exposure chamber under dynamic conditions, Airflow rates through the chambers were monitored continously by calibrated Magnehelic gauges connected across orifices at the chamber inlets. Chamber temperature and relative humidity were monitored with cole-Parmer Model No. 3310-40 (certified) temperature and humidity gauges. Gauge readings were recorded hourly during the exposure period.
- Exposure chamber volume: 450 L
- Source and rate of air: laboratory air
- Method of conditioning air: The test material was introduced into the test chamber through a specially designed glass J-tube with a flow FMI Lab pump. Laboratory air filtered and dried with Matheson #462 cartridge filter passed through the J-tube. The air/vapor mixture entered the top of the chamber where it was diluted with room air. Heating tape was used to heat the air which passed through the J-tube and glass beads were used to further help vaporize the test material.
- Treatment of exhaust air: the exhaust air was filtered (hepa and carbon) cleaned with water cyclone and then exhausted from the roof of the building.


TEST ATMOSPHERE
- Brief description of analytical method used: Airflow rates through the chambers were monitored continuously by calibrated Magnehelic gauges connected across orifices at the chamber inlets. Gauge readings were recorded hourly during the exposure Period. Chamber temperature and relative humidity were monitored with Cole-Parmer Model No. 3310-40 (certified) temperature and humidity gauges. Gauge readings were recorded hourly during the exposure Period.
Analytical verification of test atmosphere concentrations:
yes
Remarks:
calculated by weight
Duration of exposure:
4 h
Concentrations:
5000 mg/m³ (nominal), 4600 mg/m³ (analytical)
No. of animals per sex per dose:
5 males and females
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: animals observed daily on weekdays, body weight was determined prior to exposure and on day7 and 14 post exposure
- Necropsy of survivors performed: no
- Other examinations performed: clinical signs, body weight
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 4 600 mg/m³ air (analytical)
Based on:
test mat.
Remarks:
calculated by weight
Exp. duration:
4 h
Remarks on result:
other: no adverse effects or mortalities were observed
Mortality:
No mortalities were observed during the study period.
Clinical signs:
other: No other clinical signs were observed during the study period.
Body weight:
No effects on body weight were observed during the study period.
Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008
Conclusions:
In conclusion, under the conditions chosen for this experiment (according to OECD 403), the test substance was found not to be toxic by inhalation, since no mortalities or clinical signs of toxicity were observed at the maximum attainable concentration.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
discriminating conc.
Value:
4 600 mg/m³
Quality of whole database:
The study was conducted according to an appropriate OECD test guideline, with acceptable restrictions.

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Studies were chosen as key when the available study was of relevance and of sufficient quality for classification, labelling and for risk assessment.

No measured acute oral toxicity data are available for the registered substance, dimethoxymethylsilane, however, data are available for the structural analogue substance diethoxymethylsilane (CAS 2031-62-1). Both substances hydrolyse in contact with water to produce the common silanol hydrolysis products, methylsilanediol and methylsilanetriol. Therefore, it is considered that read-across between the substances is appropriate.

The molecular weight difference between target and source is 106/134 = 0.79.

The key acute oral toxicity study was conducted in compliance with GLP and according to OECD TG 423 (BSL BIOSERVICE, 2007a) and reports an LD50 value of > 2000 mg/kg bw for female rats. All 3 animals dosed with 2000 mg/kg bw did not show any clinical signs of toxicity and no mortalities were observed.

The key acute inhalation toxicity study was conducted similar to OECD 403 (limit test) (Dow Corning Corporation, 1988) with minor deviations (no gross necropsy was done at the end of the experiment). No mortalities or clinical signs of adverse effects were observed during the 14 day post exposure period following a 4 hour exposure with the highest attainable concentration of 4.6 mg/l. The LC50 value was determined to be > 4600 mg/m³.

There are no acute dermal data available.

Justification for classification or non-classification

The available data on acute oral and inhalation toxicity of the substance do not meet the criteria for classification according to Regulation 1272/2008 or EU Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.