Triethoxyisobutylsilane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13.12.1989 to 02.01.1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Triethoxyisobutylsilane

EC Number:

402-810-3

EC Name:

Triethoxyisobutylsilane

Cas Number:

17980-47-1

Molecular formula:

Hill formula: C10H24O3Si CAS formula: C10H24O3Si

IUPAC Name:

triethoxy(2-methylpropyl)silane

Details on test material:

- Name of test material (as cited in study report): Dynasylan IBTEO (isobutyltriethoxysilane)
- Substance type: Alkoxysilane
- Physical state: Liquid
- Stability under test conditions: Stated to be "Adequately stable for use in this study".
- Storage condition of test material: Dry conditions at room temperature and in original container.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Limited, Kent, UK
- Age at study initiation: 6-8 weeks
- Weight at study initiation: Approximately 200 g
- Fasting period before study: No data
- Housing: Five per polypropylene cage
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-24
- Humidity (%): 35-65
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): No data

IN-LIFE DATES: From: 13.12.1989 to 02.01.1990

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION: The generator was designed to produce and maintain an atmosphere containing a high proportion of respirable droplets. All parts of the generator in contact with the test substance were made of stainless steel or glass. The test substance was supplied to the generator at a constant flow rate from a syringe driven by a syringe pump. The compressed air supply to the generator was dried, filtered and oil-free.

The whole-body exposure chambers used for the exposure were of square section and were fitted with pyramidal tops. The chambers were made of perspex and had an internal volume of approximately 120 litres. Each chamber was divided by wire mesh partitions to provide 10 separate animal compartments.

The test atmosphere entered through a port at the base centre of the chamber and passed out through small holes in the lower edge of the square section. Each chamber was positioned inside a large glass walled cabinet equipped with an extractor fan exhausting to atmosphere through a collection filter.

A supply of clean dried air was connected to the aerosol generator and the supply pressure was adjusted to give a flow rate of 25 litres per minute measured at the generator outlet tube. For the exposure of the test group, a 50 ml syringe filled with the test substance was fitted to the syringe pump and connected to the atomiser with PTFE tubing. An initial flow rate of approximately 0.4 ml/minute was selected for the exposure. This flow rate was expected to give a concentration of aerosol just in excess of 5 mg/l of air (the flow rate was later reduced to maintain the concentration of aerosol at approximately 5 mg/l).

The rats were placed into separate compartments of the exposure chamber. The syringe pump was switched on and the exposure timed for four hours, followed an 11-minute equilibrium period. After four hours the supply of test substance was discontinued and the exposure chamber was allowed to clear before the rats were removed for examination.


TEST ATMOSPHERE
- Brief description of analytical method used: Five air samples were taken from the chamber during each exposure and analysed to determine the concentration of Dynasylan IBTEO in the chamber atmosphere. The samples were drawn through a gas absorption trap, containing approximately 20 ml of methanol. Two further air samples were taken using a May multistage liquid impinger with methanol as the trapping agent in each stage. The contents of the stages were analysed to determine the particle size distribution of the test substance in the atmosphere. The air sample was taken at a flow rate of 10 litres/minute.
- Samples taken from breathing zone: No data

TEST ATMOSPHERE
- Particle size distribution: 84% of the test substance present in the chamber atmosphere was in the respirable range (<5.5 µm aerodynamic diameter).

Analytical verification of test atmosphere concentrations:

yes

Remarks:

By GLC

Duration of exposure:

4 h

Concentrations:

The mean concentration of the test substance was 5.88 mg/l of air.

No. of animals per sex per dose:

Ten

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The rats were observed continuously during exposure for signs of reaction to the test substance and at least twice daily during the observation period. All rats were weighed daily from the day of delivery until the end of the observation period. The food and water consumption per cage of rats was measured daily. The mean daily intake of food and water for each rat was calculated.
- Necropsy of survivors performed: yes
- Other examinations performed: Detailed macroscopic examination. The lungs were removed to calculate lung weight to bodyweight ratio. Liver and kidneys were examined microscopically.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.88 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: There were no deaths.

Mortality:

There were no deaths.

Clinical signs:

other: All animals of the test group had a hunched posture with eyes closed throughout the exposure period. These signs were accompanied by lacrimation, reddening of the feet and reduced breathing rate after one hour of exposure and redness around the snout afte

Body weight:

Two female rats exposed to the test substance were found to have lost weight on Day 1 of the observation period. Subsequently the rate of bodyweight gain for exposed rats was similar to that of the control rats.

Gross pathology:

No abnormal macroscopic findings.

Other findings:

- Organ weights: Lung to body weight ratios were normal.
- Histopathology: No abnormal findings.
- Potential target organs: Lung (local effect)
- Other observations: Food consumption was reduced for 1 day following exposure. Following exposure, water consumption was found to be increased in male and female rats on several days of the observation period.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In an acute inhalation study conducted using a protocol comparable to OECD 403 and to GLP (reliability score 1) the LC50 for a triethoxyisobutylsilane aerosol was greater than 5.88 mg/l in rats.