[3-(2,3-epoxypropoxy)propyl]trimethoxysilane

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

14.08.1989 to 08.09.1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The restrictions were that only one dose and males were tested, and limited examinations were performed, i.e. no haematology, biochemistry or urinalysis. However, this study was performed primarily to investigate effects on the larynx.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

yes

Remarks:

only one concentration used, only males, limited examinations, i.e. no haematology, biochemistry or urinalysis.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-Glycidoxypropyltrimethoxysilane hydrolysate

IUPAC Name:

3-Glycidoxypropyltrimethoxysilane hydrolysate

Constituent 2

Reference substance name:

not yet allocated

IUPAC Name:

not yet allocated

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, NY.
- Age at study initiation: 41 days 
- Weight at study initiation: 131.2 + 9.0 grams
- Fasting period before study: No data
- Housing: 1/2 per cage in stainless steel, wire-mesh cages.
- Diet (e.g. ad libitum): Ad libitum (except during exposure period)
- Water (e.g. ad libitum): Ad libitum (except during exposure period)
- Acclimation period: Two days


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 62-70 (17-21°C)
- Humidity (%): 45-77
- Air flow: 300l/min (13.5 changes/min)
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 14.08.1989 to 08.09.1989

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: MMAD was 2.93 (±1.71) microns

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The inhalation chambers used in the study were constructed of stainless steel with glass windows for animal observations, with a volume of approximately 1300 litres.
- Method of holding animals in test chamber: Free
- Source: No data
- Method of conditioning air: No data
- System of generating particulates/aerosols: A 2% TMSPGE-hydrolysate solution was prepared daily and was metered from a piston pump into an atomizer fitted with a liquid nozzle and an air nozzle.  The atomizer was inserted into the top of the inhalation chamber turret where the liquid aerosol was dispersed throughout the chamber by filtered chamber supply air.  The operating pressure of the atomizer used to generate the TMSPGE-hydrolysate was 20 psig.
- Temperature, humidity, pressure in air chamber: 18.5-19.9oC, 84.9-93.8%
- Air flow rate: 300 L/min
- Air change rate: 13.5/min
- Method of particle size determination: The particle size distribution was measured using a TSI Aerodynamic Particle Sizer and a 20:1 diluter.  These determinations were made once a day for the duration of the study.  The data collected were analysed by probit analysis to obtain the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (sg).   
- Treatment of exhaust air: No data


TEST ATMOSPHERE
- Brief description of analytical method used: Chamber concentrations of TMSPGE-hydrolysate were determined by gravimetric methods. Four samples were obtained from the TMSPGE-hydrolysate aerosol exposure chamber each day.  The nominal concentration was calculated daily by dividing the total amount of material delivered to the chamber by the total airflow rate. 
- Samples taken from breathing zone: No data

      

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber concentrations of TMSPGE-hydrolysate were determined by gravimetric methods. Four samples were obtained from the TMSPGE-hydrolysate aerosol exposure chamber each day.  The nominal concentration was calculated daily by dividing the total amount of material delivered to the chamber by the total airflow rate. 

Duration of treatment / exposure:

6 hours/day

Frequency of treatment:

Five days per week for three weeks followed by four days of exposure during the fourth week for a total of 19 exposures over a 4-week period

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

119 mg/m³ air (analytical)

Doses / concentrations 2

Dose / conc.:

150 mg/m³ air (nominal)

No. of animals per sex per dose:

15 males

Control animals:

yes

Details on study design:

- Dose selection rationale: No data
- Rationale for selecting satellite groups: Five of the 15 test and control animals were assigned to a satellite group for ultrastructural evaluation of the larynges. However, this was not performed.
- Post-exposure recovery period in satellite groups: None

Positive control:

None

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
The rats were observed daily during exposure and observations were recorded on a group basis. Preceding and following each exposure, observations were recorded for animals exhibiting overt clinical signs. At the time of body weight collection and just preceding necropsy, detailed observations were performed on all animals.  On non-exposure days, animals were observed once a day for overt clinical signs and mortality.


DETAILED CLINICAL OBSERVATIONS: No


BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were measured prior to initiation of the first exposure, weekly and immediately prior to sacrifice.  


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Males: days -4 and 11; females: days -5 and 10
- Dose groups that were examined: Control and test.


HAEMATOLOGY: No


CLINICAL CHEMISTRY: No


URINALYSIS: No


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

Ten animals of the test material hydrolysate treated and control groups were sacrificed on the day following the 19th exposure. A complete necropsy was performed on these animals and the following tissues were fixed in 10% neutral buffered formalin for histologic evaluation: gross lesions, larynx, lungs, trachea, nasal turbinates and kidneys. The remaining two rats from the control group were subjected to a complete necropsy and perfusion-fixed with 5% methanol-free EM grade formaldehyde.  The perfusion-fixation was performed to allow comparison of these control rats with rats from another silane group that was also perfusion-fixed.  The larynges from these two rats were then further immersion-fixed in 2% glutaraldehyde.  Other organs, including brain, spinal cord, and peripheral nerves, were taken from these control animals and processed for light microscopic evaluation.

Other examinations:

The satellite group (5 test material hydrolysate treated and 5 control animals) was sacrificed on the day following the 18th exposure. The larynges of three control animals and five test material hydrolysate treated animals were taken and immersion-fixed in 2% glutaraldehyde for possible electron microscopic examination. 

Statistics:

The data for continuous, parametric variables were intercompared for the exposure and control groups by use of Levene's test for homogeneity of variances and by t-tests. If Levene's test indicated homogeneous variances, the groups were compared by pooled variance t-tests.  If Levene's test indicated heterogeneous variances, the groups were compared by separate variance t-test. Frequency data were compared using Fisher's exact tests.  All statistical tests, except the frequency comparisons, were performed using BDMP Statistical Software (Dixon, 1985). The frequency data tests are described in Biometry (Sokal and Rohlf, 1969). The probability value of p < 0.05 (two-tailed) was used as the critical level of significance for all tests.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

No mortality or exposure-related clinical signs were observed during the study.

Mortality:

no mortality observed

Description (incidence):

No mortality or exposure-related clinical signs were observed during the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Decreases in absolute body weight and/or body weight gain were observed for the test material hydrolysate treated animals during each week of the study.  At the end of the study the percent decrease in mean body weight of the test material hydrolysate exposed group compared to the control group was 11%. At the end of the study the percent decrease in mean body weight gain of the test material hydrolysate exposed group compared to the control group was 29%.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Description (incidence and severity):

No adverse findings.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No abnormal findings.

Histopathological findings: neoplastic:

not examined

Effect levels

Dose descriptor:

NOAEC

Basis for effect level:

other: No NOAEC was identified.

Remarks on result:

not determinable

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

No NOAEC identified

Table 1 - Individual body weight (grams), males group for 0 mg/m3

	Week 0	Week 1	Week 2	Week 3	Week 4
Animal 1	114.4	123.2	151.8	178.2	199.5
Animal 2	123.7	134.7	165.3	193.4	213.2
Animal 3	119.5	130.3	158.6	186.8	208.3
Animal 4	123.7	136.9	167.0	194.3	-
Animal 5	125.8	136.0	160.0	184.3	200.2
Animal 6	121.7	129.8	151.7	169.7	188.9
Animal 7	127.5	136.5	163.2	183.7	-
Animal 8	130.1	140.8	164.9	188.6	200.8
Animal 9	137.3	148.6	179.8	207.3	-
Animal 10	132.7	141.1	165.1	106.3	-
Animal 11	138.7	145.0	179.2	208.1	228.4
Animal 12	132.8	140.9	163.9	186.4	211.5
Animal 13	141.4	154.2	190.5	219.5	-
Animal 14	143.9	158.0	195.8	225.9	247.4
Animal 15	153.9	104.8	200.1	231.0	253.4
Mean	131.1	141.4	170.5	196.2	215.1
St. dev.	10.5	11.2	15.1	18.1	21.4
M	15.0	15.0	15.0	15.0	10.0

Table 2 - Individual body weight (grams), males with 150 mg/m3

	Week 0	Week 1	Week 2	Week 3	Week 4
Animal 1	117.4	123.2	143.1	154.7	176.9
Animal 2	132.6	120.2	142.7	160.1	177.6
Animal 3	121.8	126.2	139.4	153	166.8
Animal 4	127.7	132.1	150.2	168.1	-
Animal 5	123.9	128.7	149.7	173.8	-
Animal 6	131.1	137.6	163.3	186.3	202.1
Animal 7	131.8	135.7	160.4	180.5	-
Animal 8	131.9	138.2	157.8	178.5	192.3
Animal 9	133.7	139.8	163.4	180	193.6
Animal 10	134.4	140.4	152..9	165.7	182.4
Animal 11	132.3	138.3	154.3	175.1	193.2
Animal 12	138.5	146.6	188.4	187.9	-
Animal 13	138.8	145.1	171.6	195.9	212.3
Animal 14	145	152.5	173.9	196	213.7
Animal 15	138.3	145.5	163.9	186.5	-
Mean	131.4	137.3	156.9	178.8	191.3
St. dev.	7.52	0.32	10.54	12.73	15.47
M	15	15	15	15	10

Please see attached documents for all gained result tables.

Applicant's summary and conclusion

Conclusions:

In a four-week repeated inhalation study (reliability score 2) conducted using a protocol similar to OECD 412 (with restrictions) and GLP, rats were exposed to an aerosol of 3-glycidoxypropyltrimethoxysilane hydrolysate at a concentration of 119 mg/m3. Significant reductions in body weight gain were observed and therefore the NOAEC was <119 mg/m3. There was no evidence of laryngeal granuloma formation.

Executive summary:

In a four-week repeated inhalation study (reliability score 2) conducted using a protocol similar to OECD 412 (with restrictions) and GLP, rats were exposed to an aerosol of 3-glycidoxypropyltrimethoxysilane hydrolysate at a concentration of 119 mg/m3. Significant reductions in body weight gain were observed and therefore the NOAEC was <119 mg/m3. There was no evidence of laryngeal granuloma formation.