Reaction products of [3-(2,3-epoxypropoxy)propyl]trimethoxysilane and triacetoxyvinylsilane.

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 Days

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

No urinalysis was conducted

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Test animals

Species:

rat

Strain:

other: CD (SD)IGS BR VAF/Plus

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Removed from study report
- Age at study initiation: 34-38 days
- Weight at study initiation: 122-152 g
- Fasting period before study: No
- Housing: Housed singly in stainless steel cages, with a mesh lid and floor. The cages were suspended above absorbent paper.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: Eight days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-22
- Humidity (%): 39-66
- Air changes (per hr): At least 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: Test substance was prepared for administration by adding the required amount of corn oil to a pre-weighed amount of test substance to give the required concentration for each group. The formulations were homogenised using a Silverson Laboratory Mixer.

VEHICLE
- Justification for use and choice of vehicle: Not stated
- Concentration in vehicle: Not stated
- Amount of vehicle: Total volume of the dosage was 5 ml/kg bw/day
- Lot/batch no.: Five batches were used: U8112, A8246, H8247, X8246 and A8153.
- Purity: Not stated

Analytical verification of doses or concentrations:

yes

Remarks:

The homogeneity and concentration of the test substance in the vehicle was assessed using an atomic absorption spectrometry method.

Details on analytical verification of doses or concentrations:

The homogeneity of the test substance in the vehicle was previously assessed analytically in a trial preparation at concentrations of 20 and 200 mg/mL. Homogeneity was also assessed at the lowest concentration in this study (10 mg/mL) by analysing samples taken from the formulation prepared for administration on Day 1 of treatment. Samples were taken from the three positions in the mix initially and following restirring after 2 hours storage at 21°C. The concentrations of the test substance were also determined for formulations prepared for administration on Day 1 and 21 of treatment. The method of analysis was an adaption of an atomic absorption spectrophotometry method (no further details given).
The results of the analysis showed acceptable homogeneity of the formulation initially and after resuspension. The achieved concentrations on days 1 and 21 of treatment were satisfactory except for Group 2 on day 1, which was slightly low (88% of intended concentration). The Group 1 control for day 21 was found to contain a minor interference, however, as the method of analysis is not compound specific this could have come from any silicon containing substance.

Duration of treatment / exposure:

29 Days

Frequency of treatment:

Daily, seven days per week.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

50 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

250 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

750 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

Five

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Based on range-finding study.
- Rationale for animal assignment: Random
- Rationale for selecting satellite groups: No satellite groups
- Post-exposure recovery period in satellite groups: No post-exposure recovery group

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily during the first week of treatment and twice weekly during weeks 2 and 4.
- Cage side observations checked in table No.1 were included.

BODY WEIGHT: Yes
- Time schedule for examinations: Each animal was weighed on day 4 after arrival, on the day that treatment commenced, at weekly intervals throughout the treatment period and before necropsy.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

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: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: Daily visual inspection

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Day 30
- Anaesthetic used for blood collection: Yes (isoflurane/nitrous oxide)
- Animals fasted: Yes, overnight
- How many animals: All
- Parameters checked in table 2 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Day 30
- Animals fasted: Yes
- How many animals: All
- Parameters checked in table 2 were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Pretreatment, weeks 2 and 3, and during week 4 (over two days).
- Dose groups that were examined: All
- Battery of functions tested: In the hand observations (pretreatment and each week of treatment: exophthalmos, fur appearance, lacrimation, piloerection, reactivity to handling, removal from cage, salivation, vocalisation on handling, standard arena observations (pretreatment and each week of treatment: activity counts, arousal, convulsion, defaecation count, gait, grooming, palpebral closure, posture, rearing count, tremor, twitches, urination), manipulations (pretreatment and week 4: approach response, auditory startle reflex, body temperature, body weight, grip strength, landing footsplay, tail pinch response, pupil closure reflex, righting reflex, touch response), and motor activity (pretreatment and week 4).

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table 3)
HISTOPATHOLOGY: Yes (see table 3)

Statistics:

For numerical data recorded in the FOB, the following statistical analysis was performed: Where 75% of the data had the same value, a frequency analysis was performed based on the Mantel trend test. Where this test was considered unsuitable, Fisher's exact test of control group versus each treated group was performed. Where less than 75% of the data had the same value, Bartlett's test to evaluate homogeneity of variances was performed. If the result of this was not significant at the 1% level, a parametric analysis was performed, otherwise, unless a stabilising transformation (e.g. Log transformation) could be applied, a non-parametric analysis was performed. The parametric analysis consisted of a one-way analysis of variance (ANOVA). If significant, the ANOVA was followed by Williams' test for trend with increasing dose. Where Williams' test was considered unsuitable, multiple comparisons based on the t-test were performed. The non-parametric analysis performed was a Kruskal-Wallis one-way analysis of ranks. If significant, this was followed by Shirley's test for trend with increasing dose. Where Shirley's test was considered unsuitable, the treatment group mean ranks were compared against the control group, followed by a set of multiple comparisons. All of these comparisons were based on the Wilcoxon rank-sum test.
The significance of inter-group differences in haematology and blood chemistry was assessed by Student's t-test using a pooled error variance. For organ weights and body weight changes, homogeneity of variance was tested using Bartlett's test. Whenever this was found to be statistically significant a Brehrens-Fisher test was used to perform pairwise comparison, otherwise a Dunnett's test was used. Intergroup differences in macroscopic pathology and histopathology were assessed using Fisher's Exact test.

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Salivation was frequently observed shortly after dosing for the majority of the animals that received 250 or 750 mg/kg bw/day and on one occasion (day 20) for one female that received 50 mg/kg bw/day. Salivation had ceased by 1-2 hours after dosing. There were no other signs related to treatment.

Mortality:

no mortality observed

Description (incidence):

There were no deaths.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Overall body weight gains for males that received the highest dose were slightly low when compared with those of the controls (91% of the control values). There was no similar effect for females at this dose. Overall body weight gains for females that received 50 or 250 mg/kg bw/day were low compared with the controls (76 and 87% of control values, respectively). However, in the absence of any dose relationship or effect at the highest dose, these differences were no considered to be related to treatment.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

Food consumption for males that received the highest dose was marginally lower than that of the controls (95% of the control values). There was no similar effect for the females that received this dose. Food consumption for females that received 50 or 250 mg/kg bw/day was slightly lower than that of the controls (87 and 96% of the control values). However, in the absence of a dose-response or effect in the high dose group, the difference was not considered to be related to treatment.

Food efficiency:

no effects observed

Description (incidence and severity):

No difference between the treated or control groups.

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Activated partial thromboplastin time was shorter for males that received 750 mg/kg bw/day. This single change was observed only in one sex and is not considered as treatment related. Other inter-group differences that attained statistical significance were minor and within normal background ranges at the laboratory and therefore, not considered to be related to treatment. The cellularity and composition of the bone marrow was not affected by treatment.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

There were no treatment-related effects.

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

In the hand observations: Compared with controls, males and females that received 750 mg/kg bw/day showed an increased incidence of piloerection during weeks 3 and 4 of treatment. Three females that received the highest dose showed coat staining during week 4 of treatment. However, this observation occurred in all treatment groups including the controls throughout the study and was considered to be of no toxicological significance.

Arena observations: A few treated animals showed a flattened gait during every week of treatment. This observation was also recorded in control females and in both sexes before treatment started, and therefore, was not considered to be related to treatment. Females that received the highest dose showed group mean arena activity and rearing scores slightly by consistently lower than those of the controls during all four weeks of treatment. These decreased mean scores were generally due to two or three individuals showing atypically low levels of activity, often preventing gait assessment due to insufficient locomotion, rather than a general decrease in activity.

There were no treatment-related effects on manipulation observations.

Animals of the high dose group showed lower forelimb grip strength values during week 4 of treatment compared with controls, although hind limb values were unaffected. However, the forelimb grip strength of these animals was also lower than controls before the start of treatment and all group means were within the background control range. Therefore, the difference was not attributed to treatment.

Motor activity scores within week 4 of treatment showed considerable intra- and inter- group variation, with high beam (rearing activity) scores for females in all treated groups tending to be lower than those of controls during the first half of the 60-minute recording period. However, no indication of a dose-related trend was observed. Additionally, low beam (general locomotor activity) scores were unaffected and high and low beam scores for males were similar in all groups.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no treatment-related effects.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

A thickened stomach wall was observed in one high dose female and one mid dose male. There was also a dark area in the glandular mucosa of the stomach in one high dose male, and a distended jejunum and abnormal contents in the gastrointestinal tract for one high dose male.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The only change considered to be related to treatment was acute inflammation in the glandular region of the stomach. This was observed in three males and two females that received the highest dose and in a single male that received 250 mg/kg bw/day. The change was considered likely to depend on a slight irritant effect of the test substance that resulted in the migration of acute inflammatory cells, predominantly neutrophils, to the affected area. No other inflammatory or degenerative changes or evidence of local cytotoxicity were observed.
There was a slight increase in the incidence of cortico-medullary mineralisation in the kidneys of females that received the highest dose, but this change is commonly observed in female rats and the difference was considered to be due to sampling variation.

Histopathological findings: neoplastic:

not examined

Effect levels

1

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 50 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

gross pathology

haematology

histopathology: non-neoplastic

other: Based on local effects

2

Key result

Dose descriptor:

NOAEL

Effect level:

>= 750 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

In a repeated 28-day oral toxicity study, conducted to a protocol similar to OECD Test Guideline 407 and in compliance with GLP, the systemic NOAEL for reaction mass of 3-(2,3-epoxypropoxy)propyltrimethoxysilane and triacetoxyvinylsilane was concluded to be ≥ 750 mg/kg bw/day in CD rats based on no adverse effects observed.