Trisilicon tetranitride

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study run to a reliable method. None GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The test substance was orally administered to male and female rats for 28 days at 1,000, 300, or 100 mg/kg to evaluate its toxicity. Some animals were given a 14-day recovery period. Another group was administered the vehicle (0.5% sodium carboxymethylcellulose in water) as control. Six males and six females were sacrificed at the end of the administration period and six males and females at the end of the recovery period, or a total of 12 males and 12 females per group, in the control, 300, and 1,000 mg/kg groups. Six males and six females were sacrificed at the end of the administration period in the 100 mg/kg group.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Trisilicon tetranitride

EC Number:

234-796-8

EC Name:

Trisilicon tetranitride

Cas Number:

12033-89-5

Molecular formula:

N4Si3

IUPAC Name:

1Si-hexacyclo[3.1.1.0¹,⁴.0²,⁵.0³,⁶.0³,⁷]trisilazane

Constituent 2

Reference substance name:

Silicone Nitride

IUPAC Name:

Silicone Nitride

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Batch No.: 00205
Purity: ±97%

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 Laboratories Japan Inc
- Age at study initiation: six weeks
- Weight at study initiation: males ranging in weight from 168-183 g and females from 135-151 g
- Housing: Animals were kept in stainless steel cages in groups of up to five per cage during the quarantine and acclimatization periods and were housed individually in stainless steel cages after assignment to groups.
- Diet (e.g. ad libitum): Pellet feed (CRF-1, Oriental Yeast Co., Ltd.) was provided to the animals ad libitum during the study except during fasting from about 4:00 pm on the day before necropsy.
- Water (e.g. ad libitum): Tap water was available ad libitum throughout the study.
- Acclimation period: Males were acclimatized to laboratory conditions over a four-day period and females over a nine-day period.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-26°C
- Humidity (%): 40-70%
- Air changes (per hr): 12 air changes/hour
- Photoperiod (hrs dark / hrs light): a 12-hour light/12-hour dark cycle (lighting from 6:00 am through 6:00 pm)

No additional data

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 0.5% sodium carboxymethylcellulose in water

Details on oral exposure:

VEHICLE
- Amount of vehicle (if gavage): 5 mL/kg

No additional data

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

28 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
1000, 300 and 100 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

12 males and 12 females per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected based on the results of a 14-day preliminary oral toxicity study conducted at 0, 125, 250, 500, and 1,000 mg/kg (five male rats per group). No abnormalities in general signs, body weight, food consumption, or necropsy findings were seen even at 1,000 mg/kg. The test substance was therefore administered at the highest dose of 1,000 mg/kg, followed by 300 and 100 mg/kg with an approximate common ratio of 3.

No additional data

Positive control:

None stated

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: General signs and mortality were monitored twice daily, once before and once after administration, throughout the administration period and once daily during the recovery period.
- Cage side observations checked in table [No.?] were included.

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: twice weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

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 data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: once weekly

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: the day after final dosing and after completion of the recovery period
- Anaesthetic used for blood collection: yes, pentobarbital
- Animals fasted: No data

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: the day after final dosing and after completion of the recovery period
- Animals fasted: No data

URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine was collected in urine collection cages prior to completion of the administration and recovery periods.
- Metabolism cages used for collection of urine: No data

NEUROBEHAVIOURAL EXAMINATION: No data

No additional data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, The brain (cerebrum, cerebellum, and medulla oblongata), pituitary and thyroid glands, thymus, heart, liver, spleen, kidneys, adrenals, testes, epididymides and ovaries were weighed—pituitary and thyroid glands were weighed after fixing them overnight in 20% neutral-buffered formalin). These organs, along with lungs, trachea, pancreas, salivary glands (sublingual and submandibular), esophagus, stomach, duodenum, jejunum, ileum, appendix, colon, rectum, lymph nodes (submandibular and mesenteric), urinary bladder, seminal vesicles, prostate, uterus, vagina, parathyroids, spinal cord, sciatic nerve, eye balls, Harderian glands, sternum, femur, and mammary glands were fixed in 20% neutral-buffered formalin. However, testes and epididymides were refixed in 90% alcohol after being fixed for two to three hours in Bouin’s solution, while eye balls were refixed in 20% neutral-buffered formalin after being fixed overnight in glutaraldehyde formalin.
HISTOPATHOLOGY: Yes, HE-stained specimens of each organ and tissue harvested from animals in the control and 1,000 mg/kg groups necropsied after termination of the administration period were subjected to histopathological examinations.

Other examinations:

None stated

Statistics:

Differences in the following parameters between the control group and groups administered the test substance were statistically analyzed (p<0.05): body weight, food consumption, water consumption, urine volume, specific gravity of urine, hematological and blood biochemical data, and absolute and relative organ weights. Means and standard deviations calculated for each of these parameters in each group were subjected to Bartlett’s test for equality of variance. If equal variance was observed, Dunnett’s test was conducted, while Dunnett’s rank test was used if equal variance was not found.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not specified

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

no effects observed

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY
No male or female in any group died or was found moribund during the study.
No male or female in any group showed any abnormality in the observation of general signs.

BODY WEIGHT AND WEIGHT GAIN
Males and females in groups administered the test substance showed no statistically significant difference from the control group with respect to body weight on any day of measurement.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Males and females in the groups administered the test substance showed no statistically significant difference from the control group with respect to food consumption on any day on measurement.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Males and females in the groups administered the test substance showed no statistically significant difference from the control group with respect to water consumption on any day of measurement.

HAEMATOLOGY
1) On termination of administration period
Males in the 100 and 1,000 mg/kg groups showed no statistically significant difference from the control group with respect to any test parameter. Platelet counts in the 300 mg/kg group were significantly lower than in the control group, but since no difference was seen with the 1,000 mg/kg group, the difference was not considered to be due to administration of the test substance.
Females in the 1,000 mg/kg group showed no statistically significant difference from the control group with respect to any test parameter. In the 100 mg/kg group, RBC was significantly lower and MCH significantly higher than in the control group, while in the 300 mg/kg group fibrinogen was significantly higher than in the control group, but since the 1,000 mg/kg group showed no significant difference from the control group in any of these parameters, these differences were not considered to be due to administration of the test substance.
2) On termination of recovery period
Males and females in the groups administered the test substance showed no difference from the control group with respect to any test parameter.

CLINICAL CHEMISTRY
1) On termination of administration period
Males and females administered the test substance showed no significant difference from the control group with respect to any test parameter.
2) On termination of recovery period
Males and females in the groups administered the test substance showed no significant difference from the control group with respect to any test parameter.

URINALYSIS
1) Before termination of administration period
Males and females in the groups administered the test substance showed no statistically significant difference from the control group with respect to urine volume or specific gravity.
2) Before termination of recovery period
Males in the groups administered the test substance showed no statistically significant difference from the control group with respect to urine volume or specific gravity.

ORGAN WEIGHTS
1) On termination of administration period
Males in the groups administered the test substance showed no significant difference from the control group with respect to body weight measured on the day of necropsy.
Females in the groups administered the test substance showed no significant difference from the control group with respect to body weight or absolute and relative organ weight on the day of necropsy.
2) On termination of recovery period
Males and females in the groups administered the test substance showed no significant difference from the control group with respect to body weight or absolute and relative organ weights on the day of necropsy.

GROSS PATHOLOGY
1) On termination of administration period
Males showed no abnormality in the control, 100 mg/kg, or 300 mg/kg groups. In the 1,000 mg/kg group, one male showed atrophy of the left testis and epididymis, but this was considered an incidental since it was seen in only one animal.
No female in any group showed any abnormality.
2) On termination of recovery period
No male or female in any group showed any abnormality.

HISTOPATHOLOGY: NON-NEOPLASTIC
1) Males on termination of administration period
Males from the 1,000 mg/kg group showed focalized hepatocellular necrosis, microgranulomas and bile duct proliferation in the liver, basophilic change in the tubular epithelium in the kidneys, atrophy of seminiferous tubules in the testes, and exfoliated cell debris in the epididymal lumen, but these changes are commonly observed in control groups and were considered to be incidental.
2) Females on termination of administration period
Females from the 1,000 mg/kg group showed focalized hepatocellular necrosis, microgranulomas and bile duct proliferation in the liver and remnants of Rathke’s pouch in the pituitary glands, but these changes are commonly observed in control groups and were considered to be incidental.

No additional data

Effect levels

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The test substance was considered to show no toxicological effects in male or female rats even at 1,000 mg/kg.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The no-observed-effect level (NOEL) of the test substance was considered to be 1,000 mg/kg for both male and female Sprague-Dawley rats under the conditions of the present study.