Trisilicon tetranitride

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

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 detailed 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 effects of repeated administration of the test substance on parent animals and their reproductive performance as well as the development and growth of offspring were evaluated in Crj: CD(SD)IGS rats by administering the test substance at 0 (vehicle), 100, 300, and 1,000 mg/kg/day to 12 male and 12 female rats per group. The test substance was administered orally to males for 35 days, including 14 days prior to mating and the subsequent mating period, and to females from 14 days prior to mating until Day 3 of lactation through the mating and gestation periods. This study was conducted as part of an OECD program to inspect the safety of existing chemical substances.

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% by weight

Test animals

Species:

rat

Strain:

Crj: CD(SD)

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: (P) 10 weeks of age
- Housing: Animals were housed two to three per cage during the quarantine and acclimation period and housed individually in stainless steel cages after assignment to groups (one male and one female per cage during the mating period). Females confirmed to have copulated were housed individually in polycarbonate cages provided with nesting material.
- Diet (e.g. ad libitum): Pellet feed (CRF-1, Oriental Yeast Co., Ltd.) sterilized by autoclaving ad libitum.
- Water (e.g. ad libitum): Well water supplied by water bottles or an automatic watering system were made available ad libitum. Sodium hypochlorite was added to well water (about 2 ppm).
- Acclimation period: over a 13-day period

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24±2°C
- Humidity (%): 55±10%
- Air changes (per hr): 13-15 air changes/hour
- Photoperiod (hrs dark / hrs light): a 12-hour light/12-hour dark cycle (lighting from 7:00 am through 7:00 pm)

No additional data

Administration / exposure

Route of administration:

oral: unspecified

Vehicle:

other: Sodium carboxymethylcellulose dissolved in water at 0.5%

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The necessary amount of the test substance was measured and suspending in 0.5% CMC-Na solution to make a 20% (w/v) suspension. Suspensions of lower concentrations (2% and 6% (w/v)) were prepared by serially diluting 20% (w/v) suspension with 0.5% CMC-Na. These suspensions were prepared before use.

VEHICLE
- Concentration in vehicle: 20%

No additional data

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Males were dosed once daily for 14 days prior to mating and for 35 days thereafter for a total of 49 days, while females were dosed once daily for 14 days prior to mating, with dosing continuing during the mating period (up to 14 days until copulation was confirmed) and the gestation period up to the third day of lactation.

Frequency of treatment:

once daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 300, and 1000 mg/kg/day
Basis:
no data

No. of animals per sex per dose:

12 male and 12 female rats per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected based on the results of a preliminary two-week repeated oral dose toxicity study (0, 125, 250, 500, and 1,000 mg/kg) of male rats conducted at Nihon Bioresearch Center Inc. No abnormalities in general signs or symptoms, body weight, feed consumption, or necropsy findings were seen at any dose in that study.

No additional data

Positive control:

None stated

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Males were weighed twice weekly throughout the administration period. Females were weighed twice weekly during the administration period prior to mating and during the mating period, on Days 0, 7, 14, and 21 of gestation, and on Days 0 (day of delivery) and 4 of lactation.

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

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data

No additional data

Oestrous cyclicity (parental animals):

In females, the estrous cycle was determined by collecting vaginal smears at the same time each morning for 15 days beginning from the first day of dosing (Day 1 of treatment). The average estrous cycle was calculated based on the number of days between cycles.

Sperm parameters (parental animals):

None stated

Litter observations:

Newborns were examined at delivery to determine their total number, number of live newborns, number of stillborns, the sex of live newborns, and the presence or absence of any external abnormalities. All live newborns were weighed on the day of birth and on Day 4 of lactation and the birth index [(number of live newborns/number of implantations) × 100], stillbirth index [(number of stillborns/number of newborns) × 100], and viability index on Day 4 [(number of live newborns on Day 4 of lactation/number of live newborns) × 100] were calculated. All live newborns were sacrificed by exsanguination under ether anesthesia on Day 4 of lactation and their organs and tissues examined by the naked eye. After necropsy, each litter (including stillborns and live newborns that died after birth) was fixed and preserved in pure ethanol.

Postmortem examinations (parental animals):

Both males and females were necropsied and their organs and tissues examined with the naked eye after sacrificing them by exsanguination from the external iliac artery under ether anesthesia. After necropsy, testes and epididymides of males and ovaries of females were weighed and their weights relative to body weight on the day of necropsy (relative weight) were calculated.

Postmortem examinations (offspring):

All live newborns were sacrificed by exsanguination under ether anesthesia on Day 4 of lactation and their organs and tissues examined by the naked eye. After necropsy, each litter (including stillborns and live newborns that died after birth) was fixed and preserved in pure ethanol.

Statistics:

Means and standard deviations in each group were calculated with respect to body weight, feed consumption, number of days until copulation, estrous cycle, organ weights, organ weights relative to body weights, gestation period, number of corpora lutea, number of implantations, total number of newborns, and number and weight of live newborns were determined, and equality of variance between the control group and dosed groups was determined using Bartlett’s test. If variance was equal, comparisons with the control group were performed using Dunnett’s multiple comparison test, while Steel’s multiple comparison test was used if variance was unequal. In both cases, two-tailed tests were conducted, and differences were regarded as significant if p<0.01 or p<0.05. Each treated group was compared to the control group by the χ2 test with respect to the copulation, fertility, and gestation indices and sex ratio of live newborns, by Wilcoxon’s rank sum test with respect to the implantation, stillbirth and birth indices and viability index of newborns on Day 4 of lactation, and by Mann-Whitney’s U test with respect to histopathological findings. Differences were regarded as significant if p<0.05 in all tests. Litter was treated as a unit for reporting values found for live newborns.

Reproductive indices:

The copulation indices in the control, 100, 300, and 1,000 mg/kg groups were 100, 100, 100, and 91.67%, respectively.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No males or females in any group died during the study.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Males and females in groups administered the test substance showed no statistically significant difference from the control group with respect to body weight.
Males in groups administered the test substance showed no statistically significant difference from the control group with respect to feed consumption.
Females in the 1,000 mg/kg group showed significantly lower feed consumption on Day 2 of treatment, but the difference was transient and considered to be unrelated to administration of the test substance since no change in body weight was seen.

REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS)
Females in groups administered the test substance showed no statistically significant difference from the control group with respect to estrous cycle.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
With the exception of one pair in the 1,000 mg/kg group, all pairs copulated and all females were impregnated. As a result, the copulation indices in the control, 100, 300, and 1,000 mg/kg groups were 100, 100, 100, and 91.67%, respectively. Groups administered the test substance showed no statistically significant difference from the control group with respect to fertility index, which was 100% in each group. Groups administered the test substance also showed no statistically significant difference from the control group with respect to the number of days until copulation. Reproductive organs of the pair in the 1,000 mg/kg group that failed to copulate showed no abnormalities upon necropsy or in histopathological examination that suggested infertility.

ORGAN WEIGHTS (PARENTAL ANIMALS)
Males and females administered the test substance showed no statistically significant difference from the control group with respect to any organ weight.

GROSS PATHOLOGY (PARENTAL ANIMALS)
A grayish-white subcutaneous tumor was observed in the chest of one female in the 1,000 mg/kg group. Yellowish-white nodules considered to be incidental were seen in the epididymides of one male each in the 100 and 1,000 mg/kg groups, while hair loss considered to be incidental was seen in the chest of one male in the 300 mg/kg group.

HISTOPATHOLOGY (PARENTAL ANIMALS)
One female from the 1,000 mg/kg group showed mammary gland adenocarcinoma. In addition, one male each from the 100 and 1,000 mg/kg groups showed sperm granuloma in their epididymides, but this change was regarded as incidental. The male from the 300 mg/kg group which showed hair loss in macroscopic examination showed no histopathological change in the affected area.

No additional data

Effect levels (P0)

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Administration of the test substance was not considered to affect the reproductive performance of parent animals.

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Histopathological findings:

not specified

Details on results (F1)

VIABILITY (OFFSPRING)
Groups administered the test substance showed no statistically significant difference from the control group with respect to viability index of live newborns on Day 4 of lactation.

CLINICAL SIGNS (OFFSPRING)
No group showed any abnormality in the examination of the external appearance of newborns.

BODY WEIGHT (OFFSPRING)
Groups administered the test substance showed no statistically significant difference from the control group with respect to body weight of live newborns on Day 4 of lactation.

No additional data

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Administration of the test substance was not considered to affect the development of their offspring.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Since administration of the test substance was not considered to affect the reproductive performance of parent animals or the development of their offspring, NOEL was estimated to be 1,000 mg/kg with respect to both parent Crj: CD(SD) animals and offspring under the conditions of the present study.