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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 2019-07-11 to 2019-12-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Version / remarks:
2016
Deviations:
yes
Remarks:
Three females were dosed twice a day on day 39 since these animals were administered before measurements of their body weights on this day. Total of dosing volume was correct and did not affect evaluation of the study results.
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetravinylsilane
EC Number:
214-192-0
EC Name:
Tetravinylsilane
Cas Number:
1112-55-6
Molecular formula:
C8H12Si
IUPAC Name:
tetravinylsilane
Test material form:
liquid
Specific details on test material used for the study:
Batch No.: 707001
Purity: 98.6%

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Details on species / strain selection:
This strain is established as a laboratory animal and has historical data.
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan Hino Breeding Center
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 9 weeks old
- Weight at study initiation: 340.0-391.1 g and 220.6-264.3g for males and females, respectively.
- Housing: Housed in hanging stainless steel cages with wire-mesh floor (260 Wx380 Dx180 H mm, TOKIWA) for quarantine and acclimation. Males and females were housed in 260 Wx380 Dx180 H mm and 165 Wx300 Dx150H mm of hanging stainless cages with wire mesh floor (TOKIWA) individually after group allocation, respectively with irradiated hemp mats with gamma-ray. In the mating period each female was housed in a male's cage in each dose group. Copulated females were housed in polycarbonate cages (PC cage, 265 Wx426 Dx150 H mm, TOKIWA) with autoclaved wooden bedding, and enrichments of autoclaved gnawing wood and hemp mats from gestation day 14. Pups were housed with a dam after delivery.
- Diet: pelleted diet, ad libitum
- Water: ad libitum
- Acclimation period: 2 weeks

DETAILS OF FOOD AND WATER QUALITY:
The analytical data of contaminants in the diet were confirmed to meet the requirements of the “Toxic Substances Control Act of US-EPA" (1979). Contaminants in drinking water were analyzed twice a year according to the water regulations of the “Ordinance on drinking water quality standards" [No. 101 of MHLW]. The analytical data of contaminants in the water were confirmed to be in the stated ranges of the lab.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-25
- Humidity (%): 40-70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12 hours light (7:00-19:00): 12 hour dark(19:00-7:00).

Administration / exposure

Route of administration:
oral: gavage
Details on route of administration:
The vehicle and formulations were administered by gavage once a day using a syringe (Terumo) connected to a nelaton catheter (Terumo) at the amount of 4 mL/kg based on the latest body weights.
Vehicle:
olive oil
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
The test item was weighed, and olive oil was added to prepare the 7.50 w/v% formulation. A part of the 7.50 w/v% formulation was taken and diluted with olive oil to prepare the 0.750 and 2.50 w/v% formulation.
The formulations and vehicle were subdivided into plastic containers and stored at a cold place (target range: 1 to 10°C). On each dosing day, formulations and vehicle were taken out from the storage place and dosed to the animals.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Since solubility to water was 7.26 mg/L, olive oil was used for a preparations investigation of the dosing formulations. The test item dissolved in olive oil at concentration of 25 w/v% (non-GLP).
This vehicle is used for a general toxicity study and historical control data existed.
- Concentration in vehicle: 7.50, 2.50, 0.750 w/v%
- Amount of vehicle (if gavage): 4 mL/kg
- Lot/batch no. (if required): 801029
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Concentrations of the test item formulations were confirmed with GC in the first preparation.
Actual concentrations of the 7.50, 2.50 and 0.750 w/v% formulations were 7.34, 2.42 and 0.717 w/v%, respectively.
Duration of treatment / exposure:
Male and female rats were treated with test item for 14 days and set on mating period for maximum of 14 days. Males and females were administrated until day 29 of dosing and 13 days after delivery, respectively.
Frequency of treatment:
Once daily. Three females were treated twice a day on day 39.
Doses / concentrationsopen allclose all
Dose / conc.:
30 mg/kg bw/day (actual dose received)
Remarks:
Low dose
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Remarks:
Intermediate dose
Dose / conc.:
300 mg/kg bw/day (actual dose received)
Remarks:
High dose
No. of animals per sex per dose:
10 male/ female/ dose
non-mating satellite group: 10 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
A 14-day repeated-dose oral toxicity study was performed at the dose levels of 0, 50, 200, 500 and 1000 mg/kg/day consisting three males and three females for each group. Salivation was observed in the 200, 500 and 1000 mg/kg groups. Decreased spontaneous locomotion, decreased respiratory rate and incomplete eyelids opening were observed in the 500 and 1000 mg/kg groups. Staining lower abdomen, restlessness and staggering gait were observed in the 1000 mg/kg group. A decrease or a trend toward decrease in body weights were noted in the 500 and 1000 mg/kg groups. In organ weights, absolute and relative weights of the liver were increased and absolute weight of the spleen was decreased in the 500 and 1000 mg/kg groups. Absolute weights of the testes were decreased and relative weights of the kidneys were increased in the 1000 mg/kg group. In necropsy, enlargement of the liver was observed in the 500 and 1000 mg/kg groups. Apparent spotty pattern of the surface of the kidneys was observed in males of the 500 mg/kg group. Small testes and thymus, elevation of the limiting ridge of the forestomach were observed in the 1000 mg/kg group. Therefore 300 mg/kg/day was set for the high dose, and 100 and 30 mg/kg/day were set for the middle and low doses for the present study.
- Fasting period before blood sampling for clinical biochemistry: 16-20 h

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: During the dosing period: Twice a day; Recovery period: once a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before the dosing period and once a week thereafter.

SENSORIMOTOR FUNCTION EXAMINATIONS: yes
- Time schedule: The animals were examined for the parameters of the following listed in five males of each dose groups, non-mating five females of the control and 300 mg/kg groups, and selected five parental females of each dose group in each last dosing week. Not performed for the recovery period.
- Reflex (response to optic, pinna and pain, pupillary reflex, air righting reflex) tests and measurements of grip strengths were performed on a blind test basis. Locomotor activity of each animal was counted.


BODY WEIGHT: Yes
- Time schedule for examinations:
Males and non-mating females: Days 1, 3, 7, 14, 21 and 28 of dosing, days 1, 7 and 14 of recovery, and necropsy day.
Mating females: Days 1, 3, 7 and 14 of dosing, gestation days 0, 7, 14 and 20, postnatal days 0, 4, 8 and 13, and necropsy day.
Dead animals were weighed on the day found dead. Non-coupled female was weighed once a week after day 21 and necropsy day (day 55, equivalent pregnant day 26).


FOOD CONSUMPTION: yes
- Mean food consumption per day was calculated from their feeding and remainder weights.
- Time schedule for examinations:
Males and non-mating females: Days 1, 3, 7, 14, 21 and 28 of dosing, days 1, 7 and 14 of recovery
Mating females: Days 1, 3, 7 and 14 of dosing, gestation days 0, 7, 14 and 20, postnatal days 0, 4, 8 and 13


WATER CONSUMPTION AND COMPOUND INTAKE: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: after 16-20 h of the start of fasting
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes
- How many animals: five males, five mating females for each dose group and non-mating five females and males and females of the recovery group
- Whole blood or plasma samples were examined. Parameters examined see "Examination parameters" in attached background material.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: after 16-20 h of the start of fasting
- Animals fasted: Yes
- How many animals: five males, five mating females for each dose group and non-mating five females and males and females of the recovery group
- Serum samples were used, Parameters examined see "Examination parameters" in attached background material.

URINALYSIS: Yes
- Time schedule for collection of urine: at afternoon of the each last observation day
- Metabolism cages used for collection of urine: Yes, Five males of the main group (same animals of sensorimotor function examinations), non-mating females, and male and females of the recovery group were housed in a metabolic cages at afternoon of the each last observation day with free drinking and no feed until next morning for 15-17 h.
- Animals fasted: Yes
- Parameters examined see "Examination parameters" in attached background material.

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see "Examination parameters" in attached background material)

HISTOPATHOLOGY: Yes (see "Examination parameters" in attached background material)
Statistics:
Data regarding body weights of parental animals, food consumption, grip strength, locomotor activity counts, parameters of the hematological and blood chemical examinations, urine volume, specific gravity of urine, organ weights, body weights on necropsy day were analyzed by the Barlett's test for homogeneity of variance. If significant difference (p<0.05) was not noted, the values were analyzed by the Dunnett's test. If significant difference (p<0.05) was noted in the Bartlett test, the values were analyzed by the nonparametric Dunnett’s test. The frequencies of defecation and urination during the dosing period were analyzed by the nonparametric Dunnett's test. Data regarding body weights and food consumption during the recovery period, and parameters of the hematological and blood chemical examinations, urine volume, specific gravity of urine, organ weights and body weights on the necropsy day for the recovery group were analyzed by the F-test for variance ratio. If there were no significant differences at a significance level of 5%, the Student's t-test was performed. If there were significant differences, the Aspin-Welch t-test was performed. The frequencies of defecation and urination during the recovery period were analyzed by the Mann-Whitney U-test.

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Salivation was observed immediately after dosing to males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group. Soft stool was observed in males and non-mating females of the 300 mg/kg group. Slight decreased spontaneous locomotion and lacrimation were observed in females of the 300 mg/kg group on day 22 of gestation period. During the recovery period soft stool was observed in males of the 300 mg/kg group and disappeared by day 3.
Detailed clinical observations were not affected by the test item.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
At 300 mg/kg group, one animal was died during delivery (day 23 of the gestation period) and other animal was died on day 22 of the gestation period.
These animals did not show any severe changes compared to survived animals, and they were considered to have increased-stress related to delivery since small thymus and enlargement of the adrenals were observed.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weights were decreased in males of the 100 and 300 mg/kg groups. During the recovery period body weights were decreased in males of the 300 mg/kg group.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Food consumption was decreased in males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group.
Food efficiency:
not examined
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):
Hemoglobin conc. was decreased in males of the 300 mg/kg group. Prothrombin time was elongated in non-mating females of the 300 mg/kg group. At the end of the recovery period reticulocytes were increased in males of the 300 mg/kg group.
The test item affected the blood coagulation system.
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
In males, ALP was decreased in the 30, 100 and 300 mg/kg groups. ALT was decreased in the 100 and 300 mg/kg groups. T4 was increased in the 100 mg/kg group without dose-relationship. Potassium was decreased in the 300 mg/kg group.
In mating and non-mating females, ALT was decreased in the 300mg/kg group.
These changes were considered to be related to the decreases in body weights and food consumption, no toxicologically significant
Urinalysis findings:
effects observed, treatment-related
Description (incidence and severity):
In urinalyses, renal tubular epithelial cells were observed in males of the 30, 100 and 300 mg/kg groups. Cloudy urine was observed in males of the 300 mg/kg group.
Behaviour (functional findings):
effects observed, treatment-related
Description (incidence and severity):
Grip strength of forelimbs was decreased to mating females of the 300 mg/kg group.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Relative weight of the liver was increased in males of the 100 and 300 mg/kg groups and non-mating females of the 300 mg/kg group. At the end of the recovery period relative weights of the kidneys were increased in males of the 300 mg/kg group.
The weight change of the liver in 100 and 300 mg/kg groups was decided to be toxicologically significant since no histopathological changes were observed in the lowest dose of 30 mg/kg group.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Apparent spotty pattern of the surface of the kidneys was observed in males of the 30, 100 and 300 mg/kg groups. Enlargement of the liver was observed in males and females of the 300 mg/kg group.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Accumulation of the hyaline droplets in the proximal tubules, increased eosinophilic bodies and regeneration of the tubules in the outer medulla of the kidney were observed in males of the 30, 100 and 300 mg/kg groups.
Centrilobular hypertrophy of the hepatocytes of the liver was observed in males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group. At the end of the recovery period granular cast and regeneration of the tubules in the outer medulla of the kidney were observed in males of the 300 mg/kg group.

Effect levels

Dose descriptor:
NOAEL
Effect level:
30 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
food consumption and compound intake
histopathology: non-neoplastic
organ weights and organ / body weight ratios

Target system / organ toxicity

Critical effects observed:
yes
Lowest effective dose / conc.:
100 mg/kg bw/day (actual dose received)
System:
hepatobiliary
Organ:
liver
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified

Any other information on results incl. tables

The changes in urinalyses, organ weights and histopathology related to the kidney were considered to be male rats specific and no toxicologically significant since the hyaline droplets were confirmed to be related to α2u-globuin.

Applicant's summary and conclusion

Conclusions:
In conclusion, the No-Observed-Adverse-Effect Level (NOAEL) for repeated-dose toxicity under the conditions tested was considered to be 30 mg/kg/day due to decreases in body weights and food consumption, an increase in relative weight of the liver and centrilobular hypertrophy of the hepatocytes in the 100 and 300 m/kg groups.
Executive summary:

"A combined repeated dose toxicity study with the reproduction/developmental toxicity screening test" was performed to assess the repeated-dose, reproductive and developmental toxicities of test item in accordance with OECD 422.

Male and female Crl:CD(SD) rats at 9 weeks of age was treated with the test item for 14 days and set on mating period for maximum of 14 days. Males and females were administrated until day 29 of dosing and 13 days after delivery, respectively. The dosage levels were set at 0 (olive oil), 30, 100 and 300 mg/kg/day. Recovery groups were set for the 0 and 300 mg/kg groups after 29 days treatment for males and females of the satellite group.

Salivation was observed immediately after dosing to males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group. Soft stool was observed in males and non-mating females of the 300 mg/kg group. Slight decreased spontaneous locomotion and lacrimation were observed in females of the 300 mg/kg group on day 22 of gestation period. One each female was died on days 22 and 23 of the gestation period. During the recovery period soft stool was observed in males of the 300 mg/kg group and disappeared by day 3.

In sensorimotor function examinations, grip strength of forelimbs was decreased to mating females of the 300 mg/kg group.

Body weights were decreased in males of the 100 and 300 mg/kg groups. During the recovery period body weights were decreased in males of the 300 mg/kg group.

Food consumption was decreased in males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group.

In urinalyses, renal tubular epithelial cells were observed in males of the 30, 100 and 300 mg/kg groups. Cloudy urine was observed in males of the 300 mg/kg group.

In hematology, hemoglobin conc. was decreased in males of the 300 mg/kg group. Prothrombin time was elongated in non-mating females of the 300 mg/kg group. At the end of the recovery period reticulocytes were increased in males of the 300 mg/kg group.

In organ weights, relative weight of the liver was increased in males of the 100 and 300 mg/kg groups and non-mating females of the 300 mg/kg group. At the end of the recovery period relative weights of the kidneys were increased in males of the 300 mg/kg group.

In necropsy, apparent spotty pattern of the surface of the kidneys was observed in males of the 30, 100 and 300 mg/kg groups. Enlargement of the liver was observed in males and females of the 300 mg/kg group.

In histopathological examinations, accumulation of the hyaline droplets in the proximal tubules, increased eosinophilic bodies and regeneration of the tubules in the outer medulla of the kidney were observed in males of the 30, 100 and 300 mg/kg groups.The changes in urinalyses, organ weights and histopathology related to the kidney were considered to be no toxicologically significant since the hyaline droplets were confirmed to be related toα2u-globuin.Centrilobular hypertrophy of the hepatocytes of the liver was observed in males of the 100 and 300 mg/kg groups and females of the 300 mg/kg group. At the end of the recovery period granular cast and regeneration of the tubules in the outer medulla of the kidney were observed in males of the 300 mg/kg group.

Detailed clinical observations and blood chemistry were not affected by the test item.

In conclusion, the No-Observed-Adverse-Effect Level (NOAEL) for repeated-dose toxicity under the conditions tested was considered to be 30 mg/kg/day due to decreases in body weights and food consumption, an increase in relative weight of the liver and centrilobular hypertrophy of the hepatocytes in the 100 and 300 m/kg groups.

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