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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
29 January 2019 to 04 March 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

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

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aim of this 14-day dose-range finding study was to provide a basis for the selection of dose levels to be used in prenatal developmental toxicity study via oral (gavage) route. The dose-range finding study was planned to assess the possible health hazards, in particular local corrosive effects, which could arise from repeated exposure of dichloro(cyclohexyl)methylsilane via oral administration to rats. Therefore, macroscopic and microscopic examinations of the animals were limited to the respiratory and gastrointestinal tracts.
GLP compliance:
no
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Dichlorocyclohexylmethylsilane
EC Number:
226-956-0
EC Name:
Dichlorocyclohexylmethylsilane
Cas Number:
5578-42-7
Molecular formula:
C7H14Cl2Si
IUPAC Name:
[dichloro(cyclohexyl)methyl]silane
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: soluble and stable in corn oil
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: n/a

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was weighed into a tared plastic vial on a suitable precision balance and the vehicle was added to give the appropriate final concentration of the test item. The formulation was alternately vortexed and/or stirred until visual homogeneity was achieved.
- Preliminary purification step (if any): no
- Final dilution of a dissolved solid, stock liquid or gel: n/a
- Final preparation of a solid: n/a

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 14-15 weeks old
- Weight at study initiation: males: 343 – 368 g; females: 234 – 254 g
- Fasting period before study: no
- Housing: The animals were kept in groups of 2 animals / sex / group / cage in IVC cages
- Diet (e.g. ad libitum): Altromin 1324 maintenance diet for rats and mice ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: at least 5 days

DETAILS OF FOOD AND WATER QUALITY: Certificates of food, water and bedding are filed for two years at BSL Munich and afterwards archived at Eurofins Munich

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/-3°C
- Humidity (%): 55+/-10%
- Air changes (per hr): 10 x / hour
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: The test item was weighed into a tared plastic vial on a suitable precision balance and the vehicle was added to give the appropriate final concentration of the test item. The formulation was alternately vortexed and/or stirred until visual homogeneity was achieved.

VEHICLE
- Justification for use and choice of vehicle (if other than water): The vehicle used in this study was dried and de-acidified corn oil. The vehicle was selected in consultation with the sponsor based on the test item’s characteristics.
- Concentration in vehicle: 0, 12.5, 25, 62.5, 43.75 and 93.75 mg/mL
- Amount of vehicle (if gavage): not specified
- Lot/batch no. (if required): MKCG3257
- Purity: not specified
Analytical verification of doses or concentrations:
no
Details on analytical verification of doses or concentrations:
A dose formulation analysis was not performed in this study.
Duration of treatment / exposure:
14 days
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Remarks:
Group 1
Dose / conc.:
50 mg/kg bw/day (actual dose received)
Remarks:
Group 2
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Remarks:
Group 3
Dose / conc.:
250 mg/kg bw/day (actual dose received)
Remarks:
Group 4
Dose / conc.:
175 mg/kg bw/day (actual dose received)
Remarks:
Group 5
Dose / conc.:
375 mg/kg bw/day (actual dose received)
Remarks:
Group 6
No. of animals per sex per dose:
2 male and 2 female per dose
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: The doses for the first dose group and the control group were selected in consultation with the sponsor prior to the start of the study. The remaining doses were selected sequentially in consultation with the sponsor during the course of the treatment period of this study. The treatment was started with 50 mg/kg bw/day. Later the dose groups were tested at 100 mg/kg bw/day, 250 mg/kg bw/day, 175 mg/kg bw/day and 375 mg/kg bw/day. Before starting dosing with a new higher dose level at least 3 treatments per animal and dose group were made. The animals were treated with the test item or vehicle on 7 days per week for a period of 14 days.
- Rationale for animal assignment (if not random): random
- Fasting period before blood sampling for clinical biochemistry: yes
- Rationale for selecting satellite groups: n/a
- Post-exposure recovery period in satellite groups: n/a
- Section schedule rationale (if not random): random
Positive control:
No

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations included: morbidity and mortality

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once a day

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight was recorded once before assignment to the experimental groups and on study days 1, 3, 6, 8, 11 and 14 during the treatment period as well as on the day of necropsy

FOOD CONSUMPTION:
- Time schedule for examinations: Food consumption was measured on study days 1, 8 and 14 for each animal.

FOOD EFFICIENCY: No

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

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the treatment
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: all animals
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the treatment
- Animals fasted: Yes
- How many animals: all animals
- Parameters checked in table [No.1] were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see table No 2)

HISTOPATHOLOGY: Yes (see table No 2)
Statistics:
Toxicology and pathology data were captured either on paper according to appropriate SOPs or using the validated computerised system Ascentos® System (version 1.3.4, Pathology Data Systems Ltd.).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Description (incidence and severity):
Treatment with test item did not show any adverse clinical signs in male and females of up to 375 mg/kg bw/day. Clinical signs like moving the bedding were transiently observed in all male and female animals of group 5-6 (175 or 375 mg/kg bw/day). This is assumed to be due to discomfort caused by a local reaction to test item.
Mortality:
mortality observed, treatment-related
Description (incidence):
During the study, one female at 375 mg/kg bw/day was found dead on treatment day 9. Inflammatory lesions of the stomach were considered to be the cause of mortality, however all other animals survived until the scheduled sacrifice.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Treatment with test item in male and females did not affect the body weight gain and were found to be comparable with control. Males showed tendency to gain body weight throughout the study period.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Mean food consumption from treatment day 1 to 14 was found to be comparable up to 375 mg/kg bw/day when compared to control both in male and female.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Description (incidence and severity):
Treatment with test item had no dose-dependent effect on haematology in any of the test item-treated groups. Differences between test item-treated males and females and their respective controls showed no dose-dependency or consistency and thus were not considered toxicologically relevant.
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
Treatment with test item had no dose-dependent effect on biochemistry in any of the test item-treated groups. Differences between test item-treated males and females and their respective controls showed no dose-dependency or consistency and thus were not considered toxicologically relevant.
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
Mean organ weights showed no dose-dependent differences between males and females treated with the test item and the respective control group. Organ weights from only one female was available from group 6 (375 mg/kg bw/day) as one female rats was found dead prior to the scheduled sacrifice date.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Test item-related gross lesions were noted in the stomach and large intestine at 175 or 375 mg/kg bw/day. Gross lesions in the stomach are consisting of abnormal surface and ulcerated gastric wall. In groups 6, gas filled stomach and colon was observed. Single incidence of abnormal colour (red) lungs was observed at 100 mg/kg bw/day and at 375 mg/kg bw/day.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Test item caused inflammatory and degenerative findings in the stomach from animals at 50 mg/kg bw/day onwards. These findings consisted at 50 mg/kg bw/day of acute inflammation in the glandular stomach mucosa and single cell necrosis in the glandular mucosa. At 100 mg/kg bw/day, there were forestomach ulceration, glandular stomach erosion, inflammations in the forestomach submucosa and/or epithelial hyperplasia of the forestomach in one male and two females.
From 175 to 375 mg/kg bw/day, the findings consisted of forestomach and glandular stomach ulceration, inflammation of the forestomach and/or glandular stomach submucosa, and squamous cell hyperplasia of the forestomach. In one case at 375 mg/kg bw/day, there was an inflammation in the serosa, i.e., peritonitis. The findings caused in the stomach from both males and one female at 375 mg/kg bw/day, test item-related gross lesions consisting of crateriform or ulcerated surfaces.
One of the females at 375 mg/kg bw/day was found dead during the course of the study. This female was affected by the aforementioned inflammatory lesions of the stomach. In addition, there was an acute necrotizing inflammation in the larynx and trachea. The inflammatory lesions in the larynx and trachea were deemed to be a consequence of aspiration. Furthermore, there was inflammatory secretion in the nasal cavities.
Histopathological findings: neoplastic:
not examined
Other effects:
not examined

Effect levels

open allclose all
Dose descriptor:
NOAEL
Remarks on result:
not determinable
Dose descriptor:
LOAEL
Effect level:
50 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic

Target system / organ toxicity

Critical effects observed:
yes
Lowest effective dose / conc.:
50 mg/kg bw/day (actual dose received)
System:
gastrointestinal tract
Organ:
stomach
Treatment related:
yes
Dose response relationship:
yes

Applicant's summary and conclusion

Conclusions:
In a 14-day dose range-finding study, which was not conducted according to a guideline or GLP, a NOAEL was not concluded (Bioservice, 2019). In the study test item-related gross lesions were noted in the gastrointestinal organs at ≥ 175 mg/kg bw/day and these were evident during histopathological examination. At the microscopic examination, specific findings were found, starting at the dose of 50 mg/kg bw/day. These findings included inflammatory and degenerative lesions which consisted of inflammation, erosions, hyperplasia, ulceration and epithelial degeneration.