Registration Dossier

Administrative data

Description of key information

In the key repeated dose 90-day oral toxicity study, conducted according to OECD Test Guideline 408 and in compliance with GLP, the NOAEL for systemic toxicity was concluded to be greater than or equal to 1000 mg/kg bw/day (the highest dose tested) based on no adverse systemic effects (Charles River Laboratories, 2020a).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
7th of January 2020 to ...
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no
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, Inc., Raleigh, NC
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: approximately 7 weeks
- Weight at study initiation: Between 171 and 307 grams
- Fasting period before study: No
- Housing: 2-3 animals of the same sex and same dosing groups were housed together in polycarbonate, solid-bottom cages containing appropriate bedding material (Bed-O-Cobs® or other suitable material).
- Diet: PMI Nutrition International, LLC Certified Rodent LabDiet 5002, ad libitum. Access to diet was restricted during the conduct of the functional observational battery (FOB) and motor activity (MA) assessments.
- Water: Municipal tap water, treated by reverse osmosis and ultraviolet irradiation, ad libitum.
- Acclimation period: At least 7 days.

DETAILS OF FOOD AND WATER QUALITY: Analysis of the nutritional components and environmental contaminants were provided by the supplier and available at the Testing Facility. Periodic analysis of the water was also performed and available at the Testing Facility. It was considered that there are no known contaminants in the water or the feed that could interfere with the outcome of the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20°C - 26°C
- Humidity (%): 30 - 70%
- Air changes (per hr): Not specified
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours dark

IN-LIFE DATES: Not specified
Route of administration:
oral: gavage
Vehicle:
corn oil
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS: Dosing formulations were prepared on a weight to volume basis at appropriate concentrations to meet dose level requirements.

VEHICLE
- Justification for use and choice of vehicle: The vehicle was selected in consultation with the sponsor based on the test item’s characteristics.
- Concentration in vehicle: 0, 25, 75, 250 mg/mL
- Amount of vehicle: 4 mL/kg
- Lot/batch no.: 2IH0387
- Purity: Not specified
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
During the first dose samples preparation and the last preparation, duplicate dose formulation samples were obtained from each dose level group for concentration analysis. The samples were analysed by gas chromatography (GC) method using flame ionization detection (FID). Mean sample concentration within 100% ± 15% of theoretical concentration. Each individual sample concentration result was within or equal to ± 20%.
Prestart homogeneity investigation was included on the samples and collected from various levels (top, middle and bottom) of the low and high dose groups. As the test item was shown to be homogenous, samples were not collected during the study for the investigation of homogeneity. Stability and resuspension homogeneity of the test substance formulations were not assessed as it has previously been shown that the test substance formulations were stable and homogenous over the range of concentrations used in the study.
Duration of treatment / exposure:
90 days
Frequency of treatment:
Once daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Control group
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
Low dose group
Dose / conc.:
300 mg/kg bw/day (nominal)
Remarks:
Middle dose group
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
High dose group
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: The doses were based on the results of a previous dose range finding study (Charles River Laboratories, 2020a). In the study, the test substance was administered to 5 male and female rats by oral gavage for 14 consecutive days at doses of 0, 100, 500 and 1000 mg/kg bw/day in corn oil. On day 14, a slightly lower mean body weight (5%) was noted in the 1000 mg/kg bw/day group males. This correlated with a lower cumulative body weight gain (28%, Day 1 to 14) and minimally lower food consumption (8%) over the course of the study compared to the control group. Males in the 500 mg/kg bw/day dose group had slightly lower cumulative body weight gain (12%, Day 1 to 14) and minimally lower food consumption (5%) compared to controls. There were no effects noted in females. Based on these findings, dose levels of 100, 300, and 1000 mg/kg bw/day were selected for the main study with the aim of inducing toxic effects but not death or severe suffering in the highest dose tested.
- Rationale for animal assignment: randomised (based on mean body weight)
- Fasting period before blood sampling for clinical biochemistry: At least 8 hours although not more than 24 hours.
- Rationale for selecting satellite groups: 5 animals/sex from the control and high dose group were selected as satellite groups.
- Post-exposure recovery period in satellite groups: 28 days of recovery
- Section schedule rationale: randomised
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The health condition of the animals was recorded at least once a day, 0.5 - 3 hours post-dosing, preferably at the same time each day. Twice daily all animals were observed for morbidity and mortality except on days of receipt and necropsy where the frequency was at least once daily.
- Cage side observations checked in table were included: morbidity, mortality, health condition of the animals

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed clinical observations were conducted once prior to the first dosing, then weekly (± 2 days) during the treatment and recovery periods, and on the day of the scheduled necropsies. Detailed clinical observations included examination of posture, convulsions/tremors, biting, palpebral (eyelid) closure, faeces consistency, ease of removal from cage, ease of handling animal in hand, lacrimation/chromodacryorrhea, salivation, piloerection, fur appearance, palpebral closure, respiratory rate/character, red/crusty deposits, mucous membranes/eye/skin colour, eye prominence and muscle tone.

BODY WEIGHT: Yes
- Time schedule for examinations: once prior to the first dosing, then weekly (± 2 days) during the treatment and recovery periods, on the day prior to the first day of scheduled necropsies and on the day of the scheduled necropsies.

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
- Food consumption was measured once weekly (± 2 days) during the treatment and recovery periods.

FOOD EFFICIENCY: No

WATER CONSUMPTION AND COMPOUND INTAKE: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: before the first administration and in the last week of the treatment period as well as at the end of the recovery period in the recovery animals.
- Dose groups that were examined: all animals.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At the end of treatment and recovery period as part of the sacrifice of the animals.
- Anaesthetic used for blood collection: Not specified
- Animals fasted: Yes, at least for 8 hours but not more than 24 hours.
- How many animals: All surviving animals.
- Parameters checked in table were examined: Yes, see table 1.
- Other: Blood was taken from the venipuncture from the jugular vein. Anticoagulant K2EDTA was added.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At the end of treatment and recovery period as part of the sacrifice of the animals.
- Animals fasted: Yes, at least for 8 hours but not more than 24 hours.
- How many animals: All surviving animals.
- Parameters checked in table were examined: Yes, see table 1

URINALYSIS: Yes
- Time schedule for collection of urine: Collected overnight
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes, at least for 8 hours but not more than 24 hours.
- Parameters checked in table were examined: Yes, see table 1

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: During the final week of test substance administration (week 13) and near the end of the recovery period (week 17).
- Dose groups that were examined: All animals in the main study and the recovery group.
- Battery of functions tested:
Open field observations: Time to first step (seconds), mobility, gait, convulsions/tremors, gait score, arousal, bizarre/stereotypic behaviour, rearing. backing, grooming, urination/defecation.
Sensory observations: Approach response, touch response, startle response, tail pinch response, olfactory orientation, pupil response, eyeblink response, forelimb extension, hindlimb extension, air righting reflex.
Neuromuscular observations: Hindlimb extensor strength, grip strength hind and forelimb, rotarod performance, hindlimb foot splay.
Physiological observations: Catalepsy, body temperature, body weight.

IMMUNOLOGY: No

OTHER: Thyroid Hormone Sample Analysis
- Time schedule for examinations: On the day prior to scheduled necropsy and on the day prior to recovery necropsy.
- Method of analysis: For total T3 and T4 analysis, hormone samples were analysed using a validated UHP-LCMS/MS assay. For thyroid stimulating hormone (TSH) analysis, hormone samples were analysed using a validated Luminex Bead-Based (TSH) assay.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see table 2 & 3)

HISTOPATHOLOGY: Yes (see table 3)
Statistics:
All statistical tests were conducted at the 5% significance level. All pairwise comparisons were conducted using two sided tests and were reported at the 1% and 5% levels, unless otherwise noted. For body weight, body weight gains, food consumption, haematology, coagulation, clinical chemistry, urinalysis, organ weights and organ weight relative to body/brain weight used Levene's test. The groups were compared using an overall one-way ANOVA F-test if Levene’s test was not significant or the Kruskal-Wallis test if it was significant. If the overall F-test or Kruskal-Wallis test was found to be significant, then pairwise comparisons were conducted using Dunnett’s or Dunn’s test, respectively. Datasets with 2 groups were compared using a Dunnett’s test equivalent to t-test in Nevis 2012 tables) or Dunn’s test (equivalent to Wilcoxon Rank-Sum test in Nevis 2012 tables). Functional observation battery data, motor activity data, TSH and T3/T4 used the statistical method WTDMS: The groups were compared using an overall one-way ANOVA F-test. If the overall F-test was found to be significant, then pairwise comparisons were conducted using Dunnett’s test. The motor activity ambulatory and total counts data were statistically analysed using SAS Software and/or SAS. All statistical tests were conducted at the 5% significance level and all pairwise comparisons were performed using two-sided tests.
Clinical signs:
no effects observed
Description (incidence and severity):
There were no test substance related clinical observations. All clinical observations in the test substance treated groups were noted with similar incidence in the control group, were limited to single animals, were not noted in a dose related manner, and/or were common findings for laboratory rats of this age and strain.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
One female animal in the 1000 mg/kg bw/day group was found dead on Day 63. No gross lesions could be found at necropsy. Congestion of the adrenal gland, kidney, lung, mandibular lymph node, ovary, thymus and uterus was noted, however, attributed to post/perimortem changes. The cause of death was not determined, although, the effects were not considered as test substance related.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Body weights were unaffected by test substance administration. There were no statistically significant differences when the control and test substance treated groups were compared.
Food consumption and compound intake (if feeding study):
effects observed, non-treatment-related
Description (incidence and severity):
Food consumption was unaffected by test substance administration. However, some statistically significant differences were observed when the control and test substance-treated groups were compared. However, the differences in food consumption were considered to be due to biological variability and not test substance-related since there was no dose response.
Food efficiency:
not examined
Ophthalmological findings:
no effects observed
Description (incidence and severity):
No ophthalmic lesions indicative of toxicity were observed in any of the test substance treated groups. All findings observed were typical in prevalence and appearance for laboratory rats of this age and strain.
Haematological findings:
no effects observed
Description (incidence and severity):
There were no test substance-related effects observed in the haematology parameters, including the coagulation parameters.
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
Clinical chemistry parameters were unaffected by the test substance administration. Any differences, regardless of statistical significance, were not considered test substance-related based on their general overlap of individual mean values with the range of concurrent control, and/or were of a magnitude of change commonly observed in rats under similar study conditions.
Urinalysis findings:
no effects observed
Description (incidence and severity):
Urinalysis parameters were unaffected by the test substance administration. Any differences in urine parameters were not considered test substance related based on their general overlap of individual mean values with the range of concurrent control and/or were of a magnitude of change commonly observed in rats under similar study conditions.
Behaviour (functional findings):
effects observed, non-treatment-related
Description (incidence and severity):
Open field observations, sensory observations, neuromuscular observations and physiological observations were unaffected by test substance administration as no statistically significant difference occurred compared to the control group on weeks 13 and 17 evaluations.
No test substance-related effects were observed in the locomotor activity in any of the animals. However, a statistically significant lower ambulatory count was observed in high dose recovery females on week 17 (towards the end of recovery period) for the 0-10 minutes interval. However, no other indications of reduced activity occurred on weeks 13 or 17 therefore the incident was regarded as not test substance-related.
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
In the 1000 mg/kg bw/day male group, mean absolute brain weight was lower than the mean control brain weight. However, this was only observed in one sex, lacked histologic correlations and was within the historical control database range of values. Therefore, the effect was not observed as test substance related. Other isolated organ weight values that were statistically different from their respective controls occurred. Although, no patterns, trends or correlating data could be established to suggest these values were toxicologically relevant. Thus, the organ weight differences observed were considered incidental and/or related to difference of sexual maturity and unrelated to administration of the test substance.

In the recovery group, isolated organ weight values were statistically different from their respective controls. Mean ovary/oviduct weights (absolute and relative to terminal body weight and brain weight) were higher in the 1000 mg/kg bw/day female group than in controls, however, lacked histologic and gross correlations and were not present at the terminal euthanasia. Additionally, mean testis weight (relative to brain weight) was higher in the 1000 mg/kg bw/day male group than in the control group. Nevertheless, this was not evident in absolute weight or weight relative to terminal body weight, lacked gross/histologic correlates and was not observed at the terminal euthanasia. Additionally, no other patterns, trends, or correlating data was established to suggest these values were toxicologically relevant. Thus, the organ weight differences observed were considered incidental and/or related to difference of sexual maturity and unrelated to the administration of the test substance.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No test substance-related effects were observed in any dose groups.
Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
Adrenal glands: minimal to moderate adrenal cortical vacuolation was noted in 6 out of 10 males i n the 1000 mg/kg bw/day group and mild to moderate cortical vacuolation in 3 out of 10 males in the 300 mg/kg bw/day group. Females in either group were not affected. Minimal or mild cortical hypertrophy y was noted in 2 out of 10 males in the 1000 mg/kg bw/day group and minimal to moderate hypertrophy was noted in 5 out of 10 males in the 300 mg/kg bw/day group. There were no instances in the control group males. Low incidences of cortical hypertrophy were present in control and treated group females, although, this did not rise above background levels. Adrenal cortical vacuolation and hypertrophy are common incidental findings and due to the low severity and lack of other histologic changes were considered non-adverse in this study.
Lungs: The lungs were examined as potential target tissues due to the presence of mixed inflammation in the 1000 mg/kg bw/day group males and females at the terminal euthanasia. Evaluation of low- and middle dose groups at the terminal euthanasia and control and high-dose groups at the recovery euthanasia revealed that minimal to moderate infiltration and inflammation occurred at low levels across control and treated groups. This was characterised by mixed cell, mononuclear, histiocytic or granulomatous reactions. All findings were considered a spectrum of effects most likely secondary to accidental inhalation of vehicle or test substance during gavage or related to some other aspect of the experimental procedure. There was no clear dose relationship in incidence or severity of the findings and therefore, considered as incidental and not test substance related.
Histopathological findings: neoplastic:
no effects observed
Other effects:
effects observed, non-treatment-related
Description (incidence and severity):
No test substance-related effects were observed in the total amount of T3, T4, or TSH. However, statistically significantly lower T4 was noted in the 300 and 1000 mg/kg bw/day group males on day 90. Upon review, it was noted that the control value was artificially elevated due to the value in a single male. When this male was excluded, the values for the 300 and 1000 mg/kg bw/day group males were consistent with the concurrent control group. Therefore, this difference was not considered as test substance-related.
Additionally, statistically significantly higher T4 was noted in the 1000 mg/kg bw/day group females on day 118. This difference was attributed to a lower mean concurrent control value due to 3 control females with individual values below 20000 pg/mL and not a test substance-related effect. Furthermore, individual TSH samples across all groups were noted as result unobtainable (RU). These samples often had a high replicate variability and therefore, did not produce an acceptable result across the 3 separate occasions of analysis. The variability was considered to be due to a suspected matrix effect.

There were no test substance-related effects on the oestrous cycle for females at any dose level when evaluated prior to the terminal necropsy.
Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse effects observed
Critical effects observed:
no
Conclusions:
In a repeated dose 90-day oral toxicity study, conducted according to OECD Test Guideline 408 and in compliance with GLP, the NOAEL for systemic effects was concluded to be ≥1000 mg/kg bw/day based on no adverse effects observed up to the highest dose tested.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
1 000 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
Klimisch score of 1

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

In the key repeated dose 90-day oral toxicity study, conducted according to OECD Test Guideline 408 and in compliance with GLP, 3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane was tested in male and female Crl:CD(SD) rats at doses of 0 (vehicle only), 100, 300 or 1000 mg/kg bw/day in corn oil (Charles River Laboratories, 2020a). The dose levels were selected based on the findings of the dose range-finding study (Charles River Laboratories, 2020b) with the aim of inducing toxic effects but not death or severe suffering in the highest dose tested. Clinical signs, body weights, body weight gains, food consumption, ophthalmology, haematology, clinical chemistry, urinalysis, thyroid hormone analysis (T3, T4, and TSH), oestrous cycles, gross necropsy findings, organ weights and histopathologic examinations were evaluated. Additionally, functional observational battery (FOB) was observed which included motor activity, open field observations: Time to first step (seconds), mobility, gait, convulsions/tremors, gait score, arousal, bizarre/stereotypic behaviour, rearing. backing, grooming, urination/defecation; sensory observations: Approach response, touch response, startle response, tail pinch response, olfactory orientation, pupil response, eyeblink response, forelimb extension, hindlimb extension, air righting reflex; neuromuscular observations: Hindlimb extensor strength, grip strength hind and forelimb, rotarod performance, hindlimb foot splay; physiological observations: catalepsy, body temperature and body weight.

No clinical signs, body weight differences or food consumption differences were observed in any of the test animals. One female animal in the 1000 mg/kg bw/day group was found dead on Day 63. No gross lesions could be found at necropsy. Congestion of the adrenal gland, kidney, lung, mandibular lymph node, ovary, thymus and uterus was noted, however, this was attributed to post/perimortem changes. The cause of death was not determined, although the effects were not considered to be test substance related. There were no haematological, clinical biochemistry or urinalysis findings that were test substance-related. Open field observations, sensory observations, neuromuscular observations and physiological observations were unaffected by test substance administration. There were no test substance-related effects on locomotor activity in any of the animals at either the Week 13 (prior to scheduled necropsy) or Week 17 (towards the end of recovery period) evaluation. However, there was a statistically significant lower mean Ambulatory Count in high dose recovery females at Week 17 for the 0-10 minutes interval, compared to the control. There were no other indications of reduced activity noted during the FOB at Week 17, nor during either FOB at Week 13; therefore, this difference was not considered to be test substance-related.

In the 1000 mg/kg bw/day male group, mean absolute brain weight was lower than the mean control brain weight. However, this was only observed in one sex, lacked histologic correlation and was within the historical control database range of values. Therefore, the effect was not considered to be test substance-related. Isolated organ weight values that were statistically different from their respective controls occurred without patterns, trends or correlating data to suggest any toxicological relevance. Thus, the organ weight differences observed were considered incidental and/or related to difference of sexual maturity and unrelated to administration of the test substance.

In the recovery group, isolated organ weight values were statistically different from their respective controls. Mean ovary/oviduct weights (absolute and relative to terminal body weight and brain weight) were higher in the 1000 mg/kg bw/day female group than in controls, however, lacked histologic and gross correlations and were not present at the terminal euthanasia. Additionally, mean testis weight (relative to brain weight) was higher in the 1000 mg/kg bw/day male group than in the control group. Nevertheless, this was not evident in absolute weight or weight relative to terminal body weight, lacked gross/histologic correlates and was not observed at the terminal euthanasia. Additionally, no other patterns, trends, or correlating data was established to suggest these values were toxicologically relevant. Thus, the organ weight differences observed were considered incidental and/or related to difference of sexual maturity and unrelated to the administration of the test substance.

In the adrenal glands, minimal to moderate adrenal cortical vacuolation was noted in 6 out of 10 males in the 1000 mg/kg bw/day group and mild to moderate cortical vacuolation in 3 out of 10 males in the 300 mg/kg bw/day group. Females in either group were not affected. Minimal or mild cortical hypertrophy was noted in 2 out of 10 males in the 1000 mg/kg bw/day group and minimal to moderate hypertrophy was noted in 5 out of 10 males in the 300 mg/kg bw/day group but none in the control group males. Low incidences of cortical hypertrophy were present in control and treated group females, although, this did not rise above background levels. Adrenal cortical vacuolation and hypertrophy are common incidental findings and due to the low severity and lack of other histologic changes were considered non-adverse in the study.

Lungs were examined as potential target tissues due to the presence of mixed inflammation in the 1000 mg/kg bw/day group males and females at the terminal euthanasia. Evaluation of low- and mid-dose groups at the terminal euthanasia and control and high-dose groups at the recovery euthanasia revealed that minimal to moderate infiltration and inflammation occurred at low levels across control and treated groups. This was characterised by mixed cell, mononuclear, histiocytic, or granulomatous reactions. All findings were considered a spectrum of effects most likely secondary to accidental inhalation of vehicle or test substance during gavage or related to some other aspect of the experimental procedure. There was no clear dose relationship in incidence or severity of the findings and therefore, considered as incidental and not test substance related.

No test substance-related effects were observed in the total amount of T3, T4, or thyroid stimulating hormone (TSH). However, statistically significantly lower T4 was noted in the 300 and 1000 mg/kg bw/day group males on Day 90. Upon review, it was noted that the control value was artificially elevated due to the value in a single male. When this male was excluded, the values for the 300 and 1000 mg/kg bw/day group males were consistent with the concurrent control group. Therefore, this difference was not considered as test substance-related.

Additionally, statistically significantly higher T4 was noted in the 1000 mg/kg bw/day group females on Day 118. This difference was attributed to a lower mean concurrent control value due to 3 control females with individual values below 20000 pg/mL and not a test substance-related effect. Furthermore, individual TSH samples across all groups were noted as result unobtainable (RU). These samples often had a high replicate variability and therefore, did not produce an acceptable result across the 3 separate occasions of analysis. The variability was considered to be due to a suspected matrix effect.

The NOAEL for systemic effects for males and females was concluded to be equal to or greater than 1000 mg/kg bw/day (the highest dose tested) based on no adverse effects in any of the test animals.

In the 14-day dose range-finding study, which was not conducted according to a guideline or GLP, a NOAEL was not concluded (Charles River Laboratories, 2020b). In the study 5 male and 5 female rats per dose were administered daily oral (gavage) doses of 0, 100, 500 and 1000 mg/kg bw/day 3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane in corn oil for 14 consecutive days. The following parameters and end points were evaluated in this study: clinical signs, body weights, body weight gains, food consumption, clinical pathology parameters (serum chemistry), gross necropsy findings, and organ weights.

All animals survived to the scheduled necropsy. There were no test substance-related clinical observations or effects on serum chemistry or organ weights. There were no test substance-related macroscopic findings. Test substance-related lower body weight gains were noted from days 1 to 7 and from days 1 to 14 in the 500 and 1000 mg/kg bw/day group males. Test substance-related lower mean food consumption was noted in the 1000 mg/kg bw/day group males over days 1 to 14. The differences led to a lower mean day 14 body weight that was only considered different from controls for the 1000 mg/kg bw/day males. Based on the results of this study, oral administration of the test substance to rats at dose levels of 100, 500, and 1000 mg/kg bw/day for 14 consecutive days resulted in lower mean body weights and/or lower cumulative body weight gains in males at 500 and 1000 mg/kg bw/day. The results of this study are used to select dose levels for the main 90-day oral repeated dose toxicity study.

Justification for classification or non-classification

Based on the available information, 3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane does not require classification for target organ toxicity following repeated exposure according to Regulation (EC) No 1272/2008.