3-[3,3,3-trimethyl-1,1-bis[(trimethylsilyl)oxy]disiloxanyl]propyl methacrylate

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Description of key information

One key study is available. Study is an ICED 422 performed in accordance with GLP.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 May 2017 - 10 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Remarks:

range-finding study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

29 July 2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 05/12/2016, Date of issue: 15/03/2017

Limit test:

no

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Sponsor / 440038-285
- Expiration date of the lot/batch: 15 March 2019
- Purity test date: no data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Refrigerated (2 to 8°C) in darkness
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: stable

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: none

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:
Charles River (UK) Ltd
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation:
Males: 69 to 76 days old.
Females: 83 to 90 days old

- Weight at study initiation:
Males: 333 to 387 g.
Females: 239 to 302 g.

- Fasting period before study:
NO DATA
- Housing:
Cages comprised of a polycarbonate body with a stainless steel mesh lid; changed at appropriate intervals.
Solid (polycarbonate) bottom cages were used during the acclimatization, pre-pairing, treatment, gestation, littering and lactation periods.
Grid bottomed cages were used during pairing. These were suspended above absorbent paper which was changed daily during pairing.

Number of animals per cage
Pre-pairing up to five animals of one sex
Pairing one male and one female
Males after mating up to five animals
Gestation one female
Lactation one female + litter

- Diet (e.g. ad libitum):
ad libitum
- Water (e.g. ad libitum):
ad libitum
- Acclimation period:
Males: six days before commencement of treatment.
Females: 20 days before commencement of treatment.

Environmental Enrichment
Aspen chew block A soft white untreated wood block; provided to each cage throughout the study [(except during pairing and lactation
(returned on Day 13 of lactation, after dispatch of the litter)] and replaced when necessary.
Plastic shelter Provided to each cage throughout the study [(except during pairing and lactation (returned on Day 13 of lactation, after
dispatch of the litter)] and replaced at the same time as the cages.


DETAILS OF FOOD AND WATER QUALITY:
DIET
SDS VRF1 Certified pelleted diet.
A sample (100g) of each batch of diet used was retained within Pharmacy (frozen -10 to -30ºC) until finalization of the report. Samples were discarded after finalization of the report.
The diet contained no added antibiotic or other chemotherapeutic or prophylactic agent.

WATER
Potable water from the public supply via polycarbonate bottles with sipper tubes. Bottles were changed at appropriate intervals.

Certificates of analysis for the diet are scrutinized and approved before any batch of diet was released for use. Certificates of analysis were routinely provided by the water supplier.

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
20-24ºC
- Humidity (%):
40-70%.
- Air changes (per hr):
Filtered fresh air which was passed to atmosphere and not recirculated.
- Photoperiod (hrs dark / hrs light):
12 hours light / 12 hours dark.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

Route: Oral gavage using a suitably graduated syringe and a rubber catheter inserted via the mouth.
Treated at: constant doses in mg/kg/day.
Volume dose: 5 mL/kg body weight.
Individual dose volume: Calculated from the most recently recorded scheduled body weight.
Control (Group 1): vehicle at the same volume dose as treated groups.
Frequency: Once daily at approximately the same time each day.
Formulation: A daily record of the usage of formulation was maintained based on weights. This balance was compared with the expected usage as a check of correct administration. No significant discrepancy was found.

VEHICLE
- Justification for use and choice of vehicle (if other than water): substance insoluble in water

Details on mating procedure:

- M/F ratio per cage: 1:1 from within the same treatment groups.
- Length of cohabitation: up to two weeks.
- Proof of pregnancy: ejected vaginal plug in cage tray and sperm in vaginal smear referred to as day 0 of pregnancy
- Male/female separation: Day when mating evidence was detected.
- Pre-coital interval: Calculated for each female as the time between first pairing and evidence of mating.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of each formulation prepared for administration in Week 1 (for each treatment group) and on Day 10 to 12 of lactation (females only) were analysed for achieved concentration of the test item. See Attachment 1 for full analytical methods. The analytical procedure was successfully validated with respect to specificity of chromatographic analysis, limits of detection and quantification, linearity of detector response, repeatability, method accuracy and precision. The homogeneity and stability was confirmed for 3-(3,3,3-Trimethyl-1,1- bis( (trimethylsilyl)oxy)disiloxanyl) propyl methacrylate in Corn Oil formulations at nominal concentrations of Low nominal concentration mg/mL and High nominal concentration mg/mL during distribution be tween the bottles, during magnetic stirring for 2 hours, ambient temperature storage for 1 day and refrigerated storage for up to 15 days. The mean concentrations of 3-[3,3,3trimethyl-1,1bis[(trime thylsiyl)oxy] dissiloxanyl] propyl methacrylate in test formulations analysed for the study were within ±3% of nominal concentrations, confirming accurate formulation.

Duration of treatment / exposure:

Males Two weeks before pairing up to necropsy after a minimum of five weeks of treatment.
Females Two weeks before pairing, then throughout pairing and gestation until Day 13 of lactation.
Animals of the F1 generation were not dosed.

Frequency of treatment:

Once daily at approximately the same time each day.

Details on study schedule:

The F1 generation received no direct administration of the test item, 3-(3,3,3-Trimethyl-1,1-bis((trimethylsilyl)oxy)disiloxanyl)propyl methacrylate. Any exposure to the test item or metabolites was through the mother to the offspring in utero and/or through the milk.

Dose / conc.:

200 mg/kg bw/day

Dose / conc.:

500 mg/kg bw/day

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
- Dose selection rationale: doses were selected on the basis of a range finding study (linked to this endpoint)

Positive control:

No

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Animals were inspected visually at least twice daily for evidence of ill-health or reaction to treatment. Cages were inspected daily for evidence of animal ill-health amongst the occupant(s). Any deviation from normal was recorded at the time in respect of nature and severity, date and time of onset, duration and progress of the observed condition, as appropriate.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule:
Detailed observations were performed to establish and confirm a pattern of signs in association with dosing according to the following schedule:
F0 males Week 1 - daily
Week 2 onwards - once each week
F0 females Week 1 - daily
Week 2 - once
Gestation phase - Days 0, 7, 14 and 20
Lactation phase - Days 1, 6 and 12

Detailed observations were recorded at the following times in relation to dose administration:
Pre-dose observation
One to two hours after completion of dosing
As late as possible in the working day


BODY WEIGHT: Yes
- Time schedule for examinations:
The weight of animals was recorded as follows:
F0 males Weekly during acclimatization.
Before dosing on the day that treatment commenced (Day 0) and weekly thereafter.
On the day of necropsy.
F0 females Weekly during acclimatization.
Before dosing on the day that treatment commenced (Day 0) and weekly before pairing.
Days 0, 7, 14 and 20 after mating.
Day 1, 4, 7 and 13 of lactation.
On the day of necropsy.

FOOD CONSUMPTION:
The weight of food supplied to each cage and an estimate of any spilled was recorded as follows:
F0 animals: Weekly, from the day that treatment commenced.
Food consumption was not recorded for males and females during the period when paired for mating (Week 3), but recommenced for males in Week 4. For females after mating food consumption was performed to match the body weight recording:
Days 0-6, 7-13 and 14-19 after mating
Days 1-3, 4-6 and 7-12 of lactation.
From these records the mean daily consumption per animal (g/animal/day) was calculated for each relevant phase.


OTHER: The study performed was an OECD 422 and therefore parameters associated with repeated-dose toxicity were also recorded:
- Blood samples were collected at termination. Animals sampled: the five lowest numbered surviving males and the first five lactating females with a surviving litter per group.
- Blood chemistry: samples were collected at termination. Animals tested: The five lowest numbered surviving males and the first five lactating females with a surviving litter per group.

Oestrous cyclicity (parental animals):

Dry and wet smears were taken as follows:
Dry smears: For 15 days before pairing using cotton swabs.
Wet smears: Using pipette lavage during the following phases:
For 14 days before treatment (all females including spares); animals that failed to exhibit 4-5 day cycles were not allocated to study.

After pairing until mating.

For four days before scheduled termination (nominally Days 11-14 of lactation).

Sperm parameters (parental animals):

Parameters examined in F1 male parental generations:
For the assessment of the testes, a detailed qualitative examination was made, taking into account the tubular stages of the spermatogenic cycle. The examination was conducted in order to identify treatment related effects such as missing germ cell layers or types, retained spermatids, multinucleate or apoptotic germ cells and sloughing of spermatogenic cells in the lumen. Any cell- or stage-specificity of testicular findings was noted.

Litter observations:

PARAMETERS EXAMINED
Clinical observations: Examined at approximately 24 hours after birth (Day 1 of age) and then daily thereafter for evidence of ill health or reaction to maternal treatment; these were on an individual offspring basis or for the litter as a whole, as appropriate.
Litter size: Daily records were maintained of mortality and consequent changes in litter size from Days 1-13 of age.
Sex ratio of each litter: Recorded on Days 1, 4, 7 and 13 of age.
Individual offspring body weights: Days 1, 4, 7 and 13 of age.
Ano-genital distance: Day 1 - all F1 offspring.
Nipple/areolae count: Day 13 of age - male offspring.

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals
- Maternal animals: All surviving animals

Method of Kill:
All adult animals: Carbon dioxide asphyxiation.
Offspring - selected for thyroid hormone sampling on Day 4 and 13 of age: Decapitation. Offspring - all other: Intraperitoneal injection of sodium pentobarbitone.
Sequence: To allow satisfactory inter-group comparison.

GROSS NECROPSY
All adult animals were subject to a detailed necropsy. After a review of the history of each animal, a full macroscopic examination of the tissues was performed. All external features and orifices were examined visually. Any abnormality in the appearance or size of any organ and tissue (external and cut surface) was recorded and the required tissue samples preserved in appropriate fixative.

In female rats the following was recorded:
Each uterine horn: Number of implantation sites was counted and confirmed if none were visible at visual inspection.

Time of Necropsy
F0 males: After Week 5 investigations completed.
F0 females failing to produce a viable litter: Day 25 after mating.
F0 females: Day 14 of lactation (following terminal blood sampling).
F1 offspring Selected offspring for thyroid hormone analysis - Day 4 of age. Scheduled kill - Day 13 of age.

organs detailed in table 1 were reviewed.


HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated in Table 1 and 2 were prepared for microscopic examination and weighed, respectively.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring were sacrificed at either Day 4 of age (for thyroid analysis) or Day 13 (scheduled kill)
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows:
Premature deaths: Where possible, a fresh macroscopic examination (external and internal) with an assessment of stomach for milk content was performed. Abnormal tissues were retained.
F1 offspring on Day 4 of age: Blood sampling required (as per repeated dose study)
Externally normal offspring discarded without examination.
Externally abnormal offspring examined, and retained pending possible future examination.
F1 offspring on Day 13 of age: Blood sampling required (as per repeated dose study).
All animals were subject to an external macroscopic examination; particular attention was paid to the external genitalia. Animals observed with external abnormalities were retained pending possible future examination.
Thyroid glands were preserved from one male and one female in each litter.



GROSS NECROPSY
- Gross necropsy consisted of external macropathology only.

Statistics:

For estrous cycles an exact one-tailed (upper-tail) Linear-by-linear test (Cytel 1995) was applied to all groups, using scores appropriate to the severity of the observation assuming 4/5 day cycles to be normal. The categories were scored as follows: a 4/5 day cycle was scored as 4.5 and irregular and acyclic cycles were scored as 6. If the test was statistically significant (p<0.05), the highest dose group was excluded and the test re-applied. This ‘step down’ process was repeated until the test was no longer statistically significant (p≥0.05). If the exact version of the Linear-by-linear test could not be calculated (due to the size of the table containing the data), then the asymptotic version was used instead.
For gestation length an exact two-tailed Linear-by-linear test (Cytel 1995), with equally spaced scores, was applied to all groups. If the test was statistically significant (p<0.05), the highest dose group was excluded and the test re-applied. This ‘step-down’ process was repeated until the test was no longer statistically significant (p≥0.05). If the exact version of the Linear-by-linear test could not be calculated (due to the size of the table containing the data), then the asymptotic version was used instead.
For number conceiving and number fertile an exact one-tailed (lower-tail) Cochran-Armitage test (Cytel 1995) was applied to all groups. If the test was statistically significant (p<0.05), the highest dose group was excluded and the test re-applied. This ‘step down’ process was repeated until the test was no longer statistically significant (p≥0.05).
Sex ratio was analyzed by generalized mixed linear model with binomial errors, a logit link function and litter as a random effect (Lipsitz 1991). Each treated group was compared to control using a Wald chi-square test. For sex ratio, the numerator was Number of males, the denominator was Number of live fetuses.

Reproductive indices:

-Percentage mating (%)
- Conception rates (%)
- Fertility index (%)
- Gestation index (%)

Offspring viability indices:

- Post-implantation viability index (%)
- Live birth index (%)
- Viability index (%)
- Lactation index (%)
- Sex ratio

Clinical signs:

no effects observed

Description (incidence and severity):

No test item-related changes in general clinical condition were observed following treatment with 3- [3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.

Mortality:

mortality observed, treatment-related

Description (incidence):

Group 4 male No. 3 receiving 1000 mg/kg/day was killed for welfare reasons on Day 32 of treatment due to underactivity and reduced body temperature and had shown signs of incoordination and abnormal gait. Gross abnormalities were observed in the skin (scabs), liver (pale and dark areas), spleen (enlarged), mesenteric lymph nodes (dark), pancreatic lymph nodes (dark and enlarged), teste s (dark areas), eyes (dark areas) and meninges of the brain (thickened). At microscopic examination , vacuolated macrophage aggregates/inflammation and hepatocyte necrosis considered to be test item-related were seen in the liver. Myeloid cell leukemia was also seen in most tissues (lungs, liver, and kidneys) and was considered as a factor contributory to death, though not related to treatment.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No test item-related changes in bodyweight and bodyweight gain were observed following treatment with 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No test item-related changes in food consumption were observed following treatment with 3-[3,3,3-tri methyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.

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):

Hematology investigations after 5 weeks of treatment revealed males at 200 mg/kg/day and males and females at 500 and 1000 mg/kg/day had lower than Control hematocrit and hemoglobin concentrations, with dose responses evident in males. Males receiving 200, 500 and 1000 mg/kg/day had higher than Control reticulocytes. Males at 500 or 1000 mg/kg/day and females at 200, 500 and 1000 mg/kg/day had lower than Contro l red cell distribution width with a dose response evident in both sexes. Mean cell volume was also lower than Control in all treated groups and both sexes although no dose response was apparent. Total leucocyte count was dose-dependently increased in all treated groups of males and increased in treated females as a result of increased neutrophils and/or lymphocytes when compared with Control. All inter-group differences, including those attaining statistical significance, were minor, confined to one sex or lacked dose-relationship and were therefore attributed to normal biological variation.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

The biochemical examination of the blood plasma performed after five weeks of treatment for males and on Day 14 of lactation for females indicated revealed no test-item related changes. All inter-group differences, including those attaining statistical significance, were minor, confined to one sex or lacked dose-relationship and were therefore attributed to normal biological variation.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Sensory reactivity and grip strength: The sensory reactivity observations conducted during Week 5 of treatment for males and Day 7-9 of lactation for females revealed no findings which were considered treatment related in animals recei ving 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate at doses of 200, 500 and 1000 mg/kg/day. Motor activity: Motor activity conducted during Week 5 of treatment for males and Day 7-9 of lactation for females re vealed no findings which were considered treatment related in animals receiving 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate at doses of 200, 500 and 1000 mg/kg/day.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test item-related changes were seen in the liver and mesenteric lymph nodes. Liver: Hepatocyte hypertrophy, vacuolated macrophage aggregates associated with or without inf lammation, inflammation and necrosis were seen in the liver of males and females given 1000 mg/kg/ day. Similar findings were seen in some males given 200 or 500 mg/kg/day. Mesenteric lymph nodes: Vacuolated macrophage aggregates were seen in males and females given 1000 mg/kg/day.

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Description (incidence and severity):

Findings of an Uncertain Relationship to Treatment Skin: Epidermal erosion and/or scabs, usually accompanied by hyperplasia, dermal/subcutaneous inflammation and/ or dermal haemorrhage were seen in males of all treatment groups. These findings were present on additional sections of skin presented because of abnormalities identified at necro psy (scabs). No histopathological changes were seen in the routine skin samples. Due to the anato mical distribution of findings (side of the face) and absence in treated females, these findings were considered to be of uncertain relationship to treatment.

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

All females allocated to study showed normal 4/5 day estrous cycles during the acclimatization period. Estrous cyclicity, pre-coital interval, gestation length and gestation index were considered unaffected by treatment with 3-[3,3,3-trimethyl-1,1 bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

effects observed, non-treatment-related

Description (incidence and severity):

Mating performance and fertilit y was 100% for control animals and in animals receiving 200 or 500 mg/kg/day, and 80% for animals receiving 1000 mg/kg/day. In the 2 pairings in the 1000 mg/kg/day which did not result in pregnancy, both females were cycling normally before and during treatment and both pairs mated with reasonable mating evidence at the first possible opportunity. In view of this, and the fact that no treatment related changes were identified in the male or female reproductive organs, this low incidence of matings not resulting in pregnancy is considered unlikely to be related to treatment. All females showed diestrus at termination.

Key result

Dose descriptor:

NOAEL

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive function (oestrous cycle)

reproductive performance

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

200 mg/kg bw/day (actual dose received)

System:

hepatobiliary

Organ:

liver

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

Clinical signs:

no effects observed

Description (incidence and severity):

No signs were recorded that were considered to be related to parental treatment with 3-[3,3,3-trimet hyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Bodyweight gain between Days 7-13 and between Days 1-13 were statistically significantly low for male offspring at 500 and 1000 mg/kg/day and marginally but not significantly low for female offspring in these groups.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Description (incidence and severity):

The macroscopic examination of offspring revealed no test item related lesions.

Histopathological findings:

not examined

Other effects:

no effects observed

Description (incidence and severity):

There was no effect of parental treatment upon ano-genital distances in male or female offspring.

Additionally, the study design also included an assessment of endocrine disruptor relevant endpoints. This objecti ve was met by including the measurement of the hormone thyroxine (T4) in adult males and in offspri ng at Day 13 of age, by evaluating changes in adult organ weight and gross organ pathology of endoc rine-sensitive organs and, because some developmental stages (e.g. gestational and neo-natal) are particularly sensitive to endocrine effects, an external examination of all offspring, measurement of the ano-genital distance of offspring on Day 1 of age and nipple counts for male offspring on Day 13 of age. T4 levels were considered unaffected by treatment in F0 males and F1 offspring on Day 13 of age and no significant changes were identified at the microscopic examination of thyroid, adrenal and pituitary glands and the reproductive organs. All offspring were macroscopically normal; in particul ar no effects were seen on the external genitalia. Ano-genital distances and male nipple counts wer e not adversely affected by treatment. It was therefore concluded that, in the context of this study, 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate showed no evidence of being an endocrine disruptor.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

viability

clinical signs

mortality

Key result

Reproductive effects observed:

no

Lowest effective dose / conc.:

1 000 mg/kg bw/day

Treatment related:

no

See Attachment 3 for all tables.

Conclusions:

Reproductive performance, fertility, litter size and offspring survival and growth were not adversely affected by parental treatment and, in the context of this study, 3-[3,3,3-trimethyl- 1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate showed no evidence of being an endocrine disruptor.

Executive summary:

 Summary

The purpose of this study was the assessment of general systemic toxic potential in Crl:CD(SD) rats, including a screen for reproductive/developmental effects and assessment of endocrine disruptor relevant endpoints, with administration of 3-(3,3,3-Trimethyl-1,1-bis((trimethylsilyl)oxy)disiloxanyl)propyl methacrylate by oral gavage administration for at least five weeks.

Three groups of ten male and ten female rats received 3-(3,3,3-Trimethyl-1,1-bis((trimethylsilyl)oxy)disiloxanyl)propyl methacrylateat doses of 200, 500 or 1000 mg/kg/day by oral gavage administration. Males were treated daily for two weeks before pairing, up to necropsy after a minimum of five consecutive weeks. Females were treated daily for two weeks before pairing, throughout pairing, gestation and until Day 13 of lactation. Females were allowed to litter, rear their offspring and were killed on Day 14 of lactation. The F1 generation received no direct administration of the test item; any exposure was in utero or via the milk. A similarly constituted Control group received the vehicle, corn oil, at the same volume dose as treated groups.

During the study, clinical condition, detailed physical examination and arena observations, sensory reactivity observations, grip strength, motor activity, body weight, food consumption, hematology (peripheral blood), blood chemistry, thyroid hormone analysis, estrous cycles, pre-coital interval, mating performance, fertility, gestation length, organ weight and macroscopic pathology and histopathology investigations were undertaken.

The clinical condition, litter size and survival, sex ratio, body weight, ano-genital distance and macropathology for all offspring were also assessed. Nipple counts were performed on male offspring on Day 13 of age.

Results

F0 responses

There were no treatment related findings observed at the detailed physical examination and grip strength, motor activity, bodyweights and food consumption were all unaffected by treatment.

All females allocated to study showed normal 4/5 day estrous cycles during the acclimatization period. Estrous cyclicity, pre-coital interval, gestation length and gestation index were considered unaffected by treatment with3-[3,3,3-trimethyl-1,1 bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate.Mating performance and fertility was 100% for control animals and animals receiving 200 or500 mg/kg/day, and 80% for animals receiving 1000 mg/kg/day.

Hematology investigations after 5 weeks of treatment revealed males at 200 mg/kg/day and males and females at 500 and 1000 mg/kg/day had lower than Control hematocrit and hemoglobin concentrations, with dose responses evident in males. Males receiving 200, 500 and 1000 mg/kg/day had higher than Control reticulocytes. Males at 500 and 1000 mg/kg/day and females at 200, 500 and 1000 mg/kg/day had lower than Control red cell distribution width with a dose response evident in both sexes. Mean cell volume was also lower than Control in all groups and both sexes although no dose response was apparent. Total leucocyte count was dose-dependently increased in males and increased in females as a result of increased neutrophils and lymphocytes when compared with Control.

When compared with controls, the adjusted mean liver and spleen weights were statistically significantly high in males treated at 200, 500 and 1000 mg/kg/day with a dose-response.Liver weights were also increased in females at 200, 500 and 1000 mg/kg/day when compared to Control, although no statistical significance was attained, nor was a dose‑response evident.

Pale areas were seen in liver of both sexes given 200 and 1000 mg/kg/day and in males given 500 mg/kg/day. Hepatocyte hypertrophy, vacuolated macrophage aggregates associated with or without inflammation, inflammation and necrosis were seen in the liver of males and females given 1000 mg/kg/day. Similar findings were seen in some males given 200 or 500 mg/kg/day.

F1 responses

The clinical condition, litter size, sex ratio and survival indices of offspring were unaffected by parental treatment.

Body weight gain of offspring at 500 or 1000 mg/kg/day was slightly low during Days 7-13 of age but this was considered not to be adverse at the degree observed.

The ano-gential distances of offspring were unaffected by paternal treatment and no nipples were seen on any male offspring on Day 13 of age.

No macroscopic findings considered to be related to paternal treatment were recorded.

Conclusion

It was concluded that the oral administration of3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylateto parental Crl:CD(SD) rats at dose levels of 200, 500 or 1000 mg/kg/day for two weeks before pairing, during pairing and then up to termination of the males after five weeks of treatment and females on Day 14 of lactation was generally well tolerated, howeverhepatocyte hypertrophy, vacuolated macrophage aggregates associated with or without inflammation, inflammation and necrosis were seen in the liver of males and females given 1000 mg/kg/day. Similar findings were also seen in some males given 200 or 500 mg/kg/day

Reproductive performance, fertility, litter size and offspring survival and growth were not adversely affected by parental treatment and,in the context of this study, 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate showed no evidence of being an endocrine disruptor.

The no-observed adverse-effect level (NOAEL) of 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate for systemic toxicity was concluded to be < 200 mg/kg/day and the no-observed adverse-effect level (NOAEL) of 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylatefor reproductive/developmental toxicity was concluded to be 1000 mg/kg/day.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

One guideline (OECD 422) study is available.

Justification for classification or non-classification

In an OECD 422 study reproductive performance, fertility, litter size and offspring survival and growth were not adversely affected by parental treatment and,in the context of this study, 3-[3,3,3-trimethyl-1,1-bis[(trimethylsiyl)oxy]dissiloxanyl]propyl methacrylate showed no evidence of being an endocrine disruptor.