3-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]- 2-hydroxypropyl methacrylate and 1-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]-3-hydroxypropan-2-yl methacrylate

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 02 January 2009 and 24 November 2009. The in-life phase of the study was conducted between 26 May 2009 (first day of treatment) and 18 July 2009 (final necropsy).

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do no effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

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)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of 3-[3-(9-butyl-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxanyl)propoxy]-2-hydroxypropyl 2-methylprop-2-enoate and 1-[3-(9-butyl-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxanyl)propoxy]-3-hydroxypropan-2-yl 2-methylprop-2-enoate

EC Number:

700-043-1

Molecular formula:

C24H56O8Si5

IUPAC Name:

Reaction mass of 3-[3-(9-butyl-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxanyl)propoxy]-2-hydroxypropyl 2-methylprop-2-enoate and 1-[3-(9-butyl-1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxanyl)propoxy]-3-hydroxypropan-2-yl 2-methylprop-2-enoate

Test material form:

other: liquid

Details on test material:

Sponsor’s identification : OH-mPDMS
Description : clear, colourless liquid
Chemical name : Mono(Hydroxymethacryloxypropoxypropyl)
Polydimethylsiloxane
Lot number : 17554.025
Date received : 03 March 2008
Storage conditions : room temperature in the dark

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: A sufficient number of male and female Wistar Han™HsdRccHan™:WIST strain rats were obtained from Harlan Laboratories UK Limited, Oxon, UK.
- Age at study initiation: Approximately twelve weeks old.
- Weight at study initiation: Males weighed 304 to 382 g, the females weighed 190 to 242 g.
- Fasting period before study: Not stated.
- Housing: Initially, all animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd, Cheshire, UK). During the mating phase, animals were transferred to polypropylene grid floor cages suspended over trays lined with absorbent paper on a one male: one female basis within each dose group. Following evidence of successful mating, the males were returned to
their original cages. Mated females were housed individually during gestation and lactation, in solid floor polypropylene cages with stainless steel mesh lids and softwood flakes.
- Diet (e.g. ad libitum): The animals were allowed free access to food and water. A pelleted diet (Rodent 2018C Teklad Global Certified Diet Harlan Laboratories UK Limited, Oxon, UK) was used throughout the study period.
- Water (e.g. ad libitum): Mains drinking water was supplied from polycarbonate bottles attached to the cage.
- Acclimation period: 12 days.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): The temperature was set to achieve target values of 21 ± 2°C
- Humidity (%): The relative humidity controls were set to achieve target values of 55 ± 15%.
- Air changes (per hr): At least fifteen air changes per hour.
- Photoperiod (hrs dark / hrs light): low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Test material was prepared at the appropriate concentrations as a solution in Arachis oil BP.
The stability and homogeneity of the test material formulations were determined..
Results show the formulations to be stable for at least nineteen days. Formulations were therefore prepared every two weeks and stored at approximately 4ºC in the dark.
Samples were taken of each test material formulation and were analysed for concentration of OH-mPDMS. The results indicate that the prepared formulations were within ± 10% of the nominal concentration.


VEHICLE
For the purpose of the study, the test material was prepared at the appropriate concentrations as a solution in Arachis oil BP.

Details on mating procedure:

- M/F ratio per cage: one male: one female basis within each dose group (during mating phase).
- Length of cohabitation: Up to fourteen days.
- Proof of pregnancy: Cage tray-liners were checked each morning for the presence of ejected copulation plugs and each female was examined for the presence of a copulation plug in the vagina. A vaginal smear was prepared for each female and the stage of the oestrous cycle or the presence of sperm was recorded. The presence of sperm within the vaginal smear and/or vaginal plug in situ was taken as positive evidence of mating (Day 0 of gestation)
- After ... days of unsuccessful pairing replacement of first male by another male with proven fertility: Not applicable.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged (how): Mated females were housed individually during the period of gestation and lactation.
- Any other deviations from standard protocol: None.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Summary: The concentration of OH-mPDMS in the test material formulations was determined by high performance liquid chromatography (HPLC) using an external standard technique.
Samples: The test material formulations were extracted with methanol to give a final, theoretical test material concentration of approximately 0.1 mg/ml.
Standards: Standard solutions of test material were prepared in methanol at a nominal concentration of 0.1 mg/ml.
Procedure: The standard and sample solutions were analysed by HPLC using the following conditions:
HPLC: Agilent Technologies 1050 or 1200, incorporating autosampler and workstation.
Column: Luna 5μ C8 (150 x 4.6 mm id) @ 40°C
Mobile phase: Methanol
Flow-rate: 1 ml/min
UV detector wavelength: 210 nm
Injection volume: 25 μl
Retention time: ~ 2.8 mins

Homogeneity Determinations:
The test material formulations were mixed thoroughly and samples were taken from the top, middle and bottom of the container, shaking between sampling. Sampling was performed in triplicate.
Stability Determinations: The test material formulations were sampled and analysed initially and then after storage at approximately +4ºC in the dark for nineteen days.
Verification of Test Material Formulation Concentrations: The test material formulations were sampled and analysed within four days of
preparation.

Method Validation
Linearity: A range of standard solutions covering the concentration range 0 to 0.1560 mg/ml, were prepared and analysed.
The detector response was shown to be linear up to 0.1560 mg/ml.
Specificity: The diluent solvent methanol and a blank Arachis Oil BP (control) were analysed. Analysis of the solvent and a blank Arachis Oil BP (control) produced no signal that interfered with the signal due to the test material.
Accuracy: Samples of Arachis Oil BP were accurately fortified with known amounts of test material and analysed. The analytical method has been considered to be sufficiently accurate for the purpose of this study. The test sample results have not been corrected for recovery.

Conclusion: The analytical method has been satisfactorily validated in terms of linearity, specificity and accuracy for the purposes of the study.

Duration of treatment / exposure:

Up to fifty-four consecutive days (including a two week maturation phase, pairing, gestation and early lactation for females).

Frequency of treatment:

The test material was administered daily.

Details on study schedule:

- F1 parental animals not mated until [...] weeks after selected from the F1 litters: Not applicable.
- Selection of parents from F1 generation when pups were [...] days of age: Not applicable.
- Age at mating of the mated animals in the study: approximately 14 weeks

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Low dose

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (nominal)

Remarks:

Intermediate dose

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

High dose

No. of animals per sex per dose:

10 males and 10 females per dose group (plus control group)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose levels were chosen based on the results of a preliminary range-finder performed as part of the study.

Positive control:

None.

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All animals were examined for overt signs of toxicity, ill-health and behavioural change immediately before dosing, up to thirty minutes after dosing, and one and five hours after dosing, during the working week. Clinical observations included cage-side visual inspection of anomalies with excreta. Animals were observed immediately before dosing, soon after dosing, and one hour after dosing at weekends and public holidays
(except for females during parturition where applicable). All observations were recorded.



DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed individual clinical observations were performed for each animal using a purpose-built arena. The following parameters were observed:
Gait, Hyper/Hypothermia, Tremors, Skin colour, Twitches, Respiration, Convulsions, Palpebral closure, Bizarre/Abnormal/Stereotypic behaviour, Urination, Salivation, Defecation, Pilo-erection, Transfer arousal, Exophthalmia, Tail elevation, Lachrymation


BODY WEIGHT: Yes
- Time schedule for examinations: Individual bodyweights were recorded on Day 1 (prior to dosing) and then twice weekly for males until termination and twice weekly for females until pairing. Bodyweights were then recorded for females on Days 0, 7, 14 and 20 post coitum, and on Days 1 and 4 post partum. Bodyweights were also recorded prior to termination.


FOOD CONSUMPTION AND COMPOUND INTAKE (compound intake not applicable):
During the maturation period, weekly food consumption was recorded for each cage of adults. This was continued for males after the mating phase. For females showing evidence of mating, food consumption was recorded for the periods covering Days 0-7, 7-14 and 14-20. For females with live litters, food consumption was recorded on Days 1 and 4 post partum.

Food Efficiency:
Food efficiency (the ratio of bodyweight change/dietary intake) was calculated retrospectively for males throughout the study period and for females during maturation. Due to offspring growth and milk production, food efficiency could not be accurately calculated during gestation and during lactation.


WATER CONSUMPTION: Yes
- Time schedule for examinations:
Water intake was observed daily by visual inspection of water bottles for any overt changes.

OTHER:
Pregnancy and Parturition:
Each pregnant female was observed at approximately 0830, 1230 and 1630 hours and around the period of expected parturition. Observations were carried out at approximately 0830 and 1230 hours at weekends and public holidays. The following was recorded for each female:
i) Date of pairing
ii) Date of mating
iii) Date and time of observed start of parturition
iv) Date and time of observed completion of parturition

Oestrous cyclicity (parental animals):

Not applicable.

Sperm parameters (parental animals):

Parameters examined in all male parental generations:
testis weight, epididymis weight

Litter observations:

STANDARDISATION OF LITTERS
On completion of parturition (Day 0 of post partum), the number of live and dead offspring was recorded. Offspring were individually identified within each litter by tattoo on Day 1 post partum.
For each litter the following was recorded:
i) Number of offspring born
ii) Number of offspring alive recorded daily and reported on Day 1 and 4 post partum
iii) Sex of offspring on Day 1 and 4 post partum
iv) Clinical condition of offspring from birth to Day 5 post partum
v) Individual offspring and litter weights on Day 1 and 4 post partum

GROSS EXAMINATION OF DEAD PUPS:
Offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: Adult males were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 43.
- Maternal animals: Adult females were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 5 post partum. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 26 post coitum.


GROSS NECROPSY
For all females, the uterus was examined for signs of implantation and the number of uterine implantations in each horn was recorded. This procedure was enhanced; as necessary, by staining the uteri with a 0.5% ammonium polysulphide solution.
All adult animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.


HISTOPATHOLOGY / ORGAN WEIGHTS
Organ Weights:
The following organs, removed from all surviving animals at terminal kill were dissected free from fat and weighed before fixation:
Adrenals, Ovaries, Brain, Spleen, Epididymides, Testes, Heart, Thymus, Kidneys, Thyroid, Liver.

Histopathology:
Samples of tissues were preserved from all animals in buffered 10% formalin except where indicated. The tissues shown in bold from the remaining control and 1000 mg/kg/day were also processed. (Please see Any other information on materials and methods section for list of tissues).

All tissues were despatched to the Test Site (Harlan Laboratoties Ltd., Zelgliweg 1, CH-4452 Itingen, Switzerland) for processing . The tissues from five selected control and 1000 mg/kg/day dose group animals, any animals dying during the study, and any animals which failed to mate or did not achieve a pregnancy were prepared as paraffin blocks, sectioned at nominal thickness of 5 μm and stained with haematoxylin and eosin for subsequent microscopic examination. The tissues shown in bold from the remaining control and 1000 mg/kg/day were also processed. In addition, sections of testes and epididymides from all control and 1000 mg/kg/day males were also stained with Periodic Acid-Schiff (PAS) stain and
examined.
Since there were indications of treatment-related changes in lungs, examination was subsequently extended to include similarly prepared sections of lungs from five animals per sex from the low and intermediate groups.
Microscopic examination was conducted by the Study Pathologist. All findings were entered into the ROELEE 84 Pathology computerisation system for tabulation and report production.

Postmortem examinations (offspring):

SACRIFICE
Surviving offspring were terminated via intracardiac overdose of sodium pentobarbitone.


GROSS NECROPSY
All offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.


HISTOPATHOLOGY / ORGAN WEIGTHS
Not examined for offspring.

Statistics:

The following parameters were subjected to statistical analysis:
Quantitative functional performance data
Bodyweight and bodyweight change
Food consumption during gestation and lactation
Haematology, blood chemistry, absolute and bodyweight relative organ weights
Litter data
Sex ratio
Implantation losses and viability indices
Offspring bodyweight and bodyweight change
Offspring surface righting
Adult absolute and bodyweight relative organ weights

Reproductive indices:

Mating Performance and Fertility:
The following parameters were calculated from the individual data during the mating period of the parental generation:
i) Pre-coital Interval
Calculated as the time elapsing between initial pairing and the observation of positive evidence of mating.
ii) Fertility Indices
For each group the following were calculated:
Mating Index (%) = Number of animals mated/Number of animals paired x 100
Pregnancy Index (%) = Number of pregnant females/Number of animals mated x 100

Gestation and Parturition Data:
The following parameters were calculated for individual data during the gestation and parturition period of the parental generation.
i) Gestation Length
Calculated as the number of days of gestation including the day for observation of mating and the start of parturition.
ii) Parturition Index
The following was calculated for each group:
Parturition Index (%) = Number of females delivering live offspring/Number of pregnant females x 100

Offspring viability indices:

Litter Responses:
The standard unit of assessment was considered to be the litter, therefore values were first calculated for each litter and the group mean was calculated using their individual litter values. Group mean values included all litters reared to termination (Day 5 of age).
i) Implantation Losses (%)
Group mean percentile pre-implantation and post-implantation loss were calculated for each female/litter as follows:
% pre-implantation loss = [(Number of Corpora Lutea - Number of implantation sites)/Number of pregnant females] x 100

% post-implantation loss = [(Number of implantation site - Total number of offspring born)/Number of implantation sites] x 100

ii) Live Birth and Viability Indices
The following indices were calculated for each litter as follows:
Live Birth Index (%) = Number of offspring alive on Day 1/Number of offspring born x 100
Viability Index 1 (%) = Number of offspring alive on Day 4/Number of offspring alive on Day 1 x 100

iii) Sex Ratio (% males)
Sex ratio was calculated for each litter value on Day 1 and 4 post partum, using the following formula:
Number of male offspring / Total number of offspring x 100

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

effects observed, treatment-related

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
MORTALITY:
One female treated with 1000 mg/kg/day was killed in extremis due to difficulties during parturition. There were no further unscheduled deaths during the study.

CLINICAL OBSERVATIONS:
No clinically observable signs of toxicity were detected.
One female treated with 1000 mg/kg/day showed clinical signs consisting of prostration, hypothermia, pallor of the extremities, pilo-erection and ptosis on Day 41. This animal was in the late stage of gestation and the clinical signs observed would suggest that the animal was experiencing difficulties in parturition. Due to the severity of these observations, this animal was subsequently terminated on Day 41.
Remaining clinical signs consisted of increased salivation detected for one male treated with 100 mg/kg/day on Day 23 and swollen limbs were observed for another male treated with 100 mg/kg/day from Day 11 onwards. Generalised fur loss was evident for one female treated with 300 mg/kg/day from Day 39 onwards. This observation was also observed for one control female on Day 43 to Day 45. These findings were isolated in
each case, and were not considered to represent systemic toxicity.


BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
No adverse effects on bodyweights change were detected for treated animals when compared to controls.
Females treated with 1000 mg/kg/day showed a slightly higher overall bodyweight gain when compared to controls during gestation and lactation, although statistical differences were not observed. Statistically significant intergroup differences were detected for females from all treatment groups in comparison to controls between Days 11 to 15 (P<0.05), although a convincing dose-related response was not observed.

Males treated with 1000 and 300 mg/kg/day showed a statistically significant reduction in bodyweight gains when compared to controls between Days 1 to 4 (P<0.01), and the effect was still evident for males treated with 1000 mg/kg/day between Days 4 to 8 (P<0.05).



TEST SUBSTANCE INTAKE (PARENTAL ANIMALS): Not applicable.


REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS): Not examined.


REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): Not examined.


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Mating:
No treatment-related effects were detected in mating performance. With the exception of one control pair, which mated thirteen days following pairing, all paired animals mated within the first four days of pairing, although positive evidence of mating was not evident for one pair of animals treated with 100 mg/kg/day.

Fertility:
No treatment-related effects were detected on fertility for treated animals when compared to controls.
All control and high dose females were pregnant. One female treated with 100 and onefemale treated with 300mg/kg/day did not achieve pregnancy.

Gestation Length:
No treatment-related effects were detected in the length of gestation for treated females when compared to controls. All animals showed gestation lengths between 22 to 24½ bDays.


ORGAN WEIGHTS (PARENTAL ANIMALS)
There were no treatment-related effects detected for organ weights from treated animals when compared to controls.
Statistical analysis of the data did not reveal any significant intergroup differences.


GROSS PATHOLOGY (PARENTAL ANIMALS)
(Adults)
No treatment-related macroscopic abnormalities were detected.
The 1000 mg/kg/day female killed in extremis during parturition, showed pale kidneys and ten dead foetuses in the right uterine horn. Red staining was also recorded around the ano-genital region.
Macroscopic abnormalities for terminal kill animals were confined to small seminal vesicles seen for one control group male.


HISTOPATHOLOGY (PARENTAL ANIMALS):
REPRODUCTIVE TRACT AND RELATED ORGANS

PITUITARY: No treatment-related changes were seen.

TESTIS/EPIDIDYMIS: No treatment-related changes were seen.

SEMINAL VESICLES/COAGULATING GLAND: No treatment-related changes were seen.

PROSTATE: No pathological changes were seen.

MAMMARY GLAND: Glandular hyperplasia was observed in the mammary tissue of the majority of female rats examined. The appearance of the mammary tissue is consistent with pregnancy and lactation.

OVARY: No pathological changes were seen.

UTERUS: Areas of haemorrhage and fibrosis were seen in the myometrium and adjacent connective tissue of the uterus in the majority of female animals examined from control and high dose groups. These conditions are consistent with normal post partum uterine changes in the rat.

VAGINA: No treatment-related changes were seen.

All other morphological changes in the above and remaining tissues were those commonly observed in laboratory maintained rats of the age and strain employed and, since there were no differences in incidence or severity between control and treatment groups, all were considered to be without t oxicological significance.

Effect levels (P0)

Dose descriptor:

NOAEL

Remarks:

reproductive toxicity

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment-related effects were observed for reproduction, therefore, a ‘No Observed Adverse Effect Level’ (NOAEL) for reproductive toxicity was considered to be 1000 mg/kg/day.

Target system / organ toxicity (P0)

Critical effects observed:

no

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

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 examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

LITTER RESPONSES
In total, nine females from each of the control, 100, 300 and 1000 mg/kg/day dose groups gave birth to a live litter and successfully reared young to Day 5 of age. One female treated with 1000 mg/kg/day was killed in extremis due to difficulties encountered during parturition. One non-pregnant female was observed in both the 100 and 300 mg/kg/day dose groups, and a total litter loss was evident for one female from the control group. The following assessment of litter response is based on all litters reared to termination on Day 5 of lactation/age.


VIABILITY (OFFSPRING)
No significant differences were detected for corpora lutea and implantation counts for treated animals when compared to controls. Litter sizes and viability for treated groups were also comparable to to controls. Statistical analysis of the data did not reveal any significant intergroup differences. One control female gave birth to one dead offspring, resulting in a total litter loss for this animal. One female treated with 1000 mg/kg/day was
killed in extremis due to difficulties encountered during parturition. These isolated effects were unrelated to treatment. Finally, there were no intergroup differences in sex ratio (percentage male offspring) for litters from treated groups compared to controls.


CLINICAL SIGNS (OFFSPRING)
No obvious clinical signs of toxicity were detected for offspring from treated females when compared to controls. The incidental clinical signs detected throughout the control and treated groups, consisting of small size, offspring found dead or missing and cold to the touch, were considered to be low incidence findings observed in offspring in studies of this type, and were unrelated to test material toxicity.
No treatment-related effects were detected for surface righting reflex for offspring from treated animals when compared to offspring from control females. Statistical analysis of the data did not reveal any significant intergroup differences.


BODY WEIGHT (OFFSPRING)
There were no differences in litter weights or mean offspring bodyweights between control and treated animals. Statistical analysis of the data did not reveal any significant intergroup differences.

SEXUAL MATURATION (OFFSPRING)
Not examined.

ORGAN WEIGHTS (OFFSPRING)
There were no treatment-related effects detected for organ weights from treated animals when compared to controls.
Statistical analysis of the data did not reveal any significant intergroup differences.

GROSS PATHOLOGY (OFFSPRING)
No treatment-related macroscopic abnormalities were detected for offspring dying during lactation or at termination on Day 5 post partum.
Autolytic changes were evident for one female found dead following birth, and for one male found dead on Day 4 post partum. Macroscopic abnormalities for offspring at terminal kill were confined to a physical injury to the tail for one male offspring from the 300 mg/kg/day dose group. This was an isolated finding and considered unrelated to treatment.

HISTOPATHOLOGY (OFFSPRING)
Not examined.

Effect levels (F1)

Dose descriptor:

NOAEL

Remarks:

reproductive toxicity

Generation:

F1

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment-related effects in the reproductive parameters observed including offspring litter size and viability, offspring growth and development

Overall reproductive toxicity

Reproductive effects observed:

no

Any other information on results incl. tables

No treatment-related effects in the reproductive parameters were observed. All treated and control females showed an equal number of litters at termination on Day 5 post partum and no treatment-related effects were observed for offspring growth or development. One female treated with 1000 mg/kg/day was killed in extremis following clinical signs of prostration, hypothermia, pallor of the extremities, ptosis and piloerection. These signs were considered to represent difficulties in parturition. Pregnancy was confirmed by the presence of ten foetuses in utero during the post-mortem examination performed on this animal. Difficulties in parturition are occasionally observed in reproductive studies and, in isolation, did not represent an effect of treatment in this study.

Applicant's summary and conclusion

Conclusions:

No treatment-related effects were observed for reproduction, therefore, a ‘No Observed Adverse Effect Level’ (NOAEL) for reproductive toxicity was considered to be 1000 mg/kg/day.

Executive summary:

Introduction. The study was designed to investigate the systemic toxicity and potential adverse effects of the test material on reproduction (including offspring development) and complies with the recommendations of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996). The study was also designed to comply with the Commission Regulation No 440/2208 of 30 May 2008.

Methods. The test material was administered by gavage to three groups each of ten male and ten female Wistar Han™:HsdRccHan™:WIST strain rats, for up to fifty-four consecutive days (including a two week maturation phase, pairing, gestation and early lactation for females), at dose levels of 100, 300 and 1000 mg/kg/day. A control group of ten males and ten females was dosed with vehicle alone (Arachis oil BP).

Clinical signs, behavioural assessments, bodyweight development, food and water consumption were monitored during the study. Haematology and blood chemistry were evaluated prior to mating and at termination on five selected males and females from each dose group.

Pairing of animals within each dose group was undertaken on a one male: one female basis within each treatment group on Day 15 of the study, with females subsequently being allowed to litter and rear their offspring to Day 5 of lactation.

During the lactation phase, daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of surface righting reflex.

Extensive functional observations were performed on five selected males from each dose group after the completion of the mating phase, and for five selected parental females from each dose group on Day 4 post partum.

Males were terminated on Day 43, followed by the termination of all surviving females and offspring on Day 5 post partum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Results

Adult Responses:

Mortality. One female treated with 1000 mg/kg/day was killed in extremis due to difficulties during parturition. There were no further unscheduled deaths during the study.

Clinical Signs. No clinically observable signs of toxicity were detected. One female showed clinical signs to suggest difficulties encountered in parturition, resulting in the early sacrifice of this animal on Day 41.

Behavioural Assessment. No treatment-related effects were detected.

Functional Performance Tests. Increases in overall activity, specifically in the final 20% of motor activity assessment was observed for males treated with 1000 and 300 mg/kg/day. No treatment-related effects were detected for grip strength measurements.

Sensory Reactivity Assessments. There were no treatment-related changes in sensory reactivity.

Bodyweights. No adverse effects on bodyweights change were detected.

Food Consumption and Food Efficiency. No adverse effect on food consumption or food efficiency was detected.

Water Consumptions. No treatment-related intergroup differences in water intake were detected for treated animals when compared to controls.

Haematology. No toxicologically significant effects were detected in the haematological parameters investigated.

Blood Chemistry. No toxicologically significant effects were detected in the blood chemical parameters investigated.

Reproductive Performance:

Mating and Fertility. No treatment-related effects were detected in mating performance.

Gestation Length. No treatment-related effects were detected in the length of gestation.

Litter Responses:

Offspring Litter Size and Viability. No significant differences were detected in litter sizes and viability for treated groups when compared to controls.

Offspring Growth and Development. There were no differences in litter weights or mean offspring bodyweights between control and treated animals. No obvious clinical signs of toxicity were detected.

Pathology:

Necropsy. No treatment-related macroscopic abnormalities were detected for interim death or terminal kill animals.

Organ Weights. No treatment-related effects were detected.

Histopathology. Histopathogical examinations revealed the following treatment-related effects:

LUNGS: A greater incidence of groups of alveolar macrophages was seen among males treated with 1000 mg/kg/day; alveolar macrophages at this dose level also exhibited foamy/vacuolated cytoplasm in excess of that normally seen as spontaneous change in untreated rats. Alveolar macrophages with foamy cytoplasm or granulomatous appearance were also seen for one female treated with 1000 mg/kg/day and for one male and for two females treated with 300 mg/kg/day.

Conclusion. The oral administration of OH-mPDMS to rats by gavage, at dose levels of 1000, 300 and 100 mg/kg/day, resulted in treatment-related effects at 1000 and 300 mg/kg/day. These effects were considered not to represent an adverse effect of treatment, hence the 'No Observed Adverse Effect Level' (NOAEL) for systemic toxicity was considered to be 1000 mg/kg/day. No treatment-related effects were observed at the lowest dose level employed, hence a 'No Observed Effect Level' (NOEL) was established at 100 mg/kg/day.

No treatment-related effects were observed for reproduction, therefore, a ‘No Observed Adverse Effect Level’ (NOAEL) for reproductive toxicity was considered to be 1000 mg/kg/day.