Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

OECD 421 enhanced reproductive toxicity screening study in rats via daily oral gavage administration to groups of 10 female rats at 0 (control), 12.5, 25 and 50 mg/kg/day. These female rats were treated for 28 days prior to mating, throughout the mating (14 days), gestation and lactation periods amounting to a total of approximately 84 days. Males were not exposed. Approximately half the F1 pups were killed at weaning and the remainder were reared until day 55 post partum. The study design included evaluation of neurobehaviour effects via the water maze test in the F1 offspring and also circulating hormone levels in parental females and F1 pups (Day 55) (triiodothyronine, thyroxine, thyroid stimulating hormone, follicle stimulating hormone, luteinising hormone, prolactin, estradiol and testosterone) as additions to normal guideline requirements.

Link to relevant study records
Reference
Endpoint:
screening for reproductive / developmental toxicity
Remarks:
The standard study design has been enhanced by the inclusion of learning and memory tests and hormone analyses (TT3, TT4, TSH, FSH, LH, prolactin, E2 and testosterone) in F1 offspring
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28-days premating, during mating, gestation and lactation
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Males were used for mating only and were not exposed to the test substance prior to mating.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Version / remarks:
The test guidleline is not specifically stated in the report. The study design has been enhanced to include neurobehavioural and circulating hormone endpoints in F1 offspring.
Deviations:
yes
Remarks:
No exposure of males; inclusion of neurobehavioural and hormone measurements
GLP compliance:
yes
Limit test:
no
Justification for study design:
SPECIFICATION OF STUDY DESIGN FOR REPRODUCTION SCREENING TOXICITY STUDY WITH JUSTIFICATIONS [please address all points below]:

- Premating exposure duration for parental (P0) animals: 28 days for females only
- Basis for dose level selection: Based on a 3-month oral study in male and female rats at dose levels of 0, 25, 50, 125 and 312 mg/kg/day. Toxicological effects were recorded in females treated at 50 mg/kg/day and above on thyroid hormone levels, thyroid histopathology and blood chemistry

- Inclusion/exclusion of developmental neurotoxicity Cohorts 2A and 2B: Included

- Route of administration: Oral gavage
- Other considerations, e.g. on choice of species, strain, vehicle and number of animals: The Han Wistar rat was the strain used on previous repeat-dose oral studies from which dose levels were based; the dosing vehicle of 0.25% aqueous Methocel K4M premium was chosen as a standard vehicle for this type of solution; the number of animals per group was the minimum recommended in the guideline.
Species:
rat
Strain:
Wistar
Details on species / strain selection:
HanBrl:WIST SPF rats from RCC Ltd, Biotechnology & Animal Breeding Division, Wolfstrasse 4, CH-4414 Fullinsdorf/Switzerland
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: RCC Ltd, Switzerland
- Females (if applicable) nulliparous and non-pregnant: Yes
- Age at study initiation: (P) 13 wks
- Weight at study initiation: (P) Females: 180-216 g
- Fasting period before study: NA
- Housing: Individually housed in Type-3 Makrolon cages except during the mating period when one male/one female were housed in pairing cages
- Use of restrainers for preventing ingestion (if dermal): No
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: Eight days under test conditions
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/-3oC
- Humidity (%): 30-70%
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light):12/12
IN-LIFE DATES: From: 30 July 2002 To: 18 November 2002
Route of administration:
oral: gavage
Vehicle:
other: Hydroxypropyl methylcellulose
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test item was weighed into a glass beaker on a tared precision balance and the vehicle added (w/v). The mixtures were prepared using a homogeniser. During the daily administration period, homogeneity was maintained using a magnetic stirrer. Dose formulations were stored in a refrigerator.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Not stated
- Concentration in vehicle: Varied for each dose level
- Amount of vehicle (if gavage): 10 mL/Kg body weight dose volume
Details on mating procedure:
- M/F ratio per cage: One male/one female per cage during pairing period
- Length of cohabitation: Maximum of 14 days
- Proof of pregnancy: Vaginal plug or sperm in vaginal smear, referred to as Day 0 of pregnancy
- After successful mating each pregnant female was caged individually
- Untreated male rats of the same source and strain were used for mating only. The fertility of these males had been proven and was continuously controlled.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples of determination of concentration, homogeneity and stability (4 days) of the dose formulations were taken during the third week of the administration period, during the first week of gestation and during the last week of the administration period. On each occasion three samples of approximately 2g were taken from the top, middle and bottom of each formulation and transferred to flat-bottomed flasks. The samples were frozen and were analysed as soon as possible using an HPLC method.
Duration of treatment / exposure:
Parent females were treated during a 28-day prepairing period and also during the pairing, gestation and lactation periods amounting to a total of approximately 84 days.
Frequency of treatment:
Daily
Details on study schedule:
- F1 pups were not mated; At weaning, at least half of the pups of each sex of each litter (randomly selected) were selected for futher rearing. The remaining pups were sacrificed and examined for structural abnormalities or pathological changes. The remaining F1 offspring were reared until day 55 post partum
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Remarks:
Vehicle control
Dose / conc.:
12.5 mg/kg bw/day (actual dose received)
Dose / conc.:
25 mg/kg bw/day (actual dose received)
Dose / conc.:
50 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
10 females per dose group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Dose levels were based on the results of a 90-day rat oral study in which dose levels of 0, 25, 50, 125 and 312 mg/kg/day were used and the dose levels of 50 mg/kg/day and higher in females were shown to induce changes in thyroid pathology and hormone levels and also haematology.
- Rationale for animal assignment (if not random): Randomly grouped using a computer-generated ramdom algorithm. F1 animals were selected for sacrifice at weaning or rearing based on the randomly allocated pup numbers.
Positive control:
No positive control included
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily.
- Cage side observations checked included: Mortality, signs of reaction to treatment and symptoms of ill-health.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: P females were weighed twice weekly during the prepairing and lactation periods. During gestation females were weighed daily.

FOOD CONSUMPTION and WATER CONSUMPTION: Yes
- Food/water consumption were measured twice weekly (during prepairing and lactation together with the recoding of body weights), except during the pairing period when no food/water consumption were measured. During the lactation period of the females, food/water consumption were recorded only until day 14 post partum.

BLOOD SAMPLING FOR HORMONE ANALYSIS:
- Blood samples were collected from P females on Day 21 of the prepairing period from the retroorbital sinus (under light isoflurane anaesthesia) and at necropsy via heart puncture (under terminal anaesthesia). The following hormone levels were determined: Triiodothyronine (T3), Thyroxine (T4), Thyroid stimulating hormone (TSH), Estradiol (E2), Testosterone (Testo), Follicle stimulating hormone (FSH), Luteinising hormone (LH), Prolactin (PRL).
Oestrous cyclicity (parental animals):
Daily vaginal smears were taken commencing after two weeks of treatment and during pairing until evidence of mating had been noted.
Sperm parameters (parental animals):
Parameters examined in F1 males sacrificed at weaning or after rearing:
- testis weight, epididymis weight, seminal vesicle weight
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: No

PARAMETERS EXAMINED
The following parameters were examined in [F1] offspring:
[number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities, anogenital distance (AGD)]

GROSS EXAMINATION OF DEAD PUPS:
[yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead.]

ASSESSMENT OF DEVELOPMENTAL NEUROTOXICITY: NA

ASSESSMENT OF DEVELOPMENTAL IMMUNOTOXICITY: NA
Postmortem examinations (parental animals):
SACRIFICE
- Male animals: Remained untreated and were only used to impregnate the females
- Maternal animals: All surviving animals at or shortly after weaning of their litters

GROSS NECROPSY
- Gross necropsy consisted of macroscopic examination for any structural abnormalities or pathologial changes with special attention directed to the organs of the reproductive system, thyroid gland, adrenal glands, thymus and any suspected target organs.

HISTOPATHOLOGY / ORGAN WEIGHTS
The following tissues indicated in were weighed and prepared for microscopic examination respectively: uterus, cervix (histopathology only), ovaries, pituitary gland, thyroid gland, adrenal glands, thymus and suspected target organs.
Postmortem examinations (offspring):
SACRIFICE
- At weaning half of the F1 pups of each litter (equally divided as per sex) were sacrificed. On Day 55 post partum the remaining F1 offspring were sacrificed.
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows:

GROSS NECROPSY
- Gross necropsy consisted of macroscopic examination for any structural abnormalities or pathological changes. Special attention was directed to external and internal sex characteristics, the organs of the reproductive system, thyroid gland, adrenal glands, thymus and any suspected target organs.

HISTOPATHOLOGY / ORGAN WEIGTHS
- The following tissues indicated in were weighed and prepared for microscopic examination respectively: uterus, cervix (histopathology only), ovaries, testes, epididymides, seminal vesicles, prostate gland, pituitary gland, thyroid gland, adrenal glands, thymus, suspected target organs.
- Histopathological evaluation was conducted on the ovaries, uterus, testes and prostate of F1 offspring killed at the end of weaning only.
Statistics:
- Means and standard deviations of various data were calculated
- If the variables could be assumed to follow a normal distribution, the Dunnett many-one t-test, based on a pooled variance estimate, was used for intergroup comparisons (i.e. single treatment groups against the control group)
- The Steel test (many-one rank test) was applied when the data could not be assumed to follow a normal distribution.
- Fisher's Exact test for 2x2 tables was applied if the variables could be dichotomised without loss of information.
Reproductive indices:
- Fertility indices
- Mean precoital time
- Pre and Post implantation losses
Offspring viability indices:
- Embryonic and foetal deaths
- Breeding losses
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Prepairing period:
Increased water intake at 50 mg/kg/day (+28.7%), and also at 25 and 12.5 mg/kg/day (+12.5% and +13.4% respectively)
Gestation period:
Increased water intake at 50 mg/kg/day (+31.5%) and also at 12.5 mg/kg/day (+14.1%)
Lactation period:
Increased wter intake days 1-4 post partum at 50 mg/kg/day (+15.2%)
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not specified
Reproductive function: oestrous cycle:
effects observed, non-treatment-related
Description (incidence and severity):
The incidence of one acyclic female at 25 mg/kg/day was considered to be non-treatment-related.
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
- Increased water consumption at 40 mg/kg/day throughout the treatment period.
- Reproduction performance: Not affected by treatment
- Fertility and mating performance - neither median or mean precoital time gave any indication for treatment related effects. In all groups all pregnant females gave birth to living pups (gestation index 100%)
- Duration of gestation - Similar in all groups 1-4 (21.7, 21.7, 21.8 and 21.6 days respectively)
- Implantation rate and post-implantation loss - the mean number of implantations per dam was similar in groups 1-4 (13.2, 13.7, 12.5 and 12.3 respectively); The incidence of post implantation loss was similar in groups 1-4 (9.1, 8.9, 6.4 and 11.4% of implantation sites respectively)
- Litter size - Mean number of pups per litter was similar in groups 1-4 (12.0, 12.4, 11.7 and 10.9 respectively); Birth indices were similar in groups 1-4 (90.9, 91.1, 93.6 and 88.6% respectively)
- Postnatal loss - Viability indcies were high and similar in groups 1-4 (99.2, 99.1, 100.0 and 99.1% respectively)
- Breeding loss - Weaning indices were high and similar in groups 1-4 (100.0, 99.1, 100.0 and 100.0% respectively)
Key result
Dose descriptor:
NOAEL
Effect level:
>= 50 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
female
Basis for effect level:
water consumption and compound intake
Remarks on result:
other: Although reduced water intake was recorded at all treatment levels this was considered not to be an adverse effect. Dose levels up to 50 mg/kg/day did not influence the reproductive function of female rats.
Clinical signs:
no effects observed
Description (incidence and severity):
At birth the sex ratio, percentage of male and female pups, was close to 50% in all groups
Dermal irritation (if dermal study):
not examined
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:
no effects observed
Description (incidence and severity):
No treatment-related changes in serum levels of T3, T4, TSH, FSH, LH, E2, Prolactin and Testosterone
Urinalysis findings:
not examined
Sexual maturation:
no effects observed
Description (incidence and severity):
F1 weanlings - No effects on pinna unfolding, incisor eruption, onset of coat development, opening of the eye; no signs of nipple retention in male pups.
F1 reared to Day 55 - No effects on descensus of testes or balano-preputial separation or time of vaginal opening.
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed
Other effects:
not examined
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
No effects on learning and memory function in the water maze test.
Developmental immunotoxicity:
not examined
No treatment related changes were observed in F1 weanlings upto Day 21 or Day 55 post partum
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
50 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
sexual maturation
clinical signs
mortality
body weight and weight gain
clinical biochemistry
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic
developmental neurotoxicity
Key result
Reproductive effects observed:
no
Conclusions:
The NOAEL in this study for reproductive function of female rats and growth and development of F1 offspring was 50 mg/kg/day.
Executive summary:

Groups of 10 female rats were dosed with the test substance at dose levels of 12.5, 25, or 50 mg/kg bw/day at a standard dose volume of 10 mL/kg of vehicle (hydroxypropyl methylcellulose) for 28 days prior to mating, during pairing, gestation and lactation periods. Males remained untreated (used for pairing only) and F1 offspring were not directly treated with the test item. No clinical signs or adverse reactions to treatment were noted, and there were no effects on mortality, body weight gain or food consumption. A significant increase in water consumption was recorded for females from all treatment groups throughout the various phases of the study with the highest intake recorded for those treated at 50 mg/kg/day.

 

There were no test item related effects on any of the reproduction parameters included in the scope of investigations (estrous cycles, fertility indices, mating performance, duration of gestation, implantation rate, post-implantation loss, litter size and postnatal pup loss). There were no significant effects on the weight or histopathology of reproductive and endocrine organs. No significant differences in thyroid hormones (T3, T4, TSH) or reproductive hormones (FSH, LH, prolactin, E2 and T) were found in parental females or in F1 offspring. Developmental indices (pinna unfolding, incisor eruption, onset of coat development and eye opening) and anogenital distances in treated offspring did not differ from controls. There was no indication of effects on learning or memory function.

 

There were no other changes recorded in the study that were considered to be indicative of a reaction to treatment. Consequently, the recorded increase in water consumption was considered not to be an adverse effect and that the high dose level of 50 mg/kg/day represents the NOAEL for reproductive function of female rats and growth and development of the F1 offspring. This study was assigned a reliability rating of 2: reliable with restrictions, as the study design was similar to OECD 421, but deviated by omitting male exposure.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
50 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
Study of regulatory design and conducted to GLP
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

A significant increase in water consumption was recorded for females from all treatment groups throughout the various phases of the study with the highest intake recorded for those treated at 50 mg/kg/day. In the absence of any other treatment-related change in either the parent females or the F1 offspring, the high dose of 50 mg/kg/day was considered to represent the NOAEL for reproductive function of female rats and growth and development of the F1 offspring.

Effects on developmental toxicity

Description of key information

Description of key information: OECD 414 Prenatal developmental toxicity study in rats. Groups of female rats were treated with the test item by daily oral gavage at 0 (control), 10, 30 or 100 mg/kg/day from Day 6 to Day 15 of gestation, and were sacrificed on Day 20. Maternal well-being was assessed at regular intervals and, at termination, the ovaries and uterine contents were examined in detail to evaluate any potential effects on reproduction endpoints and the embryo. In addition, all litters and foetuses were examined for any external and internal (visceral and skeletal) changes.

Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From confirmation of pregnancy to Day 20 post coitum
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Wistar
Remarks:
Wi-AF/Han SPF
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Institute of Toxicology, E. Merck, Darmstadt, Germany
- Age at study initiation: 8-9 weeks
- Weight at study initiation: 170-191 g
- Fasting period before study: NA
- Housing: Individually housed in Makrolon cages (type III)
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 1-2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22
- Humidity (%): 40-80
- Air changes (per hr): Not specified
- Photoperiod (hrs dark / hrs light):12/12 (6 a.m. to 6 p.m.)

IN-LIFE DATES: From: 12th April 1988 To: 10th May 1988
Route of administration:
oral: gavage
Vehicle:
arachis oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Dosing solutions were prepared every 3 to 4 days and stored refrigerated and protected from light.

VEHICLE
- Justification for use and choice of vehicle (if other than water): Stability had been proven for at least 14 days in the chosen vehicle
- Concentration in vehicle: 2, 6 and 20 g/L
- Amount of vehicle (if gavage): 5 mL/Kg
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
- Impregnation procedure: Cohoused
- If cohoused:
- M/F ratio per cage: 1 male to 4 females
- Length of cohabitation: Overnight
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: Sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
Treatment was carried out daily on 10 consecutive days from the 6th to the 15th day post coitum
Frequency of treatment:
Daily on 10 consecutive days from the 6th to the 15th day post coitum
Duration of test:
From day of successful mating (designated Day 0) to sacrifice of all dams on Day 20.
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Remarks:
Vehicle control - oleum arachidis
Dose / conc.:
10 mg/kg bw/day (actual dose received)
Dose / conc.:
30 mg/kg bw/day (actual dose received)
Dose / conc.:
100 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
25 females per group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: In subchronic toxicity studies in rats dose levels of 50 and 125 mg/kg/day had shown clear, dose-dependent, toxici effects (increased TSH and T3 concentrations in serum and morphological alterations as a consequence of thyroid stimulation)
- Rationale for animal assignment: Animals were allocated to groups according to random lists, and the animals within each group were allocated to positions in the rows by random numbers. Than animal sequence at sacrifice and allocation of litters to transverse section were also randomised.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily
- Cage side observations included behaviour and appearance

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Dams were weighed on Days 0, 3 and 6 post coitum and then daily until the end of the study

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined once per week on Days 6, 10, 15 and 20

WATER CONSUMPTION: Water consumption determined on days 3, 6, 9, 12, 15, 18, 20 by weighing unconsumed water.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: Macroscopic examination of organs and detailed examination of ovaries and uterus (containing foetuses) from each animal.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: Litters from one third of females
- Skeletal examinations: Yes: Litters from two thirds of females
- Head examinations: No data
Statistics:
Body weight, food and water consumption:
For each measuring point the values of the treated animals were compared with the controls using Dunnett's multiple t-test (1955). Various nonhomogeneity between the control and dose groups were taken into account by Dunnett's procedure (1964) and, in case of variance nonhomogeneity by Welch's correction of degrees of freedom.
Reproduction and embryotoxic effects data:
Statistical evaluation was carried out by the Pitman randomisation test using the procedure described by Stucky and Vollmar (1976). Any instance of data where normal distribution could be assumed, the procedure for body weight data was followed.
Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Slightly less weight was gained by those dams treated at 100 mg/kg/day when compared to the controls (not significant).
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Water consumption was slightly increased during the treatment period at the highest dose level, and further until day 20 (significant from day 12 until day 18).
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Details on results:
The dose levels of 10 and 30 mg/kg/day proved to be non-toxic to pregnant female rats dosed daily over days 6 to 15 of gestation. The dose level of 100 mg/kg/day was shown to be minimally toxic to the dams as demonstrated by a slightly lower body weight gain by these females.
Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
The number of pregnant rats per goup were as follows: Group 1 - 22/25; Group 2 - 24/25; Grop 3 - 24/25; Group 4 - 23/25
Other effects:
no effects observed
Description (incidence and severity):
The distribution of the numbers of corpora lutea in treated groups was similar to that in controls.
Details on maternal toxic effects:
There was no evidence of an effect of treatment on maternal reproductive parameters at any of the dose levels examined.
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
body weight and weight gain
Remarks on result:
other:
Remarks:
The effect on body weight gain of the dams at 100 mg/kg/day was minimal and not considered adverse.
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Reduced body weight of male and female foetuses from Group 4 (100 mg/kg/day) when compared with the controls.
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
no effects observed
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
One foetus with hernia umbilicalis from Group 2 (10 mg/kg/day) and one foetus with anasarca, micrognathia, squatty trunk and short extremities from Group 4 (100 mg/kg/day). The malformations are the same as those that occurred spontaneously in the historical control.
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
One foetus from Group 4 (100 mg/kg/day) had retarded skeletal development, and pelvic bones, humerus, ulna, femur, tibia, fibula and cranial bones were rudimentary. All ribs were kinked with incomplete ossification. The malformations are the same as those that occurred spontaneously in the historical control.
Visceral malformations:
no effects observed
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Skeletal variations: The degree of ossification of the extremities was slightly lower in some foetuses of Group 4 (100 mg/kg/day). This finding was regarded as a consequence of maternal toxicity. Also the number of rudimentary lumbar ribs was dose-dependently increased in Groups 3 (30 mg/kg/day) and Group 4 (100 mg/kg/day) in the male and female foetuses. A finding which was similarly attributed to adverse effects on the dams.
Details on embryotoxic / teratogenic effects:
A small but statistically significant reduction in body weight was recorded for foetuses from Group 4 (100 mg/kg/day). Corresponding to these lighter foetal weights in Group 4 was the lower degree of ossification of the sternum and the extremities seen in foetuses from this treatment group. Since a level of maternal toxicity was seen in this treatment group (slightly reduced weight gain), this incidence of reduced ossification was considered to be secondary to the effect on the dams. The dose-dependent increase of rudimentary lumbar ribs in both sexes in Groups 3 and 4 (30 and 100 mg/kg/day) was also attributed to stress in the dams being sufficient to express the developmental instability inherent in the species.
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 30 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Skeletal variations
Key result
Abnormalities:
effects observed, treatment-related
Localisation:
skeletal: sternum
skeletal: rib
Description (incidence and severity):
In creased incidence of reduced ossification of sternum and extremities in foetuses of Group 4 (100 mg/kg/day) and increased incidence of rudimentary lumbar ribs in males and females of Groups 4 and 3 (100 and 30 mg/kg/day respectively).
Key result
Developmental effects observed:
yes
Lowest effective dose / conc.:
30 mg/kg bw/day
Treatment related:
yes
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects
Dose response relationship:
yes
Relevant for humans:
not specified
Conclusions:
The NOAEL for maternal toxicity, based on a slight adverse effect on body weight, was determined to be 30 mg/kg/day although the NOAEL for reproductive effects was considered to be >100 mg/kg/day. The NOAEL for foetal toxicity was considered to be 30 mg/kg/day based on the increased incidence of skeletal anomalies in Group 4 foetuses (100 mg/kg/day).
Executive summary:

Groups of female rats were dosed with the test substance at dose levels of 0, 10, 30 and 100 mg/kg/day by oral gavage between days 6 to 15 of gestation. These females were killed on day 20 of gestation and the uterine contents examined in detail to evaluate any potential effects on reproduction and the embryo. Over this treatment regime, the dose levels of 10 and 30 mg/kg/day proved to be non-toxic to the pregnant female rat. However, the dose level of 100 mg/kg/day was shown to be minimally toxic to the dams as demonstrated by a slightly lower body weight gain by these females. There was no evidence of an effect of treatment on maternal reproductive parameters at any of the dose levels examined.

A small but statistically significant reduction in body weight was recorded for foetuses from Group 4 (100 mg/kg/day). Corresponding to these lighter foetal weights in Group 4 was a lower degree of ossification of the sternum and the extremities seen in foetuses from this treatment group. Since a level of maternal toxicity was seen in this treatment group (slightly reduced weight gain), this incidence of reduced ossification was considered to be secondary to this effect on the dams. The dose-dependent increase of rudimentary lumbar ribs in both sexes of foetuses from Groups 3 and 4 (30 and 100 mg/kg/day) was also attributed to stress in the dams being sufficient to express the developmental instability inherent in this species.

Consequently, the NOAEL for both maternal and foetal toxicity in this study was determined to be 30 mg/kg/day.This study was assigned a reliability rating of 1: reliable without restrictions.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
30 mg/kg bw/day
Study duration:
subacute
Species:
rat
Quality of whole database:
Study of regulatory design and conducted to GLP
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

Maternal toxicity was recorded at the high dose level of 100 mg/kg/day in the form of slightly reduced body weight gain by these females. There was no evidence of an effect of treatment on maternal reproductive parameters at any of the dose levels examined. A small but statistically significant reduction in body weight was recorded for foetuses from Group 4 (100 mg/kg/day). Corresponding to these lighter foetal weights in Group 4 was a lower degree of ossification of the sternum and the extremities seen in foetuses from this treatment group. Since a level of maternal toxicity was seen in this treatment group (slightly reduced weight gain), this incidence of reduced ossification was considered to be secondary to this effect on the dams. The dose-dependent increase of rudimentary lumbar ribs in both sexes of foetuses from Groups 3 and 4 (30 and 100 mg/kg/day) was also attributed to stress in the dams being sufficient to express the developmental instability inherent in the species.

Justification for classification or non-classification

No effects on the reproductive ability of females treated with the test item were encountered at dose levels which caused minimal and tolerated toxicity to the maternal parent. In addition, dose levels shown to be minimally toxic to the dam showed changes in the foetuses which could be attributed to the maternal toxicity and not indicative of direct effect on the foetus. Therefore, classification for reproductive toxicity was considered inappropriate for the test item.