Methyl 3-mercaptopropionate

Toxicity to reproduction

Administrative data

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006-06-06 to 2007-07-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed according to OECD Guideline 422.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

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

Principles of method if other than guideline:

N/A

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Methyl 3-mercaptopropionate

EC Number:

220-912-4

EC Name:

Methyl 3-mercaptopropionate

Cas Number:

2935-90-2

Molecular formula:

C4H8O2S

IUPAC Name:

methyl 3-sulfanylpropanoate

Details on test material:

- Name of test material (as cited in study report): methyl 3-mercaptopropionate
- Molecular formula (if other than submission substance): N/A
- Molecular weight (if other than submission substance): N/A
- Smiles notation (if other than submission substance): N/A
- InChl (if other than submission substance): N/A
- Structural formula attached as image file (if other than submission substance): N/A
- Substance type: N/A
- Physical state: liquid

Test animals

Species:

rat

Strain:

other: HanRcc:WIST (SPF)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd. Laboratory Animal Services; Wolferstrasse 4; CH-4414 Fullinsdorf/Switzerland
- Age at study initiation: (P) 10 wks at delivery
- Weight at study initiation: (P) Males: 286-331 g; Females: 180-207 g
- Fasting period before study: N/A
- Housing: Animals were housed in Makrolon cages (type-3) with wire mesh tops and standard granulated softwood bedding. During the pre-pairing period, males and females were housed individually. Cages of males were interspersed amongst those holding females to promote the development of regular estrus cycles. During the pairing period, the rats were housed one male/one female in Makrolon pairing cages. After mating or at the end of the pairing period, the males and the females were housed individually again. During the lactation period (until day 4 of lactation), dams were housed together with their litters.
- Use of restrainers for preventing ingestion (if dermal): N/A
- Diet (e.g. ad libitum): Pelleted standard Kliba 3433 rat/mouse maintenance diet was available ad libitum.
- Water (e.g. ad libitum): Tap water from Fullinsdorf in bottles was available ad libitum.
- Acclimation period: 7 days (minimum) under test conditions with an evaluation of health status


ENVIRONMENTAL CONDITIONS
- Temperature (deg. C): 22+/- 3
- Humidity (%): 30-70
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12 (background music played at a centrally defined low volume for at least 8 hours during the light period.)


IN-LIFE DATES: From: 2006-06-13 To: 2006-07-30 (last necropsies)

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The test substance was weighed into a glass beaker on a tared precision balance and approximately 80 % of the vehicle was added (w/v). Using an appropriate homogenizer a homogeneous mixture was prepared. Having obtained a homogeneous mixture, vehicle was added until the required final volume was achieved. Separate formulations were prepared for each concentration. During the daily administration period, homogeneity of the test substance in the vehicle was maintained using a magnetic stirrer. Doses were prepared at least weekly (7-day stability was determined). All dose formulations were stored at room temperature (20 +/- 5 degrees C), away from direct sunlight. All animals received a dose volume of 4 mL/kg bw in vehicle with a daily adjustment of the individual volume to the actual body weight.


DIET PREPARATION
- Rate of preparation of diet (frequency): N/A
- Mixing appropriate amounts with (Type of food): N/A
- Storage temperature of food: N/A


VEHICLE
- Justification for use and choice of vehicle (if other than water): N/A
- Concentration in vehicle: N/A
- Amount of vehicle (if gavage): 4 mL/kg bw
- Lot/batch no. (if required): 17678674
- Purity: N/A

Details on mating procedure:

- M/F ratio per cage: Pairing of animals within each dose group was undertaken on a one male: one female basis on day 15 of the study. During the pairing period, the animals were housed in special automatic mating cages, i.e., with synchronized timing to initiate the nightly mating period. This system reduces the variation in the copulation times of the different females.
- Length of cohabitation: Mating continued until copulation was observed.
- Proof of pregnancy: Proof of pregnancy was determined if a copulation plug was observed, and/or the daily vaginal smear was sperm-positive. This day was designated day 0 post coitum.
- After ... days of unsuccessful pairing replacement of first male by another male with proven fertility: N/A
- Further matings after two unsuccessful attempts: N/A
- After successful mating each pregnant female was caged (how): After mating or at the end of the pairing period, the males and the females were housed individually.
- Any other deviations from standard protocol: N/A

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples for determination of concentration, homogeneity and stability of the dose formulations were taken during the first week of the administration period. Additionally, samples for determination of concentration and homogeneity were taken during the last week of the administration period.
On each occasion, three samples of approximately 2 g were taken from the top, middle and bottom of each formulation and transferred into flat-bottomed flasks. The samples were frozen (-265 to -15 degrees C) pending analysis. Samples were sent on dry ice to RCC Ltd., Environmental Chemistry & Pharmanalytics, CH-4452 Itingen/Switzerland. Analysis was performed using a method developed by RCC Ltd. The test substance concentrations were determined by GC couple to a FID detector and quantified with the area under the peak. After analysis, the analytical results were communicated to the Study Director. Upon receipt and evaluation of these results, the Study Director decided about discarding the samples.
The identity of the test substance was confirmed by its retention time, which was similar to that measured in the working standard. The test substance content in all samples was found to be within the accepted range of +/-20% of the nominal content. In addition, the homogeneous distribution of the test substance in corn oil was demonstrated. The application formulations were considered to be stable for at least 7 days when kept under storage conditions.

Duration of treatment / exposure:

Males were treated for at least 28 days (2 weeks during the premating period and during the mating). Females were treated for 14 days prior to pairing, through the pairing and gestation (about 21 days) periods until the F1 generation reached day 4 post partum. If birth did not occur on the expected date (day 21 post coitum), the females were treated until day 24 post coitum and sacrificed on day 25 or 26 post coitum.

Frequency of treatment:

Daily

Details on study schedule:

- F1 parental animals not mated until [...] weeks after selected from the F1 litters: N/A
- Selection of parents from F1 generation when pups were [...] days of age: N/A
- Age at mating of the mated animals in the study: [...] weeks: Animals were 10 weeks at delivery. They had a minimum of 7 days of acclimatization, followed by a 2 week pre-pairing period.

Doses / concentrations

Remarks:

Doses / Concentrations:
25, 50 and 100 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

10 per sex per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were selected in agreement with the Sponsor, based on the results of a dose range-finding study (RCC Study No. A57802) and following discussions with the sponsor.
- Rationale for animal assignment (if not random): Prior to start of treatment “P”, animals were assigned to the different groups using a computer-generated random algorithm. In addition, body weights (recorded on the day of allocation) were taken into consideration in order to ensure similar mean body weights in all groups.
- Other: N/A

Positive control:

N/A

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily
- Cage side observations included: All animals were checked for any mortalities and signs of reaction to treatment and/or symptoms of ill health. Additionally, the females were observed for signs of difficult or prolonged parturition. All rats found dead were subjected to a detailed macroscopic examination to establish, if possible, the cause of death. Dams were observed daily for survival and behavioral abnormalities in nesting and nursing.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once prior to the first test substance administration and weekly thereafter, detailed clinical observations were performed outside the home cage. Animals were observed for the following: changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g., lacrimation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling, as well as the presence of clonic or tonic movements, stereotypies or bizarre behavior were also recorded.


BODY WEIGHT: Yes
- Time schedule for examinations: The animals were weighed daily during the entire study.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined: Male food consumption was recorded weekly during the pre-pairing and post-pairing period. Female food consumption was recorded for the following periods: days 1-8 and 8-14 of the pre-pairing period; days 0-7, 7-14 and 14-21 post coitum and days 1-4 post partum. Food consumption was not recorded during the pairing period (mixed values of males and females). Values were reported as g/animal/day.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No
- Time schedule for examinations: N/A


OTHER:
-Functional Observation Battery: At one time during the study (males: shortly before scheduled sacrifice; females: on day 3 or 4 post partum) relevant parameters were evaluated for 5 P generation males and 5 P generation females randomly selected from each group. This FOB assessment was conducted following the daily dose administration. Animals were observed for the following:
1. cage side observations: unusual body movements (e.g., tremors, convulsions), abnormal behavior (e.g., circling, stereotypy) and posture, as well as resistance to removal.
2. hand-held observations: palpebral closure, pinna reflex, lacrimation, pupil size, pupil reactivity, salivation, muscle tone, extensor thrust response, righting reflex and reactivity to handling.
3. open field observations: level of ambulatory activity including rearing (one minute evaluation), responsiveness to sharp noise, paw pinch, gait evaluation, quantity of urine and fecal pellets voided.
4. categorical observations (can be made any time during the FOB): hair coat, behavior, respiration, muscle movements, eyes, hearing ability (Preyer's reflex), urine or faeces, soiling, general abnormalities, posture.
5. measurements/counts: hind limb/fore limb grip strength, landing foot splay, rectal temperature.
Additionally, locomotor activity was measured quantitatively for the same animals. Activity of the animals (basing on beam count) was recorded for 6-mintue intervals over a period of 30 minutes.

-Hematology and Clinical Chemistry: Blood samples were obtained on the day before or on the day of scheduled necropsy from 5 males (randomly selected) from each group after they had been fasted overnight. Blood samples of 5 females (randomly selected) from each group were obtained on day 5 post partum after the females had been fasted overnight. Blood samples were collected sublingually with the animal under light isoflurane anaesthesia. Blood samples were collected early in the working day to reduce biological variation caused by circadian rhythms. The following hematology parameters were determined: erythrocyte count, haemoglobin, haematocrit, mean corpuscular volume, red cell volume distribution width, mean corpuscular haemoglobin, mean corpuscular hemoglobin concentration, hemoglobin concentration distribution width, platelet count, total leukocyte count, differential leukocyte count, coagulation (thromboplastin time and activation partial thromboplastin time). The following clinical biochemistry parameters were determined: glucose, urea, creatinine, bilirubin (total), cholesterol (total), aspartate aminotransferase, alanine aminotransferase, bile acids, alkaline phosphatase, gamma-glutamyl-transferase, sodium, potassium, chloride, calcium, phosphorus inorganic, protein (total), albumin, globulin, albumin/globulin ratio.

Oestrous cyclicity (parental animals):

N/A

Sperm parameters (parental animals):

Parameters examined in [all/P/F1/F2] male parental generations: N/A

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: No
- If yes, maximum of [...] pups/litter ([...]/sex/litter as nearly as possible); excess pups were killed and discarded: N/A


PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
Litters were examined for litter size, live birth, still birth and any gross anomalies. The sex ratio of the pups was recorded. Pups were observed for survival and behavioral abnormalities in nesting and nursing. Pups were weighed on days 0 (if possible), 1 and 4 post partum.



GROSS EXAMINATION OF DEAD PUPS: All surviving offspring were terminated on day 4 postpartum. All animals were subjected to a gross necropsy examination.

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals were sacrificed on day 29.
- Maternal animals: All surviving animals were sacrificed on day 5 postpartum. If birth did not occur on the expected date (day 21 post coitum), the females were treated until day 24 post coitum and sacrificed on day 25 or 26 post coitum. Females showing no-evidence of copulation were sacrificed 24-26 days after the last day of the pairing period and, if indicated, the reproductive organs examined histopathologically in order to ascertain the reason for the infertility.


GROSS NECROPSY
- Animals were killed by exsanguination following an intraperitoneal injection of sodium pentobarbital. All animals were subject to a gross necropsy examination. The animals were examined macroscopically for any structural abnormalities or pathological changes, with special attention paid to the organs of the reproductive system. The number of implantation sites and corpora lutea was recorded for all dams with litters. The uteri of non-pregnant females were placed in a solution of ammonium sulfide to visualize possible hemorrhagic areas of implantation sites.


HISTOPATHOLOGY / ORGAN WEIGHTS: The testes* and epididymides* of all parental males were weighed. In addition for five adult males and females, randomly selected from each group, the following organs were trimmed from any adherent tissue, as appropriate, and their wet weight taken: liver, adrenals*, thymus, kidneys*, spleen, brain and heart (*paired weights). Of all parental males the following tissues were preserved in neutral phosphate buffered 4 % formaldehyde solution: prostate, seminal vesicles with coagulation gland, testes (in Bouin's fixative) and epididymides (in Bouin's fixative).
Of all parental females the following tissues were preserved in neutral phosphate buffered 4% formaldehyde solution: ovaries.
In addition, of the five males and females per group selected for organ weights, the following tissues were preserved in neutral phosphate buffered 4% formaldehyde solution: gross lesions, brain, spinal cord, small and large intestines (incl. Peyer's patches), stomach, liver, kidneys, adrenals, spleen, heart, thymus, thyroid, trachea and lungs (preserved by inflation with fixative), uterus (with vagina), urinary bladder, lymph nodes, peripheral nerve and bone marrow.
Full histopathology was carried out on the preserved organs and tissues of the animals in the vehicle control and high dose group (with special emphasis on stages of spermatogenesis and histopathology of interstitial testicular cell structure). Examinations were extended to the animals of the other dosage groups, if treatment-related changes were seen in the highest dose group.
All gross lesions were examined.
Histological examination of ovaries was carried out on any females that did not give birth.
Microscopic examination of the reproductive organs of all infertile males was made, if necessary.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring were sacrificed on day 4 post partum. Pups were killed by an intraperitoneal injection of sodium pentobarbital.
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows: Gross necropsy was performed on sacrificed pups and dead pups (except if excessively cannibalized).


GROSS NECROPSY
- Gross necropsy was performed on sacrificed pups and dead pups (except if excessively cannibalized).

HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated in Table [#] were prepared for microscopic examination and weighed, respectively: N/A

Statistics:

The following statistical methods were used to analyze body weights, food consumption, reproduction and skeletal examination data:
-Means and standard deviations of various data were calculated and included in the report.
-If the variables could be assumed to follow a normal distribution, the Dunnett 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 (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 dichotomized without loss of information.

Reproductive indices:

See above sections.

Offspring viability indices:

See above sections.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS):
1. Cage side observations (daily)-All animals survived until scheduled necropsy. In the high dose group, all animals pushed their heads through the bedding after administration of the test substance starting on day 5 of the prepairing period and continuing until the end of the treatment period. One high dose male had salivation on day 14 of the pre-pairing period and on day 1 of the pairing period. No further observations were noted in any group.
2. Detailed clinical observations (weekly)-No test substance-related findings were noted during detailed weekly clinical observations of males and females at any dosage. Common findings such as spontaneous vocalization when the rat was removed from the cage observed in all groups, or localized hair loss in one female in the mid-dose group were considered to be incidental.


BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS):
1. Males-Mean food consumption was not affected by treatment with the test substance and was generally similar in all groups. Mean absolute body weights and body weight development were similar in all groups and gave no indication of a test substance-related effect. In the low dose, mean body weight gain was statistically significantly increased in the pre-pairing period, which was considered to be incidental. The mean body weight loss noted in all groups between days 9 and 10 of the after pairing period was attributable to the overnight fasting before taking blood samples.
2. Females-In the mid and high dose groups, mean food consumption was slightly reduced in the last week of the pre-pairing period (-6.8 and -7.4 %, respectively), during the gestation period (-7.3 and -4.0 %, respectively) and during the lactation period (-7.7 and -7.7 %, respectively). Since only the difference in the first week of the gestation period in the mid dose group reached statistical significance, and in the absence of a dose-dependency, these finding were considered to be incidental. Mean absolute body weights and body weight development were similar in all groups and gave no indication of a test substance-related effect. The mean body weight loss noted in all groups between days 4 and 5 of the lactation period was attributable to the overnight fasting before taking blood samples.


TEST SUBSTANCE INTAKE (PARENTAL ANIMALS): N/A


REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS): N/A


REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): N/A


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS):
All females were mated within the first pairing period. The median and mean precoital times were unaffected by treatment with the test substance. Mean precoital times were 2.5, 2.7, 2.0 and 2.9 days in the vehicle, low, mid and high dose groups, respectively. The median precoital time was 3, 2, 2 and 3 days in order of ascending dose level. Due to 1, 2 and 1 non-pregnant female in the vehicle, low and mid dose groups, respectively, the calculated fertility indices were 90 %, 80 %, 90 % and 100 % in the vehicle, low, mid and high dose groups. The gestation index was 100 % in all groups. The mean duration of gestation was unaffected by exposure to the test substance. Mean duration of gestation was 21.9, 21.5, 21.9 and 21.5 days, in order of ascending dose level. The mean number of implantations per dam and post-implantation loss were unaffected by exposure to the test substance. In the low dose group, an incidentally although statistically significantly higher incidence of implantation sites was noted. The mean numbers of implantations per litter were 13.7, 15.5, 13.9 and 13.2 in order of ascending dose level. The mean incidence of post-implantation loss as a percentage of total implantations was 10.6, 7.3, 9.6 and 9.8 % in order of ascending dose level. The mean number of corpora lutea per dam (determined at necropsy) was similar in all groups (14.2, 16.4, 15.3 and 13.8 in order of ascending dose level) and gave no indication of a test substance-related effect.



ORGAN WEIGHTS (PARENTAL ANIMALS)
1. Males-For the mid and high dose, liver weights relative to body weights and brain weighs were dose-dependently increased. Liver weights relative to the brain weights did not reach statistical significance in the mid dose. In the absence of a histopathological correlation these higher weights were considered to be of no adverse character.
2. Females-Mean absolute organ weights, as well as organ/body weight ratios and organ/brain weight ratios, were not affected by exposure to the test substance.

GROSS PATHOLOGY (PARENTAL ANIMALS)
During necropsy, no test substance-related findings were noted. The gross necropsy findings noted were within the range of spontaneous findings which may be recorded in rats of this strain and age. Their inter-group distribution did not suggest an effect of treatment at any dose level. For males, the findings consisted of testes and epididymides reduced in size, and seminal vesicles or thymus with focal discolorations. For females, black-brown gastric contents, liver with focal discolorations, ovaries with watery cysts and/or uterus with discoloration were noted.

HISTOPATHOLOGY (PARENTAL ANIMALS)
A minimal to slight hyperplasia of the forestomach squamous epithelium partly associated with a minimal to slight hyperkeratosis and minimal inflammatory cell infiltrations was recorded in four males and four females in the high dose group. Proliferative lesions of the rodent non-glandular stomach region are relatively common in gavage and feeding studies, ranging from mild hyperplasia of the keratinized stratified squamous epithelium to extensive papillomatous hyperplasia. As no similar findings were noted in the forestomach epithelium of the control group, this finding was considered to be test substance-related.
All other microscopic findings recorded in various organs of all groups treated with the test substance did not differ significantly from the control group. All findings were considered to be spontaneous in nature and within the normal background pathology commonly seen in rats of this strain and age.

OTHER FINDINGS (PARENTAL ANIMALS):
1. FOB-None of the parameters under investigation during the functional observational battery were considered to be affected by treatment with the test substance. Common findings such as spontaneous vocalization when the rat was removed from the cage observed in the vehicle, mid and high dose groups, and few or small puddles of urine in the open field from two females in the mid dose group, were considered to be incidental.
-Grip strength, landing foot splay and body temperature-mean values of grip strength (fore- and hind paws) and landing foot splay gave no indication of test substance-related effects. Body temperature in males was statistically lower in the mid and high dose groups compared to the control group (37.5 degrees C each, compared to 38.0 degrees C in the control group). Since the difference is very small and the body temperature was similar in all groups in females, this finding was considered to be incidental.
-Locomotor activity-Locomotor activity was assessed quantitatively in terms of low beam counts in activity monitor. The level of locomotor activity was similar in all groups and gave no indication of a test substance-related effect.
2. Clinical biochemistry-The assessment of clinical biochemistry data did not reveal any test substance-related effects in males and females. In the mid dose females, the bilirubin concentration was statistically significantly higher (+46 % compared to the control group). Due to the absence of a dose-dependency, this finding was considered to be of no biological and/or toxicological relevance.
3. Hematology-The assessment of the hematology data did not reveal any test substance-related effects in males and females. In the high dose females, the mean corpuscular volume was statistically significantly lower (-5 % compared to the control group) and in the low and mid dose females, the monocytes concentration was statistically significantly higher (+57 and +107 %, respectively, compared to the control group). Due to the absence of a dose-dependency, these findings were considered to be of no biological and/or toxicological relevance.

Effect levels (P0)

1

Dose descriptor:

NOEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: Reproductive toxicity

2

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: 50 mg/kg bw/day was determined to be the general NOAEL for the parental generation based on a minimal to slight hyperplasia of the forestomach squamous epithelium noted in males and females at 100 mg/kg/day.

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

not specified

Details on results (F1)

VIABILITY (OFFSPRING)
The number of live pups at first litter check was unaffected by treatment with the test substance. The mean number of live pups per litter was 12.2, 14.4, 12.6 and 11.9 in order of ascending dose level. As a consequence of the incidentally higher incidence of implantation sites, the mean number of live pups per litter was statistically significantly higher in the low dose group than in the vehicle control group.
Neonatal mortality was generally low and considered to be unaffected by treatment with the test substance. The total numbers of pup loss during the first four days of life were 0, 0, 0 and 4 in order of ascending dose level, corresponding to 0, 0, 0.9 and 3.4 % of living pups. The slightly higher percentage in the high dose group was well in the range of the historical control data.

CLINICAL SIGNS (OFFSPRING)
No abnormal findings were noted at first litter check or during the first 4 days post partum.

BODY WEIGHT (OFFSPRING)
Mean pup weights on day 0 and day 1 post partum were unaffected by treatment with the test substance. For those litters for which pup weights were recorded on day 0 post partum, mean pup weights were 6.0, 5.7, 5.4 and 5.5 g in order of ascending dose level; combined data for male and female pups. On day 1 post partum mean pup weights were 6.3, 5.9, 6.2 and 5.9 g in order of ascending dose level. Mean pup weight development during the first 4 days post partum lactation was unaffected by treatment with the test substance. Mean pup weights on day 4 post partum were 9.4, 8.5, 8.9 and 8.9 g in order of ascending dose level.

SEXUAL MATURATION (OFFSPRING): N/A


ORGAN WEIGHTS (OFFSPRING): N/A


GROSS PATHOLOGY (OFFSPRING)
No test substance-related findings were noted at macroscopic examination. For one pup in the vehicle group and two pups in the mid dose group, no milk in the stomach was noted. These findings were considered to be incidental.

HISTOPATHOLOGY (OFFSPRING): N/A


OTHER FINDINGS (OFFSPRING)
-Sex Ratios: Sex ratios at first litter check and on day 4 post partum were unaffected by exposure to the test substance. The proportion of males on day 4 post partum was 52, 41, 43 and 57 % in order of ascending dose level.

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

100 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Developmental toxicity

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

N/A

Applicant's summary and conclusion

Conclusions:

This study was an investigation of the toxicological effects resulting from repeated oral-gavage administration of the test substance to male and female rats and the developmental effects to the offspring. Based on the results, a general NOAEL was established at 50 mg/kg/day for the parental rats. The NOEL for reproduction and developmental toxicity was considered to be 100 mg/kg/day.

Executive summary:

N/A