3-sec-[C15-18-(branched and linear)-alk-2-enyl]pyrrolidine-2,5-dione

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 April 2009 to 29 October 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines for Testing of Chemicals No. 422 "Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test"

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-sec-[C15-18-(branched and linear)-alk-2-enyl]pyrrolidine-2,5-dione

EC Number:

701-350-3

Molecular formula:

Not possible to assign, UVCB

IUPAC Name:

3-sec-[C15-18-(branched and linear)-alk-2-enyl]pyrrolidine-2,5-dione

Test material form:

liquid

Details on test material:

- Appearance: brown liquid
- Storage: room temperature, in the dark

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Wistar Han HsdRccHan:WIST

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately twelve weeks old
- Weight at study initiation: the males weighed 318 to 366 g and the females weighed 191 to 230 g
- Housing: Initially, all animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding. 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.
- Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels except for mated females during gestation and lactation. Mated females were also given softwood flakes as bedding, throughout gestation and lactation.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 1 °C
- Humidity: 55 ± 15 %
- Air changes: at least fifteen air changes per hour
- Photoperiod: 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:
For the purpose of the study, the test material was prepared at the appropriate concentrations as a solution in arachis oil. The stability and homogeneity of the test material formulations were determined by Harlan Laboratories Ltd., Shardlow, UK Analytical Services. Results showed the formulations to be stable for at least fourteen days. Formulations were therefore prepared weekly and stored at approximately 4 °C in the dark.
Samples were taken of each test material formulation and analysed for concentration of test material at Harlan Laboratories Ltd., Shardlow, UK Analytical Services. The results indicate that the prepared formulations were within 10 % of the nominal concentration.

VEHICLE
- Amount of vehicle: 4 mL/kg

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

METHOD OF ANALYSIS
- The concentration of test material in the test material formulations was determined by gas chromatography (GC) using an external standard technique.
- Samples: The test material formulations were extracted with methanol to give a final, theoretical test material concentration of approximately 1 mg/mL.
- Standards: Standard solutions of test material were prepared in methanol at a nominal concentration of 1 mg/mL containing the equivalent amount of vehicle as the sample solutions.
- Procedure: The standard and sample solutions were analysed by GC using the following conditions:
GC system: Agilent Technologies 5890, incorporating autosampler and workstation
Column: DB-1 (30 m x 0.32 mm id x 0.25 µm film)
Oven temperature program: initial: 100 °C for 0 mins, rate: 10 °C/min, final: 300 °C for 6 mins
Injection temperature: 300 °C
Flame ionisation detector temperature: 325 °C
Injection volume: 1 µL
Retention time: Profile of peaks from ~6 to 8 mins

- Homogeneity Determinations: The test material formulations were deemed homogeneous by visual inspection.
- Stability Determinations: The test material formulations were sampled and analysed initially and then after storage at approximately +4 °C in the dark for fourteen days.
- Verification of Test Material Formulation Concentrations: The test material formulations were sampled and analysed within three days of preparation.

RESULTS
- Stability of Test Material Formulations: 102 and 101 % of the initial concentration was found in the test material after storage for 14 days.
- Verification of Concentration of Weekly Test Material Formulation: 90 – 101 % of the nominal test material concentration was found.

METHOD VALIDATION
- Linearity: A range of standard solutions covering the concentration range 0 to 1.5056 mg/mL, were prepared containing the equivalent amount of vehicle as the low dose level sample solutions and analysed. The detector response was shown to be linear up to 1.5056 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. Mean recovery was 100 – 103 %. 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.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: up to 14 days
- Proof of pregnancy: vaginal plug, referred to as day 0 of pregnancy

- Animals were paired on a 1 male: 1 female basis within each dose group, for a period of up to fourteen days. 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) and the males were subsequently returned to their original holding cages (unless required for additional pairing). Mated females were housed individually during the period of gestation and lactation.

Duration of treatment / exposure:

The animals were dosed for up to 54 days, including two weeks pre-mating, gestation and early lactation period.

Frequency of treatment:

Once daily

Duration of test:

54 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

50 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

200 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

750 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 animals per sex per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: a preliminary 14-day repeated dose oral (gavage) range-finder study was conducted to establish the maximum tolerated dose level (up to 1000 mg/kg bw/day) and to provide information for selection of dose levels for use in the main OECD 422 study.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- 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. Animals were observed immediately before dosing, soon after dosing, and one hour after dosing at weekends (except for females during parturition where applicable). All observations were recorded.

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

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

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

WATER CONSUMPTION: Yes
- Water intake was observed daily by visual inspection of water bottles for any overt changes. Intergroup differences did not indicate any need for more formal gravimetric measurements.

HAEMATOLOGY AND CLINICAL CHEMISTRY: Yes
- Haematological and blood chemical investigations were performed on five males and five females selected from each test and control group on Day 14 (day prior to pairing) and blood chemical investigations were re-assessed for on five males on Day 42 and five females on Day 4 post partum from each test and control group. Blood samples were obtained from the lateral tail vein. Animals were not fasted prior to sampling.
- Haematology: The following parameters were measured on blood collected into tubes containing potassium EDTA anti-coagulant: Haemoglobin (Hb), Erythrocyte count (RBC), Haematocrit (Hct), Erythrocyte indices: mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC), Total leucocyte count (WBC), Differential leucocyte count: neutrophils (Neut), lymphocytes (Lymph), monocytes (Mono), eosinophils (Eos) and basophils (Bas), Platelet count (PLT) and Reticulocyte count (Retic): Methylene blue stained slides were prepared but reticulocytes were not assessed. Prothrombin time (CT) was assessed by 'lnnovin' and Activated partial thromboplastin time (APTT) was assessed by 'Actin FS' using samples collected into sodium citrate solution (0.11 mol/L).
- Clinical Chemistry: The following parameters were measured on plasma from blood collected into tubes containing lithium heparin anti-coagulant: Urea, Glucose, Total protein (Tot.Prat.), Albumin, Albumin/Globulin (NG) ratio (by calculation), Sodium (Na+), Potassium (K+), Chloride (Cl-), Calcium (Ca++), Inorganic phosphorus (P), Aspartate aminotransferase (ASAT), Alanine aminotransferase (ALAT), Alkaline phosphate (AP), Creatinine (Creat), Total cholesterol (Chol) and Total bilirubin (Bili).

NEUROBEHAVIOURAL EXAMINATION: Yes
- Prior to the start of treatment and at weekly intervals thereafter, all animals were observed for signs of functional/behavioural toxicity. Functional performance tests were also performed on five selected males and females from each dose level, prior to termination, together with an assessment of sensory reactivity to various stimuli.
Functional Performance Tests:
- Motor Activity. Purpose-built 44 infra-red beam automated activity monitors were used to assess motor activity. Animals were randomly allocated to the activity monitors. The tests were performed at approximately the same time each day, under similar laboratory conditions. The evaluation period was thirty minutes for each animal. The percentage of time each animal was active and mobile was recorded for the overall thirty minute period and also during the final 20 % of the period (considered to be the asymptotic period, Reiter and Macphail, 1979).
- Forelimb/Hind-limb Grip Strength. An automated meter was used. Each animal was allowed to grip the proximal metal bar of the meter with its forepaws. The animal was pulled by the base of the tail until its grip was broken. The animal was drawn along the trough of the meter by the tail until its hind paws gripped the distal metal bar. A record of the force required to break the grip for each animal was made. Three consecutive trials were performed for each animal. The assessment was developed from the method employed by Meyer et al (1979).

Sensory Reactivity
Each animal was individually assessed for sensory reactivity to auditory, visual and proprioceptive stimuli. This assessment was developed from the methods employed by Irwin (1968) and Moser et al (1988). The following parameters were observed: Grasp response, Vocalisation, Toe pinch, Tail pinch, Finger approach, Touch escape, Pupil reflex, Startle reflex and Blink reflex.


SACRIFICE:
- Adult males were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 43. Adult females were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 5 post partum. Surviving offspring were terminated via intracardiac overdose of sodium pentobarbitone. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 26 post coitum.

GROSS PATHOLOGY:
All adult animals and offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.
- Organ Weights: The following organs, removed from all surviving animals at terminal kill were dissected free from fat and weighed before fixation: Adrenals, Brain, Epididymides, Heart, Kidneys, Liver, Ovaries, Spleen, Testes, Thymus and Thyroid.

HISTOPATHOLOGY:
-Samples of the following tissues were preserved from all animals in buffered 10 % formalin except where indicated: Adrenals, Aorta (thoracic), Bone & bone marrow (femur including stifle joint), Bone & bone marrow (sternum), Brain (including cerebrum, cerebellum and pons), Caecum, Coagulation gland, Colon, Duodenum, Epididymides (preserved in Bouin's fluid then transferred to 70 % Industrial Methylated Spirits (IMS) approximately 48 hours later), Eyes (fixed in Davidson's fluid), Gross lesions, Heart, Ileum, Jejunum, Kidneys, Liver, Lungs (with bronchi) (inflated to approximately normal inspiratory volume with buffered 10 % formalin before immersion in fixative), Lymph nodes (cervical and mesenteric), Mammary gland, Muscle (skeletal), Ovaries, Pancreas, Pituitary, Prostate, Oesophagus, Rectum, Salivary glands (submaxillary) Sciatic nerve, Seminal vesicles, Skin (hind limb), Spinal cord (cervical, mid-thoracic and lumbar), Spleen, Stomach, Thyroid/parathyroid, Trachea, Testes (preserved in Bouin's fluid then transferred to 70 % Industrial Methylated Spirits (IMS) approximately 48 hours later), Thymus, Urinary bladder, Uterus/Cervix and Vagina.
-The tissues from five selected control and 750 mg/kg/day dose group animals and any animals which failed to 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 750 mg/kg/day were also processed. In addition, sections of testes and epididymides from all control and 750 mg/kg/day males were also stained with Periodic Acid-Schiff (PAS) stain and examined. Since there were indications of treatment-related changes in the liver, thyroid and thymus, examination was subsequently extended to include similarly prepared sections 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 Pathology computerisation system for tabulation and report production.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: No
- Number of implantations: Yes
- Number of early resorptions: No
- Number of late resorptions: No

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 (Salewski 1964).

Fetal examinations:

LITTER OBSERVATIONS
- 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: Number of offspring born, Number of offspring alive recorded daily and reported on Day 1 and 4 post partum, Sex of offspring on Day 1 and 4 post partum, Clinical condition of offspring from birth to Day 5 post partum and Individual offspring and litter weights on Day 1 and 4 post partum.

Physical Development
- All live offspring were assessed for surface righting reflex on Day 1 post partum.

SACRIFICE AND NECROPSY
- Necropsy was performed on offspring dying during lactation or at termination on Day 5 post partum.

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 and Offspring surface righting.
The following statistical procedures were used: Data were assessed for dose response relationships by linear regression analysis, followed by one way analysis of variance (ANOVA) incorporating Levene's test for homogeneity of variance. Where variances were shown to be homogenous, pairwise comparisons were conducted using Dunnett's test. Where Levene's test showed unequal variances the data were analysed using non-parametric methods: Kruskal­Wallis ANOVA and Mann-Whitney 'U' test.
The non-parametric methods were also used to analyse implantation loss, offspring sex ratio and landmark developmental markers.
Probability values (p) are presented as follows: p < 0.001 ***, p < 0.01 **, p < 0.05 * and p ≥ 0.05 (not significant).
Histopathology data were analysed using the following methods to determine significant differences between control and treatment groups for the individual sexes (excluding any not producing a pregnancy/litter):
Chi-squared analysis for differences in the incidence of lesions occurring with an overall frequency of 1 or greater.
Kruskal-Wallis one-way non-parametric analysis of variance for the comparison of severity grades for the more frequently observed graded conditions.
Probability values (P) were calculated as follows: P < 0.001 +++ --- ***, P < 0.01 ++ -- **, P < 0.05 + - *, P < 0.1 (+) (-) (*), P ≥ 0.01 N.S. (Not significant).
Plus (+) signs indicate positive differences from the control group and minus (-) signs indicate negative differences. Asterisks refer to overall differences between group variation which is non-directional.

Indices:

REPRODUCTIVE INDICES
- Pre-coital Interval: Calculated as the time elapsing between initial pairing and the observation of positive evidence of mating.
- 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.
Gestation Length: Calculated as the number of days of gestation including the day for observation of mating and the start of parturition.
Parturition Index: The following was calculated for each group. Parturition Index (%) = (Number of females delivering live offspring /number of pregnant females) x 100
- 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).
- 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 corpora lutea] x 100
%post-implantation loss = [(number of implantation sites – total number of offspring born) / number of implantation sites] x 100

OFFSPRING INDICES
- Live Birth Index (%) = (Number of offspring alive on Day 1 / number of offspring born) x 100
- Viability Index (%) = (number of offspring alive on day 4/ number of offspring alive on day 1) x 100
- 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: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

- No clinically observable signs of toxicity were detected.
- Episodes of increased salivation were detected in animals treated with 750 and 200 mg/kg/day. Such findings are often observed following the oral administration of an unpleasant tasting test material formulation and are considered not to be indicative of systemic toxicity. Episodes of red/brown staining of the mouth were evident in animals treated with 200 and 750 mg/kg/day along with instances of generalised fur loss seen in the 750 mg/kg/day dose group. These findings are considered to be incidental and of no toxicological significance.
- Behavioural Assessments: Weekly open field arena observations did not reveal any treatment-related effects. All inter and intra group differences in urination, defecation and transfer arousal scores were considered to be a result of normal variation for rats of the strain and age used and were of no toxicological importance.

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No effect was evident in females treated with 750, 200 or 50 mg/kg/day.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No adverse effect on dietary intake was detected for treated animals, in comparison to controls.

Food efficiency:

no effects observed

Description (incidence and severity):

No adverse effect on dietary intake was detected for treated animals, in comparison to controls.

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

no effects observed

Description (incidence and severity):

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

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There was no adverse effect on the haematological parameters measured for treated animals in comparison to controls.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

During Day 4 post partum a statistically significant increase in alanine aminotransferase levels (P < 0.01) was evident in the 750 mg/kg/day females.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

A statistically significant increase in liver weight (P < 0.01) both absolute and relative to terminal bodyweight was evident in animals treated with 750 mg/kg/day.
No such effects were evident in animals treated with 200 or 50 mg/kg/day.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

No treatment-related abnormalities were detected for treated adults in comparison to controls.
One 200 mg/kg/day female had epithelial sloughing of the glandular region of the stomach, in the absence of a dose related response or histopathological correlates this finding is considered to be of no toxicological importance.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathogical examinations revealed the following treatment-related effects:

THYMUS: Higher grades of severity of lymphoid atrophy were seen among females only treated with 750 mg/kg/day. A similar effect was not seen among female rats in the remaining dose groups.


OTHER HISTOPATHOLOGY

The remaining histopathological changes seen among surviving control and intermediate dose animals were all considered to be spontaneous in origin and unrelated to treatment. The following conditions warrant specific mention:

BONE MARROW: Adipose infiltration of the marrow is an indicator of changes in marrow cellularity and in this study there was no difference between control and treated groups.

ILEUM: Vacuolation of the lamina propria was seen for animals of either sex from the control and high dose groups. The marginally greater prevalence of the condition among high dose males was considered to be of no toxicological significance.

KIDNEYS: Focal corticomedullary mineralisation is a commonly observed background condition among female rats and hydronephrosis was reported for four animals; this is considered to be a condition of congenital origin.

LIVER: Scattered mononuclear cell foci were observed in a few control and treated animals. Such are commonly observed in the rodent liver and are not indicative of any adverse condition at the severities encountered. Isolated instances of periportal pigment generalised hepatocyte enlargement and periportal lipid vacuolation were also seen.

LUNGS: A minimal severity of bronchus associated lymphoid tissue was reported for all control and high dose animals examined in the study and is not indicative of respiratory disease. A minimal severity of accumulations of alveolar macrophages was also observed for control and high dose animals; such are commonly observed in laboratory maintained rats of this age and are not suggestive of significant respiratory disease or an effect of treatment.

OESOPHAGUS: Inflammatory cell infiltrates in the peripheral musculature is a commonly observed change that is considered to be related to the physical trauma of gavage dosing.

SKELETAL MUSCLE: Mononuclear cell foci are commonly observed in the skeletal muscle of laboratory maintained rats and are of no toxicological significance at the incidences seen in this investigation.

SPLEEN: Extramedullary haemopoiesis is a normal background condition in the rat spleen and the severities observed were considered to be within normal limits. Post partum female rats frequently demonstrate elevated severities of splenic extramedullary haemopoiesis.


REPRODUCTIVE TRACT AND RELATED ORGANS

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

OVARY: No treatment-related 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.
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 toxicological significance.

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Description (incidence and severity):

- Mating: No treatment-related effects were detected in mating performance. With the exception of one 750 mg/kg/day pair, all paired animals mated within five days of pairing.

Maternal developmental toxicity

Number of abortions:

not examined

Pre- and post-implantation loss:

not examined

Total litter losses by resorption:

not examined

Early or late resorptions:

not examined

Dead fetuses:

not examined

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

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

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

All 200 and 50 mg/kg/day females were pregnant. One control female and one female treated with 750 mg/kg/day did not achieve pregnancy.

Other effects:

not examined

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: No observed adverse effects

2

Key result

Dose descriptor:

NOEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

clinical biochemistry

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Maternal abnormalities

Abnormalities:

effects observed, non-treatment-related

Results (fetuses)

Fetal body weight changes:

no effects observed

Description (incidence and severity):

There were no differences in litter weights or mean offspring bodyweights between control and treated animals.

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

In total ten females from the 200 and 50 mg/kg/day dose groups and nine control and 750 mg/kg/day dose group females gave birth to a live litter and successfully reared young to Day 5 of age. No significant differences were detected in viability for treated groups when compared to controls.

Changes in sex ratio:

no effects observed

Description (incidence and severity):

No significant differences were detected in sex ratio for treated groups when compared to controls.

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

No significant differences were detected in litter sizes for treated groups when compared to controls. Nine litters were evident for the 750 mg/kg/day and control groups at termination and ten litters were evident for the 200 and 50 mg/kg/day groups at termination.
There were no differences in litter weights or mean offspring bodyweights between control and treated animals.

Changes in postnatal survival:

no effects observed

Description (incidence and severity):

No significant differences were detected in viability for treated groups when compared to controls.

External malformations:

not examined

Skeletal malformations:

not examined

Visceral malformations:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

No obvious clinical signs of toxicity were detected.

NECROPSY
- No treatment-related macroscopic abnormalities were detected for offspring dying during lactation or at termination on Day 5 post partum.
- One female treated with 750 mg/kg/day produced a litter with one pup which had a reddened right testis, whilst another female from this treatment group had one small pup.
- Three females treated with 200 mg/kg/day each produced a litter with a small pup. One of these litters also had a pup with no milk in the stomach. A further litter had a pup with a damaged tail.
- One female treated with 50 mg/kg/day produced a litter with one pup which had an open wound.
- Two control females each produced a litter with small pups one of these also had a pup with increased renal pelvic cavitation. Another litter had a pup with a wound on the top of its head and one with a reddened right testis.
- The effects observed in the offspring are considered to be incidental spontaneously occurring events of no toxicological significance.

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No observed adverse effects

Fetal abnormalities

Key result

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, the no observable adverse effect level (NOAEL) for maternal animals was considered to be 750 mg/kg/day. No such effects were detected at 200 mg/kg/day and the no observed effect level (NOEL) was considered to be 200 mg/kg/day.

Executive summary:

The developmental toxicity of the test material to rats was investigated in accordance with the standardised guideline OECD 422, under GLP conditions.

A Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test was performed.

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 750, 200 and 50 mg/kg/day. A control group of ten males and ten females was dosed with vehicle alone (arachis oil). 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 the blood chemistry was re-evaluated 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.

All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

The oral administration of the test material to rats for a period of up to fifty-four consecutive days at dose levels of up to 750 mg/kg/day resulted in toxicologically significant effects at 750 mg/kg/day. Females treated with 750 mg/kg/day showed changes in blood chemistry, organ weights and thymus changes identified as higher grades of severity of lymphoid atrophy. Atrophy of the thymus gland is commonly seen among post-partum females and in the absence of a convincing response of treatment this finding is not considered to be adverse.

Pregnancy was achieved for ten females treated with 200 and 50 mg/kg/day and nine 750 mg/kg/day and control females. There were no treatment-related effects in gestation length, sex ratio, litter size, litter weight, mean offspring weight by sex, viability, clinical observations or developmental signs between the treatment and control animals.

Under the conditions of this study, the no observable adverse effect level (NOAEL) for maternal animals was considered to be 750 mg/kg/day. No such effects were detected at 200 mg/kg/day and the no observed effect level (NOEL) was considered to be 200 mg/kg/day.