Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

Currently viewing:

Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
From February 9, 1998 to January 15, 1999.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted according to internationally accepted testing guidelines and performed according to GLP. Justification for Read Across is reported in the endpoint summary and in the Category Justification Report attached to the Section 13 of this dossier.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
not impairing the study results.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
TEST ANIMALS
- Reason for the Species selection: the rabbit is an acceptable model for evaluating developmental toxicity of various classes of chemicals and for which there is a large historical database. This strain is susceptible to known developmental toxicants.
- Number of animals: 106 females.
- Source: Covance Research Products, Inc., Kalamazoo, Michigan.
- Age at study initiation: 7 months.
- Weight at study initiation: 2 - 8 Kg.
- Housing: animals were individually housed in suspended, stainless steel, with deotized paper beneath the caging to control excretory odor.
- Acclimation period: 6 days.
- Observation during the acclimation period: daily for any clinical signs of disease, given a detailed clinical examination prior to selection.
- Identification: unique identification includes cage number, group, applied individually by a metal ear tag.
- Diet: Certified Rabbit Chow #53222, PMI Feeds, Inc., St. Louis, Missouri, limited at the day of arrival to 50 g and increased to 170 g per day beginning on the second day of acclimation (each diet lot were certified by the manufacturer, but no additional analysis was conducted).
- Water: tap water, ad libitum (monitored for specific contaminants at periodic intervals according to SOP by MPI Research, but no additional analysis was conducted)
No contaminants were known to have been in the water or feed which could have altered the outcome of the study.

ENVIRONMENTAL CONDITIONS
- Temperature: 67 to 70°F.
- Humidity: 453 to 69 %.
- Photoperiod: 12h day/12h night with an automatic timer.
- Parameters monitoring and recording: daily.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
CMC (carboxymethyl cellulose)
Remarks:
0.5 %, low viscosity, white powder, Sigma Chemical Company.
Details on exposure:
PREPARATION OF DOSING SOLUTIONS
Before the test no adjustments for purity were made. The test article was mixed with aqueous 0.5% CMC at a dose volume of 10 ml/kg/day to achieve the desired dose concentrations. Fresh suspensions were prepared weekly. The required amount of test article was weighed directly into a calibrated beaker and suspended in vehicle using a stainless steel spatula. The spatula was rinsed into container with vehicle. Additional vehicle was added to the cylinder to yield 9000 ml of prepared test article. The contents of the cylinder were mixed using a motor driven propeller and dispensed into amber glass containers using a syringe and stored refrigerated.

VEHICLE
185 g of CMC was weighted and mixed with deionized water using a Warning blender. The solution was transferred into a calibrated container and additional deionized water was added to yield 37 mL of prepared vehicle. The contents of the container were mixed thoroughly using a motor-driven propeller. The prepared vehicle was stored refrigerated when not in use.

ADMINISTRATION
Test and control articles were drawn into an appropriate sized, plastic disposable syringe attached to a 12-gauge, stainless steel rabbit gavage needle.
A magnetic stir bar and stir plate were used to mix dosing suspensions during administration.
All dosage volumes administered were based on most recent body weights.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The test article was characterized by AvTech Laboratories, Inc., Kalamazoo, Michigan.

HOMOGEINICITY ANALYSIS
Prior to initiation of test article administration, test batches of the dose suspensions at the low and high concentration of test article were prepared employing the same method and batch size as used during the study to assess the homogeneity of the dose preparations. Following mixing, samples were collected and analysed. Remixing was necessary to obtain satisfactory homogeneity results.
The dosing suspensions prepared for all dose levels-were homogeneous and accurately prepared.

STABILITY ANALYSIS
Stability analysis was not conducted. The stability of the test article in the vehicle (0.5%carboxymethylcellulose) over the range of dosages to be used in this study was conducted in a concurrent rat study (MPI Research Study "No. 795-003).

CONCENTRATION ANALYSIS
Samples of test article suspension at each concentration were collected from the first study preparation.
Details on mating procedure:
Day 0 of gestation was designated as the day in which mating was observed. Females were mated to males and observed for evidence of mating.

Duration of treatment / exposure:
From gestational Day 7 to through Day 28.
Frequency of treatment:
Once per day.
Duration of test:
From gestational Day 7 until Day 29.
Doses / concentrations
Remarks:
Doses / Concentrations:
100, 400, and 800 mg/kg bw
Basis:
actual ingested
constant volume of 10 ml/kg/day in 0.5 % of CMC.
No. of animals per sex per dose:
25 females/group
Control animals:
yes, concurrent vehicle
Details on study design:
Rabbits considered suitable for study, based on acceptable health status, were randomized into treatment groups using a stratified, by weight, block rendomization procedure.
See the following details of the assignment procedure:
Group 1
Dose Level (mg/kg): 0, control
Initial females: 25
Uterine Exam/Necropsy: 25
Group 2
Dose Level (mg/kg): 100 TS
Initial females: 25
Uterine Exam/Necropsy: 25
Group 3
Dose Level (mg/kg): 400 TS
Initial females: 25
Uterine Exam/Necropsy: 25
Group 4
Dose Level (mg/kg): 800 TS
Initial females: 25
Uterine Exam/Necropsy: 25

Examinations

Maternal examinations:
CLINICAL FINDINGS
- Observation: at least twice a day, 7 days each week.
- Clinical findings: morbidity, mortality, signs of injury.
- Registration: all findings on the day they were observed.
From Days 7 through 29 of gestation each rabbit was removed from the cage and given a detailed clinical examination. The detailed examination included observations of the general appearance and condition activity and behaviour, excretory matter, respiration body surface abnormalities (scabbing, hair loss), and oral, nasal, and ocular regions. Observations included location size, and colour when applicable.

BODY WEIGHT
- Time schedule for examinations: on gestational days 0 and daily on Days 7-29.
Body weight change was recorded for gestational days 0 to 7, 7 to 10, 10 to 13, 13 to 16, 16 to 19, 19 to 22, 22 to 25, 25 to 29, 7 to 29 and 0 to 29.

FOOD CONSUMPTION
- Food consumption reported on gestational days 0 to 7, 7 to 10, 10 to 13, 13 to 16, 16 to 19, 19 to 22, 22 to 25, 25 to 29, 7 to 29 and 0 to 29.

PREMATURE DELIVERY
Females that showed signs of abortion before scheduled euthanasia were subjected to a necropsy.

POST-MORTEM EXAMINATIONS
A necropsy was performed by trained personnel under the supervision of a veterinary pathologist on does that aborted, were found dead or were euthanized in extremis. Euthanized rabbits of gestation were subjected to a limited necropsy on Day 29, and special emphasis was placed on structural abnormalities or pathologic changes which may have influenced the pregnancy.
Foetuses from aborts or euthanized in extremis were examined externally to the fullest possible extent and placed in 10 % neutral buffered formalin for possible future examination.

GROSS PATHOLOGY
Gross lesions and/or target organs were saved in 100 % neutral buffered formalin and the carcasses were discarded due to excessive toxicity (16 of 25 rabbits found dead, aborted, or euthanized in extremis), the rabbits remaining in the 800 mg/kg/day dose group were euthanized and necropsied in September 16, 1998. Animals in this dose group were euthanized on Day 29 of gestation and treated as scheduled described in the protocol (standard uterine examination and teratologic examination of foetuses).
Females euthanized prior to Day 29 of gestation were treated as an interim death and their foetuses were examined externally to the fullest possible extent and placed in 10 % neutral buffered formalin for possible future examination.
Due to excessive maternal toxicity, the 800 mg/kg/day group was terminated. Six does were euthanized prior to Day 29 of gestation. On Day 29 of gestation each surviving female was euthanized by intravenous injection of approximately 2.0 ml of sodium pentobarbital euthanasia solution via a marginal ear vein followed immediately by exsanguination and laparohysterectomy.
The abdomen was opened by an incision to remove the skin and examine mammary tissue and locate any subcutaneous masses.
The abdominal cavity was opened, and the uterus was exposed.
The carcasses were discarded.

Ovaries and uterine content:
UTERINE EXAMINATION
The location of viable and nonviable foetuses, early and late resorptions for each uterine horn, position of the cervix, and the number of corpora lutea were recorded, beginning from the distal end of the left uterine horn. The uterus was excised, and gravid uterine weight was recorded.
The foetuses were removed by making a dorsal incision longitudinally along both uterine horns. The embryonic membrane of each foetus was gently removed, and each foetus was pulled away from the placenta, fully extending the umbilical cord.
The placentae were grossly examined.
Uteri from females that appeared non-gravid were opened and placed in 10 % ammonium sulphide solution for detection of implantation sites (Kopf, et al., 1964).

IMPLANTATION
Each implant was categorized according to the following criteria: a viable foetus if it responded to touch; a nonviable foetus if there were no signs of autolysis and did not respond to touch; late resorption if a recognizable foetal form and underwent autolysis; and an early resorption if there was an implantation site, but the tissue had no recognizable foetal characteristics. A necropsy was conducted on each doe and maternal gross lesions were saved in 10 % neutral buffered formalin for possible microscopic examination.
Fetal examinations:
TERATOLOGIC EXAMINATION
Before the umbilical cord was cut for each foetus, it was momentarily clamped with forceps to prevent bleeding and promote clotting.
Each foetus was individually weighed and examined for external malformations and variations. Each foetus was deeply anesthetized by approximately
0.02 mL of a sodium pentobarbital euthanasia solution injected sublingually, making every attempt to avoid injection of internal organs and subjected to a fresh foetal soft tissue dissection (Smckhardt and Poppe, 1984). Any visceral abnormalities were recorded.
After dissection and examination of internal organs was complete, the heads from approximately one-half of the foetuses were removed and placed in Bouin's solution for subsequent soft tissue examination using the Wilson razor-blade sectioning technique (Wilson, 1965).
A mid-coronal head slice was made on the remaining foetuses and the brains were examined.
The carcasses and remaining foetuses were eviscerated, skinned, and fixed in alcohol, macerated in potassium hydroxide, stained with Alizarin Red S and Aldan blue, and cleared with glycerin for subsequent skeletal examination of bone and cartilage (Kimmel and Trammel, 1981).
Foetal findings were classified as malformations or developmental variations under the supervision of a developmental toxicologist.
Statistics:
Differences between groups were assessed using:
- Group pair-wise Comparison: Levene’s test, Dunnett’s test, Welch’s test with a Bonferroni correction (homogeneity).
- Arcsin-Square-Root Transformation.
- Chi-square test (homogeneity).
- Kruskal-Wallis test, Mann-Whitney U-test (malformations).
- Parson Chi-Square, Fishers exact test (malformations and developmental variations).
- Descriptive statistics (means, SD).

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
MORTALITY
An excessive mortality and maternal toxicity were observed at 800 mg/kg/day during this study.
As a result, this group was terminated as of September 16, 1998.
A total of 8 does in this group were found dead and an additional doe was euthanized in extremis.
Two does from the control group died during the study. These deaths were considered to be related to technical error or mechanical injury. One doe in the 400 mg/kg/day group was diagnosed as moribund, but died before it could be euthanized. The necropsy endings indicated that this dam was suffering from an esophageal laceration. Hence, this death was considered to be due to gavage error, and not test article toxicity.

CLINICAL OBSERVATIONS
Treatment related clinical signs observed in the 800 mg/kg/day group included convulsions, decreased defecation soft stool, discoloured faeces and reddish fluid in the refuse pan. In addition, 7 does from the 800 mg/kg/day group aborted during the study, and these abortions were considered to be treatment related. Furthermore, 2 does from the 400 mg/kg/day group delivered early and this was considered to be related to treatment. Slight increases in soft stool and discoloured faeces were also noted in the 400-mg/kg/day group when compared with the vehicle control group, and since these signs were also observed at 800 mg/kg/day, the findings were considered to be related to test article administration.
One doe each from the 100 and 400 mg/kg/day groups aborted during the study. The 400-mg/kg/day doe that aborted had an oedematous stomach and liquid, bloody contents in the intestines at necropsy. This abortion, therefore, could have been secondary to these effects.
Furthermore, necropsy of the doe at 100 mg/kg/day that aborted revealed injuries consistent with gavage error, suggesting that this abortion also may have beensecondary to a physical trauma. For further details see Table n 1.

BODY WEIGHT
Treatment-related, statistically significant decreases in body weight gain were noted at 800 mg/kg/day when compared with the vehicle controls during the study.
Significant losses in body weight occurred in the 800 mg/kg/day group when compared with the vehicle controls during several intervals of the gestation period.
No statistically significant changes in body weight or body weight gain were noted in does at 100 or 400-mg/kg/day during gestation.
The body weight gain of both treatment groups was comparable with vehicle controls during the study.
For further details see Table n.2.

FOOD CONSUMPTION
Treatment-related reductions in food consumption were noted in the 800 mg/kg/day group when compared with the vehicle control group during the study. This was corroborated by the significant decreases in body weight gain observed in this group during gestation. No changes in food consumption were noted in the lower treatment groups when compared with the vehicle control group during the study.
For further details see Table n 3.

NECROPSY OBSERVATION
Treatment-related necropsy findings appeared to be limited to the 800 mg/kg/day group with 1 exception and included discoloration of the liver, edematous and/or discoloured stomach red discolored and/or edematous intestines, bloody and/or mucoid contents in the intestines, and loci in the lung.
The rabbit in the 400 mg/kg/day group that aborted had an edematous stomach and liquid, bloody contents in the intestines at necropsy. Since these findings were also noted in the 800 mg/kg/day group, the observations at 400 mg/kg/day were considered to be treatment related. All other necropsy endings were considered to be spontaneous in nature or observations normally seen in rabbits of this age and strain and unrelated to test article administration.
One vehicle control rabbit (Animal No. 1986) that died appeared to have suffered from a mechanical injury since it had a subdural haemorrhage in the brain at necropsy as well as some hemorrhaging around the thymic region.
This rabbit exhibited decreased activity, labored breathing and white material around the nose prior to death.
For further details see Table n 4.

UTERINE EXAMINATION
The 800 mg/kg/day group was terminated before completion of the study due to excessive maternal toxicity.
Six does were subjected to elective euthanasia prior to Day 29 of gestation. Three does from the 800 mg/kg/day group survived to Day 29 and were euthanized and subjected to the protocol-specified uterine examination, and their foetuses were examined as specified in the protocol. The data for these 3 does and litters are presented in the individual tables within the report, but were not included in the summary tables or in the statistical analysis.No treatment-related effects on uterine parameters were observed in the 100 or 400 mg/kg/day groups when compared with the vehicle control group. Numbers of corpora lutea, implantation sites, live and dead foetuses and resorptions, pre and post-implantation loss and sex ratio were comparable between the vehicle control and treatment groups.
The number of live foetuses/litter was statistically higher at 400 mg/kg/day than controls.
This was due to the lower (not statistically significant) pre-implantation loss at 400 mg/kg/day when compared with controls and was not considered to be related to test article administration.
There were no changes in uterine weight, adjusted body weight or body weight gain in the 100 or 400 mg/kg/day groups when compared with the vehicle control group. There were no changes in uterine weight, adjusted body weight or body weight gain in the 100 or 400 mg/kg/day groups when compared with the vehicle control group. For further details see Table n.5a.
Treatment-related effects on foetal body weight, however, were noted in the 400 mg/kg/day group when compared with the vehicle control group. Statistically lower foetal (all viable foetuses) body weight and male foetal body weight were noted at 400 mg/kg/day when compared with the vehicle control group. These changes may have been secondary to the maternal toxicity observed in this study and were not considered to be an indication of developmental toxicity. No changes were observed at 100 mg/kg/day when compared with the vehicle control group.
For further details see Table n.5b.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOEL
Effect level:
100 mg/kg bw (total dose)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOEL
Effect level:
100 mg/kg bw/day
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
FETAL EVALUATIONS
1) EXTERNAL EXAMINATION
No treatment-related effects were noted. The incidences of Endings were low and sporadic among the treatment groups and were within historical control ranges for this laboratory.

2) VISCERAL EXAMINATION
There were no treatment-related increases in the incidence of visceral variations or malformations in this study. Slight, but not statistically significant, increases in several malformations were noted at 400 mg/kg/day when compared with the vehicle control group.
The litter incidence of haemorrhagic iris at 400 mg/kg/day was slightly above the historical control range for this laboratory. The litter incidences of gallbladder agenesis (malformation),
hypoplasia of the gallbladder (variation) and azygous lobe of lung absent (variation) at 400 mg/kg/day were within historical control range (litter incidence).
Since all the above findings were within or only slightly above historical control range, the findings were considered to be spontaneous in nature and unrelated to test article administration.
For further details see Table n.6.

3) SKELETAL EXAMINATION
No treatment-related increases in skeletal variations or malformations were noted at 100 or 400 mg/kg/day when compared with the vehicle control group. The incidences of all endings were either comparable with the concurrent control group or within historical range for this laboratory.
Slight increases in the litter incidence of hyoid arch bent and unilateral full rib were noted at 400 mg/kg/day when compared with the vehicle control group. These findings are relatively common in rabbits, however, and both litter incidences are well within the historical control range for this laboratory.
Furthermore, decreases in foetal weight were observed at 400 mg/kg/day, suggesting that foetal development was delayed as a result of maternal toxicity. These findings may have been a further indication of delayed development as a result of maternal toxicity rather than a direct result of the test article on skeletal development.
For further details see Table n.7.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
400 mg/kg bw (total dose)
Based on:
test mat.
Basis for effect level:
other: teratogenicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

TABLE 1: Clinical observations (n. animals affected)

Clinical signs Dose level (mg/kg/day)
0 100 400 800
Found dead 2 0 0 8
Euthanizedin extremis 0 0 1 (gavage error) 1
Elective euthanasia 0 0 0 6
Aborted 0 1 1 7
Delivered early 0 0 2 0
Convulsions 0 0 0 1
Decreased defecation 9 7 11 20
Soft stool 4 7 9 13
Discoloured faeces 0 0 1 15
Reddish fluid in refuse pan 1 0 1 13

TABLE 2: Gestational Body Weight Gain (g)

Study interval Dose level (mg/kg/day)
(Interval) 0 100 400 800
0-7 249 299 259 301
7 -29 240 289 244 -221
0-29 502 585 502 53

TABLE 3: Gestational Food Consumption Data (g/animal/day)

Study interval Dose level (mg/kg/day)
(Interval) 0 100 400 800
0-7 138.4 149.2 144.1 140.8
7 -29 129.0 140.6 128.8 109.5
0-29 131.2 142.6 134.5 117.2

TABLE 4: Necropsy Observations (n. Animals Affected)

Findings Dose level (mg/kg/day)
0 100 400 800
Foci in the lungs 0 0 0 3
Discoloration of the liver 1 0 0 4
Accentuated lobulation of the liver 0 0 1 1
Discoloration of the stomach 0 0 0 2
Edematous stomach 0 0 1 2
Red discoloration of the intestines 0 0 0 2
Liquid mucoid contents of the intestines 1 0 0 4
Liquid bloody contents of the intestines 0 0 1 4
Edematous intestines 0 0 0 1

TABLE 5a: Summary of Uterine Parameters

Uterine Parameters Dose level (mg/kg/day)
0 100 400
N. Pregnant 25 25 25
N. Corpora lutea/doe 10.10 10.17 10.14
N. Implantation sites/doe 8.83 9.04 9.57
N. Live foetuses 8.35 8.79 9.00
Sex ration (% males) 50.76 53.28 55.34
N. Total resorption/doe 0.48 0.25 0.57
Gravid uterine weight (g) 489.0 493.0 524.6
Adjusted body weight gain (g) 13.5 91.9 50.2

TABLE 5b: Foetal Body weight (g)

Uterine Parameters Dose level (mg/kg/day)
0 100 400
All viable foetus 41.75 41.56 38.13
N. Corpora lutea/doe 41.00 41.43 37.61
N. Implantation sites/doe 42.29 41.64 38.81

TABLE 6: Incidence of Visceral Findings (n. Foetus/litters)

Variation Dose level (mg/kg/day) Historical control (% Litters Affected)
0 100 400
Foetus/litters examined 192/23 211/24 205/23 NA
Hemorrhagic iris 0/0 1/1 (4 %) 2/2 (9 %) 0-6
Azygous lobe of lung absent 8/7 (30 %) 6/6 (25 %) 16/9 (9 %) 0-39
Hypoplasia of gallbladder 3/2 (9 %) 1/1 (4 %) 11/6 (26 %) 0-32
Agenesis of the gallbladder 0/0 0/0 1/1 (4 %) 0-10

TABLE 7: Skeletal Variations (n. Foetus/litters)

Variation Dose level (mg/kg/day) Historical control (% Litters Affected)
0 100 400
Fetuses/litters examined 192/23 211/24 205/23 NA
Hyoid arch bent 3/3 (13 %) 5/4 (17 %) 18/10 (43 %) 0-53
27 Presacral vertebrae 57/15 (65 %) 30/9 (38 %) 35/11 (48 %) 25 -85
Extra rib  16/9 (39 %) 22/11 (46 %)  20/14 (61 %)  0 -100
7th cervical rib 1/1 (4 %)  10/4 (17 %)  1/1 (4 %) 0 -42 

Applicant's summary and conclusion

Conclusions:
The test item is considered under the study not teratogenic in rabbits.
Executive summary:

Method

The developmental toxicity, including the teratogenic potentialof the test article was assessedin rabbits in accordance with OPPTS Guideline 870.3700, EPA Guidelines, March 1997. The dose levels of 100, 400, and 800 mg/kg/day were administered via gavage, once at day, to 3 treatment groups of 25 females and 1 vehicle control group. The female rabbits were time mated at receipt. 

Exposure initiated on Day 7 of gestation and continued to and included Day 28 of gestation. Observations of does included clinical signs, gestational body weights and food consumption. Litters were delivered by caesarean section on Day 29 of gestation. Gravid uterine weights were recorded. Total number of corpora lutea, implantations, early and late resorptions, live and dead foetuses, and individual sex and body weights of foetuses were recorded. All foetuses were examined for external, visceral, and skeletal abnormalities (bone and cartilage).

Results

Excessive maternal toxicity, as evidenced by mortality, statistically significant decreases in body weight gain and food consumption as well as an increase in abortion, was observed at 800 mg/kg/day. As a result, this group was terminated prior to completion of the study. Less severe maternal toxicity was observed at 400 mg/kg/day.

Two does died in the control group, but these deaths were a result of technical gavage error or mechanical injury. A total of 8 rabbits from the 800 mg/kg/day group died during gestation and another high-dose doe was euthanized in extremis. An additional 7 does from the high-dose group aborted during the study. No treatment-related mortality was noted at 100 or 400 mg/kg/day. 

A doe in the 400 mg/kg/day group was considered to be moribund, but died prior to being euthanized. Necropsy findings suggested that this animal died due to gavage-related injury. Treatment-related clinical observations at 400 mg/kg/day included soft faeces and discoloured stool. No changes in body weight, body weight gain or food consumption were noted at 100 or 400 mg/kg/day. 

Necropsy findings in does from the 800 mg/kg/day group included discoloration of the liver, edematous and/or discoloured stomach, red discoloured and/or edematous intestines, bloody and/or mucoid contents in the intestines. The rabbit in the 400 mg/kg/day group that aborted had an edematous stomach and liquid, bloody contents in the intestines at necropsy which were also considered to be treatment related.

Foetal data collected from 3 litters that were examined prior to terminating the 800 mg/kg/day group are presented in individual tables, but were not summarized, analysed statistically or discussed in this report. No effects on uterine parameters were noted at 100 or 400 mg/kg/day.

Numbers of corpora lutea, implantations, live and dead foetuses and resorptions were comparable between the vehicle control and the 100 and 400 mg/kg/day groups.

Foetal body weights were statistically lower at 400 mg/kg/day when compared with the vehicle control group.

Based on treatment-related clinical observations and necropsy findings seen in does at 400 mg/kg/day, the No Observed Effect Level (NOEL) for maternal effects in this study was 100 mg/kg/day, the lowest dose tested. There were statistically significant decreases in foetal body weight at 400 mg/kg/day. These changes may have been secondary to the maternal toxicity observed in this study and were not considered to be an indication of developmental toxicity.