Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-07-27 - 2019-11-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no

Test material

Constituent 1
Reference substance name:
Ethanol, 2,2'-oxybis-, reaction products with ammonia, morpholine derivs. residues
EC Number:
272-712-1
EC Name:
Ethanol, 2,2'-oxybis-, reaction products with ammonia, morpholine derivs. residues
Cas Number:
68909-77-3
Molecular formula:
Not applicable (UVCB)
IUPAC Name:
Ethanol, 2,2'-oxybis-, reaction products with ammonia, morpholine derivs. residues
Test material form:
liquid
Details on test material:
Name: Ethanol, 2,2'-oxybis-, reaction products with ammonia, morpholine derivs. residues
Physical state: liquid
Appearance: brown liquid
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: Huntsman Europe BVBA and 17/19961
- Expiration date of the lot/batch: 2019-11-22
- Purity test date: Not applicable (UVCB)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At ambient temperature (15 to 25°C); protected from light and moisture.
- Stability under storage conditions: Not specified
- Stability under test conditions: Before commencement of treatment, the suitability of the proposed mixing procedures was determined and specimen formulations at 2and 200mg/mL were analyzed to assess the stability of the test item in the liquid matrix.
- Solubility and stability of the test substance in the solvent/dispersant/vehicle/test medium: Not specified
- Reactivity of the test substance with the solvent/vehicle /test medium (if applicable): Not specified

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Mixed to vehicle (purified water)
- Final preparation: The required amount of test item was weighed. Approximately 50% of the final volume of vehicle was added and magnetically stirred until the test material was uniformly mixed. The remaining vehicle was added to achieve the required volume and the formulation was mixed using a magnetic stirrer until homogeneous.
A series of formulations at the required concentrations were prepared in ascending order.
- Frequency of preparation: Weekly, in advance of dose administration.
- Storage of formulation: Refrigerated at 2 to 8°C

OTHER SPECIFICS
- Physical State/appearance: Brown liquid
- other information: No correction factor

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Envigo RMS.
- Age at study initiation (day 0 of gestation): 19 to 23 weeks old
- Weight at study initiation: 2.82 to 4.61 kg
- Fasting period before study: No
- Housing: Suspended cages fitted with perforated floor panels and mounted in batteries. Undertrays lined with absorbent paper were changed at least three times a week. Cages were also fitted with a plastic resting platform.
Number of animals per cage: acclimatization one female, during mating one stock male and one female, during gestation one female.
- Diet (e.g. ad libitum): Teklad 2930 Diet, the diet contained no added antibiotic or other chemotherapeutic or prophylactic agent. Availability was restricted (initially 150g/animal/day during acclimatization up to one week prior to the onset of mating and 200g/animal/day thereafter). Should an individual show a significant non-treatment related reduced food consumption, moistened diet (50 g pelleted diet moistened with 20 to 50 mL of water) was offered and the consumption was recorded. In addition to this diet, a small supplement of autoclaved hay was given on a daily basis to promote gastric motility and a small amount of chopped fresh vegetables were given twice weekly. Consumption of hay and vegetables were monitored qualitatively but not quantitatively.

- Water (e.g. ad libitum): Ad libitum. Potable water from the public supply via polycarbonate bottles with sipper tubes. Bottles were changed at appropriate intervals. Water bowls were offered to individuals during acclimatization.
- Acclimation period: 19 days before commencement of mating.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15 - 21°C
- Humidity (%): 45 - 70%.
- Air changes (per hr): Filtered fresh air which was passed to atmosphere and not recirculated.
- Photoperiod (hrs dark / hrs light): 10/14

IN-LIFE DATES: From: 2018-07-04 To: 2018-08-24

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
-The test item was prepared at the appropriate concentrations as a solution in Distilled Water.
- The stability of formulations was demonstrated over a period of up to 21 days at 2 to 8°C and one day at ambient temperature (15 to 25°C). Formulations were therefore prepared weekly and stored at approximately 2 to 8 ºC.
VEHICLE
- Justification for use and choice of vehicle (if other than water): not applicable (vehicle is water)
- Concentration in vehicle: 0, 25, 50,100 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg body weight
- Purity: not specified
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The homogeneity and stability was confirmed for Amine C8 in Distilled Water formulations at nominal concentrations of 2 mg/mL and 200 mg/mL when stored refrigerated for 21 days and at room temperature in the light for 24 hours.
Samples of test item formulations were taken on two occasions and analyzed for concentration and the results indicate that the prepared formulations were within 100-112% of the nominal concentration.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: 6 days
- Further matings after two unsuccessful attempts: not specified
- Verification of same strain and source of both sexes: not specified
- Proof of pregnancy: Expelled uterine contents were identified and examined, as appropriate
- Any other deviations from standard protocol: No applicable
Duration of treatment / exposure:
Day 6 to 28 after mating
Frequency of treatment:
Once daily at approximately the same time each day.
Duration of test:
29 days
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Group 1 (control)
Dose / conc.:
125 mg/kg bw/day (nominal)
Remarks:
Group 2
Dose / conc.:
250 mg/kg bw/day (nominal)
Remarks:
Group 3
Dose / conc.:
500 mg/kg bw/day (nominal)
Remarks:
Group 4
No. of animals per sex per dose:
22 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: not specified
- Rationale for animal assignment (if not random): Where possible only females mating at least twice were allocated.
Method to group and cage position in the sequence of mating: Females mating on any one day were evenly distributed amongst the groups.
Allocation was controlled to prevent any stock male from providing more than one mated female in each treated group and to prevent more than one sibling female in each group, where possible.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked in table were included.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Animals were inspected visually at least twice daily for evidence of ill-health or reaction to treatment. A detailed physical examination was performed on each animal on Days 0, 6, 12, 18, 24 and 29 after mating to monitor general health.

BODY WEIGHT: Yes
- Time schedule for examinations: The weight of each adult was recorded weekly during acclimatization, on Days 0, 3 and 6-29 after mating

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- The weight of food supplied to each animal, that remaining and an estimate of any spilled was recorded daily from Day 1 after mating.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- All adult animals were subject to a detailed necropsy. After a review of the history of each animal, a full macroscopic examination of the tissues was performed. All external features and orifices were examined visually. Any abnormality in the appearance or size of any organ and tissue (external and cut surface) was recorded and the required tissue samples preserved in appropriate fixative.


Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Fetuses (live and dead).
Fetal examinations:
- External examinations: Yes [half per litter]
- Soft tissue examinations: Yes [ half per litter]
- Skeletal examinations: Yes [half per litter]
- Head examinations: Yes: [ half per litter ]
Statistics:
The following sequence of statistical tests was used for body weight, gravid uterus weight, food consumption, corpora lutea, implantations, pre/post implantation loss, live young, sex ratio - percentage male, placental, litter and fetal weights:

A parametric analysis was performed if Bartlett's test for variance homogeneity (Bartlett 1937) was not significant at the 1% level. For pre-treatment data, analysis of variance was used to test for any group differences. Where this was significant (p<0.05) inter group comparisons using t-tests, with the error mean square from the one-way analysis of variance, were made. For all other analyses the F1 approximate test was applied.

A non-parametric analysis was performed if Bartlett's test was still significant at the 1% level following both logarithmic and square-root transformations. For pre-treatment data, Kruskal-Wallis’ test (Kruskal and Wallis 1952, 1953) was used to test for any group differences. Where this was significant (p<0.05) inter group comparisons using Wilcoxon rank sum tests (Wilcoxon1945) were made. For all other analyses the/The H1 approximate test, the non-parametric equivalent of the F1 test described above, was applied.

Significant differences between the groups compared were expressed at the 5% (p<0.05) or 1% (p<0.01) level.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Description (incidence and severity):
There were no signs were observed at either routine physical examination or in association with dose administration that could be related to treatment.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
One female dosed at 125 mg/kg/day was euthanized prematurely with evidence of abortion. Uterine examination revealed a single implantation that was resorbing. This was therefore considered to be a resorption rather than abortion and as there was a solely a single implant it is considered to relate to biological efficiency rather than an effect of treatment.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
As treatment progressed weight gain for females receiving 500 mg/kg/day was low when compared with Controls and overall the bodyweight gain from GD6 to GD29 bodyweight gain was 17% of Controls (p<0.01). The overall body weight gain for females at 125 or 250 mg/kg/day were similar to the Controls and showed no adverse effect of treatment.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
The mean food consumption for females receiving 500 mg/kg/day was slightly but consistently low from Day 6 to Day 27 of gestation when compared with Controls, with the total consumption over the treatment period at approximately 79% of the Control value.
At 250 mg/kg/day there were occasions of slightly low consumption however overall the food consumed was similar to Control values.
Food consumption at 125 mg/kg/day was unaffected by treatment with Amine C8.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
The maternal body weight loss following adjustment for the gravid uterine weight was slightly greater than Controls for females that received 500 mg/kg/day; however this difference did not attain statistical significance. The maternal weight loss for females at 125 or 250 mg/kg/day were similar to the Controls and showed no adverse effect of treatment.
Gross pathological findings:
no effects observed
Description (incidence and severity):
Macroscopic examination of females did not reveal any findings that could be attributedto treatment with the test item.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
effects observed, non-treatment-related
Description (incidence and severity):
On GD22 one female dosed at 125 mg/kg/day was euthanized prematurely with evidence of abortion. Uterine examination revealed a single implantation that was resorbing. This was therefore considered to be a resorption rather than abortion and as there was a solely a single implant it is considered to be incidental and relate to biological efficiency rather than an effect of treatment.
Pre- and post-implantation loss:
effects observed, non-treatment-related
Description (incidence and severity):
The post-implantation loss (%) for females at 500mg/kg/day was slightly high when compared with Controls and the resultant mean litter size was low when compared with Controls (p<0.05). However, the live litter size and percentage of post implantation loss were within the historical control data range so no effect of treatment is inferred.
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
effects observed, non-treatment-related
Description (incidence and severity):
On GD29 prior to sacrifice, one female dosed at 500 mg/kg/day prematurely delivered six live offspring, one dead offspring and one late resorption within the animal facility. Macroscopic examination of female no 72 and offspring did not reveal any findings that could be attributed to treatment. As this was an isolated incidence it was considered to be unrelated to administration of test item.
Changes in pregnancy duration:
not examined
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
One control female and 3 females treated at 250 mg/kg/day were found to be not pregnant at macroscopic examination. There was no effect that could be attribute to treatment on the number of pregnant females.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOEL
Effect level:
250 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
body weight and weight gain
food consumption and compound intake

Maternal abnormalities

Key result
Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
no effects observed
Description (incidence and severity):
Group mean placental weights, male or fetal weight and overall fetal weight were essentially similar to Controls at dose levels up to and including 500 mg/kg/day.
Reduction in number of live offspring:
effects observed, non-treatment-related
Description (incidence and severity):
There was no clear effect of treatment on offspring survival and litter size at 125 or 250 mg/kg/day. The post-implantation loss (%) for females at 500 mg/kg/day was slightly high when compared with Controls and the resultant mean litter size was low when compared with Controls (p<0.05). However, the live litter size and percentage of post implantation loss were within the historical control data range so no effect of treatment is inferred.
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
effects observed, non-treatment-related
Description (incidence and severity):
The mean litter weight for females that received 500 mg/kg/day was slightly but significantly low when compared with Controls; this was attributed to the low live litter size rather than the mean fetal weight at this dose level.
Changes in postnatal survival:
not examined
External malformations:
no effects observed
Description (incidence and severity):
The overall incidence of minor external abnormalities was not adversely affected by test item treatment. The incidences of individual categories of minor abnormalities were within normal ranges for all groups.
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
The total number of fetuses with major abnomalities were 0, 3, 0, 4 in control, 125, 250 and 500mg/kg/day respectively. The range and incidence of major abnormalities at 125 and 500 mg/kg/day showed no relationship to treatment.
The overall incidences of minor skeletal abnormalities were similar for all groups. One statistically significant difference was observed: at 500 mg/kg/day there was a slight increased incidence of full supernumerary 13th ribs and unilateral caudal shift of pelvic girdle when compared with both the Concurrent Controls and the historical control data range. The combination of these skeletal variants at 500 mg/kg/day indicates a slight shift in rib/vertebral configuration which is not considered adverse.
Visceral malformations:
no effects observed
Description (incidence and severity):
The overall incidence of minor visceral abnormalities was not adversely affected by test item treatment. The incidences of individual categories of minor abnormalities were within normal ranges for all groups.

Effect levels (fetuses)

Key result
Dose descriptor:
NOEL
Effect level:
250 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
skeletal malformations

Fetal abnormalities

Key result
Abnormalities:
effects observed, non-treatment-related

Overall developmental toxicity

Key result
Developmental effects observed:
yes
Lowest effective dose / conc.:
500 mg/kg bw/day (nominal)
Treatment related:
no
Relation to maternal toxicity:
not specified
Relevant for humans:
not specified

Any other information on results incl. tables

Table1: Number of pregnant dams, dams with abortions, early deliveries, resorptions, and/or dead foetuses.

Group/Sex

Total number of dams

Number of pregnant dams

Number of dams with abortions

Number of dams with early deliveries

Number of dams with resorptions

Number of dams with dead

foetuses

1F

22

21

0

0

12

0

2F

22

22

1

0

12

0

3F

22

19

0

0

6

0

4F

22

22

0

1

16

1

Table 2: Gravid uterine weight, adjusted body weight and adjusted body weight change - group mean values (kg) on Day 29 of gestation

Group/Sex

 

Body weight Day 6

Terminal body weight Day 29

Body weight change 6-29

Gravid uterine weight

Adjusted body weight Day 29

Adjusted body weight change 6-29

Statistics test

 

Av

Wi

Wi

Wi

Wi

Wi

1F

Mean

3.74

3.96

0.22

0.533

3.43

-0.31

 

SD

0.247

0.237

0.163

0.1019

0.218

0.188

 

N

21

21

21

21

21

21

2F

Mean

3.77

4.04

0.26

0.504

3.53

-0.24

 

SD

0.341

0.335

0.142

0.1221

0.349

0.172

 

N

21

21

21

21

21

21

3F

Mean

3.67

3.87

0.21

0.484

3.39

-0.28

 

SD

0.325

0.345

0.156

0.0929

0.313

0.139

 

N

19

19

19

19

19

19

4F

Mean

3.76

3.83

0.07**

0.462*

3.37

-0.39

 

SD

0.310

0.266

0.212

0.1029

0.254

0.174

 

N

21

21

21

21

21

21

Table 3: Litter data - group mean values on Day 29 of gestation

Group/Sex

 

Corpora lutea

Implantations

Resorptions Early

Resorptions Late

Resorptions Total

Live young Male

Live young Female

Live young Total

Sex ratio (%M)

Pre-Implantation loss (%)

Post-Implantation loss (%)

Statistics test

 

Wi

Wi

 

 

 

 

 

Wi

Wi

Wi

Wi

1F

Mean

10.8

10.0

0.7

0.3

1.0

4.8

4.2

9.0

53.6

7.3

10.3

 

SD

2.05

2.01

0.91

0.73

1.14

2.09

2.07

2.06

19.16

7.97

11.30

 

N

21

21

21

21

21

21

21

21

21

21

21

2F

Mean

9.8

9.0

0.9

0.2

1.1

3.7

4.2

7.9

49.5

9.4

10.9

 

SD

2.02

2.50

1.28

0.89

1.45

1.15

2.04

2.22

18.41

16.32

13.15

 

N

21

21

21

21

21

21

21

21

21

21

21

3F

Mean

10.0

8.6

0.3

0.2

0.5

3.2

4.9

8.1

40.2

14.2

5.1

 

SD

1.49

1.68

0.58

0.50

0.96

1.46

1.96

1.73

17.93

12.81

10.63

 

N

19

19

19

19

19

19

19

19

19

19

19

4F

Mean

10.2

9.3

0.9

0.7

1.6

3.9

3.9

7.7*

50.0

8.5

16.2

 

SD

1.81

2.13

1.04

1.23

1.80

1.85

1.93

2.12

17.80

13.27

16.46

 

N

21

21

21

21

21

21

21

21

21

21

21

Table 4: Litter and fetal weights - group mean values (g) on Day 29 of gestation

Group/Sex

 

Total litter weight

Male fetal weight

Female fetal weight

Overall fetal weight

Statistics test

 

Wi

Wi

Du

Wi

1F

Mean

349.7

40.0

38.2

39.3

 

SD

73.03

6.36

6.44

5.65

 

N

21

21

21

21

2F

Mean

324.1

41.8

41.9

41.9

 

SD

81.14

4.21

4.68

4.22

 

N

21

21

20

21

3F

Mean

320.5

40.2

39.9

39.8

 

SD

67.73

4.68

4.04

3.76

 

N

19

19

19

19

4F

Mean

286.6*

37.2

37.1

37.3

 

SD

81.94

6.78

6.67

6.07

 

N

21

21

21

21

Table 5: Fetal examinations

Group/Sex

 

Major abnormality findings (%)

Minor skeletal abnormalities and variations (%)

Minor visceral abnormalities/ variations and necropsy findings (%)

 

 

 

 

 

1F

N litters affected(%)

0 (0)

20 (95)

2 (9.5)

 

Total litters

21

21

21

 

N fetuses affected(%)

0 (0)

120 (63)

2 (1)

 

Total fetuses

190

190

190

 

 

 

 

 

2F

N litters affected(%)

3 (14)

21 (100)

3 (14)

 

Total litters

21

21

21

 

N fetuses affected(%)

3 (1.8)

109 (66)

4 (2.4)

 

Total fetuses

165

165

165

 

 

 

 

 

3F

N litters affected(%)

0 (0)

19 (100)

2 (10.5)

 

Total litters

19

19

19

 

N fetuses affected(%)

0 (0)

113 (73.3)

2 (1.2)

 

Total fetuses

154

154

154

 

 

 

 

 

4F

N litters affected(%)

3 (14)

21 (100)

4 (19)

 

Total litters

21

21

21

 

N fetuses affected(%)

4 (2.4)

134 (82.7)

4 (2.4)

 

Total fetuses

162

162

162

TAble 6: Historical control data (14 Studies, 2016-2017) - litter data

 

Corpora lutea

Implantations

Resorptions Early

Resorptions Late

Resorptions Total

Live young Male

Live young Female

Live young Total

Sex ratio (%M)

Pre-Implantation loss (%)

Post-Implantation loss (%)

Mean

9.8

8.7

0.6

0.3

0.9

4

3.8

7.8

50.9

12.9

10.7

Min

9

8

0.2

0.1

0.4

3.6

3.1

7

46.7

5.2

3.5

Max

10.5

10.2

1

0.9

1.8

4.8

5

9.8

57.4

20.2

18.9

Applicant's summary and conclusion

Conclusions:
Oral administration of the test substance to New Zealand White rabbits from Day 6 to Day 28 of gestation at dose levels of 125, 250 or 500 mg/kg/day was associated with low maternal body weight gain and food consumption at 500 mg/kg/day.
Embryo-fetal survival, fetal and placental weight were unaffected by treatment and the fetal pathology findings at 500 mg/kg/day were minor skeletal variants which were not considered adverse.
It was therefore concluded that 250 mg/kg/day was the no observed effect level (NOEL) for both maternal toxicity and embryo-fetal development.
Executive summary:

The purpose of this study was to assess the influence of the test item on embryo-fetal survival and development when administered during the organogenesis and fetal growth phases of the New Zealand White rabbit.

Three groups of 22 females received the test item at doses of 125, 250 or 500 mg/kg/day by oral gavage administration, from Day 6 to 28 after mating. A similarly constituted Control group received the vehicle, purified water, at at the same volume dose as treated groups.

Animals were euthanized on Day 29 after mating for reproductive assessment and fetal examination. Clinical observations, body weight and food consumption were recorded. Adult females were examined macroscopically at necropsy on Day 29 after mating and the gravid uterus weight recorded. All fetuses were examined macroscopically at necropsy and subsequently by detailed internal visceral examination of the head or skeletal examination.

There were no signs were observed at either routine physical examination or in association with dose administration that could be related to treatment.

At 500 mg/kg/day the overall body weight gain and food consumption of females was low; approximately 17 % and 79% of Controls, respectively. Maternal body weight and food consumption at 125 or 250 mg/kg/day showed no adverse effects of treatment.

Macroscopic examination of females on GD29 did not reveal any findings that could be attributed to treatment with the test item. On Day 29 of gestation, mean numbers of implantations embryo-fetal survival, litter size and sex ratio were considered to be unaffected by treatment with the test item. Group mean placental weights, male or fetal weight and overall fetal weight were essentially similar to Controls at dose levels up to and including 500 mg/kg/day. The range and incidence of major abnormalities at 125 and 500 mg/kg/day showed no relationship to treatment. At 500 mg/kg/day there was a slight increased incidence of full supernumerary 13th ribs and unilateral caudal shift of pelvic girdle when compared with both the Concurrent Controls and the historical control data range. The combination of these skeletal variants at 500 mg/kg/day indicates a slight shift in rib/vertebral configuration which is not considered adverse.

Oral administration of the test item to New Zealand White rabbits from Day 6 to Day 28 of gestation at dose levels of 125, 250 or 500 mg/kg/day was associated with low maternal body weight gain and food consumption at 500 mg/kg/day. Embryo-fetal survival, fetal and placental weight were unaffected by treatment and the fetal pathology findings at 500 mg/kg/day were minor skeletal variants which were not considered adverse.

It was therefore concluded that 250 mg/kg/day was the no observed effect level (NOEL) for both maternal toxicity and embryo-fetal development.