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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
No data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Meets generally accepted scientific standards with acceptable restrictions. The rationale to use data from individual constituents and components of the complex is explained in chapter 1 of the CSR and in the adjacent "read-across document".
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1974
Report Date:
1974

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Principles of method if other than guideline:
Adult female Dutch-belted rabbits were dosed on Day 0 with a single injection of 0.4 mL human chorionic gonadotropin (400 IU) via the marginal ear vein. After three hours each doe was artificially inseminated with 0.3 mL diluted semen from a donor buck using 20 x 10E06 motile sperm. Dosing by oral intubation with a control (Vehicle at level equivalent to group receiving the highest dose) or test article in a water suspension (10 mL/kg bw) at 2.17, 10.10, 46.7 and 217.0 mg/kg was carried out daily on Days 6 to 18 of gestation. The positive control 6-aminonicotinamide at 2.5 mg/kg was dosed on Day 9. Observations of body weight, appearence, behaviour, and food consumption were performed. On Day 29 all does underwent Caesarean section. Number of corpora lutea, implantation sites, resorption sites and live/dead foetuses recorded. Body weights of live pups recorded. Urogenital tract of each dam examined for anatomical normality. All foetuses examined grossly for presence of external congenital abnormalities. Live foetuses of each litter were then placed in an incubator for 24 hours for evaluation of neonatal survival. All pups underwent detailed visceral examination. All foetuses were cleared in potassium hydroxide, stained with alizarin red S dye and examined for skeletal defects.

Deficiencies:
Food consumption not reported
Uterine weights not determined
Test substance identification (Batch etc) missing
No details on housing conditions/source of animals
Administration only during periods of organogenesis, not until day before pregnancy
GLP compliance:
no
Remarks:
Study predates GLP
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): FDA 71-81 (Monocalcium phosphate; monohydrate)
- Physical state: Fine white crystalline material

Test animals

Species:
rabbit
Strain:
Dutch
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Outbred
- Age at study initiation: No data
- Weight at study initiation: 1.84 - 2.21 kg
- Fasting period before study: No data
- Housing: Individually housed in mesh-bottomed cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: No data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data
- Humidity (%): No data

IN-LIFE DATES: No data

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
VEHICLE: Water
- Amount of vehicle (if gavage): 1 mL/kg bw at doses equal to or below 250 mg/kg bw and 2 mL/kg at doses up to 500 mg/kg bw
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
- Impregnation procedure: artificial insemination
- Proof of pregnancy: No data
Duration of treatment / exposure:
13 days (Day 6 to Day 18 of gestation)
Frequency of treatment:
Daily
Duration of test:
29 days
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
2.17 mg/kg
Basis:
nominal in water
Remarks:
Doses / Concentrations:
10.10 mg/kg
Basis:
nominal in water
Remarks:
Doses / Concentrations:
46.7 mg/kg
Basis:
nominal in water
Remarks:
Doses / Concentrations:
217.0 mg/kg
Basis:
nominal in water
No. of animals per sex per dose:
Table 1 Number of animals dosed
Material Dose (mg/kg) Total
Mated Pregnant
Sham 0.0 21 12
6-AN 2.5 18 9
FDA 71-81 2.17 21 12
10.10 27 17
46.7 15 10
217.0 27 10
Control animals:
yes, sham-exposed
other: positive control: 2.5 mg/kg 6-aminonicotinamide (6-AN)

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Appearence, behaviour, food consumption and weight observed daily.
DETAILED CLINICAL OBSERVATIONS: No
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights recorded on days 0, 6, 12, 18 and 29.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: uterus and urogenital tract
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of resorptions: Yes
Fetal examinations:
- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: Yes
Statistics:
No data
Indices:
No data
Historical control data:
No

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
> 217 mg/kg bw/day
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
> 217 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:
No dose related response observed.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 2 Reproduction data

Dose (mg/kg)

Sham

6-AN

2.17

10.10

46.7

217.0

Pregnancies

 

 

 

 

 

 

Total No.

12

9

12

17

10

10

Died or aborted (before Day 29)

2

0

1

4

0

0

To term (on Day 29)

10

9

11

13

10

10

Corpora Lutea

 

 

 

 

 

 

Total no.

160

117

132

191

110

121

Average/dam mated

11.4

9.75

9.43

9.55

8.46

6.37

Live litters

 

 

 

 

 

 

Total No.*

10

8

10

13

9

8

Implant Sites

 

 

 

 

 

 

Total No.

58

57

62

79

50

49

Average/dam*

5.80

6.33

5.64

6.08

5.00

4.90

Resorptions

 

 

 

 

 

 

Total No*

7

6

9

3

7

4

Dams with 1 or more sites resorbed

4

4

2

2

4

2

Dams with all sites resorbed

--

1

1

--

1

2

Per cent partial resorptions

40.0

44.4

18.2

15.4

40.0

20.0

Per cent complete resorptions

--

11.1

9.09

--

10.0

20.0

Live foetuses

 

 

 

 

 

 

Total No

51

49

49

76

43

45

Average/dam*

5.10

5.44

4.45

5.85

4.30

4.50

Sex ratio (M/F)

0.96

1.13

1.29

1.30

0.87

1.05

Dead Foetuses

 

 

 

 

 

 

Total No.*

--

2

4

--

--

--

Dams with 1 or more dead

--

2

1

--

--

--

Dams with all dead

--

--

--

--

--

--

Per cent partial dead

--

22.2

9.09

--

--

--

Per cent all dead

--

--

--

--

--

--

Average foetus weight (g)

39.6

37.0

39.3

39.7

36.0

39.7

* Includes only those dams examined at term

** Positive control: 2.5 mg/kg 6-AN dosed on Day 9

 

Table 3 Summary of skeletal findings

Findings

Dose (mg/kg)

Sham

6-AN

2.17

10.10

46.7

217.0

Live foetuses examined (at term)

51/10

49/8

49/10

76/13

43/9

44/8

Sternebrae

 

 

 

 

 

 

Incomplete oss.

1/1

 

 

1/1

1/1

 

Scrambled

 

 

 

 

 

 

Bipartite

 

 

 

 

 

 

Fused

 

 

 

 

 

 

Extra

 

 

 

 

3/1

1/1

Missing

 

 

 

 

 

1/1

Other

 

 

 

 

 

 

Ribs

 

 

 

 

 

 

Incomplete oss.

 

 

 

 

 

 

Fused/split

 

 

 

 

 

 

Wavy

 

 

 

 

 

 

Less than 12

 

 

 

 

 

 

More than 13

 

 

 

 

 

 

Other

 

 

 

 

 

 

Vertebrae

 

 

 

 

 

 

Incomplete oss.

 

 

 

 

 

 

Scrambled

 

 

 

 

 

 

Fused

 

 

 

 

 

 

Extra ctrs. oss.

 

 

 

 

 

 

Scoliosis

 

 

 

 

 

 

Tail defects

 

1/1

 

1/1

1/1

 

Other

 

 

 

 

 

 

Skull

 

 

 

 

 

 

Incomplete closure

 

 

 

3/1

 

 

Missing

 

 

 

 

 

 

Craniostosis

 

 

 

 

 

 

Other; facial bones, inc

 

 

 

 

 

 

Extremities

 

 

 

 

 

 

Incomplete oss.

 

 

 

 

 

 

Missing

 

 

 

 

 

 

Extra

 

 

 

 

 

 

Miscellaneous

 

 

 

 

 

 

* Numerator = Number of foetuses affected; Denominator = Number of litters affected

** Positive control: 2.5 mg/kg 6-AN dosed on Day 9 No soft tissue abnormalities observed.

Applicant's summary and conclusion

Conclusions:
Under the conditions of the study, the test material administered to pregnant rabbits for 13 days up to a dose level of 217 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and developmental toxicity is > 217 mg/kg bw.
Executive summary:

In a teratogenicity study with Dutch-belted rabbits artificially inseminated females received on days 6 to 18 of gestation by oral intubation 0 (vehicle control), 2.17, 10.10, 46.7 and 217.0 mg/kg of the test substance. Another group was administered with the positive control 6 -aminonicotinamide at 2.5 mg/kg (dosed on gd 9). Observations of body weight, appearence, behaviour, and food consumption were performed. On gd 29 all does underwent Caesarean section. Number of corpora lutea, implantation sites, resorption sites, live/dead foetuses and pub weights were recorded. Urogenital tract of each dam examined for anatomical normality. All foetuses examined grossly for presence of external congenital abnormalities. Live foetuses of each litter were then placed in an incubator for 24 hours for evaluation of neonatal survival. All pups underwent detailed visceral examination and were examined for skeletal defects.

No effects on nidation or on maternal or fetal survival, and no abnormalities in either soft or skeletal tissues were noted in any of the test groups, which could be related to treatment. Therefore the NOAEL from this study is the highest dose tested, i.e. 217 mg/kg bw/day.