Registration Dossier

Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
January 1983 - August 1983
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983
Report Date:
1983

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
(1981)
Deviations:
no
GLP compliance:
no
Remarks:
QAU statement available, no GLP compliance statement available
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: solid
- Analytical purity: 100%
- Stability under test conditions: Determined by the sponsor
- Storage condition of test material: room temperature

Test animals

Species:
rat
Strain:
other: Sprague-Dawley Tif: RAIf (SPF)
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Closed-breeding colony, Ciba-Geigy WST
- Age at study initiation: 2 months
- Weight at study initiation: 180-200 g
- Housing: 4 per cage throughout the experiment
- Diet: standard cube diet, NAFAG No. 890, ad libitum
- Water: tap water, ad libitum
- Acclimation period: 6 days (between allocation to the corresponding group on day 0 and the first treatment on day 6 post coitum)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21+/-2
- Humidity (%): 55+/-10
- Photoperiod: 12 hrs dark /12 hrs light (Light: 6 am-6 pm)

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: water:polyethylene glycol400 (1:1)
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The suspension of the test material was freshly prepared daily by homogenization and stirring (magnetic stirrer), and administered at a rate of 10 mL/kg of body weight.
Analytical verification of doses or concentrations:
no
Details on mating procedure:
- Impregnation procedure: cohoused
- M/F ratio per cage: 1:3
- Length of cohabitation: overnight
- Proof of pregnancy: vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
day 6-15 p.c.
Frequency of treatment:
once daily
Duration of test:
day 0- 21 p.c.
Doses / concentrationsopen allclose all
Dose / conc.:
500 mg/kg bw/day (actual dose received)
Dose / conc.:
1 500 mg/kg bw/day (actual dose received)
Dose / conc.:
3 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
24 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
A preliminary experiment was carried out on 15 fertilized rats each for the vehicle control and the dose group (3000 mg/kg d). The test material was suspended in a mixture of distilled water and polyethylene glycol 400 (1:1) and administered orally by intubation from day 6 until day 15 of pregnancy, inclusive. Treatment at this 3000 mg/kg dose level caused no depression in either food consumption or body-weight gain of the mother animals. Apart from a reduced body weight no adverse effects were recorded for the progeny at sacrifice shortly before term in comparison with the vehicle control. On the basis of the foregoing results the doses for the main stpdy were selected at 0, 500, 1500 and 3000 mg/kg of body weight

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: daily

FOOD CONSUMPTION:
- On day 6, 11, 16, 21.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: ovaries and uterus (mucosa and contents, including amniotic fluid and placentae as well as abortions and resorption sites)
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: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: 1/3 per litter
- Skeletal examinations: Yes: 2/3 per litter
- Head examinations: No data
Statistics:
Average weight: Student's t test, one-tailed
Records of reproduction data:
The numbers of embryonic and/or foetal deaths (resorptions): Chi-Square-test, Yates' correction
Historical control data:
Historical cumulative control (1977-1983) of reproduction data and anomalies and malformations provided.
Historical cumulative control of visceral examination provided.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
With regard to the vehicle control and in accordance with the results of the preliminary experiment, neither food consumption nor body-weight gain was altered in the experimental groups.
Female No. 78 (3000 mg/kg d) died spontaneously on day 7 p.c. (i.e. after one application) likely in consequence of an intubation error.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
3 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: No adverse effects recorded

Results (fetuses)

Details on embryotoxic / teratogenic effects:
The pregnancy rates expressed as average number ot implantation sites per female were comparable for all groups in the present experiment. The numbers of embryonic and/or foetal deaths (resorptions) were not increased at either dose.
The male to female ratios of the foetuses were also comparable for all groups. In comparison with the vehicle control, the average body-weight of the live foetuses was not diminished at either dose. Fusion of placentas, the implantation sites consisting of a embryonic resorption and a poorly developed male foetus, respectively, was noted for one female (No. 48) of the 500 mg/kg group.
The gross inspection of the live foetuses revealed one foetus with omphalocele in the low-dose group. Carrying out the slicing technique for "visceral" examination, dilatation of the renal pelvis (unilateral) was found in one foetus of the vehicle control. These instances are considered to be of a spontaneous origin and not related to the treatment.
The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control; abnormal "wide suture" was found in one foetus of the high-dose group, in addition. Concerning the status of skeletal maturation of the foetuses shortly before term, a slight delay in ossification of the phalangeal nuclei of the hind-limbs was recorded for the high-dose group in comparison with the vehicle control; this finding, however, is not assumed to be of experimental significance.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
3 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No adverse effects recorded

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 1: Summarized reproduction data of the main study.

Dose group

(mg/kg d)

0

500

1500

3000

Historical control data (range)

Spontaneous deaths

0/24

0/24

0/24

1/24

0/858

Body-weight gain (%)

+14.6

+13.3

+16.7

+13.9

 

Females with deciduomata

0/24

0/24

0/24

0/23

1/858

Females with implantations

22/24

22/24

23/24

20/23

800/858

Implantations/female (mean, SD)

15.9±2.5

16.3±1.5

15.4±1.9

16.1±1.8

13.14±2.36

Females with total abortion

0

0

0

0

0/800

Females with partial abortion

0

0

0

0

2/800

Embryonal deaths (resorptions)

6.3

4.2

6.5

8.4

8.71

Foetal deaths (resorptions)

0

0.3

0

0

0.28

Dead foetuses

0

0

0

0

0.12

Number of live foetuses (males-females)

163-165

158-185

164-167

150-144

4662- 4888

Percent males of live foetuses

49.7

46.1

49.5

51.0

48.8

Average weight of live foetuses

5.4±0.4

5.3±0.5

5.4±0.5

5.4±0.5

5.34±0.45

 


Table 2: Summarized data of skeletal assessment of the foetuses (in percent).

Dose group

(mg/kg d)

0

500

1500

3000

Historical control data (range)

Number of skeletons examined

219

229

222

195

6180

Phalangeal nuclei (a):

Fore-limb

14.6

21.0

10.4

9.2

0-10.7

Phalangeal nuclei (a):

Hind-limb

45.2

50.2

50.5

55.4

4.5-65.6

Calcaneus

89.5

86.9

91.0

93.8

6.8-90.3

5thsternebra (c)

15.1

14.4

20.3

9.7

3.0-88.3

Vertebrae (d)

1.4

1.7

3.2

3.6

0-6.9

Vertebrae (e)

0.0

0.4

1.4

0.5

0.23

Skeletal anomalies

0.9

2.2

1.4

1.5

0.52

(a) Ossification still absent in proximal phalanges, digit 5

(b) Ossification still absent

(c) Still incompletely ossified

(d) Some thoracic vertebral centres still dumbbell-shaped

(e) Some thoracic vertebral centres bipartite

 

Applicant's summary and conclusion

Conclusions:
The test substance was devoid of an enbryotoxic potential and did not reveal teratogenic potency in the rat under the present experimental conditions.
Executive summary:

A developmental toxicity/teratogenicity study according OECD TG 414 was performed (Ciba-Geigy, 1983). 24 female rats were mated, and treated with 500, 1500, and 3000 mg test substance/kg body weight once daily on day 6 -15 p.c. On gestation day 21 the animals were sacrificed. Dams were observed for clinical signs, behavior, body weight and food consumption. After sacrifice ovaries and uterus (mucosa and contents, including amniotic fluid and placentae as well as abortions and resorption sites) were examined. In the fetuses external examinations, soft tissue examinations, and skeletal examinations were conducted. Neither food consumption nor body-weight gain was altered in the experimental groups. The pregnancy rates expressed as average number of implantation sites per female were comparable for all groups in the present experiment. The numbers of embryonic and/or fetal deaths (resorptions) were not increased at either dose. The male to female ratios of the fetuses were also comparable for all groups. In comparison with the vehicle control, the average body-weight of the live fetuses was not diminished at either dose. The gross inspection of the live fetuses revealed one fetus with omphalocele in the low-dose group. Dilatation of the renal pelvis (unilateral) was found in one fetus of the vehicle control. The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control; abnormal" wide suture" was found in one fetus of the high-dose group, in addition. Concerning the status of skeletal maturation of the fetuses shortly before term, a slight delay in ossification of the phalangeal nuclei of the hind-limbs was recorded for the high-dose group in comparison with the vehicle control; this finding, however, is not assumed to be of experimental significance.

In summary, the test article was devoid of an embryotoxic activity and did not reveal teratogenic potency in the rat under the present experimental conditions.