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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Acceptable, well documented publication/ study report which meets basic scientific principles.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report Date:
1990

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Pregnant female rats were exposed to the test substance on gestation days 6-15 to examine the maternal and developmental toxicity potential of the substance.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Purity 98.0%

Test animals

Species:
rat
Strain:
Sprague-Dawley
Remarks:
Crl:CD®BR
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, Michigan
- Weight at study initiation: mean of 225-278 g
- Fasting period before study: not reported
- Housing: Until pairing, all animals were individually housed in clean, wire-mesh cages suspended above cage-board. The animals were paired for mating in the home cage of the male. Following positive identification of mating, the females were returned to an individual suspended wire-mesh cage; nesting material was not required as the females were sacrificed prior to expected parturition
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: minimum of 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22±3°C
- Humidity (%): 40+-66%
- Air changes (per hr): approximately 10-15
- Photoperiod (hrs dark / hrs light): 12 hrs dark/ 12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:A sufficient amount of test material was weighed for all groups, transferred to a mortar and ground into a fine powder. The appropriate amount of the ground material was weighed for each group. The vehicle was added to the test material in small increments and ground with a pestle until a slurry was obtained. The mixture was transferred to a graduated cylinder via a series of vehicle rinses. A sufficient amount of vehicle was added to attain a volume of 200 mL. The cylinder was inverted several times to ensure adequate mixing and the contents were transferred to a labelled storage container. The cylinder was rinsed with an additional 60 mL of vehicle which was then added to the storage container. The solutions were visually inspected for homogeneity prior to dispensing on the first day of test material administration. Solutions for aldose groups were prepared once and were stored refrigerated. The solutions were stirred each day prior to dispensing and during the dosing procedures.
Analytical verification of doses or concentrations:
no
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: until mating occurred
- Proof of pregnancy: copulatory plug in the vagina or the presence of sperm in a vaginal smear
Duration of treatment / exposure:
gestation days 6-15
Frequency of treatment:
daily
Duration of test:
20 days
Doses / concentrationsopen allclose all
Dose / conc.:
1 mg/kg bw/day
Dose / conc.:
5 mg/kg bw/day
Dose / conc.:
10 mg/kg bw/day
Dose / conc.:
15 mg/kg bw/day
Dose / conc.:
20 mg/kg bw/day
No. of animals per sex per dose:
8
Control animals:
yes

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations checked: moribundity and mortality

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Days 0 through 20 of gestion (prior to dosing during the treatment period). In addition, animals were observed for signs of toxicity approximately 1 hour following dosing

BODY WEIGHT: Yes
- Time schedule for examinations: Individually on gestation days 0, 6, 9, 12, 16, 18, and 20. A group mean body weight was calculated. Mean body weight changes were calculated for each corresponding interval and also for days 6-16 and 0-20.

FOOD CONSUMPTION: No

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: Liver, kidneys, spleen, and thyroid were excised, trimmed and weighed
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Uteri with no macroscopic evidence of nidation were excised, opened and subsequently placed in 10% ammonium sulfide solution for detection of early implanation loss.
Fetal examinations:
- External examinations: Yes: [all per litter]
- Soft tissue examinations: No
- Skeletal examinations: No
- Head examinations: No
Statistics:
All analyse were conducted using two-tailed tests for a minimum significance level of 5% comparing each treated group to the control group. The numbers of early and late resorptions, dead foetuses and post implantation losses were compared by the Mann-Whitney U-test. The numbers of litters with malformations and variations were compared by Fisher’s Exact test. Mean numbers of corpora lutea, total implantations, viable foetuses, mean foetal and maternal body weights at each interval, maternal body weight gain and organ weights were analysed by a one-way analysis of variance and Dunnett’s test. The foetal sex ratios were compared by the Chi Square test with Yates correction factor.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Description (incidence and severity):
Occasional decreased defecation and/or urination was observed at 15 and 20 mg/kg. No other adverse clinical signs were observed. Hair loss occurred in all doses including controls.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean body weight was decreased at ≥15 mg/kg on gestation days 9, 12, 16, 18, and 20. The decreases were statistically significant only on days 12, 16, and 18 at 20 mg/kg. Body weights at 1, 5, and 10 mg/kg were comparable to control.

An adverse effect on body weight gain appeared dose-related at dose of ≥5 mg/kg, primarily during the first 3 days of dosing. A statistically significant mean body weight loss was observed at 20 mg/kg during gestation days 6-9 and 9-12. Mean body weight gain remained inhibited in this group on gestation days 12-16 resulting in a statistically significant mean body weight loss on days 6-16 (treatment period). Similar body weight effects were observed in animals given 15 mg/kg. Statistically significant mean body weight loss was observed on gestation day 6-9, and gains remained slightly reduced on days 9-12 and 12-16 resulting in a statistically significant mean body weight loss on days 6-16 (treatment period). At both 15 and 20 mg/kg body weight gain was statistically increased on days 16-18, and was comparable to control on days 18-20. Slight, non-statistically significant body weight loss was observed at 5 and 10 mg/kg on gestation day 6-9, but mean body weight gains were comparable to control for the remainder of gestation. A slight decrease in mean body weight gain was observed for the days 6-16 (treatment period) at 10 mg/kg. No effects were observed at 1 mg/kg.
Food consumption and compound intake (if feeding study):
not examined
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:
effects observed, treatment-related
Description (incidence and severity):
A non-statistically significant increase in mean thyroid weight (26% compared to control) was observed at 20 mg/kg.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
One animal at 1 mg/kg had a pitted kidney and one animal had white precipitate in kidney, ureter, and bladder. Dilated renal pelvis was observed in one animal at 1 mg/kg and one animal at 10 mg/kg. Evidence of intubation trauma was observed as red fluid and gelatinous red material in the thoracic cavity in one animal at 1 mg/kg.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
effects observed, treatment-related
Description (incidence and severity):
A slight, non-statistically significant, increase in postimplantation loss was observed at 20 mg/kg.
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
not specified
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Changes in number of pregnant:
no effects observed

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
1 mg/kg bw/day
Basis for effect level:
body weight and weight gain

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
A statistically significant decrease in foetal body weight was observed at ≥10 mg/kg.
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
External malformations:
effects observed, treatment-related
Description (incidence and severity):
Cleft palate was observed in 6 foetus from 2 litters at 20 mg/kg.
Skeletal malformations:
not examined
Visceral malformations:
not examined

Effect levels (fetuses)

open allclose all
Dose descriptor:
NOAEL
Effect level:
5 mg/kg bw/day
Basis for effect level:
other: Fetotoxicity: decrease in mean fetal weight at ≥10 mg/kg
Dose descriptor:
NOAEL
Effect level:
15 mg/kg bw/day
Basis for effect level:
other: teratogenicity: increased incidence of cleft palate at 20 mg/kg

Fetal abnormalities

Abnormalities:
effects observed, treatment-related
Localisation:
other: cleft palate at 20 mg/kg

Overall developmental toxicity

Developmental effects observed:
yes
Lowest effective dose / conc.:
10 mg/kg bw/day
Treatment related:
yes
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects

Applicant's summary and conclusion

Conclusions:
NOAEL for developmental toxicity is 5 mg/kg bw/day. NOAEL for maternal toxicity was 1 mg/kg bw/day. There were no indications for developmental toxicity in doses below maternal toxic doses.
Executive summary:

The ability of the test substance to cause maternal and developmental toxicity was evaluated. The test substance, suspended in corn oil, was administered to pregnant rats via gavage once daily on gestation days 6-15 at doses of 0, 1, 5, 10, 15, or 20 mg/kg. Throughout gestation the rats were observed for appearance and behaviour, and body weight were recorded. All animals were sacrificed on gestation day 20. The uteri and ovaries were examined and the number of foetuses, early and late resorptions, total implantations, and corpora lutea were recorded. The thyroid, kidneys, spleen, and liver of the females were weighed. Foetuses were weighed, sexed, and examined for external malformations or variations.

No mortality was observed. Maternal toxicity was observed at ≥5 mg/kg/day, expressed as a dose-related decrease in mean body weight gain. Developmental toxicity was observed at ≥10 mg/kg/day, expressed as a dose-related reduction in mean foetal body weight and the incidence of cleft palate in 6 foetuses at 20 mg/kg. The NOAELs are 1 mg/kg/day for maternal toxicity and 5 mg/kg/day for developmental toxicity.