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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, guideline compliant, unpublished study, no restrictions, fully adequate for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 1,3 Pentadiene (MRD-91-935)
- Physical state: pale yellow liquid
- Analytical purity: 98% (assumed 100% for dosing)
- Lot/batch No.: 1
- Storage condition of test material: room temperature

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Kingston Facility, Stone Ridge, New York, USA
- Age at study initiation: 69 days (males), 76 days (females)
- Weight at study initiation: 345-407 g (males), 223-262 g (females)
- Housing: Single housed during the test period, except during mating and post-parturition, in suspended stainless steel and wire mesh cages.
- Diet: Purina Certified Rodent Chow (5002 Meal), ad libitum. Manufacturer: Purina Mills, Inc., Richmond, Indiana, USA.
- Water: Mains water ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature: 68-76°F
- Humidity: 40-70%
- Air changes (per hr): Not reported
- Photoperiod: 12hrs dark / 12hrs light

IN-LIFE DATES: From: 16 September 1991 To: 12 November 1991

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The undiluted test material was thoroughly mixed with corn oil at the following concentrations to ensure a 5 mL/kg dose volume at all dose levels:
30 mg/kg = 0.6% (w/v); 100 mg/kg =2.0% (w/v); 1000 mg/kg = 20.0% (w/v). Dosing solutions were prepared every 2-5 days during the first 3 weeks of the study and weekly thereafter
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
PREPARATION OF DOSING SOLUTIONS:
The undiluted test material was thoroughly mixed with corn oil at the following concentrations to ensure a 5 mL/kg dose volume at all dose levels:
30 mg/kg = 0.6% (w/v); 100 mg/kg =2.0% (w/v); 1000 mg/kg = 20.0% (w/v). Dosing solutions were prepared every 2-5 days during the first 3 weeks of the study and weekly thereafter
Details on mating procedure:
P1 mating period began 2 weeks after pre-mating dosing and ended when all females had been confirmed mated or approximately 2 weeks had elapsed. Each P1 male was assigned randomly to be paired overnight for a maximum of 14 days with one P1 female of the same dose group to produce the F1 generation. Mating was confirmed on the following morning by the presence of a copulatory plug or sperm in a vaginal rinse. The day on which mating was confirmed was the female's Day 0 of gestation (GD 0). After confirmation of mating, each rat was placed in its own cage. On GD 20, mated females were placed in clean cages fitted with a stainless steel litter pan and fresh bedding material was provided. After GD 20, mated females were examined at least twice daily for signs of parturition.
Duration of treatment / exposure:
P1 animals were dosed daily for 2 weeks prior to mating and throughout the mating period for the F1 litter. P1 females additionally were dosed during gestation and until the day prior to euthanasia on or after postpartum Day (PPD) 4.
Frequency of treatment:
7 days/week
No. of animals per sex per dose:
12
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: In a range-finding study rats were dosed with 0, 50, 500, and 1000 mg/kg. Treatment-related body weight gain suppression was seen. Therefore, the following dose levels were used: 30 mg/kg (anticipated to be the NOAEL), 100 and 1000 mg/kg.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once daily

BODY WEIGHT: Yes
- Time schedule: Males - prior to prior to P1 selection, on the first day of dosing, and at least weekly thereafter until euthanasia. Females - prior to P1 selection, on the first day of dosing and at least weekly thereafter until mating was confirmed, then on GD 0, 7, 14, and 21 and on PPD 0 and 4.

FOOD CONSUMPTION: Yes
- Time schedule: P1 male on the first day of dosing and at least weekly thereafter, except during mating, until euthanized. Food consumption of P1 females on test Day 0 and at least weekly thereafter, except during mating, then on GD 0, 7, 14 and 21 and on PPD 0 and 4.

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS (Parental animals): Yes on post-natal day 4.
Gross Pathology: All adult animals, including those that died spontaneously were examined by gross necropsy. The uterus of each female which failed to deliver a litter was examined for evidence of implantations. The number of implantation sites and corpora lutea were recorded at the time of necropsy for all dams with litters.

Organ weights: The following organs and tissues of all adult animals euthanized at study termination were weighed prior to fixation: liver, testes, thymus, kidneys, epididymides. Organ:body weight ratios were calculated.

Histopathology: The following tissues were examined from the controls and high dose animals only: brain, heart, spleen, kidneys, liver, adrenals, testes/epididymides, abnormal tissues. In addition, ovaries and thymus were fixed but not routinely processed. Ovaries from females which failed to complete pregnancy were examined histopathologically.


POST-MORTEM EXAMINATIONS (Offspring) : Yes
All Fl pups which died were subjected to an external examination, including the palate. All live Fl pups were sexed and examined externally and weighed on the day of euthanasia. Offspring were discarded without further examination.

Ovaries and uterine content:
The uterus of each female which failed to deliver a litter was examined for evidence of implantations. The number of implantation sites and corpora lutea were recorded at the time of necropsy for all dams with litters.
Fetal examinations:
All Fl pups which died were subjected to an external examination, including the palate. All live Fl pups were sexed and examined externally and weighed on the day of euthanasia. Offspring were discarded without further examination.


Statistics:
Mean body weights, food consumption, organ weights, relative organ weights and clinical laboratory findings: Bartlett's test of homogeneity of variance, followed by a standard one-way analysis of variance. If the ANOVA was significant, Dunnett's test was performed to determine which treated groups differed from the control. A linear regression to test for a dose response also was performed and tested for lack of fit to the regression. If the variances were not equivalent, then a Kruskal-Wallis (non-parametric) test was performed to determine if the treatment effects were equivalent. If there was a difference, Dunn's Summed Rank Test was used to determine which treatment groups differed from the control. Jonckheere's test for ordered response also was performed.
The following reproductive parameters were analyzed statistically for significant differences: mean male fertility index, mean male mating index, mean female fertility index, mean female fecundity index and mean gestational index. A standard chi-square analysis was performed to determine if the proportion of incidences differed between the groups. Each treatment group was then compared to each control group using a 2 x 2 Fisher Exact test. Armitage's test for linear trend in the dosage groups was performed. Pup weight was analyzed by a standard nested analysis of covariance with pups nested within dams and with dams nested within doses, and litter size (both sexes combined) as the covariate. If differences in groups were identified, the Least Significant Difference (LSD) technique was used to determine which groups differed from the control group.Male and female pups were tested separately (the covariate was combined sexes in each analysis). All tests were reported at the 5% or 1% level of significance.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
A statistically significant decrease in mean food consumption was observed in high dose females on test Day 7 compared with that in controls.

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Basis for effect level:
other: developmental toxicity

Results (fetuses)

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

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: Developmental toxicity

Fetal abnormalities

Abnormalities:
no effects observed

Overall developmental toxicity

Developmental effects observed:
no

Applicant's summary and conclusion

Conclusions:
In conclusion, treatment-related parental toxicity was limited to a transient decrease in food consumption in high dose (1000 mg/kg/day) females. No other treatment-related effects were observed in the parents or their offspring. The developmental NOAEL for MRD-91-935 (1,3-pentadiene) was 1000 mg/kg under the conditions of this study.

Executive summary:

In a combined repeat dose and reproductive/developmental toxicity screening study, treatment-related parental toxicity was limited to a transient decrease in food consumption in high dose (1000 mg/kg/day) females. No other treatment-related effects were observed in the parents or their offspring. The reproductive and offspring NOAELs for MRD-91-935 (1,3-pentadiene) were 1000 mg/kg under the conditions of this study.