Vinyl neononanoate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to O.ECc.D. test guideline 414 with GLP compliance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Test material form:

other: Clear liquide at room temperature.

Details on test material:

As per IUCLID5 Sections 1.1. 1.2. 1.4. and 4.1.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Sprague Dawley - Hsd:SD rats were acquired from Harlan Laboratories. Only female rats were assigned to the study; male rats were used for mating purposes only. The females were a minimum of 12 weeks old at the time of the initiation of the cohabitation period. At the initiation of the cohabitation period, females weighed 206-279 grams.

Upon arrival and until cohabitation, males were individually housed and females were group-housed, a maximum of five females per cage. During cohabitation, one or two females were placed with a male breeder. Following cohabitation, males and females were housed individually. Study animals were acclimated to their housing for 8 days prior to their first day of dosing.

The animal room was maintained at a temperature of 21.0 to 23.7°C and relative humidity of 43.9 to 65.8%. The light cycle within the animal room was set to maintain 12 hours light/12 hours dark. All animals had access to Harlan Teklad Rodent Diet (certified) or equivalent ad libitum. Water was available ad libitum to each animal via an automatic watering device.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

The test substance formulations and control corn oil were administered to presumed pregnant females once daily beginning on the day of confirmed mating (Gestation Day 0) through presumed Gestation Day 19 inclusive. Each female rat received a daily total volume (ml) based on each animal’s most recent body weight and a dose volume of 4 ml/kg. Doses were administered using a 16-gauge stainless steel gavage needle attached to an appropriate size syringe. The test substance formulations and the corn oil vehicle were maintained on a stir plate during dose administration.

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Animals were mated by placing one male and one or two females in a breeding cage until the females were determined to be Day 0 of gestation. This was determined by the examination of vaginal smears made daily to determine if sperm were present in a smear of vaginal contents or by the presence of a copulatory plug in situ.

Duration of treatment / exposure:

Once daily beginning on the day of confirmed mating (Gestation Day 0) and continuing through presumed Gestation Day 19 inclusive. Dose administration was performed at approximately the same time each day.

Frequency of treatment:

Once per day.

Duration of test:

Beginning on the day of confirmed mating (Gestation Day 0) and continuing through presumed Gestation Day 19 inclusive.

No. of animals per sex per dose:

24 females per group.

Control animals:

yes, concurrent vehicle

Details on study design:

All adult females were sacrificed by CO2 asphyxiation. Fetuses were euthanized by an intrathoracic injection of a barbiturate overdose. Surviving females were sacrificed on Day 20 of gestation. The uterus, ovaries and placenta, in addition to any gross lesions, were retained in 10% neutral buffered formalin. A complete gross necropsy was performed on all adult females assigned to study groups. The necropsy included the examination of the following:
• the external body surface
• all orifices
• the cranial, thoracic and abdominal cavities and their contents

Examinations

Maternal examinations:

Mortality/morbidity was recorded twice daily (a.m. and p.m.). Animals were also observed for mortality/morbidity once prior to schedule sacrifice. During the treatment period (presumed Gestation Days 0 through19 inclusive), females were observed for clinical signs of toxicity a minimum of twice daily (prior to dose administration and a minimum of once post-dose – approximately 1-2 hours post-dose). Females were also observed prior to the scheduled cesarean on presumed Gestation Day 20.

Female body weights were collected during the treatment perio when each female was weighed on presumed Gestation Day 0 (after evidence of mating was observed and the female was assigned to a study group), on presumed Gestation Day 3 and on presumed Gestation Days 6 through 19 inclusive. On each scheduled occasion of body weight assessment, females were weighed prior to dose administration. Females were also weighed prior to the scheduled cesarean on presumed Gestation Day 20.

Feed Consumption was made whenfFull feeder weights and/or feeder weigh backs were recorded for each female for interval Days 0-3, 3-6, 6-9, 9-12, 12-15, 15-18 and 18-20 of gestation.

Ovaries and uterine content:

The uterus of each presumed pregnant female was excised, weighed and examined for early and late resorptions. The number of implantation sites and the number of viable and non-viable fetuses were recorded. The total number of corpora lutea were recorded for each ovary. Fetuses were examined externally, sexed and weighed Dead fetuses and early and late resorptions were placed in 10% neutral buffered formalin for possible histopathological evaluation. The uterus, ovaries and placenta, were retained in 10% neutral buffered formalin. The uterus were stained with 10% ammonium sulfide to assess the presence of implantation sites.

Fetal examinations:

Approximately 50% of fetuses determined to be viable were euthanized and an incision was made in the abdominal area of each of these fetuses prior to fixation to allow perfusion of the tissues. These fetuses were placed in 70% isopropyl alcohol for subsequent skeletal evaluation. The remaining fetuses determined to be viable were euthanized and were placed in Bouin’s fixative for subsequent whole body visceral evaluation using an adaptation of Wilson’s sectioning technique. Approximately one-half of the fetuses in each litter were eviscerated, cleared and examined for skeletal alterations after staining with alizarin red S.

Statistics:

Cesarean data were hand-tabulated and statistically evaluated using SYSTAT version 9.01 developed by SPSS, Inc. The number of early and late resorptions, the number of viable and nonviable fetuses, the total number of implantations sites, the number of corpora lutea per ovary and the percent of pre- and post-implantations losses were compared across groups using the Kruskal-Wallis non parametric ANOVA test. If a significant effect occurred (p<0.05), the Wilcoxon (Mann-Whitney U) test was used for pair-wise comparisons of each treated group to the control group. Male-to-female sex ratios were compared using the Chi-Square test.
Continuous data (fetal anomaly data) were analyzed using Bartlett’s Test of Homogeneity of Variances and the Analysis of Variance , when appropriate [i.e. Bartlett’s Test was not significant (p > 0.001)]. If the Analysis of Variance was significant (p ≤ 0.05), Dunnett’s Test was used to identify the statistical significance of the individual groups. If the Analysis of Variance was not appropriate [i.e. Bartlett’s Test is significant (p ≤ 0.001)], the Kruskal-Wallis Test was used (≤ 75% ties). In cases where the Kruskal-Wallis Test was statistically significant (p ≤ 0.05), Dunn’s Method of Multiple Comparisons was used to identify the statistical significance of the individual groups. If there were greater than 75% ties, Fisher’s Exact Test was used to analyze the data. Count data were evaluated using the procedures described above for the Kruskal-Wallis Test.7 Fetal alteration proportional data were analyzed using the Variance Test for Homogeneity of the Binomial Distribution.

Indices:

Male Sex Ratio, % Early Resorptions, % Late Resorptions, % Non-Viable Fetuses, % Pre-Implantation Loss and % Post-Implantation Loss

Historical control data:

No data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Treatment-related clinical sign suggestive of neurotoxicity were recorded during the study for 71% of the high dose females (18 of 24 females) treated with 600 mg/kg/day of test substance. A combination of two or more of the following treatment-related signs were recorded for these 18 females: increased activity, hypersensitivity to sound and/or to touch, whole body tremors, twitching of the ears, an abnormal gait and/or stance. . None of these signs remained apparent from Gestation Day 8 onwards.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

ca. 300 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

ca. 300 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
The mean % early resorptions and % post-implantation loss of females treated with 600 mg/kg/day were statistically significantly increased (P < 0.01) 5-6-fold compared to the control female values. There was a reduced number of litters with viable fetuses (68% of litters compared to 100% of control litters) and an increased number of litters with nonviable fetuses (16% of litters compared to 5% of control litters). Reduced uteri weights and fetal body weights were also recorded for females treated with 600 mg/kg/day.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

300 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: developmental toxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

There were no adverse effects of the test substance on adult pregnant female body weight and feed consumption. There were no treatment-related gross necropsy findings observed on Gestation Day 20 for females treated with Vinyl neononanoate at doses of 100, 300 or 600 mg/kg/day. There were no treatment-related effects on any of the cesarean parameters examined for females treated with 100 or 300 mg/kg/day of test substance.

Applicant's summary and conclusion

Conclusions:

The test substance, vinyl neononoanoate is a developmental toxicant in the rat at a maternally toxic dose of 600 mg/kg/day. This is based upon findings of statistically significant (P < 0.01) increased % early resorptions and % post-implantation fetal loss. Also, there wasa decrease in the mean number of viable fetuses relative to control value at the high dose of test substance. At the high dose of 600 mg/kg/day substantial maternal toxicity occured based on the observation of clinical signs of neurotoxicity in 71% of the animals. The maternal and embryo/fetal developmental NOAEL for this study is 300 mg/kg of maternal body weight.

Executive summary:

The test substance, vinyl neononoanoate was evaluated for the potential to cause developmental toxicity in an O.E.C.D. test guideline 414 study in the rat by the oral gavage route of exposure at dose levels of 0, 100, 300 and 600 mg/kg/day. The test substance, vinyl neononoanoate is a developmental toxicant in the rat at a maternally toxic dose level of 600 mg/kg/day. This is based upon findings of statistically significant (P < 0.01) increased % early resorptions and % post-implantation fetal loss at 600 mg/kg/day. Furthermore, a reduced number of litters with viable fetuses (68% of litters compared to 100% of control litters) and an increased number of litters with nonviable fetuses (16% of litters compared to 5% of control litters) was observed at the high dose level.