Vinyl ethylene carbonate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 28 Sep 2021 to 13 June 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Vinyl ethylene carbonate

EC Number:

700-261-7

Cas Number:

4427-96-7

Molecular formula:

C5H6O3

IUPAC Name:

Vinyl ethylene carbonate

Test material form:

liquid

Specific details on test material used for the study:

Batch No.: 10121040902
Purity: 99.92%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: SPF (Beijing) biotechnology Co., Ltd.
- Age at study initiation: 13-14 weeks old
- Weight at study initiation: 215.08~319.62g
- Fasting period before study:
- Housing: All animals were housed in plastic cages (L46.0×W31.5 ×H20.0cm) on cage racks (L170.0cm×W50.0cm×H160.0cm). There were 5 cages per layer, and 4 layers per rack. There were two rats at most per cage, and mated females were housed individually in cages.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 29 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.2-25.0°C
- Humidity (%): 47-70%
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
In this test, purified water was used as vehicle. Calculate the theoretical weight and range of the test item according to the prepared volume and concentration. Weigh the test item and place into a jar lined at the prepared volume. Add the vehicle to the scale of prepared volume. Put into a rotor, stir until the test item completely dissolved, and label all bottles for use.

VEHICLE
- Justification for use and choice of vehicle: Based on the solubility of the test item in water, the purified water was selected as the vehicle in this study, that is also the preferred vehicle in OECD TG414.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

In this study, the analytical check for the concentrations of prepared test item was analyzed at the first week and last week preparation.
As the analysis, the prepared test item of different concentrations and the vehicle control were sampled and analyzed using the validated GC method.

Details on mating procedure:

- Impregnation procedure:
For each mating, two female rats and one male rat were paired at afternoon and separated in the next morning.
- Proof of pregnancy: the female rats were examined for presence of the sperm using vaginal smear method.

Duration of treatment / exposure:

14 days: day 5~19 of pregnancy (GD 5~19)

Frequency of treatment:

once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

Dose / conc.:

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

No. of animals per sex per dose:

24 females per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
In the two preliminary tests, the test item was suspended in purified water and administrated orally to the SD rats by gavage once daily for 14 days at six dose levels of 1000, 300, 150, 100, 60 and 30mg/kg body weight/day (mg/kg/d), with five female rats respectively (5/sex/concentration). A vehicle control group with the same number of animals as the administration group was included in parallel. All animals were daily observed for clinical signs. In addition, the body weights of the animals were measured every three days.
In the two preliminary the tests, the animals in the group of 1000 mg/kg/d were all dead after the first administration, and all the animals in the group of 300 mg/kg/d were observed with moist hair, but no dead and any other toxic symptom were observed. No dead and any toxic symptom were observed in the animals of the other four groups. At the same time, the body weights of the animals in the dosed groups had no significant decrease compared to the control group.
Based on the above results, referred to the results of acute oral test (LD50:300 mg/kg/d) and OECD Guideline TG414, three dose levels were used in this study including 200, 100 and 30mg/kg/d.

Examinations

Maternal examinations:

CLINICAL OBSERVATIONS: Yes
- Time schedule: Each animal was observed daily during dosing. The observation contained the appearance, fur, activity, breathing, posture, excrement and urine. All abnormalities, signs of ill health and reactions were recorded.
For animals of non-dosing, cage-side observation daily was done.

BODY WEIGHT: Yes
- Time schedule for examinations: All pregnant rats were weighed on GD0, then were weighed once per 3 days during the dosing period (GD5~19), and on the day of scheduled kill (GD20).

FOOD CONSUMPTION: Yes
During the period of administration, all pregnant rats were provided with a known quantity within 200±20g of feed on the day before body-weight determination, and the remaining feed were weighed on the next day within 24h±1.5h. The average food consumption of each animal was calculated.
Computing formula:
Daily food consumption (g) = added food weight (g) -remaining food weight (g)

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: uteri, thyroid glands

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Blood sampling:

- Plasma: Yes, Blood samples of pregnant females were used for the analysis of T3, T4 and TSH.

Fetal examinations:

FETAL EXTENAL EXAMINATION:
Viable fetuses were euthanized with CO2 before examination. The bodyweight, anogenital distance (AGD) and sex of each viable fetus were determined. Each fetus was examined for external alterations, including head, trunk, limbs and tail examination.
FETAL VISCERA EXAMINATION:
One-half fetuses of each litter were immersed in modified Davidson`s fixative for near one week, and stored in 70% isopropyl alcohol for viscera examination. As examination, limbs and tail of the fetus were cut down firstly. Then four chips were cut to examine the structural alterations of head. Open thorax and abdomen of the fetus to examine the size, shape and position of organs.
FETAL SKELETON EXAMINATION:
One-half fetuses of each litter were prepared and examined for skeletal alterations. Remove the skin and viscera of fetus and soak in absolute ethanol after the external examination firstly, then stain them using alizarin red staining method, after completely stained, replace with 1%KOH and 20% glycerine, store in 70% glycerin for examination. The prepared fetus samples were examined for skeletal including skull, vertebra, sternum, ribs, limb bones and pelvis.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Endocrine findings:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Maternal developmental toxicity

Pre- and post-implantation loss:

no effects observed

Early or late resorptions:

effects observed, non-treatment-related

Description (incidence and severity):

In the mid-dose group, the percent of viable fetuses and absorbed fetuses were significantly lower than the control group (P<0.01), but it was not dosed-related, so it was considered that results had no treatment-related.

Dead fetuses:

effects observed, non-treatment-related

Description (incidence and severity):

In the mid-dose group, the percent of dead fetuses were significantly higher than the control group(P<0.01), but it was not dosed-related, so it was considered that results had no treatment-related.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Results (fetuses)

External malformations:

no effects observed

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Some examined fetuses in the control group, low- and mid- dose groups showed signs of incomplete ossification of interparietal, parietal and occipital; Some examined fetuses in the control group and high-dose group showed sign of sternebra or sternum incomplete ossification, but the frequency of above abnormalities in the dose groups had no significant increase compared with the control group (P≥0.05). Some examined fetuses had less than six sternal ossification points, but the mean number of sternal ossification points in the dosed groups had no statistically difference compared with the control group (P≥0.05).

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Some examined fetuses in the control group, low-, mid- and high- dose groups showed signs of unilateral or bilateral kidney uronephrosis, one fetuse in the low-dose group showed sign of kidney small, but the frequency of above abnormalities in all dosed groups had no significant increase compared with the control group (P≥0.05).

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

external malformations

skeletal malformations

visceral malformations

Overall developmental toxicity

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, test item administered to pregnant SD rats by gavage in purified water, had not produced any maternal toxicity, or embryotoxicity and teratogenic at the dose of 200 mg/kg.d.
Based on these findings, the following effect levels, No Observed Adverse Effect Level (NOAEL) were derived:
NOAELmaternal toxicity: 200 mg/kg/d;
NOAELembryotoxicity: 200 mg/kg/d;
NOAELteratogenicity: 200 mg/kg/d.

Executive summary:

The exposure of gestating rats to different doses of test item by gavage during GD5~GD19 did not result in any death or significant specific toxicity at the highest dose of 200mg/kg/d and below. At the same time, no treatment related effect on the body weight gain and food consumption of pregnant rats was observed. Based on these results, it is concluded that the test item had no maternal toxicity at this dose level.
Developmental endpoints showed no treatment-related effect was observed in the mean numbers of corpora lutea and implantation sites. The fetal examination showed that no adverse effect in the survival, fetal body weight and sex distribution was observed in all dosed groups, additionally, no adverse effect attributable to treatment was observed across all groups with respect to external, viscera and skeletal malformations or variations. Based on these results, it is concluded that the test item had no embryotoxicity and teratogenicity at the dose levels.
In conclusion, under the conditions of this study, test item administered to pregnant SD rats by gavage in purified water, had not produced any maternal toxicity, or embryotoxicity and teratogenic at the dose of 200 mg/kg.d.
Based on these findings, the following effect levels, No Observed Adverse Effect Level (NOAEL) were derived:
NOAELmaternal toxicity: 200 mg/kg/d;
NOAELembryotoxicity: 200 mg/kg/d;
NOAELteratogenicity: 200 mg/kg/d.