1,4-divinylbenzene

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Justification for type of information:

Data from secondary source

Data source

Reference

Reference Type:

secondary source

Title:

The Developmental toxicity study of test material

Author:

HPVIS

Year:

2018

Bibliographic source:

HPVIS ,2018

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Principles of method if other than guideline:

Developmental toxicity study of test material was performed on Charles River COBS CD rats.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-ethyltoluene

EC Number:

210-761-2

EC Name:

4-ethyltoluene

Cas Number:

622-96-8

Molecular formula:

C9H12

IUPAC Name:

1-ethyl-4-methylbenzene

Details on test material:

- Name of test material (as cited in study report):1-ethyl-4-methylbenzene- Molecular formula:C9H12- Molecular weight :120.194 g/mol - Substance type:Organic

Test animals

Species:

rat

Strain:

CD-1

Details on test animals or test system and environmental conditions:

Details on test animals and env. conditionsTEST ANIMALS- Source:- Age at study initiation: 12 weeks old- Acclimation period: 13 days

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

Mazola corn oil

Details on exposure:

Details on exposurePREPARATION OF DOSING SOLUTIONS:The appropriate amount of test material was added to 50 ml of the vehicle, Mazola corn oil, and mixed by hand to ensure a homogeneous mixture. The test substance was prepared fresh dailyDIET PREPARATION- Rate of preparation of diet (frequency):No data available- Mixing appropriate amounts with (Type of food )- Storage temperature of food: No data availableVEHICLE- Justification for use and choice of vehicle (if other than water): test material dissolved in , Mazola corn oil- Concentration in vehicle: 0, 25, 100, and 200 mg/kg/day. - Amount of vehicle (if gavage): 5 ml/kg- Lot/batch no. (if required): No data available- Purity: No data available

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: [artificial insemination / purchased timed pregnant / cohoused] - If cohoused: - M/F ratio per cage: 1::1 - Length of cohabitation: - After ... days of unsuccessful pairing replacement of first male by another male with proven fertility. - Further matings after two unsuccessful attempts: [no / yes (explain)] - Verification of same strain and source of both sexes: [yes / no (explain)] - Proof of pregnancy: [vaginal plug / sperm in vaginal smear] referred to as [day 0 / day 1] of pregnancy:The day that evidence of mating was detected was designated day 0 of gestation - Any other deviations from standard protocol:

Duration of treatment / exposure:

20 days ( from day 6 through day 19 )

Frequency of treatment:

daily

Duration of test:

20 days

Doses / concentrations

Remarks:

0, 25, 100, 200mg/kg bw/day

No. of animals per sex per dose:

Total:1000 mg/kg bw/day:2525mg/kg bw/day:25100mg/kg bw/day:25200 mg/kg bw/day:25

Control animals:

yes, concurrent vehicle

Details on study design:

No data available

Examinations

Maternal examinations:

Parental animals observation and examinationsCAGE SIDE OBSERVATIONS: yes DETAILED CLINICAL OBSERVATIONS: Yes Time schedule: They were observed daily for mortality and clinical signs of toxicityBODY WEIGHT: YesTime schedule for examinations: Individual maternal body weights were recorded on gestation days 0, 6, 9, 12, 16, and 20.FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes Food consumption was determined weekly. Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: : No data availableCompound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data: No data availableWATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data Time schedule for examinations:

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 - Other:

Fetal examinations:

- External examinations: Yes:[all per litter - Soft tissue examinations: Yes: half per litter - Skeletal examinations: Yes: half per litter - Head examinations: No data

Statistics:

All statistical analyses compared the treatment groups to the control group with the level of significance at p<0.0l and p<0.05. The male to female fetal sex distribution and the number of litters with malformations were compared using the Chi-square test criterion with Yates' correction for 2 x 2 contingency tables and/or Fisher's exact probability tests to judge significance of differences. The number of early resorptions and postimplantation losses were compared by the Mann-Whitney U-test. The mean number of viable fetuses, total implantations, corpora lutea, and mean fetal body weights were compared by ANOVA, Bartlett's test for homogeneity of variances and Dunnett's multiple comparison tables to judge significance of differences.

Indices:

No data available

Historical control data:

No data available

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Hair loss (primarily of the limbs and abdomen) occurred with similar frequency in all treatment and control groups at various intervals throughout the treatment period.

Dermal irritation (if dermal study):

not specified

Mortality:

no mortality observed

Description (incidence):

Survival was 100% in the control and all treated groups.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no biologically meaningful differences in mean maternal body weight gain throughout the entire gestation period in any treated group when compared to controls

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

A slight increase in mean postimplantation loss was observed in the 25 mg/kg/day group when compared to controls. However, no dose-related trend was evident and this response was considered to be due to a random occurrence. Mean postimplantation loss number for 0, 25, 100, and 200 mg/kg/day was 13, 29, 19, and 19, respectively.

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

Other effects:

not specified

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

body weight and weight gain

clinical signs

dead fetuses

early or late resorptions

effects on pregnancy duration

maternal abnormalities

mortality

number of abortions

pre and post implantation loss

total litter losses by resorption

Remarks on result:

other: overall no toxic effects observed

Maternal abnormalities

Abnormalities:

not specified

Localisation:

not specified

Results (fetuses)

Fetal body weight changes:

no effects observed

Description (incidence and severity):

Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.DescriptionIncidenceAndSeverityFetalPupBodyWeightChanges): no effects observed in mean fetal body weight in any of the treated groups when compared to the control group.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

no effects observed in the fetal sex distribution in any of the treated groups when compared to the control group

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Description (incidence and severity):

There were no biologically meaningful or statistically significant differences in the number of litters with malformations in any of the treated groups compared to controls. Microphthalmia and thoracoschisis each occurred in one fetus in one litter in the 25 and 200 mg/kg/day groups, respectively. Scoliosis was observed in one litter from both of the 200 mg/kg/day and control groups. The number of litters (and fetuses) with genetic and developmental variations in the treated groups was comparable to controls.

Visceral malformations:

no effects observed

Other effects:

not specified

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

not specified

Basis for effect level:

reduction in number of live offspring

fetal/pup body weight changes

changes in postnatal survival

external malformations

skeletal malformations

visceral malformations

Remarks on result:

other: No effects on developmental parameters

Fetal abnormalities

Abnormalities:

not specified

Localisation:

other: not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Treatment related:

not specified

Relation to maternal toxicity:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Applicant's summary and conclusion

Conclusions:

No Observed Adverse Effect Level (NOAEL) for developmental was considered to be 200mg/kg/day. When female CD 1rats were treated with test material orally.

Executive summary:

The developmental toxicity study of test material was performed inPregnant Charles River COBS CD rats. Dosage levels of 25, 100, and 200 mg/kg/day were administered orally by gavage as a single daily dose on days 6 through 19 of gestation at a constant volume of 5 ml/kg.The control group received the vehicle only, Mazola corn oil, on a comparable regimen.One female and one male rat of the same strain and source were placed together for mating. The occurrence of copulation was determined by daily inspection for a copulatory plug. The day that evidenice of mating was detected was designated day 0 of gestation and the female was returned to an individual cage.Dams were observed daily for mortality and clinical signs of toxicity .Individual maternal body weights were recorded on gestation days 0, 6, 9, 12, 16, and 20. A Cesarean section was performed on each female on gestation day 20 immediately following sacrifice by carbon dioxide inhalation. The uterus was excised and weighed prior to removal of the fetuses. The number and location of viable and nonviable fetuses, early and late resorptions, total implantations and corpora lutea were recorded. The thoracic and abdominal cavities and organs of the dams were examined for grossly evident morphological changes and the carcasses discarded. Uteri from females that appeared nongravid were opened and placed in 10% ammonium sulfide solution for confirmation of pregnancy status. All fetuses were individually weighed and examined for external malformations and variations, including the palate and eyes. Each fetus was externally sexed and individually numbered and tagged for identification. Approximately one-half of the fetuses were placed in Bouin's fixative for subsequent visceral examination by razor blade sectioning. The remaining one-half of the fetuses were fixed in alcohol, macerated in potassium hydroxide, and stained with Alizarin Red S for subsequent skeletal examination.

There were no biologically meaningful differences in the appearance or behavior of the rats in the 25, 100, or 200 mg/kg/day groups when compared to controls. Hair loss (primarily of the limbs and abdomen) occurred with similar frequency in all treatment and control groups at various intervals throughout the treatment period. Survival was 100% in the control and all treated groups. There were no biologically meaningful differences in mean maternal body weight gain throughout the entire gestation period in any treated group when compared to controls. There were no biologically meaningful or statistically significant differences in the mean numbers of corpora lutea, total implantations, early resorptions, postimplantation loss, viable fetuses, the fetal sex distribution or mean fetal body weight in any of the treated groups when compared to the control group. Non viables and late resorptions were not observed in the control or in any of the treated groups. A slight increase in mean postimplantation loss was observed in the 25 mg/kg/day group when compared to controls. However, no dose-related trend was evident and this response was considered to be due to a random occurrence. Mean postimplantation loss number for 0, 25, 100, and 200 mg/kg/day was 13, 29, 19, and 19, respectively.
 There were no biologically meaningful or statistically significant differences in the number of litters with malformations in any of the treated groups compared to controls. Microphthalmia and thoracoschisis each occurred in one fetus in one litter in the 25 and 200 mg/kg/day groups, respectively. Scoliosis was observed in one litter from both of the 200 mg/kg/day and control groups. The number of litters (and fetuses) with genetic and developmental variations in the treated groups was comparable to controls.  Hence No Observed Adverse Effect Level (NOAEL) for developmental was considered to be 200mg/kg/day.When femaleCD 1rats were treated with test materialorally.