1,4-divinylbenzene

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / 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 reproductive 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:

other: EPA 870.3700

Principles of method if other than guideline:

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

GLP compliance:

not specified

Limit test:

no

Justification for study design:

No data available

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 species / strain selection:

No data available

Sex:

female

Details on test animals or test system and environmental conditions:

Details on test animals and env. conditionsTEST ANIMALS- 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

Details on mating procedure:

- M/F ratio per cage:1:1 - Length of cohabitation: - 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 . - After ... days of unsuccessful pairing replacement of first male by another male with proven fertility. - Further matings after two unsuccessful attempts: [no / yes (explain)] - After successful mating each pregnant female was caged (how): - Any other deviations from standard protocol:

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

20 days ( from day 6 through day 19 )

Frequency of treatment:

Daily

Details on study schedule:

No data available

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

Positive control:

No data available

Examinations

Parental animals: Observations and 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:

Oestrous cyclicity (parental animals):

No data available

Sperm parameters (parental animals):

No data available

Litter observations:

All fetuses were individually weighed and examined for external malformations and variations, including the palate and eyes.

Postmortem examinations (parental animals):

Postmortem examinations (Parent Animal)SACRIFICE: A Cesarean section was performed on each female on gestation day 20 immediately following sacrifice by carbon dioxide inhalation.GROSS NECROPSY: The thoracic and abdominal cavities and organs of the dams were examined for grossly evident morphological changes and the carcasses discardedHISTOPATHOLOGY / ORGAN WEIGHTSThe tissues indicated in Table [#] were prepared for microscopic examination and weighed, respectively.: macroscopic examination was performed

Postmortem examinations (offspring):

SACRIFICE - The F1 offspring not selected as parental animals and all F2 offspring were sacrificed at [#?] days of age. - These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows: GROSS NECROPSY: yes - Gross necropsy consisted of [external and internal examinations .] HISTOPATHOLOGY / ORGAN WEIGTHS: yes 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

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

Reproductive indices:

No data available

Offspring viability indices:

No data available

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

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

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

Description (incidence and severity):

There were no biologically meaningful or statistically significant differences in the mean numbers of corpora lutea, total implantations, early resorptions, postimplantation loss, viable fetuses,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.Non viables and late resorptions were not observed in the control or in any of the treated groups

Effect levels (P0)

Key result

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

reproductive performance

Remarks on result:

other: No effects on reproductive performance

Target system / organ toxicity (P0)

Critical effects observed:

not specified

System:

other: not specified

Organ:

not specified

Treatment related:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Results: F1 generation

General toxicity (F1)

Clinical signs:

not specified

Dermal irritation (if dermal study):

not specified

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

no effects observed in mean fetal body weight in any of the treated groups when compared to the control group

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

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

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.

Histopathological findings:

not specified

Other effects:

not specified

Developmental neurotoxicity (F1)

Behaviour (functional findings):

not specified

Developmental immunotoxicity (F1)

Developmental immunotoxicity:

not specified

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

not specified

Basis for effect level:

viability

mortality

body weight and weight gain

gross pathology

Remarks on result:

other: No effects on developmental parameters

Target system / organ toxicity (F1)

Critical effects observed:

not specified

System:

other: not specified

Organ:

other: not specified

Treatment related:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Overall reproductive toxicity

Reproductive effects observed:

not specified

Treatment related:

not specified

Relation to other toxic effects:

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 reproductive and developmental was considered to be 200mg/kg/day. When female CD 1rats were treated with test material orally

Executive summary:

The reproductive and developmental toxicity study of test material was performed in Pregnant 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 reproductive and developmental was considered to be 200mg/kg/day.When femaleCD 1rats were treated withtest materialorally.