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Toxicological information

Developmental toxicity / teratogenicity

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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:
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

Reference
Name:
Unnamed
Type:
Constituent
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 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:
clinical signs
mortality
body weight and weight gain
maternal abnormalities
number of abortions
pre and post implantation loss
total litter losses by resorption
effects on pregnancy duration
early or late resorptions
dead fetuses
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.