2-Propyl-4-methyl-6-(1-methylbenzimidazol-2-yl)benzimidazole

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-08-20 to 2010-02-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with national standard methods (China) with acceptable restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: Section 4 of the Guidelines for the Testing of Chemicals: Health Effects (ministry of environmental protection of People´s Republic of China)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-Propyl-4-methyl-6-(1-methylbenzimidazole-2-yl)benzimidazole

IUPAC Name:

2-Propyl-4-methyl-6-(1-methylbenzimidazole-2-yl)benzimidazole

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Storage condition of test material: storage room of the institute, -preservation condition: room temperature

Test animals

Species:

rat

Strain:

other: SD

Details on test animals or test system and environmental conditions:

TEST ANIMALS- Source: Sino-British Sipper/BK Lab.Animal LTD.,CO.- Age at study initiation: 3 months- Weight at study initiation: after mating on day 0 mean: 275 +-19 to 277+-18 g- Housing: animal barrier system- Diet (e.g. ad libitum): ad libitum- Water (e.g. ad libitum): ad libitum- Acclimation period: 5 daysENVIRONMENTAL CONDITIONS- Temperature (°C): 20-25°C- Humidity (%): 40-70%- Air changes (per hr): no data- Photoperiod (hrs dark / hrs light): no data

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% Carboxymethyl Cellulose Sodium (CMC-Na)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The test article was mixed with 1% CMC-Na. Animals were gavaged based on 10 mL/kg bwVEHICLE- Concentration in vehicle: The concentrations of the test substance in the vehicle were 0.3; 1.2; 5.0 and 20.0 mg/mL respectively.1% CMC-Na solution was used as negative control.

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: cohoused- If cohoused: for mating female and male rats in the same cage- M/F ratio per cage: 25 females, no data about males - Length of cohabitation: until day 0- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy

Duration of treatment / exposure:

from day 6 to day 15 after their pregnancy

Frequency of treatment:

daily

Duration of test:

20 days

No. of animals per sex per dose:

20 pregnant females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Repeated dose 28-day oral toxicity study in rats

Examinations

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS: Yes- Time schedule: dailyBODY WEIGHT: Yes - Time schedule for examinations: day 0, 5, 8, 11, 14, 17, 20POST-MORTEM EXAMINATIONS: Yes - Sacrifice at day 20 (of pregnancy)

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 dead fetus: Yes - Number of late dead fetus: Yes - Other: absorption fetuses, live fetuses were recorded

Fetal examinations:

- External examinations: Yes: [for all live fetuses]- Soft tissue examinations: No- Skeletal examinations: Yes: [2/3 fetuses from each litter]- Other examinations: splanchnic malformations [1/3 fetuses from each litter]

Statistics:

SPSS10.0 was used to perform statistics. All ratios were analyzed by x^2 test. Study measurements were analyzed by ANOVA or nonparametric statistics. Fetus body length, tail length and body weight were compared by t test. The data of fetuses was analyzed in the unit of litter.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yesDetails on maternal toxic effects:- Most pregnant rats in 200 mg/kg bw group appeared listless, fluffy fur and body weight descended after dosing 3 days. Four pregnant rats died one after the other on day 14 after getting pregnant. In the 200 mg/kg bw group, the dose was obviously toxic and the ration of death the pregnant rats appeared obvious toxicity and the ratio of death for the pregnant rats was more than 10% (4/25, mortality was 16%)- No abnormality was detected in the 3, 12 and 50 mg/kg bw groups (body weight, uterus and fetus weight, number of corpus luteum, of balastocyst implantation)- The five rats of non-pregnancy in each group received no treatment, and after negropsy on day 20 no obvious abnormality were found.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

50 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yesDetails on embryotoxic / teratogenic effects:no significant differences versus the control group in:- live fetus, dead fetus, number of absorption fetus, sexual ratio in the test groups 3, 12, 50 mg/kg bw- external malformations in the test groups 3, 12, 50 mg/kg bw (cephalocele, exencephaly; microcephaly, micrencephaly, microphthalmia; cleft lip, cleft mandible; gastoschisis, abdomen; hernia, umbilical hernia; spina bifida; small limb, short limb; syndactyly, polydactyly, adactyly; anury, bobtail; anal atresia; sacrococcygeal cleft)- skeletal malformations in the test groups 3, 12, 50 mg/kg bw (fontanel close incompletion; sagittal suture broadening; lack of skull; cervical vertebrae malformations; hyoid bone; clavicle malformations; rib malformations; sternum ossification rudimentary or not ossified; thoracic vertebra malformations; lumbar vertebra malformations; bone of limb; bone of poe; spinal aplasia; pelvis malformations; coccyx; cauda vertebra; sphenoid malformations) - splanchnic malformations in the test groups 3, 12, 50 mg/kg bw (cleft tongue, cleft palate; eyeball; brain; medulla oblongata and spinal cord; trachea and oesophagus; nose; heat; liver; lung; hydronephrosis or cavity; Spleen; diaphragm; genitalia; bladder)- growth and development at 50 mg/kg bw (fetus body length; fetus tail length; fetus bodyweight)significant differences versus the control group in:- growth and development at 3 and 12 mg/kg bw (fetus body length; fetus tail length; fetus bodyweight)

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

> 50 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reduction in number of live offspring

changes in sex ratio

changes in litter size and weights

changes in postnatal survival

external malformations

skeletal malformations

other: splanchnic malformations, growth and development

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The NOAEL of the substance item in this study is considered to be 50 mg/kg bw for maternal toxicity.