Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
From 25 JAN 1999 to 11 FEB 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: according to the OECD and it is GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report Date:
1999

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Qualifier:
according to
Guideline:
other: U.S. EPA: OPPTS 870.5395
Qualifier:
according to
Guideline:
other: EEC Directive 92/69, L 383 A, Annex B.12., 154-156
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
mouse
Strain:
other: HsdWin: NMRI
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 7 weeks
- Weight at study initiation: Male: 33.0 g; Female: 25.7 g
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days under study conditions


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/-3ºC
- Humidity (%): 50+/-20%
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
On the days of administration the test substance was dissolved in sesame oil at appropriate concentrations. A magnetic stirrer was used to keep the preparations homogeneous until dosing had been completed.
Details on exposure:
The test substance was administered twice at an interval of 24 hours orally by gavage to the test animals at doses of 120, 400 and 1200 mg per kg body weight. The vehicle, sesame oil, was administered in the same way to the negative control groups. The study included a concurrent positive control using the reference substance, which was administered once orally by gavage at a dose of 50 mg per kg body weight.
Duration of treatment / exposure:
24 h
Frequency of treatment:
twice at an interval of 24 hours
Post exposure period:
24 h after dosing animas were killed.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 120, 400 or 1200 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
5 male and 5 female
Control animals:
yes, concurrent vehicle
Positive control(s):
cyclophosphamide dissolved in distilled water on the second day of experiment, final concentration 0.5 % (w/v). 50 mg/kg bw administered to positive control group.

Examinations

Tissues and cell types examined:
femora bone marrow cells.
Evaluation criteria:
2000 polychromatic erythrocytes were counted for each animal. The number of cells with micronuclei was recorded, not the number of individual micronuclei. In addition, the ratio of polychromatic erythrocytes to 200 total erythrocytes was determined. Main parameter for the statistical analysis, i.e. validity assessment of the study and mutagenicity of the test substance, was the proportion of polychromatic erythrocytes with micronucleiout of the 2000 counted erythrocytes. All bone marrow smears for evaluation were coded to ensure that the group from which they were taken remained unknown to the investigator.
Statistics:
A one-sided Wilcoxon-test was evaluated to check the validity of the study. The study was considered as valid in case the proportionof polychromatic erythrocytes with micronuclei in the positive control was significantly higher than in the negative control.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Remarks:
in the highest dose group: motor activity decreased, diarrhea, palpebral fissure narrow, movements uncoordinated, stupor, tonic convulsion, and prone position
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Doses: 120, 400 and 1200 mg subtance per kg body weight
Oral administration of 1200 mg substance per kg body weight resulted in the death of six out of ten animals treated. These animals were replaced and survived after treatment.
signs of toxicity: decreased motor activity, diarrhea, palpebral fissure narrow, uncoordinated movements, stupor, tonic convulsions and prone position, 24 hours after application all animals were free of clinical signs of toxicity.
The dissesction of the animals revealed no test subtance related findings. The bone marrow smears were examined for the occurrence of micronuclei in red blood cells.

- no increase in the incidence of micronucleated polychromatic erythrocytes in treated groups in comparison to control
- ratio of polychromated erythrocytes to total erythrocytes decreased in the highest dose group: 20% of control value

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
The substance did not lead to a substantial increase of micronucleated polychromatic erythrocytes, i.e. it is not mutagenic in the micronucleus test under the conditions described in this report.
Executive summary:

An in vivo micronucleus test was carried in NMRI mice with the test substance according to OECD guideline 474. The test compound was dissolved in sesame oil and was given twice at an interval of 24 hours as oral doses of 0, 120, 400 and 1200 mg per kg body weight to male and female mice, based on the results of a previous dose range finding assay. According to the test procedure the animals were killed 24 hours after administration.

Oral administration of 1200 mg substance per kg body weight resulted in the death of six out of ten animals treated. These animals were replaced and survived after treatment. The following signs of toxicity were observed: decreased motor activity, diarrhea, palpebral fissure narrow, uncoordinated movements, stupor, tonic convulsions and prone position. 24 hours after application all animals were free of clinical signs of toxicity. The dissesction of the animals revealed no test subtance related findings. The bone marrow smears were examined for the occurrence of micronuclei in red blood cells. No increase in the incidence of micronucleated polychromatic erythrocytes in treated groups in comparison to control group. The ratio of polychromated erythrocytes to total erythrocytes decreased in the highest dose group: 20% of control value. Under the conditions of the present study the substance is not mutagenic.