Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
other: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
From January 16 to April 12, 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study is conducted on a read across test material. The complete read across justification is attached in section 13. The reliability of the original study is 1.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidelines for Testing of Toxic Chemicals, Ministry of Health, People’s Republic of China, 272.
Deviations:
no
Qualifier:
according to
Guideline:
other: Guidelines for the testing of chemicals Section 4: Health Effects, Ministry of environmental protection of People’s Republic of China, 474, 2003.
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.5395 (In Vivo Mammalian Cytogenetics Tests: Erythrocyte Micronucleus Assay)
Deviations:
no
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
mouse
Strain:
ICR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Shanghai SLAC Laboratory Animals Co., Ltd
- Age at study initiation: 6-8 weeks old
- Weight at study initiation: 26.7 - 29.6 g.
- Quarantined: for 5 days after receipt and were observed each day for signs of illness.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.8 - 22.5 °C
- Humidity (%): 42 - 50 %.
- Photoperiod: 12 hour light/dark cycle.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle used: corn oil
- Concentration of test material in vehicle: 10 ml/kg body weight




Duration of treatment / exposure:
Two oral gavages (two treatments at 24 hour intervals).
Frequency of treatment:
Single application.
Post exposure period:
All mice were euthanized at approximately 24 hours following the final treatment.
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
range finding study
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
range finding study
Dose / conc.:
500 mg/kg bw/day (nominal)
Remarks:
range finding study
Dose / conc.:
2 000 mg/kg bw/day (nominal)
Remarks:
range finding study
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
main study
Dose / conc.:
250 mg/kg bw/day (nominal)
Remarks:
main study
Dose / conc.:
500 mg/kg bw/day (nominal)
Remarks:
main study
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Remarks:
main study
No. of animals per sex per dose:
1 animal per sex per dose (range finding test)
5 animals per sex per dose (main test)
Control animals:
yes

Examinations

Tissues and cell types examined:
Polychromatic erythrocytes (PCEs) and normochromatic erythrocytes (NCEs) were analyzed.
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: range finding study.
Evaluation criteria:
CRITERIA FOR A VALID TEST
The mean incidence of micronucleated PCEs must not exceed 5/1000 PCEs (0.5 %) in the negative (vehicle) control. The incidence of micronucleated PCEs in the positive control group must be significantly increased relative to the vehicle control group (p <0.01).

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not examined
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Range finding study: no death was observed in animals at 500, 100, 0 mg/kg bw during the course of the range finding study. However, sag, fluffy fur, salivating and death were observed in animals at 2000 mg/kg bw. All mice treated with the control articles, other test article appeared normal following administration.
Main study: no death was observed during the course of the study. Sag, fluffy fur and salivating were observed in animals at 1000 mg/kg bw. Reductions in PCEs/ECs ratio weren’t observed in Aluminium hypophosphite-treated groups compared to the vehicle control at 24 hours post dosing. A statistically significant increase in the number of micronucleated PCEs per 10,000 PCEs (total PCEs per group) was not observed at any dosage at harvest relative to the respective vehicle control.

Any other information on results incl. tables

All criteria for a valid test were met. Cyclophosphamide (CP) induced a significant increase in micronucleated PCEs (p<0.01) and a reduction in the PCEs/ECs ratio of 14.1 % and 13.4 % in female and male mice, respectively. In addition, the negative and positive control data were consistent with historical control data, indicating that the study was validly conducted.

Applicant's summary and conclusion

Conclusions:
A two oral administration (two treatment at 24 hour intervals) of the test item did not induce a statistically significant increase in the incidence of micronucleated PCEs in the bone marrow of male and female ICR mice. Therefore, the substance was concluded to be negative in the in vivo mouse micronucleus assay.
Executive summary:

The purpose of this study was to evaluate the clastogenic potential of the test item, as measured by its ability to induce micronuclei in the polychromatic erythrocytes (PCEs) in the bone marrow of ICR mice.

According to the result to mice in the range finding study, a two oral administration at 24 hours interval of the substance was conducted by oral gavages to 5 male mice and 5 female mice per group at 0 (vehicle control, corn oil), 250, 500, 1000 mg/kg bw. Five male mice and five female mice received a two abdominal injection dosage of 40 mg/kg of CP as positive control. The dose volume for all groups was 10 ml/kg. All mice were euthanized at approximately 24 hours following the final treatment. After euthanasia, bone marrow was collected from sternum, and smears were prepared and stained with Giemsa stain. 2000 PCEs per animal were examined microscopically for the presence of micronucleated PCEs. The proportion of PCEs to total erythrocytes (PCEs/ECs ratio) was also determined to evaluate the test article bone marrow toxicity.

Under the conditions of the assay described in this report, a two oral administration of the test item at all dose level, did not induce a significant increase in the incidence of micronucleated PCEs in the bone marrow of male and female ICR mice. Therefore, the substance was concluded to be negative in the in vivo mouse micronucleus assay.