Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 26 October to 12 December 1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study run to a method comparable with current guidelines and to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
no
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Batch No.: 20.9.88/1
Purity: Not specified

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River UK Limited, Margate, Kent, England
- Age at study initiation: Approximately 35 days old
- Weight at study initiation: 22 to 24 grams
- Assigned to test groups randomly: yes
- Fasting period before study:
- Housing: Each group of 2 or 5 mice was kept in a plastic disposable cage.
- Diet (e.g. ad libitum): Free access to pelleted Labsure LAD 1 rodent breeding diet.
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: Approximately 4 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%):
- Air changes (per hr): 30 changes of air per hour.
- Photoperiod (hrs dark / hrs light): The room was illuminated by artificial light for 12 hours per day.

IN-LIFE DATES: From: 26 October 1988 To: 12 December 1988

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
Corn oil
Duration of treatment / exposure:
Immediately
Frequency of treatment:
Single dose
Post exposure period:
24, 48 or 72 hours
Doses / concentrations
Remarks:
Doses / Concentrations:
5000 mg/kg
Basis:
actual ingested
No. of animals per sex per dose:
Preliminary toxicity test:
2 males and 2 females per dose for Phase I.
5 males and 5 females per dose for Phase II.

Micronucleus test:
15 males and 15 females for vehicle control.
17 males and 19 females for the test substance.
5 males and 5 females for positive control.
Control animals:
yes
Positive control(s):
Mitomycin C
- Justification for choice of positive control(s):
- Route of administration: Oral by intragastric gavage.
- Doses / concentrations: 12 mg/kg

Examinations

Details of tissue and slide preparation:
The femurs were cleared of tissue and one epiphysis removed from each bone. A direct bone marrow smear was made onto a slide containing a drop of calf serum. One smear was made from each femur. The prepared smears were fixed in methanol. The smears were air-dried and stained for 10 minutes in 10% Giemsa. Following rinsing in distilled water and differentiation in buffered distilled water, the smears were air-dried and mounted with coverslips using DPX.
Evaluation criteria:
None stated
Statistics:
For a comparison of an individual treated group with a concurrent control group, Wilcoxon's sum of ranks test is used.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Signs and mortalities:
One male and five female animals died after treatment with the test substance in the main study. On post mortem examination, none of the animals showed signs of having been mis-dosed. No clinical signs were observed in the vehicle control or positive control groups for the duration of the test.

Micronucleated polychromatic erythrocyte counts (mnp):
The test substance did not cause any statistically significant increases in the number of micronucleated polychromatic erythrocytes at any of the three kill times.
Mitomycin C caused large, highly significant increases in the frequency of micronucleated polychromatic erythrocytes.

Micronucleated normochromatic erythrocytes (mnn):
The test substance did not cause any substantial increases in the incidence of micronucleated normochromatic erythrocytes at any of the three kill times.

Ratio of polychromatic to normochromatic erythrocytes (p/n):
Statistically significant decreases in the p/n ratios were observed at the 24 hour and 72 hour sampling times, using Wilcoxon's sum of ranks test. These may be evidence of slight bone marrow cell toxicity/depression.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
From the results obtained it is concluded that the test substance shows no evidence of mutagenic potential or bone marrow cell toxicity when administered as a single oral dose in this in vivo test procedure.