Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1978
Report Date:
1978

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
GLP compliance:
no
Type of assay:
other: Micronucleus test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Specific details on test material used for the study:
- Name of the test material as used in report: 4-Methyl-7-diethylamino-cumarin (SWN), Fluoresc. Br. 140

Test animals

Species:
rat
Strain:
other: CFY
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS - Source: Anglia Labaratory Animals, Alconbury, Huntingdon. - Weight at study initiation: Between 57 and 62 grams - Assigned to test groups randomly: yes - Fasting period before study: Overnight - Housing: Five rats per plastic disposable cage. - Diet: "Grain Harvester" Anglia Labaratory Animal Diet, ad libitum - Water: ad libitum - Acclimation period: One week ENVIRONMENTAL CONDITIONS - Temperature (°C): 21 ± 2 - Humidity (%): 50 ± 5 - Air changes (per hr): 20 - Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
- Vehicle(s)/solvent(s) used: Distilled water adjusted to pH 7- Concentration of test material in vehicle: 40, 80 and 160 mg/mL- Amount of vehicle: 0.1 mL/10 g
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:The test substance was received as an off-white coloured powder. It was prepared as a suspension in sterile distilled water, using a Silverson high speed mixer and the pH of each concentration was adjusted to 7.0. Sterile distilled water was used as the negative control and all dosages were administered by intragastric intubation.
Frequency of treatment:
Two equal administrations separated by an interval of 24 hours
Post exposure period:
Following the last dose, the animals were observed for a further six hours before killing.
Doses / concentrationsopen allclose all
Dose / conc.:
800 mg/kg bw/day
Remarks:
Two equal administration of 400 mg/kg bw separated by an interval of 24 hours.
Dose / conc.:
1 600 mg/kg bw/day
Remarks:
Two equal administration of 800 mg/kg bw separated by an interval of 24 hours.
Dose / conc.:
3 200 mg/kg bw/day
Remarks:
Two equal administration of 1600 mg/kg bw separated by an interval of 24 hours.
No. of animals per sex per dose:
5
Control animals:
yes, concurrent vehicle
Positive control(s):
Mitomycin C - Route of administration: intraperitoneal injection - Doses / concentrations: 0.1 mL/10 g (7mg/kg) twice.

Examinations

Tissues and cell types examined:
Bone marrow smear from the epiphysis of the femur.
Details of tissue and slide preparation:
The animals were killed by cervical dislocation and one femur dissected out from each animal. The femur was cleared of tissue and one epiphysis removed. A direct bone marrow smear was made onto a slide containing a drop of calf serum. The slide was cleaned by immersion in methanol for 24 hours and air-dried immediately before use. One smear was made from each femur. The prepared smears were air-dried and fixed in methanol overnight. After fixation, the smears were air-dried and placed in buffered distilled water (pH 6.8) for 10 minutes prior to staining in Giemsa (dilution factor 1 part Giemsa : 9 parts buffered distilled water pH 6.8) for 10 minutes. After rinsing in buffered distilled water (pH 6.8), the slides were air-dried. Prior to mounting in DPX, the slides were defatted by immersion in xylene for 10 minutes.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
After administration of sterile distilled water, the vehicle control, no toxic reactions or mortalities were observed.After administration of the test substance at a total dosage of 800 mg/kg bw/day, no toxic reactions or mortalities were observed.After administration of the test substance at a total dosage of 1600 mg/kg bw/day, no mortalities were observed, but a toxic reaction consisting of slight ataxia and slightly increased lacrimation was observed.After administration of the test substance at a total dosage of 3200 mg/kg bw/day, a toxic reaction consisting of severe ataxia, loss of righting reflex, hypopnoea and increased lacrimation was observed and all animals in the group excreted dark yellow pigmented urine. There was one mortality at this dose level, which died overnight after the administration of the first dose, between 8 and 24 hours. Advanced visceral autolysis prevented any post-mortem examination.After administration of Mitomycin C, the positive control compound, no toxic reactions or mortalities were observed.In this experiment the negative control group gave a mean count of 2.5 micronucleated cells which was within the range for previous unrelated experiments. After administration of the test substance at all dosages, the group mean micronucleated cell counts were comparable with the concurrent control value and within the laboratory standard range for negative controls obtained in previous unrelated experiments.The positive control, Mitomycin C, administered intraperitoneally gave a mean count of 85.9 micronucleated cells per 2000 polychromatic erythrocytes.

Applicant's summary and conclusion