Registration Dossier

Toxicological information

Genetic toxicity: in vivo

Currently viewing:

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:
weight of evidence
Study period:
1991
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
CI Disperse Blue 284

Test animals

Species:
mouse
Strain:
C57BL
Details on species / strain selection:
C57BL/6JfBL10/Alpk male and female mice
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Duration of treatment / exposure:
Bone marrow samples were taken 24 hours after dosing at 3130 mg/kg and 24, 48 and 72 hours after dosing at 5000 mg/kg.
Frequency of treatment:
Twice at an interval of 24 h

Post exposure period:
Bone marrow samples were taken 24 hours after dosing at 3130 mg/kg and 24, 48 and 72 hours after dosing at 5000 mg/kg.

Doses / concentrationsopen allclose all
Dose / conc.:
3 130 mg/kg bw (total dose)
Dose / conc.:
5 000 mg/kg bw (total dose)
No. of animals per sex per dose:
5/sex/dose and killing time

Control animals:
yes, concurrent vehicle
Positive control(s):
Cyclophosphamide
- Route of administration: oral, gavage
- Doses / concentrations: 65 mg/kg bw

Examinations

Tissues and cell types examined:
Bone marrow erythrocytes

Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: Based on patterns of lethalities or severe toxicity observed over a 4-d observation period following a single oral dose in a maximum tolerated dose (MTD)-Phase I

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): Bone marrow smears were prepared 24 and 48 h after dosing for the vehicle control and treated animals and 24 h after dosing for the cyclophosphamide treated animals.

DETAILS OF SLIDE PREPARATION: The preparations were stained with polychrome methylene blue and eosin to visualise the various cell types.

METHOD OF ANALYSIS: Prior to microscopic assessment, all slides were furnished with code numbers, so that the counting was blind. The following counts were made:
Number of polychromatic erythrocytes (PCE) per slide: 1000 PCE
Percentage of polychromatic erythrocytes in the total erythrocyte population: 1000 Erythrocytes

Evaluation criteria:
A substance is considered positive if there is a significant increase in the number of micronucleated polychromatic erythrocytes compared with the concurrent negative control group
Statistics:
- The incidence of micronucleated PCE and percentage PCE in the erythrocyte sample, were considered by ANOVA.
- All analyses were carried out using the GLM procedure in SAS.
- One-sided Student's t-test:

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Under the test conditions, test substance is not clastogenic in the mouse micronucleus assay.
Executive summary:

Disperse Blue 284 was tested in C57BL/6JfBL10/Alpk male and female mice at dose levels of 3130 and 5000 mg/kg, the higher dose level being the limit dose for this assay. Bone marrow samples were taken 24 hours after dosing at 3130 mg/kg and 24, 48 and 72 hours after dosing at 5000 mg/kg.

No statistically or biologically significant increases in the incidence of micronucleated polychromatic erythrocytes, over vehicle control values, were seen at either dose level in the females at any of the sampling times investigated. A small but statistically significant increase in the incidence of micronucleated polychromatic erythrocytes was noted in male mice 24 hours after being dosed at 5000 mg/kg. Extended analysis of a further 2000 polychromatic erythrocytes from all males at the 24 hour sampling time was conducted. No statistically or biologically significant increases were observed in the extended analyses or when the original andextended analyses were combined prior to statistical analysis. The original increase observed in the males is therefore considered not to be of any biological significance.

The test system positive control, cyclophosphamide, induced statistically significant and biologically meaningful increases in micronucleated polychromatic erythrocytes, compared to the vehicle control values, thus demonstrating the sensitivity of the test system to a known clastogen.

It is therefore concluded Disperse Blue 284, under the conditions of test, is not clastogenic in the mouse micronucleus test.