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Toxicological information

Genetic toxicity: in vivo

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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Comparable to guideline method with acceptable restrictions - purity of the test substance can not be ascertained (commercial grade) - only 1000 cells scored for micronuclei - PCE to NCE proportion not determined - not up to 5 animals were analysed per sex

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1985
Report Date:
1985

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
(purity of the test substance can not be ascertained - only 1000 cells were scored for micronuclei - PCE to NCE proportion not determined, not up to 5 animals were analysed per sex)
Principles of method if other than guideline:
The experiment was performed to evaluate any mutagenic effect on somatic interphase cells in vivo. The test substance is administered by gavage. Treatment consists of one daily dose of 1,250, 2,500 or 5,000 mg/kg on each of two consecutive days. The animals are sacrificed 24 h after the second application. Smears of the bone marrow are prepared and scored for anomalies. Following parameters are evaluated: single Jolly bodies, fragments of nuclei in erythrocytes, micronuclei in erythroblasts, micronuclei in leucopoietic cells and polyploid cells.
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Physical state: white powder
- Analytical purity: commercial grade
- Storage condition of test material: room temperature
- Solubility: practically insoluble in water
Specific details on test material used for the study:
- Source: Ciba Geigy Ltd. Plastics and Additives Division, Basel, Switzerland
- Batch No.: EN 02885.32
- Analytical purity: Commercial grade

Test animals

Species:
hamster, Chinese
Strain:
other: Cricetulus griseus
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Ciba Geigy Tierfarm, Sisseln
- Age at study initiation: 6- 10 wks (female), 4-9 wks (male)
- Weight at study initiation: preliminary test: 21-27 g (male and female); main test: 22-30 g (female), 20-34 g (male)
- Housing: individually in cages
- Diet: Standard diet, NAFAG No. 924; ad libitum
- Water: tap water; ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 -24
- Humidity (%): 56 - 57
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
0,5% aqueous solution of sodium-carboxymethylcellulose (CMC)
Details on exposure:
- Dosing volume: 20 mL/kg bw
Duration of treatment / exposure:
single dose application
Frequency of treatment:
once daily, on two consecutive days.
Post exposure period:
The animals were sacrificed 24 hours after the second application.
Doses / concentrations
Remarks:
Doses / Concentrations:
1,250, 2,500, 5,000 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
3
Control animals:
yes, concurrent vehicle
Positive control(s):
- Name: Cyclophosphamide (CPA)
- Justification for choice of positive control(s): Known clastogen
- Vehicle: CMC (0.5%)
- Application volume: 20 mL/kg bw
- Route of administration: oral gavage
- Doses / concentration in vehicle: 128 mg/kg bw

Examinations

Tissues and cell types examined:
Bone marrow and erythrocytes.
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
- Based on the results of a range finder study
- Doses in the range finder study: 200, 1,000, and 5,000 mg/kg bw
- No. of animals/sex/dose: 2
- Frequency of treatment: once daily for two consecutive days with the test article and observations made over a day period following the second administration.

TREATMENT AND SAMPLING TIMES:
- Sacrifice of animals and sampling time: 24 hours after second treatment.

DETAILS OF SLIDE PREPARATION:
- Procedure: Bone marrow was harvested from the shafts of both femurs. In a siliconized pipette filled with approx, 0.5 µL rat serum, the bone marrow was drawn up. The content of pipette was aspirated gently about three times. Small drops of the mixture were transferred on the end of a slide, spread out with a cover glass and air dried.
- Staining: 3 hours after slide preparation, the staining was performed for 2 min then in May-Grünwald solution/water 1/1 for 2 min and then in Giemsa's, 40% for 20 min. Slide were then rinsed with methanol (55%) for 5 - 6 sec, washed (twice), immersed for 2 min in water and air dried.

METHOD OF ANALYSIS:
- No. of cells scored per animal: 1000
- Ratio of PCE to NCE (%PCE): not performed
- Parameters checked: a) single Jolly bodies, b) fragments of nuclei in erythrocytes, c) micronuclei in erythroblasts, d) micronuclei in leucopoietic cells, e) polyploid cells.
Statistics:
The significance of difference was assessed by X -test.

Results and discussion

Test results
Key result
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
In the preliminary test, doses up top 5,000 µg/kg bw did not cause overt toxicity or death.
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
In all dosage groups the percentage of cells displaying anomalies of nuclei did not differ significantly from the negative control. By contrast, the positive control (cyclophosphamide, 128 mg/kg) yielded a marked increase of the percentage of cells with anomalies. Here the mean percentage of anomalies was 9.42 whereas the negative control yielded a percentage of 0.033. The difference is highly significant (p < 0.05).

Any other information on results incl. tables

Table 1: The effect of the test substance on bone marrow cells of Chinese hamster sacrificed 24 hours after last application (percent of cells with anomalies of nuclei).

Test substance

Number of animals

Single Jolly bodies

Fragment of nuclei in erythrocytes

Micronuclei in erythroblast

Micronuclei in leucopoietic cells

Polyploidy cells

Total

Control (0.5% CMC)

1

0.1

-

-

-

-

0.1

2

0.1

-

-

-

-

0.1

Cyclophophamide (128 mg/kg bw)

1

5.9

2.1

1.2

0.1

 

9.3

2

5.4

1.2

1.0

0.3

0.2

8.1

3

3.7

0.3

0.5

0.2

0.4

5.1

4

8

1.3

2.4

0.2

0.1

12

5

7.2

1.0

1.5

0.1

-

9.8

6

9.1

1.3

1.8

-

--

12.2

1,250 mg/kg bw

1

0.1

-

-

-

-

0.1

2

0.1

-

-

-

-

0.1

3

0.1

-

-

-

-

0.1

2,500 mg/kg bw

1

0.3

-

-

-

-

0.3

2

0.1

-

-

-

-

0.1

3

0.1

-

-

-

-

0.1

4

0.2

-

-

-

-

0.2

5,000 mg/kg bw

1

0.2

-

-

-

-

0.2

2

0.2

-

-

-

-

0.2

 

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative