Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restricitions

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
Unnamed
Year:
1993
Reference Type:
publication
Title:
Evaluation of a Three-Exposure Mouse Bone Marrow Micronucleus Protocol: Results With 49 Chemicals
Author:
Shelby M.D. et al.
Year:
1993
Bibliographic source:
Environ. Mol. Mutagen., 21, 160-179

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
only 5-7 males per dose used, differing staining agent
Principles of method if other than guideline:
Standard protocol of the US National Toxicology Program
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
The test item was received from the NTP chemical repo s ito ry (Radian Corporation , Austin, TX).

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
- Vehicle(s)/solvent(s) used: corn oil
Details on exposure:
Injection volume was 0.4 ml.

Duration of treatment / exposure:
3 days
Frequency of treatment:
one injection/day on 3 consecutive days
Post exposure period:
1st study: For evaluation of bone marrow smears animals were sacrificed 24 hours after the 3rd exposure; for evaluation of peripheral blood smears
animals were sacrificed 48 hours after the 3rd exposure
2nd study: animals were sacrificed 24 hours after the 3rd exposure for both evaluation of bone marrow smears and evaluation of peripheral blood smears.
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0; 500; 1000; 2000 mg/kg (1st study)
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
1000 and 2000 mg/kg (2nd study)
Basis:
nominal conc.
No. of animals per sex per dose:
5 (exemption: only 3 animals were scored at the concentration of 2000 mg/kg bw in the first study)
Control animals:
yes, concurrent vehicle
Positive control(s):
7,12-dimethylbenzanthracene (12.5 mg/kg)

Examinations

Tissues and cell types examined:
bone marrow and peripheral blood
Details of tissue and slide preparation:
DETAILS OF SLIDE PREPARATION:
Staining with acridine orange

METHOD OF ANALYSIS:
Bone marrow:
Slides were evaluated for the number of MN-PCE among 2000 PCE and for the percentage of PCE among 200 erythrocytes.
Peripheral blood:
According to the NTP-Standard protocol 2000 PCEs are evaluated for the number of MN-PCE and 1000 erythrocytes are evaluated for teh percentage of PCE among erythrocytes.
Evaluation criteria:
A positive response is determined by statistical difference from the control group.
Statistics:
The data were analyzed using the Micronucleus Assay Data Management and Statistical software package (version 1 . 4 ), which was designed specifically for in vivo micronucleus data. The level of significance was set at an alpha level of 0.05.
To determine whether a specific treatment result ed in a significant increase in MN -PCE, the number of MN-PCE were pooled within each dose group and analyzed by a one- tailed trend test. In the software package used , the trend test incorporates a variance inflation factor to account for excess animal variability. In the event that the increase in the dose response cu rve is nonmonotonic , the software program allows for the data to be analyzed for a significant positive trend after data at the highest dose only has been excluded . However, in this event, the alpha level is adjusted to 0 .01 to protect against false positives.
The %PCE data were analyzed by an analysis of variance (ANOVA) test based on pooled data. Pairwise comparisons between each group and the concurrent solvent control group was by an unadjusted one-tailed Pearson chi -squared test which incorporated the calculated variance inflation factor for the study

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
No signs of toxicity were observed

Any other information on results incl. tables

Table 1: MN data analysis

Dose (mg/kg)

MN-PCE/1000

(No. of animals scored)

P value (a)

Survival

%PCEs (b)

1st study, bone marrow

(Sample collection time: 24 hours)

0.003

0

2.10 +/- 0.62 (5)

5/5

57.3

500

1.80 +/-0.34 (5)

0.685

5/5

56.6

1000

2.20 +/- 0.25 (5)

0.439

5/5

57.1

2000

3.80 +/- 0.70 (5)

0.013

6/6

56.1

Positive control

6.90 +/-

0.87 (5)

0.0001

-

-

2nd study, bone marrow

(Sample collection time: 24 hours)

0.340

0

4.60 +/- 0.64 (5)

5/5

60.9

1000

4.20 +/- 1.21 (5)

0.596

5/5

51.7

2000

5.30 +/- 1.59 (5)

0.344

5/6

56.3

Positive control

8.40 +/-

0.56 (5)

-

-

1st study, peripheral blood (c)

(Sample collection time: 48 hours)

0.964

0

2.70 +/- 0.26 (5)

5/5

1.2

500

3.50 +/- 0.91 (5)

0.154

5/5

1.5

1000

2.40 +/- 0.56 (5)

0.663

5/5

1.1

2000

1.50 +/- 0.76 (3)

0.940

3/5

1.2

2nd study, peripheral blood

(Sample collection time: 24 hours)

0.411

0

4.10 +/-

0.73 (5)

 no data available

  no data available

1000

3.60 +/-

0.93 (5)

0.716

no data available

no data available

2000

4.30 +/-

0.56 (5)

0.413

no data available

no data available

Positive control

8.40 +/-

0.40 (5)

0.0001

no data available

no data available

(a) omitting the high dose value

 (b) ((No. of PCEs)/(No. of PCEs + No. of NCEs)) x 100

(c) no data on positive control available

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Executive summary:

The initial test gave a positive trend (P = 0 .003) from 2 .1 in the control to 3 .8 in the high dose (2,000 mg/kg) . Peripheral blood smears from the dose determination test were scored and were negative as was a repeat bone marrow test using doses of 1,000 and 2,000 mg/kg .