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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: The study is comparable to OECD Guideline 474 with acceptable restrictions (partly limited documentation, e.g. no details about the test substance or housing conditions).

Data source

Reference
Reference Type:
publication
Title:
Evaluation of a three-exposure mouse bone marrow micronucleus protocol: results with 49 chemicals
Author:
Shelby MD, Erexson GL, Hook GJ, and Tice RR
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:
no
Principles of method if other than guideline:
According to Tice, R.R. et al.: Mutagenesis 5, 313-321 (1990)
GLP compliance:
not specified
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Source: NTP chemical repository (Radian Corporation, Austin, Tx)
No further details

Test animals

Species:
mouse
Strain:
B6C3F1
Sex:
male
Details on test animals and environmental conditions:
Source: NTP Taconic Farms
Age: 9-14 weeks at initiation
Weight: 25-33 g at initiation
Additional information on housing in Tice, R.R. et al.: Mutagenesis 5, 313-321 (1990)

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
PBS (physiol. saline)
Details on exposure:
Application volume: 0.4 ml/mouse
Duration of treatment / exposure:
3 days
Frequency of treatment:
once daily (totally 3 injections)
Post exposure period:
24 h after the last application animals were sacrificed and bone marrow samples prepared.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 25, 50, 100 mg/kg bw
Basis:
other: actual injected
No. of animals per sex per dose:
5 males
Control animals:
yes, concurrent vehicle
Positive control(s):
Yes, 0.2 mg/kg bw mitomycin C in PBS

Examinations

Tissues and cell types examined:
Polychromatic erythrocytes (PCEs) of bone marrow.
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION:
In preliminary studies the dose for the mutagenicity test was determined. Mortality and depression of erythropoiesis were studied after an exposure period of 3 days (i.p. application once daily; 3 dose levels) and sacrifice 48 h after the last application; bone marrow samples were analysed for PCEs. The dose level resulting in depression of percentage of bone marrow PCE (no less than 15% of the erythrocytes) was determined and used as max. dose level in the main mutagenicity experiment. Three dose levels were used in the mutagenicity assay: max. dose level, 50% of max. dose and 25% of max. dose.
DETAILS OF SLIDE PREPARATION:
Air dried cells fixed using absolute methanol and stained with acridine orange; cells evaluated at 1000x magnification, fluorescence microspopy. 2000 PCEs per animal were analysed for micronuclei. Percentage of PCEs in 200 erythrocytes determined.
Evaluation criteria:
Not clearly specified by the authors except statistical significance. Presumably also comparison with historical control range.
Statistics:
Data analysed by Micronucleus Assay Data Management and Statistical software package (version 1.4); level of significance was 0.05; pooled data analysed by a one-tailed trend test and %PCEs analysed by ANOVA plus unadjusted one-tailed Pearson chi-squared test

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No clastogenic activity was found; details are presented in the Table below.

Any other information on results incl. tables

Micronuclei in PCEs of the mouse bone marrow after i.p. injection of 2-chloroethanol

Dose in mg/kg bw/day

%o micronucleated PCEs (no. of animals)

Survival of mice

% PCEs

0

2.30+-0.26 (5)

5/5

55.9

25

2.10+-0.25 (5)

5/5

50.8

50

1.25+-0.25 (4)

5/5

55.9

100

2.60+-0.53 (5)

5/5

53.1

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
In the mouse bone marrow micronucleus assay no mutagenic activity was detected at dose levels reaching toxicity threshold.
Executive summary:

The study is comparable to OECD Guideline 474 with acceptable restrictions (partly limited documentation, e.g. no details about the test substance or housing conditions).

In the mouse bone marrow micronucleus assay 5 male B6C3F1 mice per group were i.p. injected with 0, 25, 50, 100 mg/kg bw/day for 3 days. The dose level was determined in preliminary toxicity studies. The mice were sacrificed 24 h after the last injection and bone marrow samples prepared. There was no increase in micronucleated polychromatic erythrocytes. The vehicle control and the positive control were valid.

Conclusion: In the mouse bone marrow micronucleus assay no mutagenic activity was detected at dose levels reaching toxicity threshold.