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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to a test protocol that is comparable to the appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1981

Materials and methods

Principles of method if other than guideline:
other: Rodent Bone Marrow Cytogenetic Assay  as recommended by the Ad hoc Committee on Chromosome Methodologies in 
Mutagen Testing (TAP 22: 269-275, 1972), with modifications per the EPA Gene-Tox Program Cytogenetics Committee (12/3 to 
12/5, 1980, Washington, D.C.)
GLP compliance:
yes
Type of assay:
chromosome aberration assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male

Administration / exposure

Route of administration:
intraperitoneal
Duration of treatment / exposure:
6, 24, or 48 hours
Frequency of treatment:
Single i.p. injection
Post exposure period:
none
Doses / concentrations
Remarks:
Doses / Concentrations:
5, 11, 22, 32, 43, 54 mg/kg
Basis:
other: Criteria for selection of MTD based on the results of a range-finding study
No. of animals per sex per dose:
No. of animals per dose: 5 per sacrifice time
Positive control(s):
cyclophosphamide

- Route of administration: Intraperitoneally

- Doses / concentrations: 43, 107, 428, 1070 and 4280 mg/kg

Examinations

Tissues and cell types examined:
Bone marrow
Evaluation criteria:
Criteria for evaluating results:  Suitable cell spreads were those with both properly condensed and well-spread chromosomes.  A 
minimum of 100 metaphase cells was evaluated per animal.
Statistics:
Statistical methods: A comparison of the expected and observed distribution values was performed using the Chi2 test as a 
measure of "goodness to fit".  The Wilcoxon test was used as a non-parametric test to compare the distribution of breaks per 
animal between the negative control animals and the highest test doses.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
not specified
Positive controls validity:
valid

Any other information on results incl. tables

Mortality at each dose level by sex:  

Range-finding experiment, male rats
Dose level      Number dead/number animals
54 mg/kg        3/10
43 mg/kg        5/10
32 mg/kg        0/10
22 mg/kg        2/10
11 mg/kg        0/10
5 mg/kg        0/10

For the cytogenetic experiments (dose levels: 32, 22, 11, 5 mg/kg): all animals survived.

Mutant/aberration/mPCE/polyploidy frequency, as appropriate: not different from negative controls

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Appropriate concurrent negative and positive controls were included and the expected responses were observed. The
test substance, dimethyldichlorosilane (CAS No. 75-78-5) did not cause an increase in the frequency of chromosomal breaks
or aberrations in bone marrow cells of rats. Thus, there was no evidence in this study that it caused chromosomal damage.