Registration Dossier

Toxicological information

Genetic toxicity: in vitro

Currently viewing:

Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
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
Study period:
1982
Reliability:
2 (reliable with restrictions)

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1984

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
Deviations:
yes
Remarks:
No metabolic activation employed
GLP compliance:
not specified
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Potassium bitartrate (potassium hydrogen tartrate). 100% purity reported.

Method

Species / strain
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Details on mammalian cell type (if applicable):
Established originaly from lung of newborn female at the Cancer Research Institute, Tokyo (1970). Maintained by 4-day passages in Minnimum Essential Medoum (MEM) of GIBCO. The modal chromosomal number is 25 and the doubling time was approximately 15h.
Metabolic activation:
without
Test concentrations with justification for top dose:
Three concentrations were used, although the report only states maximum concentration employed which is 2 mg/ml. This concentration is stated to be that producing 50% growth inhibition, as determined in a prelimnary study.
Vehicle / solvent:
Test medium
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
not specified
Details on test system and experimental conditions:
The cells were exposed to each sample at three different doses for 24 and 48 hr. No metabolic activation systems were applied. The maximum dose of each sample was selected by a preliminary test in which the dose needed for 50% cell-growth inhibition was estimated using a cell densitometer (Monocellater, Olympus Co., Ltd).
Previous studies indicated that the osmotic pressure of the medium generally rose with sample concentrations of more than 10 raM, SO that the maximum dose for some samples was limited to around this level, at which cytotoxic effects were not necessarily observed.

Chromosome preparations were made as follows. Colcemid (final concn 0.2/~g/ml) was added to the culture 2 hr before cell harvesting. The cells were then trypsinized and suspended in a hypotonic KCI solution (0.075 M) for 13 min at room temperature. After centrifugation the cells were fixed with acetic acid-methanol (1:3, v/v) and spread on clean glass slides. After air-drying, the slides were stained with Giemsa solution (1.5%, at pH 6.8; E. Merck) for 12-15 min. A hundred well-spread metaphases were observed under the microscope (x 600 with a nocover objective lens). The incidence of polyploid cells as well as of cells with structural chromosomal aberrations such as chromatid or chromosome gaps, breaks, exchanges, ring formations, fragmentations and others, was recorded on each culture plate.
.
Evaluation criteria:
The results were considered to be negative if the incidence was less than 4.9%, equivocal if it was between 5.0 and 9.9%, and positive if it was more than 10.0 %. Untreated cells and solvent-treated cells served as negative controls, in which the incidence of aberrations was usually less than 3.0%

Results and discussion

Test results
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
other: Reported as valid although not verifiable in report avaiable
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative without metabolic activation

The analogue substance potassium bitartrate (potassium hydrogen tartrate) was tested up to a maximum concentration of 2 mg/ml on a Chinse Hamster lung established cell line and tested without metabolic activation. Results obtained at maximum non severly toxic concentrations after 48 hours of exposure do not indicate any significant amounts of structural aberrations or polyploidy (1%). Thereby the results point to the tested substancxe as being negative for clastogenesis in this mammalian cell line.
Executive summary:

The analogue substance potassium bitartrate (potassium hydrogen tartrate) was tested up to a maximum concentration of 2 mg/ml on a Chinse Hamster lung established cell line and tested without metabolic activation. Results obtained at maximum non severly toxic concentrations after 48 hours of exposure do not indicate any significant amounts of structural aberrations or polyploidy (1%). Thereby the results point to the tested substancxe as being negative for clastogenesis in this mammalian cell line.