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Toxicological information

Genetic toxicity: in vitro

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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-guideline study For justification for read across see endpoint summary.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes
Remarks:
RCC-Cytotest Cell Research GmbH
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Constituent 1
Reference substance name:
Silicic acid, sodium salt
EC Number:
215-687-4
EC Name:
Silicic acid, sodium salt
Cas Number:
1344-09-8
IUPAC Name:
sodium hydroxy(oxo)silanolate
Details on test material:
CAS 1344-09-8
Sodium silicate solution (weight ratio 3.3)
Tradename: Natronwasserglas 37/40 PE
36% active ingredient, 64% water

Method

Species / strain
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Details on mammalian cell type (if applicable):
CELL CULTURE DETAILS:
- Type and identity of media: Minimal Essential Medium supplemented with  10% fetal calf serum.
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital / ß-Naphthoflavone induced  rat liver S9-mix
Test concentrations with justification for top dose:
19.5, 39.1, 78.1 & 156.3 µg active ingredient/ml
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Remarks:
medium
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 300-400 µg/ml  Ethylmethane sulfonate (-S9), 1.4-2.0 µg/ml Cyclophosphamide (+S9)
Details on test system and experimental conditions:
- Spindle inhibitor: 0.2 µg/ml Colcemid
- Stain: Giemsa
- No. of metaphases analyzed: 100
- Dosing: Cytotoxic concentrations were determined in a range-finder study with and without metabolic activation. 312.5 µg/ml was chosen as  top concentration in the actual experiments.
- Number of replicates: 2
Evaluation criteria:
Breaks, fragments, deletions, exchanges,  and chromosome disintegrations were recorded as structural chromosome  aberrations. Gaps were recorded as well, but not included in the  calculation of aberration rates. Only metaphases with characteristic  chromosome numbers (22+-1) were included in the analysis. The mitotic  index (% cells in mitosis) and the percentage of polyploid cells in 500  metaphase plates/culture were determined.

Results and discussion

Test results
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: 156.3 - 312.5 µg active ingredient/mL
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

PRECIPITATION CONCENTRATION:

156.3 µg active ingredient/ml (except experiment II after 18h preparation interval without S9 mix where precipitation occurred at 78.1 µg/ml and above)

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Sodium silicate showed no chromosome aberratins in V79 cells in vitro.
Executive summary:

In a mammalian cell cytogenetics assay (Chromosome aberration assay) V79 cell cultures were exposed to sodium silicate (36% active ingredient, 64% water) at concentrations of 19.5, 39.1, 78.1 & 156.3 µg active ingredient/ml with and without metabolic activation (Phenobarbital / ß-Naphthoflavone induced rat liver S9-mix).

Sodium silicate was tested up to cytotoxic or precipitating concentrations. Positive controls induced the appropriate response. There was no evidence of chromosome aberration induced over background.

This study is classified as acceptable. This study satisfies the requirement for Test Guideline (In vitro mammalian cytogenetics, OECD 473) for in vitro cytogenetic mutagenicity data.

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