Silicic acid, sodium salt

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2006

Reference 2

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2004

Report date:

2004

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

Test material information

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

Molecular formula:

Na2O x (SiO2)n with Molar Ratio (MR) (SiO2/Na2O): 1.5 – 4

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

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)