Synthetic amorphous magnesium silicate, with molar ratio (SiO2:MgO) range of 1.4-4

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 November to 12 December 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Justification for read-across is warranted given the similarities in toxicity profile and physico-chemical properties for silicon dioxide and magnesium silicate.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

Plate incorporation assay

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Silicon dioxide

EC Number:

231-545-4

EC Name:

Silicon dioxide

Cas Number:

7631-86-9

Molecular formula:

O2Si

IUPAC Name:

dioxosilane

Details on test material:

- Name of test material (as cited in study report): Cab-O-Sil EH-5:
CAS-Name: Silica, amorphous, fumed, cryst.-free;
CAS-No.: 112945-52-5
- Analytical purity: >99%
- Lot/batch No.: 1H049
- Stability under test conditions: stable

Specific details on test material used for the study:

Name of test material (as cited in study report): Cab-O-Sil EH-5:
CAS-Name: Silica, amorphous, fumed, cryst.-free;
CAS-No.: 112945-52-5
- Analytical purity: >99%
- Lot/batch No.: 1H049
- Stability under test conditions: stable

Method

Target gene:

Histidine

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1538

Metabolic activation:

with and without

Metabolic activation system:

S9 mix prepared from the livers of Aroclor induced adult male SD rats

Test concentrations with justification for top dose:

667, 1000, 3333, 6667 and 10000 µg/plate

Vehicle / solvent:

DMSO

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

not specified

Details on test system and experimental conditions:

Ames test
METHOD OF APPLICATION: in medium; in agar (plate incorporation)

DURATION
- Exposure duration: no data

NUMBER OF REPLICATIONS: 3/concentration

NUMBER OF CELLS EVALUATED: seeded cells 10^8/plate

DETERMINATION OF CYTOTOXICITY
- Background lawn evaluated in pre-tests using TA 100

OTHER EXAMINATIONS:
- Other: Reversion rate

Evaluation criteria:

Standard Ames test criteria looking for doubling ortrebling of mutation rates in test plates

Statistics:

Arithmetic averages with standard deviations.

Results and discussion

Test results

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

No further information

Remarks on result:

other: strain/cell type: Salmonella typhimurium TA98, TA100, TA1535, TA1537,TA1538

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

No further information

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

No evidence of reverse mutation in five test strains used in the Ames test to determine potential genotoxicity of magnesium silicate

Executive summary:

An Ames bacterial mutation study has been conducted with silicon dioxide in strains TA98, TA100, TA1535, TA1537 and TA1538. Concentrations of 667, 1000, 3333, 6667 and 10000 µg/plate were used.

The test substance showed no evidence of mutagenicity.