Silicon dioxide

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Nov. 20-27, 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 84-2

Principles of method if other than guideline:

8 dose l., 5h duration, w & w/o S9-activation, 7d post obs.

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell gene mutation test using the Hprt and xprt genes

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

Test material form:

solid: nanoform, no surface treatment

Details on test material:

CAS 112945-52-5, Pyrogenic; Surface area / BET [m2/g] 370-420

Specific details on test material used for the study:

synthetic amorphous silicon dioxide CAB-O-SIL EH-5

Method

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

CHO-K1-BH4 cells were obtained directly from Dr. Abraham Hsie, Oak Ridge National Laboratories, Oak Ridge, TN, USA. The freeze lot of cells was tested and found to be free of mycoplasma using both the agar culture and Hoechst stainibg procedures.

Metabolic activation:

with and without

Metabolic activation system:

S9 mix.

Test concentrations with justification for top dose:

50, 100, 150 ,200, 250, 300, 400, 500 µg/ml

Vehicle / solvent:

The treatment medium consisted of 4 ml F12FBS5-Hx containing various concentrations of test article and 1 ml S-9 reaction mixture for the activated study and 5 ml F12FBS5-Hx containing various concentrations of test article for the non-activated study. The final solvent concentration in the culture medium was 1% by volume.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

ethylmethanesulphonate

Results and discussion

Test results

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

The cytotoxic effects (concurrent cytototoxicity) of a 5 hour treatment of CHO cells in the presence ad absence of an exogenous metabolic activation system are presented in Table 2. Mutagenicity data are presented in Tables 3 and 4.

Applicant's summary and conclusion

Conclusions:

synthetic amorphous silicon dioxide Cab-O-Sil EH-5 was negative in the CHO/HGPRT mutation assay both with and without metabolic activation.

Executive summary:

synthetic amorphous silicon dioxide CAB-O-SIL EH-5C was tested according to EPA guideline OPP 84 -2 under GLP conditions