Silicic acid, aluminum salt

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

27.11.1989-31.01.1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance Cab-O-Sil EH5 (CAS 112945-52-5). According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

112945-52-5

EC Number:

601-216-3

Cas Number:

112945-52-5

IUPAC Name:

112945-52-5

Details on test material:

- Name of test material (as cited in study report): Cab-O-Sil EH-5
- Physical state: white powder
- Analytical purity: > 99 %
- Storage condition of test material: room temperature
- Other: The test material was protected from exposure to light.

Method

Target gene:

HPRT

Species / strain

Species / strain / cell type:

other: CHO-K1-BH4 (Chinese Hamster Ovary)

Details on mammalian cell type (if applicable):

- Type and identity of media: Ham´s F-12 medium without hypoxanthine supplemented with 5 % dialysed FBS, 1 % penicillin-streptomycin and 1 % L-glutamine (F12FBS5-Hx)
- Periodically checked for Mycoplasma contamination: yes; free of mycoplasma

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9 mix of an Aroclor-1254 (single ip injection of 500 mg/kg bw 5 days prior to sacrifice) induced Sprague-Dawley rat liver homogenate

Test concentrations with justification for top dose:

10, 50, 100, 150, 250 µg/mL: non-activated study
100, 200, 300, 400, 500 µg/mL: activated study

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO (Fisher Chemical Company, Springfield, USA)

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

growth medium

Negative solvent / vehicle controls:

yes

Remarks:

DMSO: final conc. 1 % v/v

True negative controls:

no

Positive controls:

yes

Remarks:

non-activated study

Positive control substance:

ethylmethanesulphonate

Remarks:

Migrated to IUCLID6: finial conc. 0.2 µL/mL

Controls 2

Untreated negative controls:

yes

Remarks:

growth medium

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Remarks:

activated study

Positive control substance:

benzo(a)pyrene

Remarks:

Migrated to IUCLID6: final conc. 4 µg/mL

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 5 hours
- Expression time for the phenotype (cells in growth medium): 7-9 days
- Selection time (if incubation with a selection agent): 7 days

SELECTION AGENT (mutation assays): 6-Thioguanine

STAIN (for cytogenetic assays): Giemsa stain, 10 % aqueous

DETERMINATION OF CYTOTOXICITY
- Method: relative cloning efficiency; the cell survival of the test material treated groups was expressed relative to the solvent control.

Evaluation criteria:

The cytotoxic effects of each treatment condition were expressed relative to the solvent-treated control (relative cloning efficiency).
The mutagenic response after treatment would be considered significant only when the treatment mutant frequency was increased above that of the solvent control and the untreated control by at least 11 mutants per 10E5 clonable cells and also was at least twice that of both the solvent control and the untreated control.

Statistics:

All calculations were computed using a LOTUS 1-2-3 program on an IBM PC or compatible computer.

Results and discussion

Test results

Test results 1

Species / strain:

other: CHO-K1-BH4 (Chinese Hamster Ovary)

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

>50 µg/mL: cytotoxic effects

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

other: CHO-K1-BH4 (Chinese Hamster Ovary)

Metabolic activation:

with

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:

COMPARISON WITH HISTORICAL CONTROL DATA:
The medium, the DMSO and the positive controls fulfilled the requirements for a valid test, also in accordance with historical control data.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Under the test conditions, the Cab-O-Sil EH-5 was negative in both the presence and absence of exogenous metabolic activation.

Tab.1 without metabolic activation

treatment [µg/mL]	total mutant colonies	mutants/10E5 clonable cells	survival (relative cloning efficiency) [%]
medium	9	7.2	111
DMSO	1	1.0	100
250	0	<1.2	14
150	0	<0.9	12
100	1	1.0	27
50	10	10.3	58
10	9	7.3	95
EMS	274	351.3	79

Tab.2 with metabolic activation

treatment [µg/mL]	total mutant colonies	mutants/10E5 clonable cells	survival (relative cloning efficiency) [%]
medium	1	0.8	109
DMSO	9	8.0	100
500	5	4.2	56
400	6	6.2	50
300	2	1.8	66
200	0	<0.8	95
100	11	8.2	111
B(a)P	154	184.1	11