Silicon tetrachloride

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:

1981-03-25 to 1981-03-28

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

range of strains used, only 4 doses used which were not replicated.

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Silicon tetrachloride

EC Number:

233-054-0

EC Name:

Silicon tetrachloride

Cas Number:

10026-04-7

Molecular formula:

Cl4Si

IUPAC Name:

tetrachlorosilane

Method

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA-98, TA-100, TA-1535, TA-1537, TA-1538

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

0.5-500 µl/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Absolute ethanol was used for the test substance. Dimethylsulfoxide (DMSO) was used for positive control substances except sodium azide which was dissolved in water or saline.

- Justification for choice of solvent/vehicle: Previously shown to be non-mutagenic

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 100, TA 1535 (without activation)

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

TA 1537 (without activation)

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA 98, TA 1538 (without activation)

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-anthramine

Remarks:

All strains (with activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation);
other: spot plate test

DURATION

- Expression time (cells in growth medium): 48 - 72 hours

NUMBER OF REPLICATIONS: 1 plate for each test concentration

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

Evaluation criteria:

For TA 1535, TA 1537 and TA 1538, the test substance is considered mutagenic if a positive dose response is produced over three concentrations with the lowest increase equal to twice the solvent control value.

For TA 98 and TA 100, the test substance is considered mutagenic if a positive dose response is produced over three concentrations with the highest increase equal to twice the solvent control value for TA 100, and two to three times the solvent control value for TA 98.

Results and discussion

Test results

Species / strain:

other: Salmonella typhimurium: TA-98, TA-100, TA-1535, TA-1537, TA-1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

500 µl/plate (TA 1535 -MA / TA 1537 +MA)

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Any other information on results incl. tables

 

Table 2a: Experiment 1 Overlay plate test, Number of revertants per plate

Conc. (µg/plate)	TA98			TA100			TA1535
	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0	41	36	No	225	196	No	29	30	No
0.5	31	37	No	238	186	No	26	22	No
5	34	36	No	236	134	No	31	17	No
100	33	45	No	246	218	No	23	18	No
500	38	30	No	250	160	No	12	25	Yes
Positive Control	431	>10^3	No	476	>10^3	No	311	173	No

*solvent control with Ethanol

 

Table 2b: Experiment 1 Overlay plate test, Number of revertants per plate

Conc. (µg/plate)	TA1537			TA 1538
	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0	10	17	No	24	35	No
0.5	7	11	No	23	45	No
5	9	14	No	27	41	No
100	9	8	No	20	38	No
500	9	7	Yes	20	27	No
Positive Control	121	103	No	130	>10^3	No

*solvent control with Ethanol

Applicant's summary and conclusion

Conclusions:

Silicon tetrachloride has been tested for mutagenicity in a reliable in vitro bacterial reverse mutation assay, conducted according to a protocol similar to OECD Test Guideline 471 and in compliance with GLP. Silicon tetrachloride did not demonstrate any genetic activity in the bacterial strains Salmonella typhimurium TA98, TA100, TA1535, TA1537, TA1538, when tested in the presence and the absence of metabolic activation up to cytotoxic concentration. Appropriate solvent and positive controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity in the Salmonella typhimurium strains used under the conditions of the test .