Dichloro(dimethyl)silane

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:

1987-06-03 to 1987-07-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

other: Ames et al. 1973

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Dichloro(dimethyl)silane

EC Number:

200-901-0

EC Name:

Dichloro(dimethyl)silane

Cas Number:

75-78-5

Molecular formula:

C2H6Cl2Si

IUPAC Name:

dichlorodimethylsilane

Method

Species / strain

Species / strain / cell type:

other: Salmonella typhimurium: TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

See table 1.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: acetone

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: N-Methyl-N-nitro-N-nitrosoguanidine

Remarks:

WP2uvrA (without activation)

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

All strains (with activation)

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

All strains (with activation)

Details on test system and experimental conditions:

ACTIVATION: Male Sprague Dawley rats (200-300g) were dosed with 500 mg/ kg bw Aroclor 1254 5 d before sacrifice. Livers from 5-6 animals were polled and used to prepare S9 homogenate. S9 mix included 10% v/v S9, 8 mM MgCl2, 33 mM KCl, 5mM glucose-6-phosphate, 4 mM NADP+ and 100 mM phosphate buffer pH 7.4. 0.5 ml of S9 mix were added to 2 ml top agar, 0.1 ml bacterial culture and 0.1 ml test substance solution (total volume 2.7 ml) giving a final concentration of S9 of approximately 2%.

METHOD OF APPLICATION: in agar (plate incorporation)


DURATION
- Exposure duration:

SELECTION AGENT (mutation assays):
SPINDLE INHIBITOR (cytogenetic assays):
STAIN (for cytogenetic assays): 48-72 hours

NUMBER OF REPLICATIONS: 3 plates per test concentration. The experiment was repeated.

DETERMINATION OF CYTOTOXICITY

- Method: other: Background lawn assessment

Evaluation criteria:

Mutagenicity of the test substance is indicated by an increase in the number of revertant colonies.

Statistics:

Statistical methods: Responses (numbers of revertants) to the test substance were compared to concurrent negative and positive 
controls, as well as to historical data.

Results and discussion

Test results

Species / strain:

other: Salmonella typhimurium: TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other: >1500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

The test compound was toxic to most of the bacterial strains and precipitate was observed at doses greater than or equal to 2500 ug/plate, both with and without metabolic activation.  Final mutagenicity testing was conducted with 5000 ug/plate as the top dose.  The results of the tests conducted on the test substance in the absence or presence of a metabolic activation system were all negative.
Revertants per plate for positive control substances ranged from 18- 680, depending on the agent and strain.

Any other information on results incl. tables

 

Table 2 : Exp 1 : Mutagenicity assay for all strains with and without metabolic activation (mean of 3 plates)

	TA98			TA100			TA1535
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	25	30	No	158	175	No	13	12	No
4	21	29	No	153	159	No	12	11	No
20	19	28	No	148	174	No	11	12	No
100	23	28	No	152	181	No	12	10	No
500	27	24	No	148	187	No	14	12	No
2500	18	23	No	166	174	No	8	14	No
10,000	-	3	Yes	-	-	Yes	6	2	Yes
Positive Control	364	437	No	554	611	No	404	119	No

*solvent control with Acetone

 

Table 2 : Exp 1 : Mutagenicity assay for all strains with and without metabolic activation (mean of 3 plates)

	TA1537			TA1538			WP2uvrA
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	12	8	No	17	17	No	47	52	No
4	9	8	No	16	20	No	43	51	No
20	7	8	No	13	20	No	44	53	No
100	7	9	No	16	22	No	40	48	No
500	8	5	No	16	24	No	46	57	No
2500	8	6	No	16	11	No	43	41	No
10,000	-	0	Yes	4	1	Yes	-	12	Yes
Positive Control	155	84	No	591	547	No	241	174	No

*solvent control with Acetone

 

Table 3 : Exp 2 : Repeat Assay Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA1535
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	19	32	No	168	205	No	16	13	No
4	27	40	No	153	234	No	17	13	No
20	23	36	No	180	2335	No	17	13	No
100	26	35	No	182	197	No	15	12	No
500	24	27	No	141	207	No	11	16	No
2500	24	29	No	183	207	No	16	16	No
5000	-	25	Yes	119	167	No	13	16	No
Positive control	249	377	No	483	628	No	308	76	No

*solvent control with Acetone

 

Table 3 : Exp 2 : Repeat Assay Number of revertants per plate (mean of 3 plates)

	TA1537			TA1538			WP2uvrA
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	12	9	No	14	23	No	48	75	No
4	8	9	No	13	26	No	61	68	No
20	9	8	No	13	26	No	59	58	No
100	9	7	No	15	20	No	63	52	No
500	8	7	No	12	23	No	50	35	No
2500	9	10	No	16	19	No	39	37	No
5000	4	6	Yes	14	18	No	23	26	Yes
Positive control	94	91	No	458	515	No	365	304	No

*solvent control with Acetone

 

 

Applicant's summary and conclusion

Conclusions:

Dichlorodimethylsilane has been tested for mutagenicity to bacteria according to a protocol similar to the current guideline. The test substance did not demonstrate genetic activity in any of Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA1537, TA1538 and Escherichia coli WP2uvrA, up to cytotoxic concentration, with or without metabolic activation. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is not mutagenic to bacteria under the conditions of the test.