Dibutoxy(dimethyl)silane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014-12-11 to 2015-01-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to the appropriate OECD test guideline, and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Version / remarks:

2008

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Dibutoxy(dimethyl)silane

EC Number:

216-467-0

EC Name:

Dibutoxy(dimethyl)silane

Cas Number:

1591-02-2

Molecular formula:

C10H24O2Si

IUPAC Name:

dibutoxydimethylsilane

Test material form:

other: liquid

Method

Target gene:

histidine operon

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital and β-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

Experiment I
31.6, 100, 316, 1000, 2500 and 5000 µg/plate
(TA 98, TA 100, TA 1535, TA 1537 and TA 102)
Experiment II
31.6, 100, 316, 1000, 2500 and 5000 µg/plate
(TA 98, TA 100 (with metabolic activation), TA 1535, TA 1537 and TA 102)
3.16, 10.0, 31.6, 100, 316, 1000, 2500 and 5000 µg/plate
(TA 100 (without metabolic activation))

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: acetone
- Justification for choice of solvent/vehicle: aprotic solvent used at request of sponsor. DMSO produced a two phase solution, so acetone was used.

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 100, TA 1535; Without metabolic activation; 10 µg/plate

Controls 2

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 4-NOPD; 4-nitro-o-phenylene-diamine

Remarks:

Without metabolic activation; 10 µg/plate for TA 98, 40 µg/plate for TA 1537

Controls 3

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

Without metabolic activation; TA 102; 1 µL/plate

Controls 4

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-AA; 2-aminoanthracene

Remarks:

With metabolic activation; all strains; 2.5 µg/plate; 10 µg/plate for TA 102

Details on test system and experimental conditions:

ACTIVATION: phenobarbital and β-naphthoflavone induced rat liver S9 was prepared; the biological activity was determined using 2-aminoanthracene and benzo[a]pyrene.
S9 mix contained:
- 8 mM MgCl2
- 33 mM KCl
- 5 mM glucose-6-phosphate
- 4 mM NADP
- 100 mM sodium-ortho-phosphate-buffer, pH 7.4
- 5% S9
0.5 ml of S9 mix were added to a total volume of 2.7 ml, giving a final concentration of S9 of approximately 1%.

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 60 min at 37 °C
- Exposure duration: at least 48 h in the dark at 37 °C.

SELECTION AGENT (mutation assays): histidine deficient agar

NUMBER OF REPLICATIONS: 3 plates per dose. A pre-experiment for toxicity was carried out using strains TA98 and TA 100. The initial plate incorporation assay was repeated using the preincubation method.

DETERMINATION OF CYTOTOXICITY
- Method: other: clearing or rather diminution of the background lawn or a reduction in the number of revertants down to a mutation factor of approximately ≤ 0.5 in relation to the solvent control.

Evaluation criteria:

A test item is considered as mutagenic if:
- a clear and dose-related increase in the number of revertants occurs and/or
- a biologically relevant positive response for at least one of the dose groups occurs
in at least one tester strain with or without metabolic activation.
A biologically relevant increase is described as follows:
- if in tester strains TA 98, TA 100 and TA 102 the number of reversions is at least twice as high
- if in tester strains TA 1535 and TA 1537 the number of reversions is at least three times higher
than the reversion rate of the solvent control

Statistics:

Not regarded as necessary

Results and discussion

Test results

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

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

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Pre-experiment for toxicity (mean of 3 plates)

Dose (µg/plate)	TA98		TA100
	-MA	+MA	-MA	+MA
Solvent control	1.0	1.0	1.0	1.0
3.16	1.1	1.5	1.2	1.1
10.0	1.1	1.2	1.2	1.1
31.6	1.4	1.1	1.1	1.0
100	1.4	1.1	0.9	0.9
316	1.2	1.1	1.1	0.8
1000	1.1	1.0	1.2	0.9
2500	1.2	1.0	1.4	1.0
5000	1.0	1.0	1.1	0.9
Positive control	14.8	80.7	12.5	24.3

Experiment 1: Plate-incorporation test: revertant colonies per plate (mean of 3 plates)

Dose (µg/plate)	TA 98		TA 100		TA 1535		TA 1537		TA 102
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
Negative control	19	27	78	93	9	11	5	6	419	517
Solvent control	19	23	72	99	13	8	5	5	415	512
31.6	27	26	83	99	13	9	6	7	363	495
100	28	26	64	85	12	10	5	5	435	492
316	23	26	82	82	12	11	4	7	446	497
1000	21	24	83	87	12	8	3	6	464	535
2500	24	24	100	99	10	12	3	5	461	579
5000	19	23	80	91	16	9	4	6	394	488
Positive control	286	1882	906	2402	776	125	50	177	2698	1187

 

Experiment 2: Pre-incubation test: revertant colonies per plate (mean of 3 plates)

Dose (µg/plate)	TA 98		TA 100		TA 1535		TA 1537		TA 102
	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA
Negative control	19	19	114	75	15	7	6	4	223	369
Solvent control	16	20	119	78	20	6	8	6	198	399
3.16	-	-	115	-	-	-	-	-	-	-
10.0	-	-	104	-	-	-	-	-	-	-
31.6	13	20	72	79	21	12	7	6	282	328
100	15	17	86	83	20	7	9	6	251	304
316	15	18	77	64	15	7	4	4	258	326
1000	11	19	77	81	15	5	5	5	233	306
2500	14	22	66	76	16	5	6	4	208	294
5000	20	23	86	89	14	4	8	8	255	385
Positive control	375	503	1316	941	1100	65	66	158	1847	917

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolic activation

Dibutoxy(dimethyl)silane has been tested for mutagenicity to bacteria, in a study which was conducted according to the OECD TG 471 and in compliance with GLP. No evidence of a test-substance related increase in the number of revertants was observed with or without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 102 in the initial plate incorporation assay or the repeat experiment conducted using the preincubation method, up to limit concentrations. Appropriate positive, solvent and negative (water) controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.