tert-butylchlorodimethylsilane

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:

2002-04-18 to 2002-07-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EC directive 92/69/, L383 A part B, 1992

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

tert-butylchlorodimethylsilane

EC Number:

242-042-4

EC Name:

tert-butylchlorodimethylsilane

Cas Number:

18162-48-6

Molecular formula:

C6H15ClSi

IUPAC Name:

tert-butyl(chloro)dimethylsilane

Test material form:

solid: crystalline

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:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

31.6, 100, 316, 1000, 3160 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Ethylene glycol dimethylether

- Justification for choice of solvent/vehicle: The solvent was chosen because of its solubility properties and its relative nontoxicity to the bacteria

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 1535, TA 100 (without activation) 10µg/plate

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

TA 98 (without activation) 10 µg/plate

Controls 3

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) 100 µg/plate

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

TA 102 (without activation) 1300 µg/plate

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-anthracene amide

Remarks:

TA 98, TA 102, TA 1537 (with activation) 2 µg/plate

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

TA 100, TA 1535 (with activation) 1500 µg/plate

Details on test system and experimental conditions:

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

DURATION

- Preincubation period: 60 minutes

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

NUMBER OF REPLICATIONS: 3 plates for each test concentration. The experiment was repeated using the pre-incubation method

DETERMINATION OF CYTOTOXICITY

- Method: other: background lawn assessment

METABOLIC ACTIVATION
S9 was prepared from Aroclor 1254 induce rats, and checked for protein content and P-450 content. S9 mix contained 5% S9; 2% 0.4 M MgCl2/1.65 M KCl solution; glucose-6-phosphate and NADP as co-factors. 0.5 ml of S9 mix was added to 2 ml of top agar, 0.1 ml test material (or control) and 0.1 ml cell suspension, giving a final concentration of approximately 1% S9.

Evaluation criteria:

A result is positive if the number of revertants is significantly increased compared with the solvent control to at least 2-fold of the solvent control for TA 98, TA 100 and TA 102 and 3-fold of the solvent control for TA 1535 and TA 1537 in both experiments.

Positive results have to be reproducible and the histidine independence of the revertants has to be confirmed by streaking on histidine-free agar plates.

Cytotoxicity is defined as a reduction in the number of colonies by >50% compared with the solvent control and/or a sparse background lawn.

Statistics:

MANN and WHITNEY and Spearman’s rank.

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:

cytotoxicity

Remarks:

1000 μg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: no precipitation was observed.

Any other information on results incl. tables

Table 2: Dose range-finding study Number of revertants per plate (TA 100 - MA)

	TA100
Conc. (µg/plate)	Plate 1	Plate 2	Cytotoxic (yes/no)
0*	160	134	No
0.316	152	196	No
1	152	172	No
3.16	141	150	No
10	143	162	No
31.6	157	135	No
100	143	151	No
316	155	162	No
1000	181	144	No
3160	0	0	Yes
5000	0	0	Yes

*solvent control with Ethylene glycol dimethylether

Table 3: Experiment 1 Plate incorporation Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA102
Conc. µg/plate	— MA	+  MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	36	36.7	No	151	134.3	No	268.7	278.7	No
31.6	35	35	No	143	159	No	268.3	274.7	No
100	32	36	No	134.7	158.7	No	286.3	282	No
316	37.3	37.3	No	140.7	169.3	No	290	283	No
1000	30.7	37.3	No	149	136.3	No	288	270	No
3160	0	0	Yes	0	0	Yes	284.7	265.3	No
Positive control	1291	845.7	No	1243	1266.3	No	1310	1228	No

*solvent control with Ethylene glycol dimethylether

Table 3: Experiment 1 Plate incorporation Number of revertants per plate (mean of 3 plates)

	TA1535			TA1537
Conc. µg/plate	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	18.3	16.7	No	6	4.3	No
31.6	19.3	16	No	3.7	5.3	No
100	12.3	15.3	No	4	4.3	No
316	20.3	15.3	No	5.3	4.3	No
1000	18	13	No	4.7	5	No
3160	0	0	Yes	0	0	Yes
Positive control	964.3	970	No	360.7	383.7	No

*solvent control with Ethylene glycol dimethylether

Table 4: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA98			TA100			TA102
Conc. µg/plate	— MA	+  MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	34.7	29	No	131	132.3	No	269.7	266.3	No
31.6	31.3	27.3	No	130.7	133.3	No	258.7	267	No
100	31.7	29	No	128	131.7	No	283.3	282.3	No
316	38.3	27.3	No	122.7	118.7	No	259.7	278.3	No
1000	0	0	Yes	0	0	Yes	0	0	Yes
3160	0	0	Yes	0	0	Yes	0	0	Yes
Positive control	1238	1238.7	No	1349.3	1351	No	1317	1216.3	No

*solvent control with Ethylene glycol dimethylether

Table 4: Experiment 2 Preincubation Number of revertants per plate (mean of 3 plates)

	TA1535			TA1537
Conc. µg/plate	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	16	14.3	No	13	14	No
31.6	12.3	15.3	No	12.7	14	No
100	13.3	15.3	No	9.3	13.3	No
316	12	11.3	No	7	11	No
1000	0	0	Yes	0	0	Yes
3160	0	0	Yes	0	0	Yes
Positive control	1354.7	1341.7	No	1337.7	1330.7	No

*solvent control with Ethylene glycol dimethylether

Applicant's summary and conclusion

Conclusions:

tert-Butyl(chloro)dimethylsilane has been tested in a reliable test conducted in accordance with OECD 471 (1997) and in compliance with GLP, using Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102. No test-substance induced increase in the number of revertants was observed with or without metabolic activation up to cytotoxic concentrations in either the initial plate incorporation assay or the independent repeat experiment using the pre-incubation method. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.