Dichlorocyclohexylmethylsilane

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:

2002-05-13 to 2002-09-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Dichlorocyclohexylmethylsilane

EC Number:

226-956-0

EC Name:

Dichlorocyclohexylmethylsilane

Cas Number:

5578-42-7

Molecular formula:

C7H14Cl2Si

IUPAC Name:

dichloro(cyclohexyl)methylsilane

Method

Target gene:

Histidine

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 102

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

3.16, 10, 31.6, 100 and 316 µg/plate

Vehicle / solvent:

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

- Justification for choice of solvent/vehicle: Solubility properties and relative non-toxicity to 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)

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)

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)

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)

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)

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)

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

DETERMINATION OF CYTOTOXICITY
- Method: Background lawn assessment, revertant colony counts

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

Test results 1

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

(316 µg/plate)

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

(316 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

Any other information on results incl. tables

Table 2: Dose range-finding studyNumber of revertants per plate (2 plates)

	TA100
Conc. (µg/plate)	Plate 1	Plate 2	Cytotoxic (yes/no)
0*	137	124	No
0.316	154	166	No
1	133	147	No
3.16	157	162	No
10	154	147	No
31.6	139	172	No
100	135	147	No
316	143	151	Yes
1000	154	165	Yes
3160	0	0	Yes
5000	0	0	Yes

*solvent control withEthylene glycoldimethylether

Table 3: Experiment 1 Plate incorporationNumber 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*	36.7	35	No	147.7	141.3	No	281.7	285	No
3.16	23.7	29	No	150	148.7	No	271.7	260	No
10	23.3	34	No	143.7	151.3	No	300	252.7	No
31.6	27.7	27.3	No	143.7	152	No	287.7	269.3	No
100	35	34.7	No	133.3	173	No	276.3	272.7	No
316	29	29.7	Yes	143	159	Yes	279	268.7	Yes
Positive control	871	867	No	1027.7	1035.7	No	1025.7	285	No

*solvent control withEthylene glycoldimethylether

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

	TA1535			TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	15.3	14	No	8.7	7	No
3.16	15.7	16.7	No	6.3	5.7	No
10	15	14.7	No	6.3	7.3	No
31.6	15.7	17.3	No	7	6	No
100	11.3	16	No	6	6.3	No
316	13.3	11.7	Yes	5	7	Yes
Positive control	420.7	422	No	424.7	424	No

*solvent control withEthylene glycoldimethylether

Table 4: Experiment 2 PreincubationNumber 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*	35.3	31.7	No	159.3	128	No	271.7	267.3	No
3.16	27	25.7	No	160.7	142	No	271	270.3	No
10	25.7	25	No	137.3	130	No	266.3	263.3	No
31.6	24.7	25.3	No	140	137	No	270	273	No
100	29.3	36.7	No	129.3	125.7	No	264	263.3	No
316	29.7	28.7	Yes	134.7	129	Yes	256.3	271.3	Yes
Positive control	526	535	No	1059	1051.7	No	1032.3	1066	No

*solvent control withEthylene glycoldimethylether

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

	TA1535			TA1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	12.3	15	No	4	6	No
3.16	13.7	13.3	No	4	3.3	No
10	12.7	14.3	No	3.7	5	No
31.6	14.3	13.7	No	4.7	4.3	No
100	13.3	12	No	2.7	4	No
316	11.7	13.3	Yes	4	4	Yes
Positive control	527.7	521.3	No	517	522	No

*solvent control withEthylene glycoldimethylether

Applicant's summary and conclusion

Conclusions:

In a highly reliable test, conducted under OECD 471 with GLP, no mutagenic effect was observed for the test substance tested up to cytotoxic concentration in any of the test strains in two independent experiments without and with metabolic activation. The test substance is non-mutagenic in test strains used.