Ethane-1,2-diylbis[dichloromethylsilane]

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-11-02 to 2016-03-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Version / remarks:

2014

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Ethane-1,2-diylbis[dichloromethylsilane]

EC Number:

222-123-0

EC Name:

Ethane-1,2-diylbis[dichloromethylsilane]

Cas Number:

3353-69-3

Molecular formula:

C4H10Cl4Si2

IUPAC Name:

dichloro({2-[dichloro(methyl)silyl]ethyl})methylsilane

Constituent 2

Reference substance name:

1,2-bis[dichloro(methyl)silyl]ethane

IUPAC Name:

1,2-bis[dichloro(methyl)silyl]ethane

Test material form:

other: liquid

Method

Species / strain

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media: minimum essential medium (MEM)
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital (80 mg/kg bw) and -naphthoflavone (100 mg/kg bw) induced rat liver S9

Test concentrations with justification for top dose:

Experiment I:
200, 400, 600 and 800 μg/mL, without metabolic activation
500, 1000 and 1500 μg/mL, with metabolic activation
Experiment II:
400, 600, 800 and 1000 μg/mL, without metabolic activation

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: tetrahydrofuran (THF)
- Justification for choice of solvent/vehicle: The solvent was compatible with the survival of the cells and the S9 activity.

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

treatment medium

Negative solvent / vehicle controls:

yes

Remarks:

THF

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

without metabolic activation

Controls 2

Untreated negative controls:

yes

Remarks:

treatment medium

Negative solvent / vehicle controls:

yes

Remarks:

THF

True negative controls:

no

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

ACTIVATION: The S9 supernatant was mixed with S9 co-factors to result in a final protein concentration of 0.75 mg/mL in the cultures. The added co-factors were: 8 mM MgCl2, 33 mM KCl, 5 mM Glucose-6-phosphate, 5 mM NADP in 100 mM sodium-phosphate-buffer pH 7.4.

DURATION

- Exposure duration:
Experiment I: 4 hours exposure, with and without metabolic activation
Experiment II: 21 hours exposure, without metabolic activation
- Expression time (cells in growth medium):
Experiment I: 16 +/- 2 hours
Experiment II: Preparation of the cells straight after the 21-hour exposure
- Fixation time (start of exposure up to fixation or harvest of cells): at 21 hours after the start of exposure

SPINDLE INHIBITOR (cytogenetic assays): Colcemid (0.2 μg/mL culture medium) ) added 2.5 hours before cell preparation
STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: Duplicate cultures

NUMBER OF CELLS EVALUATED: 150 metaphases per culture

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index and RICC (%) (relative increase in cell count)

OTHER EXAMINATIONS:
- Determination of polyploidy: yes

Evaluation criteria:

The result was considered positive when:
- at least one of the test concentrations exhibits a statistically significant increase compared with the concurrent negative control
- the increase is dose-related when evaluated with an appropriate trend test
- any of the results are outside the distribution of the historical negative control data

Statistics:

Fisher´s exact test - to verify the results in the experiment
Χ2 test for trend - to test whether there is a concentration-related increase in cells with chromosome aberrations

Results and discussion

Test results

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 800 μg/mL without metabolic activation

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: Precipitation of the test item was noted at 1000 μg/mL in experiment I with metabolic activation and experiment II without metabolic activation.

ADDITIONAL INFORMATION ON CYTOTOXICITY: In experiment I without metabolic activation at concentration of 800 μg/mL, only one of the two cultures was evaluated for mitotic index and aberrant cells.

Remarks on result:

other: No mutagenic potential

Any other information on results incl. tables

Table 1: Summary, Experiment I and II with and without metabolic activation

	Dose Group	Concentration µg/mL	Relative Mitotic Index  (%)	RICC (%)	Mean % Aberrant Cells			Historical Laboratory Negative Control Range	Precipitation
					Including Gaps		Excluding Gaps
Experiment I and II, without metabolic activation
Experiment I 4 hour treatment, 21 hour preparation interval	C	0	102	114	2.3	0.7		0.0% - 4.0 % aberrant cells	-
	S	0	100	100	2.3	0.7			-
	aC	0	97	97	2.0	1.7			-
	3	200	92	85	5.0	2.0			-
	4	400	98	75	3.3	2.3			-
	5	600	92	72	3.0	2.3			-
	6	800	39	7	2.7	2.0			-
	EMS	600	94	78	10.0	6.0			-
Experiment II 21 hour treatment, 21 hour preparation interval	C	0	102	110	1.3	0.3		0.0 % - 4.0 % aberrant cells	-
	S	0	100	100	1.7	0.7			-
	aC	0	74	114	3.3	1.7			-
	6	400	89	88	1.7	1.0			-
	7	600	65	87	2.3	1.7			-
	8	800	8	25	1.2	0.8			-
	9	1000	13	31	4.9	1.8			+
	EMS	600	70	78	17.3	15.7			-
Experiment I, with metabolic activation
Experiment I 4 hour treatment, 21 hour preparation interval	C	0	106	103	2.0	1.3		0.0 % - 4.3 % aberrant Cells	-
	S	0	100	100	3.0	2.0			-
	aC	0	113	114	3.3	1.3			-
	5	500	117	91	5.0	2.7			-
	6	1000	119	80	6.0	3.3			+
	7	1500	116	88	3.3	1.7			+
	CPA	1.5	115	78	10.0	5.7			-

C: Negative Control (Culture Medium)

S: Solvent Control (DMSO)

aC: Acidic Control

CPA: Cyclophosphamide

EMS: Ethylmethanesulfonate

+ : Precipitation

- : No precipitation

Applicant's summary and conclusion

Conclusions:

1,2-Bis[dichloro(methyl)silyl]ethane has been tested for ability to cause chromosome aberrations in Chinese hamster lung fibroblasts V79 according to OECD TG 473 and in compliance with GLP (Eurofins BioPharma, 2016). No increase in the number of cells with aberrations was observed either with or without metabolic activation up to cytotoxic or precipitating concentrations. Appropriate solvent (THF), negative (treatment medium) and positive controls were included and gave expected results. It is concluded that the test substance is negative for the induction of chromosome aberrations under the conditions of this study.