3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Gene mutation (Bacterial reverse mutation assay / Ames test): negative with and without activation in Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 Escherichia coli WP2 (OECD TG 471) (Dow Corning Corporation, 2011b).
Cytogenicity in mammalian cells: negative with and without activation in cultured human lymphocytes (OECD TG 473) (Dow Corning Corporation, 2011c).
Mutagenicity in mammalian cells: negative with and without activation in L5178Y mouse lymphoma cells (OECD TG 476) (Bioservice, 2012).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25.08.2011 - 15.09.2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Version / remarks:

Kanpoan No.287

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbitol/beta-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

3, 10, 33, 100, 333, 1000, 2500 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: the solvent was requested by the sponsor.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

TA 1535, TA100 without metabolic activation 10 µg/plate

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 4-nitro-o-phenylene-diamine 10 µg/plate TA98 and 50 µg/plate TA1537

Remarks:

TA1537, TA98 without metabolic activation

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

WP2 uvrA without metabolic activation 3 µl/plate

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene 2.5 µg/plate TA1535, TA1537, TA98, TA100 and 10 µg/plate WP2 uvrA

Remarks:

TA1535, TA1537, TA98, TA100, WP2 uvrA with metabolic activation

Details on test system and experimental conditions:

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

ACTIVATION: S9 mix contained glucose-6-phosphate and NADP as co-factors. The amount of S9 supernatant was 10% v/v in the S9 mix. 0.5 ml S9 was added to test solution, bacterial suspension and top agar giving a final concentration in the cultures of approximately 2% S9.

DURATION
- Preincubation period: 60 minutes at 37C
- Exposure duration: 72 hours

SELECTION AGENT (mutation assays): histidine deficient agar

NUMBER OF REPLICATIONS: triplicate plates, pre-experiment for toxicity and experiment 1 used plate incorporation, the test was repeated using pre-incubation.

DETERMINATION OF CYTOTOXICITY
- Method: other: condition of background lawn

Evaluation criteria:

A test item is considered as a mutagen if a biologically relevant increase in the mean number of revertant colonies exceeding the threshold of twice (strains TA98, TA100 and WP2 uvrA) or thrice (strains TA1535 and TA1537) the mean colony count of the corresponding solvent control is observed. A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration. An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.

Statistics:

No statistical evaluation of the data was required.

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:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: No precipitation was observed


ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxicity was not evident at any concentrations

Table 1: Experiment 1 - Mean revertant colony counts

	TA 1535		TA 1537		TA 98		TA 100		WP2 uvrA
Concentration (µg/plate)	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Solvent control	14	21	15	25	33	38	126	130	47	49
Negative control	16	17	17	21	37	54	120	127	44	49
3	12	21	16	24	32	41	123	120	52	49
10	13	18	14	24	34	37	117	131	40	56
33	15	21	18	21	36	37	129	105	44	49
100	13	24	16	24	39	39	139	131	40	53
333	15	18	18	19	38	29	134	134	47	48
1000	14	16	16	15	38	23	142	135	51	46
2500	18	17	18	16	38	23	127	124	45	44
5000	14	18	17	15	29	18	129	119	39	31
Positive control	1536	313	71	388	326	1266	1791	2270	956	227

 

  Table 2: Experiment 2 Mean revertant colony counts 

 

	TA 1535		TA 1537		TA 98		TA 100		WP2 uvrA
Concentration (µg/plate)	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Solvent control	16	21	22	26	37	37	132	139	49	63
Negative control	18	16	24	28	41	45	142	143	52	64
3	NA	19	NA	26	NA	41	NA	159	NA	58
10	NA	21	NA	24	NA	39	NA	162	NA	55
33	18	24	21	26	31	44	124	124	50	61
100	16	21	24	30	33	40	140	161	58	53
333	17	18	24	19	37	35	134	150	51	53
1000	17	15	21	19	33	29	155	145	58	58
2500	15	16	20	17	30	31	156	127	56	37
5000	17	16	24	16	38	29	155	114	57	42
Positive control	1780	318	118	266	329	1655	1782	1602	643	261

Conclusions:

3,3-Bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane has been tested for mutagenicity to bacteria, in a study which was conducted according to OECD Test Guideline 471 and in compliance with GLP. No evidence of a test substance related increase in the number of revertant colonies was observed with or without metabolic activation in the pre-experiment for toxicity or the initial assay using the plate incorporation method using S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2. The result was confirmed the repeat preincubation experiment. Appropriate positive, negative and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-07-28 - 2011-09-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

lymphocytes: peripheral human lymphocytes

Details on mammalian cell type (if applicable):

Blood cultures were set up in bulk within 24 hours of collection in 75 cm flasks. Culture medium was DMEM:F12 ( Dulbeccos's modified eagle medium)/Hams F:12; mixed 1:1. Medium included 15mM HEPES and 200 mM L-glutamine. Also added was 10,000 U/ml penicillin and 10,000 µg/ml streptomycin, Phytohemagglutinin - 3 µg/ml, 10% FBS (foetal bovine serum), heparin 25,000 USP-U/ml. All incubations were at 37°C in humified atmosphere with 5.5% CO2.

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and beta-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

0.01, 0.02, 0.04, 0.08, 0.16, 0.3, 0.6, 1.3, 2.5 and 5.0 µl/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Acetone
- Justification for choice of solvent/vehicle: Solvent chosen due to its solubility properties and its relative non-toxicity to the cell cultures.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

without metabolic activation exp 1: 825 µg/ml exp 2: 660 µg/ml

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation exp 1 and 2: 7.5 µg/ml

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

ACTIVATION: S9 mix contained glucose-6-phosphate and NADP as co-factors

DURATION

- Exposure duration: Exp 1 - 4 hours with and without S9. Exp 2 - 4 hours with S9 mix and 22 hours without S9
- Expression time (cells in growth medium):94 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 22 hours

SPINDLE INHIBITOR (cytogenetic assays): colcemid
STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: duplicate flasks, test repeated

NUMBER OF CELLS EVALUATED: 200 metaphases scored for chromosome aberrations per dose group, 2000 cells per dose group were counted for determination of the mitotic index.

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: no

Evaluation criteria:

The test item is classified as mutagenic if the number of induced structural chromosome aberrations is not within the range of the historical control data and a concentration related increase or a significant increase in the number of structural chromosome aberrations is observed.

Statistics:

Fisher's exact test

Key result

Species / strain:

lymphocytes: peripheral human lymphocytes

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no relevant influence was observed
- Effects of osmolality: slightly decreased at the highest concentration
- Precipitation: none observed

COMPARISON WITH HISTORICAL CONTROL DATA: aberration rates of cells after treatment were close to the range of the solvent control values and within the range of the historical data

Summary of results from Experiments I and II with and without metabolic activation

Experiment	Preparation interval (hrs)	Dose level µl/ml	% Polyploid cells	MI* in % of control	% Aberrant cells
					Incl gaps	Excl gaps	With exchanges
Exposure period 4 hours without S9 mix
I	22	Solvent control	0.2	100.00	1.5	1.0	0.0
		Positive control	-	116.4*	13.0	10.0	1.0
		0.3	0.0	116.4	0.5	0.5	0.0
		1.3 PS	0.0	82.5	1.0	0.5	0.0
		2.5 PS	0.0	98.8	3.0	2.5	0.5
		5.0 PS	0.0	84.2	1.0	1.0	0.0
Exposure period 22 hours without S9 mix
II	22	Solvent control	0.0	100.0	2.5	2.0	0.5
		Positive control	-	51.5	13.5	12.5	1.5
		0.3	0.0	97.5	1.0	1.0	0.0
		1.3 PS	0.4	92.8	0.5	0.5	0.0
		2.5 PS	0.2	92.0	1.5	1.5	0.0
		5.0 PS	0.0	89.9	0.0	0.0	0.0
Exposure period 4 hours with S9 mix
I	22	Solvent control	0.0	100.0	0.5	0.5	0.0
		Positive control	-	65.9	10.0	8.5	0.5
		0.3	0.2	87.0	1.5	1.0	0.0
		1.3 PS	0.0	86.2	1.0	0.5	0.0
		2.5 PS	0.2	91.3	1.5	1.5	0.0
		5.0 PS	0.2	97.8	2.0	2.0	0.0
Exposure period 4 hours with S9 mix
II	22	Solvent control	0.0	100.0	2.5	2.5	0.0
		Positive control	-	46.8	16.5	16.5	2.0
		0.3	0.0	98.2	2.0	1.5	0.5
		1.3 PS	0.4	80.1	1.0	1.0	0.0
		2.5 PS	0.2	100.0	0.5	0.5	0.0
		5.0 PS	0.0	111.7	0.5	0.5	0.0

MI = mitotic indices

PS = Phase separation was observed

* It is noted by the reviewer that this positive control does not exhibit mitotic inhibition, and that the value is the same as that for the lowest test concentration in the row below.

Conclusions:

3,3-Bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane has been tested in an in vitro chromosome aberration assay in peripheral human lymphocytes, conducted according to OECD Test Guideline 473 and in compliance with GLP. No evidence of a test substance related increase in chromosome aberrations was observed with or without metabolic activation in the initial or the repeat experiment. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is negative for cytogenicity under the conditions of the test.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-11-08 to 2012-01-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5300 - In vitro Mammalian Cell Gene Mutation Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: IWGT Recommendations

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

(Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Germany)

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: RPMI
- Properly maintained: Yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital and ß-Naphthoflavone-induced rat liver S9

Test concentrations with justification for top dose:

Pre-expt I: 0.1, 0.5, 2.5, 5.0, 7.5 and 10.0 mM (+/-S9); Pre-expt II: 2.5, 5.0, 7.5 and 10.0 mM (24 h -S9);
Expt I: 0.5, 1.0, 2.0, 4.0, 5.0, 7.0, 8.0 and 10.0 mM (+S9), 0.25, 1.0, 2.0, 4.0, 7.0, 8.0, 9.0 and 10.0 mM (-S9);
Expt II: 0.75, 1.5, 3.5, 6.5, 7.5, 8.5, 9.5 and 10.0 mM (+S9), 0.1, 0.5, 1.0, 2.0, 4.0, 7.0, 9.0 and 10.0 mM (-S9)

Vehicle / solvent:

The test item was soluble in acetone (final concentration of 0.5% solvent v/v).
The solvent was compatible with the survival of the cells of the S9 activity.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

with metabolic activation 2.5 µg/mL

Positive control substance:

ethylmethanesulphonate

Remarks:

without metabolic activation 200 µg/mL and 300 µg/mL

Positive control substance:

methylmethanesulfonate

Remarks:

without metabolic activation 10 µg/mL

Details on test system and experimental conditions:

METHOD OF APPLICATION: suspended / dissolved in medium
DURATION: 4 h (short-term exposure), 24 h (long-term exposure)
Expression time (cells in growth medium): 48 h
Selection time (if incubation with selection agent): about 14 days

SELECTION AGENT ( mutation assay) 5 µg/mL trifluorothymidine
NUMBER OF REPLICATIONS: two separate experiments (I+II) with single exposure; cells were seeded in 4 plates and evaluated
NUMBER OF CELLS SEEDED: 2000 cells per well
DETERMINATION OF CYTOTOXICITY: relative total growth (RTG)

METABOLIC ACTIVATION: S9 mix included glucose-6-phosphate and NADP, and sufficient S9 to give a protein concentration of 0.75 mg/ml in the cultures.

Evaluation criteria:

The test item is considered mutagenic if following criteria are met:
-The induced mutant frequency meets or exceeds the Global Evaluation factor (GEF) of 126 per 10^6 cells
- A dose-dependent increase in mutant frequency is detected.

Besides, combined with a positive effect in the mutant frequency, an increased occurrence of small colonies (≥40% of total colonies) is an indication for potential clastogenic effects and/or chromosomal aberrations.
According to the OECD guideline, the biological relevance is considered first for the interpretation of results. Statistical methods might be used as an aid in evaluation the test result.
A test item is considered to be negative if the induced mutant frequency is below the GEF and the trend test is negative.

Statistics:

The non-parametric Mann-Whitney test is applied to the mutation data to prove the dose groups for any significant difference in mutant frequency compared to the negative /solvent controls.

Key result

Species / strain:

mouse lymphoma L5178Y cells

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

Pre-experiment toxicity with and without metabolic activation

Concentration (mM)	Number of cells 4 h after treatment		Number of cells 24 h after treatment		Number of cells 48 h after treatment		SG^a		RSG^b  (%)
	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9
Negative control	315000	308000	1050000	500000	1280000	226000	13.4	11.3	82.2	94.0
Negative control	328000	294000	966000	513000	1600000	223000	15.5	11.4	94.5	95.2
Solvent control	311000	309000	9850000	658000	1630000	179000	16.1	11.8	100.0	100.0
Solvent control	328000	329000	1010000	632000	1650000	194000	16.7	12.3
0.1	290000	249000	1050000	697000	1370000	171000	17.8	11.9	108.9	99.2
0.5	327000	290000	1050000	821000	1510000	170000	15.9	14.0	96.9	116.1
2.5 (P)	217000	209000	747000	491000	1640000	198000	12.3	9.7	74.9	80.9
5.0 (P)	217000	236000	742000	670000	1620000	177000	12.0	11.9	73.5	98.7
7.5 (P)	253000	228000	865000	860000	1480000	160000	12.8	13.8	78.3	114.5
10.0(P)	244000	231000	761000	830000	1500000	159000	11.4	13.2	69.8	109.8

P = precipitation SG = suspension growth RSG = relative suspension growth

Summary: Experiment I and II with and without metabolic activation

Treatment (mM)	RTG (%)		MF (mutants/10^6cells		IMF (mutants/10^6cells)		Precipitate
Experiment 1	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Negative control	79.6	90.7	132.8	117.1**	/	/	-	-
Negative control	110.3	188.2*			/	/	-	-
Solvent control	100.0	100.0	134.5	96.8	/	/	-	-
Solvent control					/	/	-	-
0.25	75.5	na	129.5	na	-5.0	na	-	na
0.5	na	118.2	na	125.8	na	29.0	na	-
1.0	89.4	104.4	135.6	83.7	1.1	-13.2	+	+
2.0	89.4	96.5	182.4	86.2	47.9	-10.6	+	+
4.0	85.0	83.1	118.2	121.0	-16.3	24.1	+	+
5.0	na	78.9	na	93.7	na	-3.1	na	+
7.0	97.0	72.4	155.7	103.0	21.2	6.2	+	+
8.0	108.6	77.7	154.2	110.9	19.7	14.1	+	+
9.0	85.5	na	158.2	na	23.7	na	+	Na
10.0	74.4	84.0	174.2	102.7	39.7	5.8	+	+
Positive control 1	74.2	52.1	612.2	477.4	477.7	380.6	-	-
Positive control 2	67.4	na	438.5	na	304.0	na	-	na
Experiment 2	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Negative control	121.7	100.5	73.0	70.2	/	/	-	-
Negative control	132.5	75.2			/	/	-	-
Solvent control	100.0	100.0	73.3	80.8	/	/	-	-
Solvent control					/	/	-	-
0.1	119.7	na	85.0	na	11.7	na	-	na
0.5	132.2	na	78.7	na	5.4	na	-	na
0.75	na	86.1	na	60.9	na	-19.9	na	-
1.0	117.1	na	84.8	na	11.5	na	+	na
1.5	na	67.0	na	91.4	na	10.6	na	-
2.0	97.9	na	72.9	na	-0.4	na	+	na
3.5	na	99.7	na	65.5	na	-15.3	na	+
4.0	134.5	na	68.3	na	-5.1	na	+	na
6.5	na	52.3	na	64.2	na	-16.6	na	+
7.0	134.0	na	64.9	na	-8.4	na	+	na
7.5	na	62.9	na	81.1	na	0.3	na	+
8.5	na	79.5	na	62.4	na	-18.4	na	+
9.0	134.8	na	79.7	na	6.3	na	+	na
9.5	na	60.6	na	56.0	na	-24.8	na	+
10.0	148.5	59.0	77.1	65.7	3.8	-15.1	+	+
Positive control 1	27.2	53.4	1873.4	544.2	1800.1	463.4	-	-
Positive control 2	129.5	na	418.3	na	344.9	na	-	na

None of the test substance mutation frequencies exceed GEF (global evaluation factor). Positive control results exceed GEF and were statistically significant: test substance results did not exceed GEF and were not statistically significant. na: these concentrations were not tested.

*Outlier, excluded from evaluation

Conclusions:

Tetra(dimethylvinylsiloxy)silane (3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane) has been tested for mutagenicity to mammalian cells in a reliable study conducted according to OECD 476 and in compliance with GLP. No evidence for a test-substance induced increase in mutant frequency was observed with or without activation when the substance was tested in mouse lymphoma L5178Y cells up to limit concentrations. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the condition of the study.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Data are available from reliable studies for all the required in vitro endpoints. The results of all the studies are in agreement.

3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane has been tested for mutagenicity to bacteria, in a study which was conducted according to OECD Test Guideline 471 and in compliance with GLP (Dow Corning Corporation, 2011b). No evidence of a test substance related increase in the number of revertant colonies was observed with or without metabolic activation in the pre-experiment for toxicity or the initial assay using the plate incorporation method. The result was confirmed in the repeat preincubation experiment. The bacteria used were S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2. Appropriate positive, negative and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane has been tested in an in vitro chromosome aberration assay in peripheral human lymphocytes, conducted according to OECD Test Guideline 473 and in compliance with GLP (Dow Corning Corporation, 2011c). No evidence of a test substance related increase in chromosome aberrations was observed with or without metabolic activation in the initial or the repeat experiment. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is negative for cytogenicity under the conditions of the test.

Information on the mutagenicity of 3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane to mammalian cells is available from a reliable study conducted according to OECD Test Guideline 476 and in compliance with GLP (Bioservice, 2012). No evidence for a test-substance induced increase in mutant frequency was observed with or without activation when the substance was tested in mouse lymphoma L5178Y cells up to limit concentrations. Appropriate positive and solvent controls were included and gave expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the condition of the study.

In vivo testing is not required as no evidence for genetic toxicity was found in the in vitro studies.

Justification for classification or non-classification

Based on the available in vitro genotoxicity data, 3,3-bis[(dimethylvinylsilyl)oxy]-1,1,5,5-tetramethyl-1,5-divinyltrisiloxane is not classified for mutagenicity according to Regulation (EC) No 1272/2008.