1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Bacterial reverse mutation assay: the substance 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane was negative with and without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102 (LPT, 2002) (OECD TG 471).

Cytogenicity in mammalian cells: the substance 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane was negative with and without metabolic activation in peripheral human lymphocytes (WIL Research, 2016) (OECD TG 473).

Mammalian mutagenicity study: the substance 1,3,5-trimethyl-1,1,3,5,5-pentaphenyltrisiloxane was negative with and without metabolic activation in mouse lymphoma L5178Y cells (Charles River, 2016) (OECD TG 490).

The studies were conducted according to an appropriate OECD test guideline, and in compliance with GLP.

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:

2002-05-10 to 2002-09-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

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 TA 102

Metabolic activation:

with and without

Metabolic activation system:

Aroclor induced rat liver S9

Test concentrations with justification for top dose:

See table 1

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

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

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)

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)

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)

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)

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)

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: relative total growth; background lawn assessment

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.

Key result

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 nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: precipitation noted at 3160 - 5000 μg/plate

COMPARISON WITH HISTORICAL CONTROL DATA: Results were within range of historical control data

Remarks on result:

other: No mutagenic potential

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

	TA 100
Concentration (μg/Plate)	Plate 1	Plate 2	Cytotoxic (Yes/No)
0	143	146	No
0.316	154	138	No
1	188	140	No
3.16	171	144	No
10	161	162	No
31.6	144	145	No
100	145	138	No
316	115	130	No
1000	156	135	No
3160	195	154	No
5000	171	146	No

*solvent control with DMSO

Table 3: Experiment 1 Plate incorporation Assay 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*	32	36	No	131	137.3	No	298	279.7	No
10	39.3	43	No	130.7	133.3	No	272	280.3	No
31.6	38.3	39.3	No	122	136.7	No	258.3	260.7	No
100	34.3	31.3	No	131	123.7	No	265.3	283.3	No
316	27.7	36.7	No	113	131	No	276	284.3	No
1000	23.3	24.7	No	120	132.3	No	293.7	285.3	No
Positive control	1255	1295.7	No	1194	1169	No	1130.7	1289	No

*solvent control with DMSO

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

	TA1535			TA 1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	13.7	13.7	No	5.3	6	No
10	12.7	13.7	No	4	5.3	No
31.6	13	13	No	3.7	7.3	No
100	14.3	13.3	No	3	7	No
316	13	12	No	5.3	6	No
1000	12.7	14	No	5	5	No
Positive control	564.3	563	No	570.7	566.7	No

*solvent control with DMSO

Table 4: Experiment 2 Pre incubation test 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*	31	34.7	No	144.7	160.7	No	286.3	280	No
100	37.3	36.7	No	128.3	135	No	288	281	No
316	35	33.3	No	155.7	164.3	No	257.3	261.7	No
1000	31.3	27.3	No	150.7	155	No	271.3	267.7	No
3160	30.3	37.3	No	145.3	127	No	270.3	268.7	No
5000	30.7	33	No	131	129	No	282.7	264.3	No
Positive control	1033.7	1141	No	1186.7	1139.7	No	1163.3	1103.7	No

*solvent control with DMSO

Table 3: Experiment 2 Pre incubation test Number of revertants per plate (mean of 3 plates)

	TA1535			TA 1537
Conc. (µg/plate)	— MA	+ MA	Cytotoxic (yes/no)	— MA	+ MA	Cytotoxic (yes/no)
0*	15	14	No	5.7	5.7	No
100	13.7	13.7	No	3.7	5	No
316	13	13.7	No	4.7	6	No
1000	14.3	13	No	5	5.7	No
3160	15.7	12.7	No	5.7	5.7	No
5000	14	13	No	4.7	5	No
Positive control	554.3	548	No	553.3	550	No

*solvent control with DMSO

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.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-01-15 to 2016-03-08

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)

Version / remarks:

2014

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

other: Peripheral human lymphocytes

Details on mammalian cell type (if applicable):

- Type and identity of media: RPMI 1640 medium
- Properly maintained: yes

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital (80 mg/kg body weight) and ß-naphthoflavone (100 mg/kg) induced rat liver S9

Test concentrations with justification for top dose:

Experiment 1: 1.7, 5.4, 17, 52, 164 µg/ml, with and without metabolic activation
Experiment 2: 5.4, 17 and 52 µg/ml, without metabolic activation

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: dimethyl sulfoxide (DMSO)
- Justification for choice of solvent/vehicle: The solvent was chosen based on the results from the solubility test.

Untreated negative controls:

yes

Remarks:

DMSO

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

without metabolic activation, 48 hour exposure period

Untreated negative controls:

yes

Remarks:

DMSO

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation, 3 hour exposure period

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

ACTIVATION: To 0.5 ml S9-mix components 0.5 ml S9-fraction was added (50% (v/v) S9-fraction) to complete the S9-mix. The added co-factores were: 1.63 mg MgCl2.6H2O; 2.46 mg KCl; 1.7 mg glucose-6-phosphate; 3.4 mg NADP; 4 µmol HEPES.

DURATION

- Exposure duration:
Experiment 1: 3 hours, with and without metabolic activation
Experiment 2: 24 and 48 hours, without metabolic activation
- Expression time (cells in growth medium):
Experiment 1: 20-22 hours

- Fixation time (start of exposure up to fixation or harvest of cells):
Experiment 1: 24 hours
Experiment 2: The cells were fixed immediately after exposure

SPINDLE INHIBITOR (cytogenetic assays): colchicine (0.5 µg/ml medium) was added during the last 2.5 - 3 h of the culture period
STAIN (for cytogenetic assays): 5 % v/v Giemsa

NUMBER OF REPLICATIONS: duplicate cell cultures

NUMBER OF CELLS EVALUATED: 1000 cells

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes

Evaluation criteria:

A test item is considered positive (clastogenic) in the chromosome aberration test if all of the following criteria are met:
a) at least one of the test concentrations exhibits a statistically significant (Fisher’s exact test, one-sided, p < 0.05) increase compared with the concurrent negative control.
b) The increase is dose related when evaluated with an Cochran Armitage trend test.
c) Any of the results are outside the 95% control limits of the historical control data range.

Statistics:

Fisher’s exact test and Cochran Armitage trend test

Key result

Species / strain:

other: Peripheral human lymphocytes

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation:
Experiment 1: At the 3 h exposure time a concentration of 164 µg/ml the test item precipitated in the culture medium
Experiemnt 2: ). At 24 and 48 hour exposure times a concentration of 52 µg/ml test item precipitated in the culture medium

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Polyploidy: The test item did not increase the number of polyploid cells.
- Endoreplication: The test item did not increase the number of endoreplicated chromosomes

Remarks on result:

other: No mutagenic potential

Table 1: Mitotic index of human lymphocyte cultures treated with the test item in the first (experiement 1) cytogenetic assay

Test item concentration (µg/ml)	Number of metaphases
	Absolute	Number of cells scored	Percentage of control
3 hour exposure, 24 hour fixation time, without metabolic activation
Control (DMSO)	96 - 110	1027 - 1011	100
17	82 - 89	1018 - 1010	83
52	86 - 95	1008 - 1011	88
164	72 - 93	1015 - 1002	80
MMC-C; 0.5 µg/ml	55 - 63	1020 - 1011	57
MMC-C; 0.75 µg/ml	45 - 43	1022 - 1007	43
3 hour exposure, 24 hour fixation time, with metabolic activation
Control	107 – 98	1007 – 1014	100
17	99 – 85	1009 – 1026	90
52	95 – 101	1016 – 1008	96
164	94 – 82	1002 – 1012	86
CP; 10 µg/ml	62 - 50	1014 - 1004	55

Table 2: Chromosome aberrations in human lymphocyte cultures treated with the test item in the absence of S9-mix in the first (experiment 1) cytogenetic assay (3 h exposure time, 24 h fixation time)

Concentration	DMSO (1.0% v/v)			17 µg/ml			52 µg/ml			164 µg/ml			MMC-C 0.5µg/ml
Culture	A           B     A+B			A           B     A+B			A           B     A+B			A           B     A+B			A           B     A+B
Mitotic Index (%)	100			83			88			80			57
No. of Cells scored	150    150     300			150    150     300			150    150     300			150    150     300			150    150     300
No. of Cells with aberrations (+ gaps)^a)	1	0	1	0	0	0	0	0	0	0	0	0	40	48	***^) 88
No. of Cells with aberrations (- gaps)	1	0	1	0	0	0	0	0	0	0	0	0	40	46	***^) 86
total aberr (+ gaps)	1	0		0	0		0	0		0	0		51	48
total aberr (- gaps)	1	0		0	0		0	0		0	0		51	46

Table 3: Chromosome aberrations in human lymphocyte cultures treated with the test item in the presence of S9-mix in the first (experiment 1) cytogenetic assay (3 h exposure time, 24 h fixation time)

Conc	DMSO (1.0% v/v)			17 µg/ml			52 µg/ml			164 µg/ml			CP 10µg/ml
Culture	A           B     A+B			A           BA+B			A           BA+B			A           BA+B			A           B A+B
Mitotic Index (%)	100			90			96			86			55
No. of Cells scored	150    150     300			150    150300			150    150300			150    150300			150    150 300
No. of Cells with aberrations (+ gaps)^a)	0	1	1	0	0	0	0	0	0	0	0	0	36	30	***^) 66
No. of Cells with aberrations (- gaps)	0	1	1	0	0	0	0	0	0	0	0	0	36	30	***^) 66
total aberr (+ gaps)	0	1		0	0		0	0		0	0		42	37
total aberr (- gaps)	0	1		0	0		0	0		0	0		42	37

Table 4: Mitotic index of human lymphocyte cultures treated with the test item in the second (experiement 2) cytogenetic assay

Test item concentration (µg/ml)	Number of metaphases
	Absolute	Number of cells scored	Percentage of control
24 hour exposure, 24 hour fixation time, without metabolic activation
Control	69 - 78	1021 - 1013	100
5.4	68 - 69	1013 - 1016	93
17	76 - 66	1033 -1002	97
52	73 - 69	1030 - 1018	97
MMC-C; 0.2 µg/ml	39 - 45	1029 - 1005	57
MMC-C; 0.3 µg/ml	18 - 23	1017 - 1010	28
48 hour exposure, 48 hour fixation time, without metabolic activation
Control	44 - 44	1014 - 1013	100
5.4	47 – 43	1013 - 1021	102
17	37 - 37	1003 - 1004	84
52	38 - 37	1013 - 1006	85
MMC-C; 0.1 µg/ml	34 - 36	1020 – 1016	80
MMC-C; 0.15 µg/ml	29 - 31	1003 - 1021	68

Table 5: Chromosome aberrations in human lymphocyte cultures treated with the test item in the absence of S9-mix in the second (experiment 2) cytogenetic assay (24 h exposure time, 24 h fixation time)

Conc	DMSO (1.0% v/v)			5.4 µg/ml			17 µg/ml			52 µg/ml			MMC-C 0.2µg/ml
Culture	A           B  A+B			A           B  A+B			A           B  A+B			A           B  A+B			A           B    A+B
Mitotic Index (%)	100			93			97			97			57
No. of Cells scored	150    150   300			150    150   300			150    150   300			150    150   300			150    150     300
No. of Cells with aberrations (+ gaps)^a)	0	1	1	1	1	2	2	0	2	1	0	1	53	43	***^) 96
No. of Cells with aberrations (- gaps)	0	1	1	1	1	2	2	0	2	1	0	1	52	42	***^) 94
total aberr (+ gaps)	0	1		1	1		2	0		1	0		60	56
total aberr (- gaps)	0	1		1	1		2	0		1	0		59	53

Table 6: Chromosome aberrations in human lymphocyte cultures treated with the test item in the absence of S9-mix in the second (experiement 2) cytogenetic assay (48 h exposure time, 48 h fixation time)

Conc	DMSO (1.0% v/v)			5.4 µg/ml			17 µg/ml			52 µg/ml			MMC-C 0.1µg/ml
Culture	A           B     A+B			A           B     A+B			A           B     A+B			A           B     A+B			A           B     A+B
Mitotic Index (%)	100			102			84			85			80
No. of Cells scored	150    150     300			150    150     300			150    150     300			150    150     300			150    150     300
No. of Cells with aberrations (+ gaps)^a)	0	1	1	0	0	0	0	1	1	0	0	0	42	53	***^) 95
No. of Cells with aberrations (- gaps)	0	1	1	0	0	0	0	0	0	0	0	0	42	52	***^) 94
total aberr (+ gaps)	0	1		0	0		0	1		0	0		51	66
total aberr (- gaps)	0	1		0	0		0	0		0	0		51	65

*) Significantly different from control group (Fisher’s exact test), * P < 0.05, ** P < 0.01 or *** P < 0.001

Conclusions:

1,3,5-Trimethyl-1,1,3,5,5-pentaphenyltrisiloxane has been tested in a valid study for ability to induce chromosome aberrations in Peripheral human lymphocytes according to OECD TG 473 (2014), and in compliance with GLP. No statistically significant or biologically relevant increase in the number of cells with chromosome aberrations was observed either with or without metabolic activation when tested up to precipitating concentrations. Appropriate positive and negative controls were used and gave the expected results. It is concluded that the test item is negative for the induction of chromosome aberrations under the conditions of the study.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-06-07 to 2016-08-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 490 (In Vitro Mammalian Cell Gene Mutation Tests Using the Thymidine Kinase Gene)

Version / remarks:

2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

other: in vitro mammalian cell gene mutation assay

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 0006760363
- Expiration date of the lot/batch: 8th November 2016
- Purity test date: 8th October 2015

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: dimethyl sulfoxide
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: stable in dimethyl sulfoxide

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: no specific handling conditions required
- Preliminary purification step (if any): no correction was made for the purity/composition of the test item

Target gene:

thymidine kinase locus

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

CELLS USED
- Source of cells: American Type Culture Collection, USA
- Suitability of cells: recommended test system in international guidelines
- Cell cycle length, doubling time or proliferation index: no data
- Sex, age and number of blood donors if applicable: no data
- Whether whole blood or separated lymphocytes were used if applicable: no data
- Number of passages if applicable: no data
- Methods for maintenance in cell culture if applicable: no data
- Modal number of chromosomes: no data
- Normal (negative control) cell cycle time: no data

MEDIA USED
- Type and identity of media including CO2 concentration if applicable:
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
- Periodically 'cleansed' against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

of phenobarbital (80 mg/kg body weight) and ß-naphthoflavone (100 mg/kg body weight) induced rat liver S9

Test concentrations with justification for top dose:

Dose range finding test: 1.7, 5.4, 17, 52, 164, 512 μg/ml (with and without S9 mix)
Experiment I: 0.056, 0.18, 0.55, 1.7, 5.4, 17, 52 and 164 μg/ml (with and without S9 mix)
Experiment II: 0.018, 0.056, 0.18, 0.55, 1.7, 5.4, 17, 52 and 164 μg/ml (without S9 mix)
Doses were selected based on cytotoxicity results from dose-range finding test

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: dimethyl sulfoxide
- Justification for choice of solvent/vehicle: based on solubility in dimethyl sulfoxide observed during a solubility test.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

dimethyl sulfoxide

True negative controls:

no

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without metabolic activation

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

dimethyl sulfoxide

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium
- Cell density at seeding: 9.6 x 10⁵ cells/ concentration

ACTIVATION: S9 mix was prepared immediately before use and kept on ice. S9-mix components contains per ml physiological saline: 1.63 mg MgCl2 H2O; 2.46 mg KCl; 1.7 mg glucose-6-phosphate; 3.4 mg NADP; 4 µmol HEPES. The final concentration of the S9-fraction in the exposure medium was 4%.

DURATION
- Exposure duration:
Dose-range finding test: 3-hour treatment with and without metabolic activation
Experiment I: 3-hour treatment, with and without metabolic activation
Experiment II: 24-hour treatment, without metabolic activation
- Expression time (cells in growth medium): the remaining cells were cultured for 2 days after the treatment period.
- Selection time (if incubation with a selection agent): 11-12 days
- Fixation time (start of exposure up to fixation or harvest of cells):

SELECTION AGENT (mutation assays): selective medium (TFT-selection agent)

NUMBER OF REPLICATIONS: duplicate plates

METHODS OF SLIDE PREPARATION AND STAINING TECHNIQUE USED: the plates of the TFT-selection were stained for 2 hours by adding 0.5 mg/ml 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) (Sigma) to each well.

NUMBER OF CELLS EVALUATED:

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency; relative total growth
- Any supplementary information relevant to cytotoxicity: suspension growth

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

Rationale for test conditions:

The test concentrations in experiment I and II were selected based on cytotoxicity data from a dose-range finding study.

Evaluation criteria:

A test item is considered positive (mutagenic) in the mutation assay if it induces a mutation frequency (MF) of more than MF(controls) + 126 in a dose-dependent manner. Any observed increase should be biologically relevant and will be compared with the historical control data range.

Statistics:

A Cochran Armitage trend test (p < 0.05) was performed to test whether there was a significant trend in the induction of mutations.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no data
- Effects of osmolality: no data
- Evaporation from medium: the test item was insoluble in exposure medium and ethanol
- Water solubility: no data
- Precipitation: when mixing with exposure medium the test item precipitated at the concentration of 16.4 mg/ml and higher.
- Definition of acceptable cells for analysis: no data


RANGE-FINDING/SCREENING STUDIES: No toxicity in the suspension growth was observed up to and including the highest test item concentration of 512 μg/ml compared to the suspension growth of the solvent control both in the absence and presence of S9-mix. No toxicity in the relative suspension growth was observed up to the test item concentrations of 512 μg/ml compared to the solvent control.


HISTORICAL CONTROL DATA
- Positive historical control data: within the ranges of historical control data
- Negative (solvent/vehicle) historical control data: within the ranges of historical control data. One of the solvent/negative control cultures in experiment II was just above the 95% control limits of the historical control data range. The observed mutation frequency, however, was within the acceptability criteria of this assay.
ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Measurement of cytotoxicity used: No cytotoxicity was observed in experiment I and II.
- Other observations when applicable: In experiment I the number of small and large colonies in the test item treated cultures were comparable to the number of small and large colonies of the solvent controls. In experiment II the test item precipitated in the exposure medium at concentration of 52 µg/ml after 24-hour treatment.

Remarks on result:

other: No mutagenic potential

Remarks:

Experiment I and II

Table 1: Experiment I, 3 -hour exposure without metabolic activation

Test Group	Concentrations µg/ml	RCE %	RTG %	RSG %	MF (mutants/10^6cells)	GEF exceeded	Statistical Significant Increase
SC1	0	100	100	100	79	-	-
SC2	0	100	100	100	124	-	-
1	0.056	102	101	99	93	-	-
2	0.18	104	92	89	97	-	-
3	0.55	111	102	92	106	-	-
4	1.7	134	126	94	95	-	-
5	5.4	105	103	98	51	-	-
6	17	111	100	90	64	-	-
7	52	104	96	93	76	-	-
8	164*	116	104	90	94	-	-
MMS	15	63	39	62	632	+	+

Table 2: Experiment I, 3 -hour exposure with metabolic activation

Test Group	Concentrations µg/ml	RCE %	RTG %	RSG %	MF (mutants/10^6cells)	GEF exceeded	Statistical Significant Increase
SC1	0	100	100	100	91	-	-
SC2	0	100	100	100	117	-	-
1	0.056	100	90	90	105	-	-
2	0.18	86	75	87	116	-	-
3	0.55	104	97	93	100	-	-
4	1.7	97	83	86	136	-	-
5	5.4	110	82	75	81	-	-
6	17	110	96	87	85	-	-
7	52	94	82	87	97	-	-
8	164*	118	103	87	92	-	-
CP	7.5	25	7	27	1938	+	+

Table 3: Experiment II, 24 -hour treatment without metabolic activation

Test Group	Concentrations µg/ml	RCE %	RTG %	RSG %	MF (mutants/10^6cells)	GEF exceeded	Statistical Significant Increase
SC1	0	100	100	100	118	-	-
SC2	0	100	100	100	133	-	-
1	0.018	117	109	93	72	-	-
2	0.056	104	95	91	122	-	-
3	0.18	104	93	89	102	-	-
4	0.55	117	111	95	70	-	-
5	1.7	106	107	101	108	-	-
6	5.4	124	120	97	81	-	-
7	17	114	109	96	85	-	-
8	52*	99	87	88	108	-	-
MMS	15	88	65	74	583	+	+

* the test item precipitated in the exposure medium

RSG: Relative suspension growth

RCE: Relative cloning efficiency

RTG: Relative total growth

SC: solvent control

MMS: methylmethanesulfonate

CP: cyclophosphamine

Conclusions:

1,3,5-Trimethyl-1,1,3,5,5-pentaphenyltrisiloxane has been tested for mutagenicity in mouse lymphoma L5178Y cells, according to OECD 490 and in compliance with GLP. No test substance induced increase in the number of mutations was observed when tested up to precipitating concentration. Appropriate solvent and positive controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the conditions 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

1,3,5-Trimethyl-1,1,3,5,5-pentaphenyltrisiloxane has been tested in a valid bacterial reverse mutation assay, according to the OECD TG 471, and in compliance with GLP, using Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102 (LPT, 2002). No increase in the number of revertants was observed in any test strain, with or without metabolic activation, up to limit concentration. Appropriate positive and solvent controls were added and gave expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.

1,3,5-Trimethyl-1,1,3,5,5-pentaphenyltrisiloxane has been tested in a valid study for ability to induce chromosome aberrations in peripheral human lymphocytes according to OECD TG 473 (2014), and in compliance with GLP. No statistically significant or biologically relevant increase in the number of cells with chromosome aberrations was observed either with or without metabolic activation when tested up to precipitating concentrations. Appropriate positive and negative controls were used and gave the expected results. It is concluded that the test item is negative for the induction of chromosome aberrations under the conditions of the study.

1,3,5-Trimethyl-1,1,3,5,5-pentaphenyltrisiloxane has been tested for mutagenicity in Mouse lymphoma L5178Y cells, according to OECD 490 and in compliance with GLP (Charles River, 2016). No test substance induced increase in the number of mutations was observed when tested up to precipitating concentration. Appropriate solvent and positive controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to mammalian cells under the conditions of the study.

Justification for classification or non-classification

Based on the available data for 1,3,5 -trimethyl-1,1,3,5,5-pentaphenyltrisiloxane, no classification is required for genetic toxicity according to Regulation (EC) No 1272/2008.