1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane

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:

2002-05-10 to 2002-09-09

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

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:

1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane

EC Number:

223-620-5

EC Name:

1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane

Cas Number:

3982-82-9

Molecular formula:

C28H32O2Si3

IUPAC Name:

1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane

Method

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:

See table 1

Vehicle / solvent:

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

- 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: Relative cell count / background lawn

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.

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

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:

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

Remarks on result:

other: No mutagenic potential

Any other information on results incl. tables

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

	TA100
Conc. (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 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*	28	37	No	150	147.3	No	285.3	282.3	No
100	26.7	35.7	No	129	154.7	No	267	268	No
316	32	40.3	No	141	153.7	No	283.7	264.7	No
1000	29.3	29	No	140.7	147	No	287.3	259.3	No
3160	27.3	39	No	138	135.3	No	274.7	272	No
5000	27.3	36	No	128	150.7	No	263.7	296.7	No
Positive control	575.3	641.7	No	1009.7	941.7	No	1035	1038	No

*solvent control with DMSO

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*	17.3	18.3	No	6.7	4	No
100	17.3	14.7	No	4.7	6.3	No
316	20.7	18.7	No	6.7	6.3	No
1000	18	13.7	No	5.7	4.7	No
3160	17	18.7	No	8	5.7	No
5000	16.3	17.7	No	6.3	4.7	No
Positive control	740.7	645.3	No	324.3	320	No

*solvent control with DMSO

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*	42.3	41.7	No	152.3	123.7	No	278.3	279.3	No
100	36.3	31	No	129.7	122	No	282.7	290.3	No
316	30	30	No	128.3	158	No	262.7	270.7	No
1000	32	40	No	117	128.3	No	270.7	272.3	No
3160	23.3	29.3	No	121	142.7	No	274.3	270.7	No
5000	33.3	37.7	No	140.7	117	No	281.3	269	No
Positive control	546.7	533.3	No	1143.7	1139.0	No	1249.7	1249.7	No

*solvent control with DMSO

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*	15.3	14.7	No	4	4.3	No
100	13.3	12.3	No	3.3	3	No
316	12.7	13.7	No	5.0	4.3	No
1000	12	15.7	No	3.3	4.3	No
3160	13	15.7	No	3	3	No
5000	13.7	16	No	4.3	4.3	No
Positive control	321.3	333	No	338.3	348.7	No

*solvent control with DMSO

Applicant's summary and conclusion

Conclusions:

In a reliable test conducted in compliance with OECD 471, under 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.