Tetradecamethylhexasiloxane

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:

23 September 2014 to 03 November 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

adopted 21st July 1997

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: EC No. 440/2008 B.13/14:"Mutagenicity - Reverse Mutation Test using Bacteria"

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Tetradecamethylhexasiloxane

EC Number:

203-499-5

EC Name:

Tetradecamethylhexasiloxane

Cas Number:

107-52-8

Molecular formula:

C14H42O5Si6

IUPAC Name:

2,2,4,4,6,6,8,8,10,10,12,12-dodecamethyl-3,5,7,9,11-pentaoxa-2,4,6,8,10,12-hexasilatridecane

Method

Target gene:

histidine operon

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:

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

Test concentrations with justification for top dose:

0.0316, 0.100, 0.316, 1.0, 2.5, 5.0 µL/plate

Vehicle / solvent:

ethanol

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Remarks:

dissolved in distilled water

Positive control substance:

sodium azide

Remarks:

-MA; TA 100, TA 1535; 10 µg/plate

Controls 2

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Remarks:

dissolved in DMSO

Positive control substance:

other: 4-nitro-o-phenylene-diamine

Remarks:

-MA; 10 µg/plate TA 98; 40 µg/plate TA 1537

Controls 3

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Remarks:

dissolved in distilled water

Positive control substance:

methylmethanesulfonate

Remarks:

-MA; TA 102; 1 µL/plate

Controls 4

Untreated negative controls:

yes

Remarks:

distilled water

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Remarks:

dissolved in DMSO

Positive control substance:

other: 2-aminoanthracene

Remarks:

+MA; all strains; 2.5 µg/plate, 10 µg/plate for TA 102

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation), pre-incubation

ACTIVATION:
Protein concentrations in S9 preparation:
- 34.7 mg/mL phenobarbital
- 33 mg/mL ß-naphthoflavone

S9 mix included 5% S9 and the following cofactors: 8 mM MgCl₂; 33 mM KCl; 5 mM glucose-6-phosphate; 4 mM NADP. The final concentration of S9 in the plates was approximately 1%.

DURATION
- Preincubation period: 60 min at 27°C
- Exposure duration: after solidification, the plates were inverted and incubated at 37°C for at least 48 h in the dark

SELECTION AGENT: histidine deficient agar

NUMBER OF REPLICATIONS: triplicate plates. The inital plate incorporation assay was repeated using the preincubation method.

DETERMINATION OF CYTOTOXICITY
- Method: other: clearing or diminuation of background bacterial lawn/reduction in number of revertants down to a mutation faction of approximately ≤0.5 in relation to the solvent control

Evaluation criteria:

A test item is considered as mutagenic if:
- a clear and dose-related increase in the number of revertants occurs and/or
- a biologically relevant positive response for at least one of the dose groups occurs
in at least one test strain with or without metabolic activation.
A biologically relevant increase is:
- if in tester strains TA 98, TA 100 and TA 102 the number of reversions is at least twice as high
- if in test strains TA 1537 and TA 1535 the number of reversions is at least three times higher than the reversion rate of the solvent control.

Results and discussion

Test results

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

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other:

Remarks:

No mutagenic potential observed

Any other information on results incl. tables

Plate incorporation test: number of revertant colonies per plate (mean of 3 plates)

Dose/plate	TA 98		TA 100		TA 1535		TA 1537		TA 102
	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA
Distilled water	29	21	121	83	8	6	6	9	313	268
Ethanol	31	21	103	90	6	5	4	8	261	258
0.0316 µL	27	25	117	96	7	11	4	6	367	305
0.100 µL	30	25	111	102	8	7	11	11	369	300
0.316 µL	32	27	110	105	7	12	6	6	397	305
1.000 µL	32	26	121	103	6	6	7	8	337	290
2.50 µL	34	23	122	100	10	6	7	9	338	324
5.0 µL	34	21	111	86	7	6	7	7	369	279
4-NOPD 10 µg	-	283	-	-	-	-	-	51	-	-
2-AA 2.5 µg	2822	-	2300	-	157	-	285	-	964	-
NaN310 µg	-	-	-	482	-	463	-	-	-	-
MMS 1 µL	-	-	-	-	-	-	-	-	-	2395

 

Plate-incubation test: number of revertant colonies per plate (mean of 3 plates)

Dose/plate	TA 98		TA 100		TA 1535		TA 1537		TA 102
	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA	+ MA	- MA
Distilled water	32	19	82	81	16	17	5	7	236	187
Ethanol	29	21	97	61	11	9	5	4	208	198
0.0316 µL	35	20	93	92	16	18	10	7	212	198
0.100 µL	28	19	92	81	14	11	7	6	185	164
0.316 µL	31	21	77	74	14	14	7	7	151	136
1.000 µL	26	19	89	62	12	10	8	7	142	109
2.50 µL	28	23	92	77	16	17	10	8	182	134
5.0 µL	28	21	100	94	15	15	11	6	232	197
4-NOPD 10 µg	-	291	-	-	-	-	-	84	-	-
2-AA 2.5 µg	2908	-	1124	-	92	-	179	-	567	-
NaN310 µg	-	-	-	226	-	1226	-	-	-	-
MMS 1 µL	-	-	-	-	-	-	-	-	-	2199

 

4-NOPD = 4-nitro-o-phenylene-diamine

2-AA = 2-aminoanthracene

NaN₃= sodium azide

MMS = methylmethanesulfonate

Applicant's summary and conclusion

Conclusions:

Tetradecamethylhexasiloxane has been tested for mutagenicity to bacteria, in a study which was conducted according to the OECD TG 471, compliant with GLP. No evidence of a test-substance related increase in the number of revertants was observed with or without metabolic activation in Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 or TA 102. in the initial plate incorporation assay or the repeat experiment using the preincubation method, up to limit concentrations. Appropriate positive, solvent and negative (water) controls were included and gave the expected results. It is concluded that the test substance is negative for mutagenicity to bacteria under the conditions of the test.