Trisiloxane, 1,1,1,3,5,5,5-heptamethyl-3-tetradecyl-

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Myristyl Trisiloxane during mutagenicity test and under the experimental conditions did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, myristyl trisiloxane is considered to be non-mutagenic in this bacterial reverse mutation assay.

Link to relevant study records

Reference

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:

From May 22, 2007 to June 21, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant with international guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5100 (Escherichia coli WP2 and WP2 UVRA Reverse Mutation Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

The Salmonella typhimurium histidine (bis) reversion system measures his - → his+ reversions. The S. typhimurium strains are constructed to differentiate between base pair (TA 100, TA 1535, TA 102) and fra neshift (TA 98, TA 1537) mutations.

Five strains of S. typhimurium with the following characteristics were used:

TA 98:
his D 3052; rfa-; uvrB-; R-factor: frame shift mutations
TA 100:
his G 46; rfa- ; uvrB- ; R-factor: base-pair substitutions
TA 1535:.
his G 46; rfa- ; uvrB-: base-pair substitutions
TA 1537:
his C 3076; rfa- ; uvrB- : frame shift mutations
TA 102:
his G 428 (pAQ1I); rfa- ; R-factor: base-pair substitutions

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9

Test concentrations with justification for top dose:

Pretest: 3.16, 10.0, 31.6, 100, 316, 1000, 2500 and 5000 µg/plate
Main test 31.6, 100, 316, 1000, 2500 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used:DMSO
- Justification for choice of solvent/vehicle:The test item was dissolved in DMSO and diluted prior to treatment. The solvent was compatible with the survival of the bacteria and the S9 activity.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 4-nitro-o-phenylene-diamine

Remarks:

Without metabolic activation

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

With metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar (plate incorporation)
The Salmonella tester strains TA 98, TA 100, TA 1535 and TA 102 were obtained from Xenometrix, San Diego, CA., USA. Tester strain TA 1537 was obtained from MOLTOX, INC, NC 28607, USA. They are stored as stock cultures in ampoules wich nutrient broth (OXOID) supplemented with DMSO (approx. 8% v/v) over liquid nitrogen.

Agar Plates
The Vogel-Bonner Medium E agar plates wich 2% glucose used in the Ames test were prepared by BSL BIOSERVICE or provided by an appropriate supplier. Quality controls were performed.
Vogel-Bonner-salts contain per litre:
10 g MgSO4 x 7 H2O
100 g Citric acid
175 g NaNH4HPO4 x 4 H2O
500 g K2HP04
Sterilisation was performed at 121 °C in an autoclave.
Vogel-Bonner Medium E agar plates contain per litre:
15 g Agar Agar
20 mL Vogel-Bonner salts
50 mL Glucose-solvent (40%)
Sterilisation was perforined at 121 °C in an autoclave.
Overlay Agar
The overlay agar contains per litre:
7.0 g Agar Agar
6.0 g NaCl
10.5 mg L-histidine x HC1 x H20
12.2 mg Biotin
Sterilisation was performed at 121 °C in an autoclave.

DURATION
- Preincubation period:Samples of each tester strain were grown by culturing for 12 h at 38.5 °C in nutrient broth to the late exponential or early stationary phase of growth (approx. 10^9 cells/ml).
- Exposure duration:
- Expression time (cells in growth medium):
- Selection time (if incubation with a selection agent):
- Fixation time (start of exposure up to fixation or harvest of cells):

SELECTION AGENT (mutation assays):
SPINDLE INHIBITOR (cytogenetic assays):
STAIN (for cytogenetic assays):

NUMBER OF REPLICATIONS:3

NUMBER OF CELLS EVALUATED:10^9 cells/ml

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other:
Cytotoxicity can be detected by a clearing or rather diminution of the background lawn or a reduction in the number of revertants down to a mutation factor of approximately < 0.5 in relation to the solvent control.

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

OTHER:

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:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation of the test item was observed in any of the five tester strains used up to the highest dose group evaluated with and without metabolic activation in experiment I and II.
- Other confounding effects:

ADDITIONAL INFORMATION ON CYTOTOXICITY: No toxic effects of the test item were noted in any of the five tester strains used up to the highest dose group evaluated with and without metabolic activation in experiment I and II. The reduction in the number of revertants down to mutation factors of 0.5 (without metabolic activation) and 0.4 (with metabolic activation) found in tester strain TA 102 in experiment II at a dose of 31.6 µg/plate was regarded as not biologically relevant due to the lacking dose-response relationship.

Remarks on result:

other: strain/cell type: base pair changes or frameshifts in the genome of the tester strains used.

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, the test item did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, Myristyl Trisiloxane is considered to be non-mutagenic in this bacterial reverse mutation assay.

Executive summary:

In order to investigate the potential of test item for its ability to induce gene mutations the plate incorporation test (experiment I) and the pre-incubation test (experiment II) were performed with the Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537 and TA 102.

In two independent experiments several concentrations of the test item were used. Each assay was conducted with and without metabolic activation. The concentrations, including the controls, were tested in triplicate. The following concentrations of the test item were prepared and used in the experiments: 31.6, 100, 316, 1000, 2500 and 5000 µg/plate.

No precipitation of the test item was observed in any tester strain used in experiment I and II (with and without metabolic activation).

No toxic effects of the test item were noted in any of the five tester strains used up to the highest dose group evaluated (with and without metabolic activation) in experiment I and II. No biologically relevant increases in revertant colony numbers of any of the five tester strains were observed following treatment with test item at any concentration level, neither in the presence nor absence of metabolic activation in experiment I and II.

The reference mutagens induced a distinct increase of revertant colonies indicating the validity of the experiments.

In conclusion, it can be stated that during the described mutagenicity test and under the experimental conditions reported, The test item did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used.

Therefore, myristyl trisiloxane is considered to be non-mutagenic in this bacterial reverse mutation assay.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Justification for selection of genetic toxicity endpoint
Well performed test, exhaustive report

Justification for classification or non-classification

Based on REGULATION (EC) No 1272/2008 the test item Myristyl Trisiloxane don't produce any permanent change in the amount or structure of the genetic material in a cell; therefore no classification is required..