3-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]propane-1,2-diol

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:

05 January - 19 January, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

(1997)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(2008)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Food and Agricultural Materials Inspection Centre (FAMIC), 12 Nousan, Notification No 8147, April 2011, including the most recent partial revisions.

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:

3-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]propane-1,2-diol

EC Number:

807-413-2

Cas Number:

70280-68-1

Molecular formula:

C13H34O5Si3

IUPAC Name:

3-[3-(1,1,1,3,5,5,5-heptamethyltrisiloxan-3-yl)propoxy]propane-1,2-diol

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): X-22-1927
- Appearance: Clear light yellow liquid
- CAS Number: 70280-68-1

Method

Target gene:

- S. typhimurium: Histidine gene
- E. coli: Tryptophan gene

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced with Aroclor 1254 (500 mg/kg bw)

Test concentrations with justification for top dose:

Experiment 1
Preliminary test (without and with S9) TA100 and WP2uvrA: 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 µg/plate
Main study: TA1535, TA1537 and TA98:
Without and with S9-mix: 52, 164, 512, 1600 and 5000 µg/plate
Experiment 2:
Without and with S9-mix: 52, 164, 512, 1600 and 5000 µg/plate

Vehicle / solvent:

- Solvent used: DMSO
- Justification for choice of solvent/vehicle: Test compound was soluble and stable in DMSO and DMSO has been accepted and approved by authorities and international guidelines.

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without S9

Migrated to IUCLID6: 650 µg/plate in DMSO for TA100

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

other: 2-nitrofluorene 10 µg/plate in DMSO for TA98 (both experiments) and 15 µg/plate in DMSO for TA1537 in the preincubation assay

Remarks:

without S9

Controls 3

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

other: ICR-191 2.5 µg/plate in DMSO for TA1537 in the direct plate assay

Remarks:

without S9

Controls 4

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

without S9

Migrated to IUCLID6: 10 µg/plate in DMSO for WP2uvrA

Controls 5

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

sodium azide

Remarks:

without S9

Migrated to IUCLID6: 5 µg/plate in saline for TA1535

Controls 6

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene in DMSO for all tester strains

Remarks:

with S9

Details on test system and experimental conditions:

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

DURATION
- Preincubation period: 30 minutes
- Exposure duration: 48 hour

NUMBER OF REPLICATIONS:
- Doses of the test substance were tested in triplicate in each strain. Two independent experiments were conducted, first experiment: direct plate assay and second experiment: pre-incubation assay

NUMBER OF CELLS EVALUATED: 10E8 per plate

DETERMINATION OF CYTOTOXICITY
- Method: The reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies.

OTHER EXAMINATIONS:
- The presence of precipitation of the test compound on the plates was determined.

Evaluation criteria:

A test substance is considered negative (not mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 is not greater than two (2) times the concurrent control, and the total number of revertants in tester strains TA1535, TA1537, TA98 or WP2uvrA is not greater than three (3) times the concurrent control.
b) The negative response should be reproducible in at least one independently repeated experiment.

A test substance is considered positive (mutagenic) if:
a) The total number of revertants in tester strain TA100 is greater than two (2) times the concurrent control, or the total number of revertants in tester strains TA1535, TA1537, TA98 or WP2uvrA is greater than three (3) times the concurrent control.
b) In case a repeat experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one independently repeated experiment.

Results and discussion

Test results

Test results 1

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:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation:
Direct plate assay: Oily droplets of X-22-1927 on the plates were observed at the start of the incubation period at concentrations of 1600 and 5000 μg/plate and at 5000 μg/plate at the end of the incubation period.
Preincubation assay: At the start of the incubation period: Oily droplets of X-22-1927 on the plates were observed at concentrations of 1600 and 5000 μg/plate. At the end of the incubation period: Oily droplets of X-22-1927 on the plates were observed at 5000 μg/plate in the absence of S9-mix. Precipitation of the test substance on the plates was observed at concentration of 1600 and 5000 μg/plate in the presence of S9-mix.

RANGE-FINDING/SCREENING STUDIES:
- In tester strain TA100, slight to extreme reductions in the number of revertant colonies were observed at test substance concentrations of 512 μg/plate and above in the absence of S9-mix and at 1600 and 5000 μg/plate in the presence of S9-mix. In the other tester strains, there was no reduction in the bacterial background lawn and no biologically relevant decrease in the number of revertants at any of the concentrations tested in the absence and presence of S9-mix. No increase in the number of revertants was observed upon treatment with X-22-1927 under all conditions tested.

COMPARISON WITH HISTORICAL CONTROL DATA:
- The negative and strain-specific positive control values were within our laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
Preincubation assay:
In the absence of S9-mix, a slight reduction of the bacterial background lawn was observed at the concentration of 5000 μg/plate in the tester strains TA1537, TA98 and TA100 and at 1600 μg/plate in the tester strains TA1537 and TA100. Furthermore, a slight reduction in the number of revertants was observed at test concentrations of 164 μg/plate and upwards in tester strain TA100. In the presence of S9-mix, a slight reduction in the number of revertants was observed at the test concentration of 5000 μg/plate in tester strain TA100.
In the other tester strains, there was no reduction in the bacterial background lawn and no biologically relevant decrease in the number of revertants at any of the concentrations tested in the absence and presence of S9-mix.

MUTAGENICITY:
In the direct plate test, no increase in the number of revertants was observed upon treatment with X-22-1927 under all conditions tested.
In the pre-incubation test, no increase in the number of revertants was observed upon treatment with X-22-1927 under all conditions tested.
In tester strain TA1535 in the presence of S9-mix, X-22-1927 induced a three-fold increase compared to the solvent control. However the observed increase was not above the limit of the laboratory historical control data range and the increase was caused by only one out of three plates (85, 9 and 9 revertant colonies/plate). Therefore, this increase is considered to be not biologically relevant and X-22-1927 is considered to be not mutagenic.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

In an AMES test, performed according to OECD 471 guideline and GLP principles, X-22-1927 was found not to be mutagenic with or without metabolic activation.

Executive summary:

An AMES test was performed according to OECD 471 guideline and GLP principles. All bacterial strains, TA98, TA100, TA1535, TA1537 and WP2uvrA, showed negative responses up to and including 5000 µg/plate, i.e. no significant dose-related increase in the number of revertants with or without metabolic activation was seen. The first test was a direct plate assay and the independent repeat was a preincubation assay. Cytotoxicity, as evidenced by a decrease in the number of revertants or reduction of the bacterial background lawn, was observed in the tester strains TA1537, TA98 and TA100 in the absence of S9-mix and at TA100 in the presence of S9-mix. Precipitation of the test substance was observed. The negative and strain-specific positive control values were within the laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

Based on the results of this study it is concluded that X-22 -1927 is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with or without metabolic activation.