5-methyl-5-phenylhexan-3-one

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 April, 2016 - 21 April, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

21 July, 1997

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

31 May 2008

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

5-methyl-5-phenylhexan-3-one

EC Number:

225-561-0

EC Name:

5-methyl-5-phenylhexan-3-one

Cas Number:

4927-36-0

Molecular formula:

C13H18O

IUPAC Name:

5-methyl-5-phenylhexan-3-one

Test material form:

liquid

Method

Target gene:

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

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced by Aroclor 1254.

Test concentrations with justification for top dose:

Direct plate:
- Dose range finding test:
TA 100 and WP2uvrA (without and with S9): 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 μg/plate
Based on the results of experiment 1, the following dose levels were used:
- Experiment 1:
TA 1535, TA 1537 and TA 98 (without and with S9): 17, 52, 164, 512 and 1600 μg/plate
Preincubation:
- Experiment 2:
Based on the results of experiment 1, the following dose levels were used:
TA 1535, TA 1537, TA 98, TA 100 and WP2uvrA (without and with S9): 5.4, 17, 52, 164, 512 and 1600 μg/plate

Vehicle / solvent:

- Vehicle used: Dimethyl sulfoxide (DMSO)
- Justification for choice of vehicle: A solubility test was performed. The test item was dissolved in dimethyl sulfoxide.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

100 μL/plate DMSO

Positive controls:

yes

Positive control substance:

other: see section "Any other information on materials and methods incl. tables"

Details on test system and experimental conditions:

METHOD OF APPLICATION:
- Experiment 1: in agar (plate incorporation)
- Experiment 2: (independent repeat): preincubation

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

NUMBER OF REPLICATIONS:
- Doses of the test substance were tested in triplicate in each strain (in all experiments)

DETERMINATION OF CYTOTOXICITY
- Method: on the basis of a decline in the number of spontaneous revertants, a thinning of the background lawn or a microcolony formation.

Evaluation criteria:

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

Statistics:

Not performed.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

direct plate: at 1600 and 5000 μg/plate; pre-incubation assay: at 164, 512 and 1600 μg/plate

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

direct plate without and with S9: at 1600 μg/plate; pre-incubation assay without and with S9: at 164, 512 and 1600 μg/plateg/plate.

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

direct plate without and with S9: at 1600 μg/plate; pre-incubation assay without and with S9: at 164, 512 and 1600 μg/plateg/plate.

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

direct plate without S9 only: at 1600 μg/plate; pre-incubation assay without and with S9: at 164, 512 and 1600 μg/plateg/plate.

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

direct plate: no toxicity was observed; pre-incubation assay without S9: at 164, 512 and 1600 μg/plateg/plate, with S9: at 512 and 1600 μg/plateg/plate.

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation:
Dose range finding test: Precipitation of the test item on the plates was observed at the start of the incubation period at the concentration of 5000 μg/plate and at 1600 and 5000 μg/plate at the end of the incubation period. The precipitation of 5000 μg/plate at the end of the incubation period was observed as small droplets of the test item.
First mutation experiment: No precipitation of Damascol/4 on the plates was observed at the start of the incubation period and the test item precipitated at the concentration of 1600 μg/plate at the end of the incubation period.
Precipitation of Damascol/4 on the plates was not observed at the start or at the end of the incubation period.

RANGE-FINDING/SCREENING STUDIES: In tester strain TA100, toxicity was observed at dose levels of 1600 μg/plate and above in the absence and presence of S9-mix. In tester strain WP2uvrA, no toxicity was observed at any of the dose levels tested.

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Positive historical control data:
TA1535 TA1537 TA98
S9-mix - + - + - +
Range 78 - 1932 81 - 1332 62 – 1565 55 – 1112 347 – 1967 261 - 1885
Mean 791 234 662 409 976 821
SD 261 98 206 126 251 298
n 1732 1737 1409 1428 1721 1737

TA100 WP2uvrA
S9-mix - + - +
Range 549 – 1798 640 - 2760 123 – 1958 85 - 1390
Mean 914 1387 1367 261
SD 150 324 276 276
n 1734 1752 1373 1404

SD = Standard deviation
n = Number of observations

Historical control data from experiments performed between November 2013 and January 2016.

- Negative (solvent/vehicle) historical control data:
TA1535 TA1537 TA98 TA100 WP2uvrA
S9-mix - + - + - + - + - +
Range 5 - 36 3 - 34 3 – 25 3 - 28 9 - 50 9 - 57 63 - 153 60 - 156 13 – 68 12 - 70
Mean 177 14 7 9 18 26 104 105 28 34
SD 6 5 3 3 6 7 17 17 7 7
n 1644 1716 1425 1443 1707 1730 1725 1739 1368 1404

SD = Standard deviation
n = Number of observations

Historical control data from experiments performed between November 2013 and January 2016.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
Experiment 1: Cytotoxicity, as evidenced by a slight to extreme decrease in the number of revertants, was observed in the tester strains TA1535 and TA1537 (absence and presence of S9-mix), TA98 (absence of S9-mix) at the highest tested concentration. No toxicity was observed in tester strains TA98 in the presence of S9-mix.
Experiment 2: Cytotoxicity, as evidenced by a slight to extreme decrease in the number of revertants and/or reductions of the bacterial background lawn, was observed in all tester strains.

Applicant's summary and conclusion

Conclusions:

The substance is not mutagenic in the Salmonella typhimurium reverse mutation assay and Escherichia coli reverse mutation assay performed according to OECD 471 (1997) and GLP principles. Therefore, Damascol 4 does not need to be classified for mutagenicity in accordance with the criteria outlined in Annex I of the CLP regulation (1272/2008/EC).

Executive summary:

The mutagenic activity of the substance was evaluated in accordance with OECD 471 (1997) guideline and according to GLP principles. The test was performed in two independent experiments: at first a direct plate assay was performed and secondly a pre-incubation assay, both in the absence and presence of S9-mix up to and including 1600 μg/plate. The dose levels were selected based on a dose range finding test with strain TA100 and WP2uvrA. In experiment 1, cytotoxicity, as evidenced by a slight to extreme decrease in the number of revertants, was observed in the tester strains TA1535 and TA1537 (absence and presence of S9-mix), TA98 (absence of S9-mix) at the highest tested concentration. No toxicity was observed in tester strains TA98 in the presence of S9-mix and in tester strain WP2uvrA. In the second mutation assay, cytotoxicity, as evidenced by a slight to extreme decrease in the number of revertants and/or reductions of the bacterial background lawn, was observed in all tester strains. The substance did not induce a significant dose related increase in the number of revertant (His+) colonies in each of the four S. typhimurium tester strains (TA1535, TA1537, TA98 and TA100) and E. coli tester strain (WP2uvrA), both in the absence and presence of S9 -metabolic activation. These results were confirmed in independently repeated experiments. Based on the results of this study it is concluded that the substance is not mutagenic in the Salmonella typhimurium reverse mutation assay and Escherichia coli reverse mutation assay. Therefore, Damascol 4 does not need to be classified for mutagenicity in accordance with the criteria outlined in Annex I of the CLP regulation (1272/2008/EC).