2,4-dimethyl-6-(1-methyl-pentadecyl)phenol

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:

15.10. - 11.12.1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study, GLP

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Reference 2

Reference Type:

other: Summary Report

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

adopted May 26, 1983

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1984

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5265 (The Salmonella typhimurium Bacterial Reverse Mutation Test)

Version / remarks:

1987

Test guideline 4

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Version / remarks:

THE MINISTRY OF HEALTH AND WELFARE, Japan, 1984

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2,4-dimethyl-6-(1-methyl-pentadecyl)phenol

EC Number:

411-220-5

EC Name:

2,4-dimethyl-6-(1-methyl-pentadecyl)phenol

Cas Number:

134701-20-5

Molecular formula:

C24 H42 O

IUPAC Name:

2-(hexadecan-2-yl)-4,6-dimethylphenol

Method

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:

S-9 mix prepared from male RAI rat liver five days after i.p. application of 500 mg/kg bw Aroclor 1254.

Test concentrations with justification for top dose:

- Range finding test in WP2 uvrA and TA 100: 0, 20.58, 61.73, 185.19, 555.56, 1666.67, 5000 µg/plate; with and without S9-mix.
- Mutagenicity test: 0, 312.5, 625, 1250, 2500, 5000 µg/plate; with and without S9-mix tested with all tester strains.

Vehicle / solvent:

The test substance was completely dissolved in acetone at a concentration of 50 mg/mL. No precipitates or aggregates were noted at any concentration.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other:

Remarks:

see under "Details on test system and conditions"

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hrs

NUMBER OF REPLICATIONS: three plates for each dose level

NUMBER OF INDEPENDENT EXPERIMENTS: 2

DETERMINATION OF CYTOTOXICITY
- Method: colony counting

POSTIVE CONTROLS
Without S9 mix:
TA 100, TA 1535: sodium azide (5 µg/plate in bidest water)
WP2 uvrA: 4-nitroquinoline-N-oxide (2 µg/plate in DMSO)
TA 98: 2-nitrofluorene (20 µg/plate in DMSO)
TA 1537: 9-aminoacridine (150 µg/plate in DMSO)
with S9 mix:
TA 100, TA 98, TA 1537: 2-aminoanthracene (2.5 µg/plate in DMSO)
TA 1535: cyclophosphamide (400 µg/plate in bidest water)
WP2 uvrA: 2-aminoanthracene (50 µg/plate in DMSO)

Evaluation criteria:

Reaction to a substance is regarded as positive if all of the following criteria are met
- doubling of spontaneous control mutation rate
- dose-response relationship
- reproducibility of results

Statistics:

Not performed.

Results and discussion

Test results

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Remarks:

precipitating of test substance at 1666.67, 5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: Precipitation of the test article was observed at concentrations of 2500 µg/plate and higher

RANGE-FINDING/SCREENING STUDIES:
From the results obtained the highest concentration suitable for the mutagenicity test was selected to be 5000 µg/plate.

COMPARISON WITH HISTORICAL CONTROL DATA:
Historical values of negative and positive controls obtained with each strain without and with microsomal activation, which contained mean values of controls obtained from separate experiments over the period of 15.01.1990 to 02.01.1991.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Experimental Results:

Main Experiment

	TA 100		TA 1535		WP2 uvra		TA 98		TA 1537
Dose (µg/plate)	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Solvent Control	115	86.7	15.3	14.7	26	29	45	61.3	8.3	9
312.5	100.3	87.3	15	13.7	24.7	27	45.3	58.7	7.7	10
625	119	76.3	14.7	13	24.3	30	43.7	67.3	9	6.7
1250	99	76.7	12.3	16	29.7	32.7	41.7	64	6.3	8.7
2500	107.3	85	13.3	14.7	25.7	19.3	45.7	68.3	9.7	10
5000	110	80.3	14.7	16.3	30	28	44.3	62.7	9	11.7
positive control	1250.7	1763	972.3	460.7	876.3	1102.7	1941.3	1839.3	294	2100.7

Confirmatory Experiment

	TA 100		TA 1535		WP2 uvra		TA 98		TA 1537
Dose (µg/plate)	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9	-S9	+S9
Solvent Control	146.3	131.3	15.7	16	17.7	20.7	21.3	35	8	6.3
312.5	132.7	129.7	15.7	18.7	13.7	20.3	15.7	37	6.7	11.7
625	134	136	16	14	15	13.7	21.7	42	8.7	10
1250	129.7	113.7	16.3	15	16	16	17.7	31	10.7	7.7
2500	139	143.7	15	17.7	17.7	17.7	24.7	42.3	8.3	8.7
5000	127.3	129.3	15.3	16.3	20.7	16.3	23.3	35.3		10.3
positive control	1919	2613	698	373.7	1121.7	894.7	1333.7	2524.7	1189.7	137

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

Based on the results of these experiments and on standard evaluation criteria, it is concluded that the test article and its metabolites did not induce gene mutations in the strains of S. typhimurium and E. coli used.

Executive summary:

The test substance was tested in the Salmonella typhimurium reverse mutation assay with Salmonella typhimurium TA98, TA100, TA1535 and TA1537 and with Escherichia coli WP2 uvrA. In the dose range finding test, the test article was tested up to concentrations of 5000 µg/plate in the absence of S9-mix in the strains TA100 and in E.coli WP2 uvrA. At this dose level no toxicity was observed. Consequently, the main test was performed with concentrations of up to 5000 µg/plate in the absence and presence of S9 -mix. In the experiments performed without and with microsomal activation, treatment with the test article did not lead to an increase in the incidence of either histidine- or tryptophanprototrophic mutants in comparison with the negative control. In the confirmatory experiment performed without and with microsomal activation, again after treatment of the bacteria with the test substance no increase in the incidence of either histidine- or tryptophan-prototrophic mutants was observed in comparison with the negative control. Precipitation of the test material occurred at concentrations of 2500 µg/plate and up. Based on the results of this study it is concluded that the test article is not mutagenic in the Salmonella typhimurium reverse mutation assay.