Isopropyl myristate

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:

04 -29 Sep 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

adopted in 1997

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Isopropyl myristate

EC Number:

203-751-4

EC Name:

Isopropyl myristate

Cas Number:

110-27-0

Molecular formula:

C17H34O2

IUPAC Name:

isopropyl myristate

Details on test material:

- Name of test material (as cited in study report): Isopropyl myristate
- Physical state: colourless liquid
- Analytical purity: 98%
- Lot/batch No.: OE30926X01
- Expiration date of the lot/batch: 26 September 2015
- Storage condition of test material: at room temperature

Method

Target gene:

his operon for S. typhimurium strains and trp operon for E.coli strain

Species / strain

Species / strain 1

Species / strain / cell type:

E. coli WP2 uvr A

Species / strain 2

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of rats treated with Aroclor 1254 (500 mg/kg bw)

Test concentrations with justification for top dose:

Dose range finding assay = 1.7, 5.4, 17, 52, 164, 512, 1600 and 5000 µg/plate in the absence and presence of 5% (v/v) S9-mix in tester strains TA 100 and WP2 uvrA.
First mutation assay = 52, 164, 512, 1600 and 5000 µg/plate in the absence and presence of 5% (v/v) S9-mix in tester strains TA 1535, TA 1537 and TA 98.
Second mutation assay = 52, 164, 512, 1600 and 5000 µg/plate in the absence and presence of 10% (v/v) S9-mix in tester strains TA 1535, TA 1537, TA 98, TA100 and WP2 uvrA.
Third mutation assay = 52, 164, 512, 1600 and 5000 µg/plate in the absence of S9-mix in tester strains TA 98, only.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: +S9: 2-aminoanthracene (2.5 µg/plate for TA1535 + TA1537; 5 µg/plate for TA1537; 1 µg/plate for TA98 + TA100; 2 µg/plate for TA100 and 15 µg/plate for WP2uvrA)

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

ethanol

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: -S9: sodium azide (5 µg/plate) for TA1535; ICR-191 (2.5 µg/plate) for TA1537; 4-nitroquinoline N-oxide (10 µg/plate) for WP2uvrA; methylmethanesulfonate (650 µg/plate) for TA100 and 2-nitrofluorene (10 µg/plate) for TA98

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 h

NUMBER OF REPLICATIONS: 3 replications in 3 independent experiments.

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

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 vehicle control.
b) The negative response should be reproducible in at least one a follow-up experiment.

A test substance is considered positive (mutagenic) in the test 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 vehicle control.
b) In case a follow up 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:

Mean values and standard deviation were calculated

Results and discussion

Test results

Test results 1

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

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

Remarks:

was observed in tester strain TA 100 in the presence of S9-mix at ≥ 512 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, droplets of isopropyl myristate on the plates was observed at the start of the incubation period at concentrations of 512 μg/plate and upwards and at 1600 and 5000 μg/plate at the end of the incubation period in all experiments.

RANGE-FINDING/SCREENING STUDIES: Isopropyl myristate was tested up to concentrations of 5000 μg/plate in the absence and presence of S9-mix in the strains TA100 and WP2uvrA. Isopropyl myristate precipitated (observed as droplets) on the plates at dose levels of 1600 and 5000 μg/plate. In tester strain TA100, toxicity was only observed at dose levels of 512 and 1600 μg/plate in the presence of S9-mix. In tester strain WP2uvrA, no toxicity was observed at any of the dose levels tested. Based on the results of the dose range finding test, the following dose range was selected for the mutation assay with the tester strains, TA1535, TA1537 and TA98 in the absence and presence of S9-mix: 52, 164, 512, 1600 and 5000 μg/plate.

ADDITIONAL INFORMATION ON CYTOTOXICITY: Cytotoxicity was only observed in tester strain TA100 in the presence of S9-mix, where a moderate to extreme reduction of the revertant colonies was observed at test substance concentrations of 512 µg/plate and above. 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 other tester strains in the absence and presence of S9-mix.

ADDITIONAL INFORMATION ON MUTAGENICITY: In tester strain TA98 a 3.3-fold increases in the number of revertant colonies compared to the solvent control in the absence of S9-mix was observed. Since this increase was observed at a precipitating dose level and was not reproducible in two other experiments, this increase was not considered to be relevant.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative