Ethylcyclohexane

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:

2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

not specified

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Ethylcyclohexane

EC Number:

216-835-0

EC Name:

Ethylcyclohexane

Cas Number:

1678-91-7

Molecular formula:

C8H16

IUPAC Name:

ethylcyclohexane

Test material form:

liquid: volatile

Specific details on test material used for the study:

Name:Ethylcyclohexane
Additional name: Hexahydroethylbenzene
CAS registry number: 1678-91-7
Batch number:
Purity: 99.9%

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:

S9 mix

Test concentrations with justification for top dose:

With the direct method, the range of 0.156–5 µg per plate (common divisor: 2) was set for all strains. With the metabolic activation method, 3.13–100 µg per plate was set for TA100, TA1535, TA98, and TA1537, and 6.25–200 µg per plate for WP2uvrA (common divisor: 2).

Vehicle / solvent:

acetone

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

9-aminoacridine

sodium azide

other: 2-(2-Furyl)-3-(5-nitro-2-furyl)-acrylamide, 2-Aminoanthracene

Evaluation criteria:

A result that met the following three criteria was determined positive based on mean revertant colony count per plate at each dose.
(1) The revertant colony count at least two times higher than that in the negative control group was observed in a test substance group.
(2) The revertant colony count was raised as an increase in the dose of test substance (dose dependency).
(3) Reproducibility of the increase in revertant colony count was observed based on the results of the tests performed two times. However, a result was determined positive if no significant dose dependency but reproducibility in positive results was observed.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

Ethylcyclohexane was determined not mutagenic for bacteria under the described test conditions.

Executive summary:

A reverse mutation test was performed to investigate mutagenesis of ethylcyclohexane using Salmonella typhimurium TA100, TA1535, TA98, TA1537, and Escherichia coli WP2uvrA as indicator bacteria without the S9 mix (direct method) and with the S9 mix (metabolic activation method) by preincubation. Based on results of a dose finding study (preliminary test), dose inhibiting bacterial growth was considered the maximum dose. With the direct method, the range of 0.156–5 µg per plate (common divisor: 2) was set for all strains. With the metabolic activation method, 3.13–100 µg per plate was set for TA100, TA1535, TA98, and TA1537, and 6.25–200 µg per plate for WP2uvrA (common divisor: 2). The test was performed two times. The results showed no increase in the revertant colony count in all strains, irrespective of metabolic activation. With the direct method, bacterial growth inhibition was observed at 5 μg per plate in all strains and at 2.5 μg per plate in TA1537 during the second test. With the metabolic activation method, bacterial growth inhibition was observed at 100 μg per plate in TA100, TA1535, TA98, and TA1537, at 200 μg per plate in WP2uvrA, and at 50 μg per plate in TA1535 during the first test. From the findings above, ethylcyclohexane was determined not mutagenic for bacteria under the test conditions.