A mixture of: 4-(2,2,3-trimethylcyclopent-3-en-1-yl)-1-methyl-2-oxabicyclo[2.2.2]octane; 1-(2,2,3-trimethylcyclopent-3-en-1-yl)-5-methyl-6-oxabicyclo[3.2.1]octane; spiro[cyclohex-3-en-1-yl-[(4,5,6,6a-tetrahydro-3,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]furan]; spiro[cyclohex-3-en-1-yl-[4,5,6,6a-tetrahydro-4,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]]furan]

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:

The experimental phase of the study was conducted between 14 and 30 April 1993.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

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:

A mixture of: 4-(2,2,3-trimethylcyclopent-3-en-1-yl)-1-methyl-2-oxabicyclo[2.2.2]octane; 1-(2,2,3-trimethylcyclopent-3-en-1-yl)-5-methyl-6-oxabicyclo[3.2.1]octane; spiro[cyclohex-3-en-1-yl-[(4,5,6,6a-tetrahydro-3,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]furan]; spiro[cyclohex-3-en-1-yl-[4,5,6,6a-tetrahydro-4,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]]furan]

EC Number:

422-040-1

EC Name:

A mixture of: 4-(2,2,3-trimethylcyclopent-3-en-1-yl)-1-methyl-2-oxabicyclo[2.2.2]octane; 1-(2,2,3-trimethylcyclopent-3-en-1-yl)-5-methyl-6-oxabicyclo[3.2.1]octane; spiro[cyclohex-3-en-1-yl-[(4,5,6,6a-tetrahydro-3,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]furan]; spiro[cyclohex-3-en-1-yl-[4,5,6,6a-tetrahydro-4,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]]furan]

Cas Number:

426218-78-2

Molecular formula:

C16H26O

IUPAC Name:

1-methyl-4-(2,2,3-trimethylcyclopent-3-en-1-yl)-2-oxabicyclo[2.2.2]octane; 3,6',6',6'a-tetramethyl-2',3'a,4',5',6',6'a-hexahydrospiro[cyclohexane-1,3'-cyclopenta[b]fura]-3-ene; 4,6',6',6'a-tetramethyl-2',3'a,4',5',6',6'a-hexahydrospiro[cyclohexane-1,3'-cyclopenta[b]fura]-3-ene; 5-methyl-1-(2,2,3-trimethylcyclopent-3-en-1-yl)-6-oxabicyclo[3.2.1]octane

Test material form:

liquid

Method

Target gene:

Histidine for Salmonella.
Tryptophan for E.Coli

Species / strain

Species / strain 1

Species / strain / cell type:

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

Details on mammalian cell type (if applicable):

Not applicable.

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1538

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Species / strain 3

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

Not applicable.

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced rat liver, S9

Test concentrations with justification for top dose:

Preliminary Toxicity Test: 5, 50, 500, 5000 µg/plate
Experiment 1: 0, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250 and 500 µg/plate.
Experiment 2: 0, 3.91, 7.81, 15.63, 31.25, 62.5, 125, 250 and 500 µg/plate

Vehicle / solvent:

Vehicle: Dimethyl sulphoxide

Justification for choice of solvent/vehicle:
Prior to commencing testing the solubility of the test material was assessed at 50 mg/ml in dimethyl sulphoxide. Water was not assessed as the Sponsor indicated that it was not a suitable solvent. The test material was found to be completely miscible with dimethyl sulphoxide and so this was chosen as the solvent for the assay.

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA100

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene: 1 µg/plate

Remarks:

With S9 mix

Controls 2

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA1535 and TA1537

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene: 2 µg/plate

Remarks:

With S9 mix

Controls 3

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA98 and TA1538

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene, 0.5 µg/plate

Remarks:

With S9 mix

Controls 4

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of WP2uvrA

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene: 20 µg/plate

Remarks:

With S9 mix

Controls 5

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA100

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

3µg/plate - without S9 mix

Controls 6

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA1535

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

5µg/plate - Without S9 mix

Controls 7

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA1537

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

without S9 mix Migrated to IUCLID6: 9-Aminoacridine: 80 µg/plate

Controls 8

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of TA98 and TA1538

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

2-nitrofluorene

Remarks:

2µg/plate for TA1538 and 1µg/plate for TA98 - without S9 mix

Controls 9

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates of WP2uvrA

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

2µg/plate - Without S9 mix

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation) Experiments 1 and 2

DURATION
- Preincubation period for bacterial strains: 10h
- Exposure duration: 48 - 72 hrs
- Expression time (cells in growth medium): Not applicable
- Selection time (if incubation with a selection agent): Not applicable

NUMBER OF REPLICATIONS: Triplicate plating.

DETERMINATION OF CYTOTOXICITY
- Method: plates were assessed for numbers of revertant colonies and examined for effects on the growth of the bacterial background lawn.

Evaluation criteria:

Acceptance Criteria:
The mean number of revertant colonies for all treatment groups is compared with those obtained for solvent control groups. The mutagenic activity of a test substance is assessed by applying the following criteria:
(a) If treatment with a test substance produces an increase in revertant colony numbers of at least twice the concurrent solvent controls, with some evidence of a positive dose-relationship, in two separate experiments, with any bacterial strain either in the presence or absence of S-9 mix, it is considered to show evidence of mutagenic activity in this test system. No statistical analysis is performed.
(b) If treatment with a test substance does not produce reproducible increases of at least 1.5 times the concurrent solvent controls, at any dose level with any bacterial strain, it is considered to show no evidence of mutagenic activity in this test system. No statistical analysis is performed.
(c) If the results obtained fail to satisfy the criteria for a clear "positive" or "negative" response given in paragraphs (a) and (b), the following approach is taken in order to resolve the issue of the substance's mutagenic activity in this test system.

(i) Repeat tests may be performed using modifications of the experimental method. These modifications include (but are not restricted to), the use of a narrower dose range than that already tested; the use of different levels of liver homogenate S9 fraction in the S9 mix. Should an increase in revertant colony numbers be observed which satisfies paragraph (a) the substance is considered to show evidence of mutagenic activity in this test system. No statistical analysis is performed.
(ii) If no clear "positive" response can be obtained the test data may be subjected to analysis to determine the statistical significance of any observed increases in revertant colony numbers. The statistical procedures used will be those described by Mahon et al (1989).

Statistics:

Standard deviation

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

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative 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

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative 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

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative 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

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 6

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Tested up to the toxic limit of the test material

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING STUDY
The substance was toxic towards all the tester strains at both 5000 and 500 µg/plate. 500 µg/plate was chosen as the top dose level in the mutation tests but a total of eight dose levels were included to ensure that sufficient non-toxic concentrations were tested.

FIRST MUTATION TEST
In the first mutation test, toxicity was observed towards all the tester strains at 500 µg/plate. Toxicity was also observed down to 125 µg/plate with strains TA 100 and TA 1538. As enough non-toxic dose levels were obtained it was decided to use the same dose levels for the second mutation test.

SECOND MUTATION TEST
No substantial increases in revertant colony numbers of any of the tester strains were observed following treatment with the substance at any dose level, either in the presence or absence of S9 mix.
The concurrent positive control compounds demonstrated the sensitivity of the assay and the metabolising activity of the liver preparations.

Applicant's summary and conclusion

Conclusions:

Under the test conditions, the test substance is not considered mutagenic in the Salmonella typhimurium and Escherichia coli reverse mutation assay (OECD TG 471).

Executive summary:

The substance is tested in the Ames test (OECD TG 471), using Salmonella typhimurium strains TA100, TA1535, TA98 and TA1537 and E. coli strain WP2uvrA. In the range finding test (plate incorporation), the substance was tested up to a concentration of 5000 µg/plate. The substance was toxic towards all tester strains in both 5000 µg/plate and 500 µg/plate. In the main test, the substance was tested up to a concentration of 500 µg/plate in two mutation experiments (plate incorporation). In the first experiment, toxicity was observed in all tester strains at a concentration of 500µg/plate. In strains TA100 and TA1538, toxic responses were also observed at 125 µg/plate. No growth in bacterial background lawns and/or substantial decreases in revertant colony frequency were recorded for any of the bacterial strains, with any dose of the test substance, either with or without metabolic activation. Based on this, the substance is not mutagenic in the Ames test.