3,7-dimethylnona-1,6-dien-3-ol

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

02/03/1983 - 24/03/1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Test was conducted similar to OECD Test Guideline No. 473, under early GLP Standards. Ethyllinalool and linalool are structural homologues which differ only by a methyl-group. Their physical-chemical properties are comparable and available experimental data on same toxicological endpoints, showed identical toxicological properties. Therefore, it is assumed that all toxicological properties are as well comparable and thus read-across is justified.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

yes

Remarks:

only 100 cells per concentration scored

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Linalool

EC Number:

201-134-4

EC Name:

Linalool

Cas Number:

78-70-6

Molecular formula:

C10H18O

IUPAC Name:

3,7-dimethylocta-1,6-dien-3-ol

Details on test material:

- Name of test material (as cited in study report): Linalool
- Physical state: liquid

Method

Target gene:

Not relevant

Species / strain

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

S9 mix (no further data)

Test concentrations with justification for top dose:

Without S9-mix: a) 16.7, 50.0, and 167.0 nl/ml; b) 100, 150, 200, 250, and 300 nl/ml
With S9-mix: a) 16.7, 50.0, and 167.0 nl/ml; b) 150, 200, 250, 300, and 400 nl/ml

Vehicle / solvent:

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

Controls

Untreated negative controls:

yes

Remarks:

untreated (medium)

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Mitomycin C and Cyclophosphamide

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION: No data

SPINDLE INHIBITOR (cytogenetic assays): No data
STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: No data

NUMBER OF CELLS EVALUATED: 100

DETERMINATION OF CYTOTOXICITY
- Method: % reduction in confluence; suppression of mitosis.

Evaluation criteria:

Statistically significance, dose response relationship, historical control range.

Statistics:

No data

Results and discussion

Test results

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

toxic at 300 nl/ml (-S9 mix) and at 400 nl/ml (+S9 mix)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES: At 1.67 ul/ml and higher concentrations there were visible globules of compound in cultures, but at 0.5 ul/ml and higher concentration an initial cloudy precipitate cleared rapidly so that the compound was apparently in solution. At 0.5, 1.67, and 5.0 ul/ml survival ranged from severely reduced to complete lethality.

COMPARISON WITH HISTORICAL CONTROL DATA: The aberration levels in the negative and solvent controls were normal for this laboratory. The frequencies of breaks were within the normal historical control level for this laboratory.

ADDITIONAL INFORMATION ON CYTOTOXICITY: The test was repeated in an attempt to obtain results in a narrow dose range at toxic levels of B105. Without S9 mix the doses tested were a closely-spaced series from 100 to 400 nl/ml. At 400 nl/ml and 350 nl/ml, there was severe toxicity with many dead cells and no dividing cells so that the highest dose at which results were available was 300 nl/ml. A this dose there were very few dividing cells although confluence was reduced by only about 25-30%. Mitosis was also suppressed at doses of 200nl/ml or more.
With S9 mix the dose range tested was from 100-500 nl/ml. There was complete lethality at 500 nl/ml, and at 400 nl/ml confluence was reduced by about 70% compared with the negative and solvent controls and mitosis was greatly suppressed. Confluence was reduced also at 200-300 nl/ml but there was no marked suppression of mitosis. Little toxicity was apparent at 100 and 150 nl/ml.

Any other information on results incl. tables

Read across:

Linalool, dehydrolinalool (CAS 29717-20-8) and ethyllinalool are structurally related substances having similar chemical structures. Difference between linalool and dehydrolinalool is the triple bond at position 1 in dehydrolinalool compared to a double bond at the same position in linalool. Both substances have similar physical-chemical properties. Ethyllinalool is a structural homologue of linalool which differs by a methyl-group only. The physical-chemical properties of ethyllinalool are comparable to the two other substances and available experimental data on the same toxicological endpoints, showed identical toxicological properties. Therefore, it is assumed that all toxicological properties are as well comparable and thus read-across is justified.

Overall, mutagenicity and genotoxicity testing was unremarkable. All three substances were negative in the Ames test. Linalool and dehydrolinalool were negative in an in vivo micronucleus test. Linalool was also negative in an in vitro chromosome aberration test and in an in vitro forward mutation testing. Although dehydrolinalool was positive in the in vitro chromosomal aberration test in the absence of metabolic activation, the next higher Tier test i.e. the in vivo MNT in the bone marrow was clearly negative.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

With and without metabolic activation there was no significant increase in aberrations, and no evidence for a dose relation. Linalool is therefore considered negative in the chromosome aberration test under the conditions of these assays. It was concluded that linalool does not need to be classified as mutagenic according to Annex I of 1272/2008/EC.

Executive summary:

Linalool (B105) was assessed for its ability to induce chromosomal aberrations in cultured CHO cells in vitro. Without metabolic activation doses between 16.7 nl/ml and 300 nl/ml were tested. In presence of a metabolic activation mix doses between 16.7 nl/ml and 400 nl/ml were tested. Linalool was toxic at 300 nl/ml (-S9 mix) and at 400 nl/ml (+S9 mix). The sensitivity of the test system and the activity of the metabolic activation were demonstrated by using the direct acting mutagen Mitomycin C and the promutagen Cyclophosphamide as positive controls. Both substances increased significantly the rate of structural chromosome aberrations.

Exposure of the CHO cells to Linalool with and without metabolic activation did not result in statistically significant increases of the rate of structural chromosome aberrations, and there was no evidence for a dose relation. Linalool is therefore considered negative in the chromosome aberration test under the conditions of these assays. It was concluded that linalool does not need to be classified as mutagenic according to Annex I of 1272/2008/EC.