(3R)-3,7-dimethyloct-6-enenitrile

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:

November 1980

Reliability:

2 (reliable with restrictions)

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

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

Adequacy of study:

key study

Study period:

November 1980

Reliability:

2 (reliable with restrictions)

Justification for type of information:

ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The structures of the target and source substances are identical and differ only with respect to the ratio of enantiomers where the target substance is a single pure L-isomer and the source substance is an equimolar mixture of L and D isomers.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target substance, L-Citronellyl nitrile, is a mono-constituent substance (EC No. 695-909-8, CAS no. 35931-93-2).
The source substance, DL-Citronellyl nitrile, is a mono-constituent substance (EC No. 257-288-8, CAS no. 51566-62-2).
The source and target substances are both of high purity with a low concentration of impurities.

3. ANALOGUE APPROACH JUSTIFICATION
The read across hypothesis is based on structural similarity where the only difference between target and source molecules is the enantiomeric ratio. In a non-chiral environment the target and source chemicals will have identical properties but in the chiral environment of living organisms the enantiomers may possess different carcinogenicity and teratogenicity (in a chiral environment, stereoisomers might experience selective absorption, protein binding, transport, enzyme interactions and metabolism, receptor interactions, and DNA binding). Therefore, as a precaution for the developmental toxicity endpoint it is suggested that the NOAEL 250 mg/kg bw/day for L-Citronellyl nitrile is used instead of 500 mg/kg bw/day, as it is not known which form is more potent in vivo. All other endpoints are considered to be acceptable for this substance assuming that 50% of the target compound is available in the test material.

4. DATA MATRIX
Please refer to the data matrix included in the read-across justification document attached in Section 13.2.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: Ames et al. (1975)

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine

Species / strain / cell type:

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

Species / strain / cell type:

S. typhimurium TA 1538

Metabolic activation:

with and without

Metabolic activation system:

S9 mix

Test concentrations with justification for top dose:

In the preliminary test conducted to assess the toxicity of the test liquid for the bacteria 0.1mg test liquid per plate appeared slightly toxic as revealed by a less dense background lawn of bacterial growth.
Top dose: 0.06mg test liquid per 0.1mL methanol per plate

Vehicle / solvent:

- Vehicle/solvent used: methanol

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

0mg test liquid per 0.1mL methanol per plate

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

other: hycanthone methanesulphonate (1), 2-aminoanthracene (2)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)
- Cell density at seeding: 1 - 4 x 10 9 cells / ml

DURATION
- Exposure duration:three days

NUMBER OF REPLICATIONS: triplicate

Rationale for test conditions:

Based on the test method Ames et al. (1975).

Evaluation criteria:

The colonies (revertants which are histidine independent) are counted and the background lawn of bacterial growth is examined microscopically.

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

0.06mg test liquid per 0.1 mL methanol per plate, with S9 mix: background lawn of bacterial growth less dense than in concomitant control plates

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not applicable

Positive controls validity:

not specified

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Additional information on results:

See attachment.

Conclusions:

Incorporation of the test liquid with the bacteria at levels up to 0.06 mg per plate did not increase the numbers of his+ revertants with any of the five tester strains, either in the presence or in the absence of the S-9 mix.
From the present results it can be concluded that the test item did not reveal any mutagenic activity in the plate incorporation assay with S. typhimurim TA 1535, TA 1537, TA 1538, TA 98 or TA 100 in the presence or absence of the liver microsome activation system under the test conditions employed in this evaluation.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1980

Report date:

1980

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Ames et al. (1975)

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

3,7-dimethyloct-6-enenitrile

EC Number:

257-288-8

EC Name:

3,7-dimethyloct-6-enenitrile

Cas Number:

51566-62-2

Molecular formula:

C10H17N

IUPAC Name:

3,7-dimethyloct-6-enenitrile

Test material form:

liquid

Details on test material:

Colourless liquid

Method

Target gene:

Histidine

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1538

Metabolic activation:

with and without

Metabolic activation system:

S9 mix

Test concentrations with justification for top dose:

In the preliminary test conducted to assess the toxicity of the test liquid for the bacteria 0.1mg test liquid per plate appeared slightly toxic as revealed by a less dense background lawn of bacterial growth.
Top dose: 0.06mg test liquid per 0.1mL methanol per plate

Vehicle / solvent:

- Vehicle/solvent used: methanol

Controls

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

0mg test liquid per 0.1mL methanol per plate

True negative controls:

no

Positive controls:

yes

Positive control substance:

sodium azide

other: hycanthone methanesulphonate (1), 2-aminoanthracene (2)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)
- Cell density at seeding: 1 - 4 x 10 9 cells / ml

DURATION
- Exposure duration:three days

NUMBER OF REPLICATIONS: triplicate

Rationale for test conditions:

Based on the test method Ames et al. (1975).

Evaluation criteria:

The colonies (revertants which are histidine independent) are counted and the background lawn of bacterial growth is examined microscopically.

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:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

0.06mg test liquid per 0.1 mL methanol per plate, with S9 mix: background lawn of bacterial growth less dense than in concomitant control plates

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not applicable

Positive controls validity:

not specified

Test results 3

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Test results 4

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Test results 5

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not valid

Positive controls validity:

not specified

Additional information on results:

See attachment.

Applicant's summary and conclusion

Conclusions:

Incorporation of the test liquid with the bacteria at levels up to 0.06 mg per plate did not increase the numbers of his+ revertants with any of the five tester strains, either in the presence or in the absence of the S-9 mix.
From the present results it can be concluded that the test item did not reveal any mutagenic activity in the plate incorporation assay with S. typhimurim TA 1535, TA 1537, TA 1538, TA 98 or TA 100 in the presence or absence of the liver microsome activation system under the test conditions employed in this evaluation.