3,7-dimethyloct-6-enyl isobutyrate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames assay:

The test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

In vitro chromosome aberration study:

The test chemical did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Experimental data from various test chemicals

Justification for type of information:

Data for the target chemical is summarized based on the various test chemicals

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

WoE derived based on the experimental data from various test chemicals

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine

Species / strain / cell type:

S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98

Remarks:

1

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not specified

Species / strain / cell type:

S. typhimurium, other: TA97, TA98, TA100, TA1535, TA1537

Remarks:

2

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not specified

Cytokinesis block (if used):

No data

Metabolic activation:

with and without

Metabolic activation system:

The liver microsome fraction (S-9) was prepared from the liver of Fischer rats

Test concentrations with justification for top dose:

1. 6 different concentrations were used; 10 mg/plate was the maximum concentration
2. 0, 10, 33, 100, 333, 1000, 1666, 3333, 6666 or 10000 µg/plate

Vehicle / solvent:

1./2. - Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: DMSO

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

not specified

Positive control substance:

not specified

Remarks:

1

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

9-aminoacridine

sodium azide

other: 4-nitro-o-phenylenediamine (TA98 and TA1538; -S9) and 2-aminoanthracene (all strains; +S9)

Details on test system and experimental conditions:

1. METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 mins
- Exposure duration: 48 hrs
- Expression time (cells in growth medium): 48 hrs
- Selection time (if incubation with a selection agent): No data
- Fixation time (start of exposure up to fixation or harvest of cells): No data

SELECTION AGENT (mutation assays): No data
SPINDLE INHIBITOR (cytogenetic assays): No data
STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: Duplicate

NUMBER OF CELLS EVALUATED: No data

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: No data
- Determination of endoreplication: No data
- Other: No data

OTHER: No data

2. METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 mins
- Exposure duration: 48 hrs
- Expression time (cells in growth medium): 48 hrs
- Selection time (if incubation with a selection agent): No data
- Fixation time (start of exposure up to fixation or harvest of cells): No data

SELECTION AGENT (mutation assays): No data
SPINDLE INHIBITOR (cytogenetic assays): No data
STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: No data

NUMBER OF CELLS EVALUATED: No data

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: No data
- Determination of endoreplication: No data
- Other: No data

OTHER: Plates were machine counted unless precipitate was present which interfered with the count, or the color of the test chemical on the plate reduced the contrast between the colonies and the agar.

Rationale for test conditions:

No data

Evaluation criteria:

1. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated).

2. The plates were observed for a dose dependent increase in the number of Histidine- independent (his+) colonies.

Evaluations were made at both the individual trial and chemical levels.

Individual trials were judged mutagenic (+), weakly mutagenic (+ W), questionable (?), or nonmutagenic (-), depending on the magnitude of the increase in his+ revertants, and the shape of the dose response. A trial was considered questionable (?) if the dose-response was judged insufficiently high to support a call of “+ W”, if only a single dose was elevated over the control, or if a weak increase was not dose-related. The distinctions between a questionable response and a nonmutagenic or weakly mutagenic response, and between a weak mutagenic response and mutagenic response are highly subjective. It was not necessary for a response to reach two-fold over background for a trial to be judged mutagenic.

A chemical was judged mutagenic (+) or weakly mutagenic (+W) if it produced a reproducible, dose-related response over the solvent control, under a single metabolic activation condition, in replicate trials. A chemical was judged questionable (?) if the results of individual trials were not reproducible, if increases in his+ revertants did not meet the criteria for a “+W” response, or if only single doses produced increases in his+ revertants in repeat trials. Chemicals were judged nonmutagenic (-) if they did not meet the criteria for a mutagenic or questionable response.

Statistics:

1. No data
2. The initial test of a chemical was without activation and with 10% S-9. If a positive result was obtained, the positive trial(s) was repeated. If the trials were negative the chemical was retested without S-9 and with 30% S-9. If all trials were negative, no further testing was performed.

Initial testing was in strains TA98 and TA100 without activation and with 30% rat and hamster S-9. If a positive response was obtained in one or both strains, only the positive test condition(s) was repeated. If an equivocal or weak positive response was obtained in one or both of these
strains, the corresponding plasmid-free parent strain( s), TA1535 and/or TA1538 was used to determine whether a more definitive response could be obtained. If the results with TA98 and TA100 were negative, strains TA97 and TA1535 were used without activation and with 30% S-9. If a positive response was obtained, a confirmation test was run. If a negative response was obtained in these two strains, the test was repeated using all four strains without activation and with 10% S-9.

Species / strain:

S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98

Remarks:

1

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Species / strain:

S. typhimurium, other: TA97, TA98, TA100, TA1535, TA1537

Remarks:

2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

1. ADDITIONAL INFORMATION ON CYTOTOXICITY: The maximum dose for negative results represents the highest non-cytotoxic dose used in the experiment

2. TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: No data
- Effects of osmolality: No data
- Evaporation from medium: No data
- Water solubility: No data
- Precipitation: No data
- Other confounding effects: No data

RANGE-FINDING/SCREENING STUDIES: All chemicals were run initially in a toxicity assay to determine the appropriate dose range for the mutagenicity assay. The toxicity assay was performed using TA100. Toxic concentrations were defined as those that produced a decrease in the number of his+ colonies, or a clearing in the density of the background lawn, or both.

COMPARISON WITH HISTORICAL CONTROL DATA: No data

ADDITIONAL INFORMATION ON CYTOTOXICITY: No data

Remarks on result:

other: No mutagenic potential

Conclusions:

The test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Executive summary:

Data available for the test chemicals was reviewed to determine the mutagenic nature of the test chemical. The studies are as mentioned below:

Gene mutation toxicity study was performed to determine the mutagenic nature of the test chemical. The study was performed using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 with and without S9 metabolic activation system. The test was performed as per the preincubation assay at six different concentrations with 10 mg/plate being the maximum concentration. The chemical was dissolved in DMSO. Preincubation was performed for 20 mins and the exposure duration was for 48 hrs. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). The test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Gene mutation toxicity study was also performed to determine the mutagenic nature of the test chemical. The study was performed using Salmonella typhimurium strains TA97, TA98, TA100, TA1535 and TA1537 in the presence and absence of S9 metabolic activation system. The chemical was dissolved in DMSO as solvent and used at dose levels 0, 10, 33, 100, 333, 1000, 1666, 3333, 6666 or 10000 µg/plate by the preincubation method. The doses were selected on the basis of preliminary dose range finding study and concurrent solvent and positive controls were included in the study. The test chemical did not induce mutation in Salmonella typhimurium TA97, TA98, TA100, TA1535 and TA1537 in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

Based on the observations made, the test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Experimental data from various test chemicals

Justification for type of information:

Data is from peer reviewed publication

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Principles of method if other than guideline:

WoE derived based on the experimental data various test chemicals

GLP compliance:

not specified

Type of assay:

other: Chromosome aberration assay

Target gene:

No data

Species / strain / cell type:

mammalian cell line, other: Chinese hamster fibroblast cell line CHL

Remarks:

1./2.

Details on mammalian cell type (if applicable):

- Type and identity of media: Minimum
Essential Medium (MEM; GIBCO) supplemented by 10% calf serum
- Properly maintained: yes by 4 day passages
- Periodically checked for Mycoplasma contamination: No data available
- Periodically checked for karyotype stability: No data available
- Periodically "cleansed" against high spontaneous background: No data available

Additional strain / cell type characteristics:

not specified

Cytokinesis block (if used):

No data

Metabolic activation:

without

Metabolic activation system:

Metabolic activation system

Test concentrations with justification for top dose:

1. At three different doses with 2.0 mg/mL being the maximum dose concentration
2. At three different doses with 0.25 mg/mL being the maximum dose concentration

Vehicle / solvent:

1./2.
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The chemical was soluble in DMSO

Untreated negative controls:

yes

Remarks:

Untreated cells served as negative control

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

not specified

Positive control substance:

not specified

Remarks:

1./2.

Details on test system and experimental conditions:

1./2.
METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: No data
- Exposure duration: 24 and 48 hrs
- Expression time (cells in growth medium): 24 and 48 hrs
- Selection time (if incubation with a selection agent): No data
- Fixation time (start of exposure up to fixation or harvest of cells): No data

SELECTION AGENT (mutation assays): Giemsa solution (1.5%, pH 6.8)
SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): No data

NUMBER OF REPLICATIONS: No data

NUMBER OF CELLS EVALUATED: 100 well spread metaphases

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: Yes
- Determination of endoreplication: No data
- Other: No data

OTHER: No data

Rationale for test conditions:

No data

Evaluation criteria:

1./2.
The incidence of polyploid cells as well as of cells with structural chromosomal aberrations such as chromatid or chromosome gaps, breaks, exchanges, ring formations, fragmentations and others, was recorded on each culture plate. The results were considered to be negative if the incidence was less than 4.9%, equivocal if it was between 5.0 and 9.9%, and positive if it was more than 10.0%.

Statistics:

No data

Species / strain:

S. typhimurium, other: Chinese hamster fibroblast cell line CHL

Remarks:

1./2.

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

not specified

Additional information on results:

1./2.
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: No data
- Effects of osmolality: No data
- Evaporation from medium: No data
- Water solubility: No data
- Precipitation: No data
- Other confounding effects: No data

RANGE-FINDING/SCREENING STUDIES: The maximum dose of each sample was selected by a preliminary test in which the dose needed for 50% cell-growth inhibition was estimated using a cell densitometer

COMPARISON WITH HISTORICAL CONTROL DATA: No data

ADDITIONAL INFORMATION ON CYTOTOXICITY: No data

Remarks on result:

other: No mutagenic potential

Conclusions:

The test chemical did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Executive summary:

Data available for the test chemicals was reviewed to determine the mutagenic nature of the test chemical. The studies are as mentioned below:

Chromosomal aberration study was performed to determine the mutagenic nature of the two test chemicals. The cells were exposed to the test material at three different doses with 2.0 mg/mL being the maximum concentration for 48hr for test chemical 1 and with 0.25 mg/mL being the maximum concentration for 48 hr for test chemical 2. Colcemid (final concn 0.2µg/ml) was added to the culture 2 hr before cell harvesting. The cells were then trypsinized and suspended in a hypotonic KCI solution (0.075 M) for 13 min at room temperature. After centrifugation the cells were fixed with acetic acid-methanol (1:3, v/v) and spread on clean glass slides. After air-drying, the slides were stained with Giemsa solution for 12-15 min. A hundred well-spread metaphases were observed under the microscope. In the present studies, no metabolic activation systems were applied. The incidence of polyploid cells as well as of cells with structural chromosomal aberrations such as chromatid or chromosome gaps, breaks, exchanges, ring formations, fragmentations and others, was recorded on each culture plate. Untreated cells and solvent-treated cells served as negative controls, in which the incidence of aberrations was usually less than 3.0%. The results were considered to be negative if the incidence was less than 4.9%, equivocal if it was between 5.0 and 9.9%, and positive if it was more than 10.0%. The two test chemicals did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Based on the observations made, the test chemical did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Gene mutation in vitro:

Data available for the test chemicals was reviewed to determine the mutagenic nature of the test chemical. The studies are as mentioned below:

Ames test:

Gene mutation toxicity study was performed to determine the mutagenic nature of the test chemical. The study was performed using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 with and without S9 metabolic activation system. The test was performed as per the preincubation assay at six different concentrations with 10 mg/plate being the maximum concentration. The chemical was dissolved in DMSO. Preincubation was performed for 20 mins and the exposure duration was for 48 hrs. The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). The test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

Gene mutation toxicity study was also performed to determine the mutagenic nature of the test chemical. The study was performed using Salmonella typhimurium strains TA97, TA98, TA100, TA1535 and TA1537 in the presence and absence of S9 metabolic activation system. The chemical was dissolved in DMSO as solvent and used at dose levels 0, 10, 33, 100, 333, 1000, 1666, 3333, 6666 or 10000 µg/plate by the preincubation method. The doses were selected on the basis of preliminary dose range finding study and concurrent solvent and positive controls were included in the study. The test chemical did not induce mutation in Salmonella typhimurium TA97, TA98, TA100, TA1535 and TA1537 in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

Based on the observations made, the test chemical did not induce a doubling of revertant colonies over the control using S. typhimurium strains in the presence and absence of S9 metabolic activation system and hence the chemical is not likely to classify as a gene mutant in vitro.

In vitro chromosome aberration study:

Chromosomal aberration study was performed to determine the mutagenic nature of the two test chemicals. The cells were exposed to the test material at three different doses with 2.0 mg/mL being the maximum concentration for 48hr for test chemical 1 and with 0.25 mg/mL being the maximum concentration for 48 hr for test chemical 2. Colcemid (final concn 0.2µg/ml) was added to the culture 2 hr before cell harvesting. The cells were then trypsinized and suspended in a hypotonic KCI solution (0.075 M) for 13 min at room temperature. After centrifugation the cells were fixed with acetic acid-methanol (1:3, v/v) and spread on clean glass slides. After air-drying, the slides were stained with Giemsa solution for 12-15 min. A hundred well-spread metaphases were observed under the microscope. In the present studies, no metabolic activation systems were applied. The incidence of polyploid cells as well as of cells with structural chromosomal aberrations such as chromatid or chromosome gaps, breaks, exchanges, ring formations, fragmentations and others, was recorded on each culture plate. Untreated cells and solvent-treated cells served as negative controls, in which the incidence of aberrations was usually less than 3.0%. The results were considered to be negative if the incidence was less than 4.9%, equivocal if it was between 5.0 and 9.9%, and positive if it was more than 10.0%. The two test chemicals did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Based on the observations made, the test chemical did not induce chromosomal aberration in Chinese hamster fibroblast cell line CHL and hence it is not likely to classify as a gene mutant in vitro.

Based on the data available and applying the weight of evidence approach, the test chemical is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.

Justification for classification or non-classification

Based on the data available and applying the weight of evidence approach, the test chemical is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.