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Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames assay:

The test chemical did not induce mutation in the Salmonella typhimurium strains both in the presence and absence of S9 metabolic activation system and hence is not likely to be mutagenic under the conditions of this study.

In vitro mammalian chromosome aberration study:

The test chemical did not induce chromosome aberrations in the mammalian cell line in the absence of S9 metabolic activation system and hence it is not mutagenic in the chromosome aberration study performed.

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
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 data from various test chemicals.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: As mentioned below
Principles of method if other than guideline:
WoE for the target CAS is summarized based on 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: TA100, TA1535, TA1537, TA97, TA98
Remarks:
2
Details on mammalian cell type (if applicable):
not applicable
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98
Remarks:
3
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:
2. The S-9 (9,000 x g supernatant) fractions of Aroclor 1254-induced, male Sprague-Dawley rat and male Syrian hamster livers
3. The liver microsome fraction (S-9) was prepared from the liver of Fischer rats
Test concentrations with justification for top dose:
2. 0, 10, 33, 100, 333, 1000, 1666, 3333, 6666 or 10000 µg/plate
3. 6 different concentrations were used; 10 mg/plate was the maximum concentration
Vehicle / solvent:
2. - Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The test chemical was soluble in DMSO
3. - Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The test chemical was soluble in DMSO
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; Without S9); 2-aminoanthracene (With S9; all strains)
Remarks:
2
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:
3
Details on test system and experimental conditions:
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.
3. 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
Rationale for test conditions:
No data
Evaluation criteria:
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.
3. 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).
Statistics:
No data
Species / strain:
S. typhimurium, other: TA100, TA1535, TA1537, TA97, TA98
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
True negative controls validity:
not specified
Positive controls validity:
valid
Species / strain:
S. typhimurium, other: TA92, TA1535, TA100, TA1537, TA94 and TA98
Remarks:
3
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
True negative controls validity:
not specified
Positive controls validity:
not specified
Additional information on results:
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
3. ADDITIONAL INFORMATION ON CYTOTOXICITY: The maximum dose for negative results represents the highest non-cytotoxic dose used in the experiment
Remarks on result:
other: No mutagenic potential
Conclusions:
The test chemical did not induce mutation in the Salmonella typhimurium strains both in the presence and absence of S9 metabolic activation system and hence is not likely to be mutagenic under the conditions of this study.
Executive summary:

In different studies, the given test chemical has been investigated for the mutagenic nature. The studies are as mentioned below:

 

Gene mutation toxicity study was performed to determine the mutagenic nature of the given 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 given 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.

 

In another study, gene mutation toxicity test was performed to determine the mutagenic nature of the given 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 given 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.

 

Thus, based on the above summarized studies on test chemical, it can be concluded that the given test chemical did not induce mutation in the Salmonella typhimurium strains both in the presence and absence of S9 metabolic activation system and hence is not likely to be mutagenic under the conditions of this study.

 

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
read-across from supporting substance (structural analogue or surrogate)
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:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: As mentioned below
Principles of method if other than guideline:
WoE for the target CAS is summarized based on data from various test chemicals.
GLP compliance:
not specified
Type of assay:
in vitro mammalian chromosome aberration test
Target gene:
No data
Species / strain / cell type:
mammalian cell line, other: Chinese hamster fibroblast cell line CHL
Remarks:
5
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
Additional strain / cell type characteristics:
not specified
Species / strain / cell type:
mammalian cell line, other: Chinese hamster fibroblast cell line CHL
Remarks:
6
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
Additional strain / cell type characteristics:
not specified
Cytokinesis block (if used):
No data
Metabolic activation:
without
Metabolic activation system:
No data
Test concentrations with justification for top dose:
5. At three different doses with 2.0 mg/mL being the maximum dose concentration
6. At three different doses with 0.25 mg/mL being the maximum dose concentration
Vehicle / solvent:
5. - Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The chemical was soluble in DMSO
6. - Vehicle(s)/solvent(s) used: Ethanol
- Justification for choice of solvent/vehicle: The chemical was soluble in ethanol
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:
5
Untreated negative controls:
yes
Remarks:
Untreated cells served as negative control
Negative solvent / vehicle controls:
yes
Remarks:
Ethanol
True negative controls:
not specified
Positive controls:
not specified
Positive control substance:
not specified
Remarks:
6
Details on test system and experimental conditions:
5. 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
6. METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: No data
- 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): 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: No data
- Determination of endoreplication: No data
- Other: No data

OTHER: No data
Rationale for test conditions:
No data
Evaluation criteria:
5. 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%.
6. 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:
mammalian cell line, other: Chinese hamster fibroblast cell line CHL
Remarks:
5
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
mammalian cell line, other: Chinese hamster fibroblast cell line CHL
Remarks:
6
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
True negative controls validity:
not specified
Positive controls validity:
not specified
Additional information on results:
5. 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.
6. No data
Remarks on result:
other: No mutagenic potential
Conclusions:
The test chemical did not induce chromosome aberrations in the mammalian cell line in the absence of S9 metabolic activation system and hence it is not mutagenic in the chromosome aberration study performed.
Executive summary:

In different studies, the given test chemical has been investigated for the mutagenic nature. The studies are as mentioned below:

 

Chromosomal aberration study was performed to determine the mutagenic nature of the test chemical. The cells were exposed to the test material at three different doses with 2.0 mg/mL being the maximum concentration for 48 hr. 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 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.

 

In another study, chromosomal aberration test was performed to determine the mutagenic nature of the given test chemical. The cells were exposed to the test material at three different doses with 0.25 mg/mL being the maximum concentration for 48 hr. Colcemid (final concn 0.2 µg/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 study, no metabolic activation system was 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 given 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.

 

Thus, based on the above summarized studies on test chemical, it can be concluded that the given test chemical did not induce chromosome aberrations in the mammalian cell line in the absence of S9 metabolic activation system and hence it is not mutagenic in the chromosome aberration study performed.

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 from various sources was reviewed to determine the mutagenic nature of the given test chemical. The studies are as mentioned below:

Ames assay:

Gene mutation toxicity study was performed to determine the mutagenic nature of the given 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 given 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.

 

In another study, gene mutation toxicity test was performed to determine the mutagenic nature of the given 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 given 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.

 

Thus, based on the above summarized studies on test chemical, it can be concluded that the given test chemical did not induce mutation in the Salmonella typhimurium strains both in the presence and absence of S9 metabolic activation system and hence is not likely to be mutagenic under the conditions of this study.

 

In vitro mammalian chromosome aberration study:

Chromosomal aberration study was performed to determine the mutagenic nature of the test chemical. The cells were exposed to the test material at three different doses with 2.0 mg/mL being the maximum concentration for 48 hr. 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 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.

 

In another study, chromosomal aberration test was performed to determine the mutagenic nature of the given test chemical. The cells were exposed to the test material at three different doses with 0.25 mg/mL being the maximum concentration for 48 hr. Colcemid (final concn 0.2 µg/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 study, no metabolic activation system was 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 given 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.

 

Thus, based on the above summarized studies on test chemical, it can be concluded that the given test chemical did not induce chromosome aberrations in the mammalian cell line in the absence of S9 metabolic activation system and hence it is not mutagenic in the chromosome aberration study performed.

 

Justification for classification or non-classification

Based on the data available and applying weight of evidence approach, the given test chemical does not exhibit gene mutation in vitro by ames assay and In vitro mammalian chromosome aberration study. Hence, the test chemical is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.