6-aminonaphthalene-2-sulphonic acid

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Ames assay:

The test chemical did not induce gene mutation in the genome of the Salmonella typhimurium strains in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.

Chromosomal aberration test:

The test chemical did not induce chromosomal aberrations in the CHO cells in the presence and absence of exogeneous metabolic activation system 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:

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 for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

WoE derived based on the experimental data of various test chemicals

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, TA 100 and TA 102

Remarks:

1

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

other:

Species / strain / cell type:

S. typhimurium, other: TA98 and TA100

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:

Aroclor 1254 induced S9 metabolic activation system

Test concentrations with justification for top dose:

1. 0.0 (NC), 0.005, 0.016, 0.050, 0.158, 0.501 mg/plate
2. 0 (Negative control), 50 or 200 µg/plate

Vehicle / solvent:

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

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

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

RO water

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

sodium azide

methylmethanesulfonate

other: 4-Nitro-o-phenylenediamine (TA 1537, TA 98, without S9); 2-Aminoanthracene (TA 1535, TA 1537, TA 98, TA 100 and TA 102, with S9)

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:

benzo(a)pyrene

other: 1,6-dinitropyrene

Remarks:

2

Details on test system and experimental conditions:

1. METHOD OF APPLICATION: in agar (plate incorporation- Trial I); preincubation (Trial II)

DURATION
- Preincubation period: Trial I: Not applicable Trial II: 60 min
- 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: Each concentration, including the negative, vehicle and positive controls was tested in triplicate in two independent experiments performed

METHODS OF SLIDE PREPARATION AND STAINING TECHNIQUE USED: Not applicable

NUMBER OF CELLS EVALUATED: No data

NUMBER OF METAPHASE SPREADS ANALYSED PER DOSE (if in vitro cytogenicity study in mammalian cells): No data

CRITERIA FOR MICRONUCLEUS IDENTIFICATION: No data

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: No data
- Any supplementary information relevant to cytotoxicity: No data

OTHER EXAMINATIONS:
- Determination of polyploidy: No data
- Determination of endoreplication: No data
- Methods, such as kinetochore antibody binding, to characterize whether micronuclei contain whole or fragmented chromosomes (if applicable): No data

- OTHER: No data

2. METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: Not applicable
- Exposure duration: No data
- Expression time (cells in growth medium): No data
- 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:

1. A test item is considered as a mutagen, if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100 and TA 102) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding vehicle/solvent control is observed.

2. A positive result in the Ames test was defined as a reproducible, dose-related, at least twofold increase in the number of revertants over background

A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration.

An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment.

A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative control and vehicle control such an increase is not considered biologically relevant.

Statistics:

No data

Species / strain:

S. typhimurium, other: TA 1535, TA 1537, TA 98, TA 100 and TA 102

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:

valid

Species / strain:

S. typhimurium, other: TA98 and TA100

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. 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 precipitation was noted at a dose upto 5 mg/plate in the pre-experiment
- Definition of acceptable cells for analysis: No data
- Other confounding effects: No data

RANGE-FINDING/SCREENING STUDIES: To evaluate the toxicity of the test item, a pre-experiment was performed with strains TA 98 and TA 100. Eight concentrations (0.0 (NC), 0.002, 0.005, 0.016, 0.050, 0.158, 0.501, 1.582 and 5.0 mg/plate) were tested for toxicity and mutation induction with 3 plates each (triplicates). The experimental conditions in this pre-experiment were the same as described below for the Trial-I (Plate incorporation test). Toxicity of the test item results in a reduction in the number of spontaneous revertants or a clearing of the bacterial background lawn.

In the pre-experiment, the concentration range of the test item was 0.002 – 5 mg/plate based on the solubility and precipitation test. There was no reduction in colony count as well as in background lawn in treated concentrations 5 (T8) mg/plate – 0.002 (T1) mg/plate) both in absence and in the presence of metabolic activation. Based on the results of pre-experiment following doses were selected for the main study trials: 0.050, 0.158, 0.501, 1.582 and 5 mg/plate, both in the absence (-S9) as well as in the presence of metabolic activation (+S9).

CYTOKINESIS BLOCK (if used)
- Distribution of mono-, bi- and multi-nucleated cells: No data

NUMBER OF CELLS WITH MICRONUCLEI
- Number of cells for each treated and control culture: No data
- Indication whether binucleate or mononucleate where appropriate: No data

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Positive historical control data: No data
- Negative (solvent/vehicle) historical control data: No data

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Measurement of cytotoxicity used: No data
- Other observations when applicable: No data

2. No data

Remarks on result:

other: No mutagenic potential

Conclusions:

The test chemical did not induce gene mutation in the genome of the Salmonella typhimurium strains in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.

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:

Ames assay was performed to investigate the potential of the test chemical to induce gene mutations in comparison to negative control according to the plate incorporation test (Trial I) and the pre-incubation test (Trial II) using the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, TA 100 and TA 102. The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration, including the negative, positive controls was tested in triplicate. Based on the solubility and precipitation test results eight different concentrations viz., 0.0 (NC), 0.002, 0.005, 0.016, 0.050, 0.158, 0.501, 1.582 and 5.0 mg/plate were selected for pre-experiment. Based on the pre-experiment results, the test item was tested with the following concentrations 0.0 (NC), 0.005, 0.016, 0.050, 0.158, 0.501 mg/plate for main study, both in the presence of metabolic activation (+S9) and in the absence of metabolic activation (-S9). No substantial increase in revertant colony numbers in any of the tester strains were observed following treatment with the test chemical at any dose level in both the confirmatory trials, neither in the presence nor in the absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. The spontaneous reversion rates in the negative, positive controls are within the range of our historical data. The positive controls used for various strains showed a distinct increase in induced revertant colonies in both the methods i.e. Plate incorporation method and Pre-incubation method. In conclusion, it is stated that during the described mutagenicity test and under the experimental conditions reported, the test chemical did not induce gene mutations by base pair changes or frame shifts in the genome of the strains used.  

Gene mutation toxicity study was performed to determine the mutagenic nature of the test chemical. The study was performed using S. typhimurium strains TA98 and TA100 with and without S9 metabolic activation system. The test was performed as per the plate incorporation assay at dose level of 0 (negative control), 50 or 200µg/plate. The chemical was dissolved in water. The result was considered positive when a reproducible, dose-related, at least two-fold increase in the number of revertants over background was observed. Concurrent positive and negative control chemicals were also included in the study. The test chemical did not induce a doubling of revertant colonies over the negative control using S. typhimurium strains TA98 and TA100 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.

Based on the observations made, the test chemical did not induce gene mutation in the genome of the Salmonella typhimurium strains in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

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 for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: Refer below principle

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:

in vitro mammalian chromosome aberration test

Target gene:

No data

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Remarks:

CHO-WBL / 1

Details on mammalian cell type (if applicable):

No data

Additional strain / cell type characteristics:

not specified

Species / strain / cell type:

Chinese hamster Ovary (CHO)

Remarks:

2

Details on mammalian cell type (if applicable):

- Type and identity of media: McCoy’s 5A
medium (modified) supplemented with L-glutamine (2 mM), antibiotics, and 10% fetal bovine serum (FBS)
- Properly maintained: Yes
- Periodically checked for Mycoplasma contamination: Yes, At least once per year representative cells were sent to Flow Laboratories (McLean, VA) for mycoplasma testing using the Hoechst stain test followed by the Agar and Hyorhinis test. Results from all tests for mycoplasma contamination were negative.
- Periodically checked for karyotype stability: No data
- Periodically "cleansed" against high spontaneous background: No data

Additional strain / cell type characteristics:

not specified

Cytokinesis block (if used):

No data

Metabolic activation:

with and without

Metabolic activation system:

S9 fractions (livers of Aroclor 1254-treated male Sprague-Dawley rats.)

Test concentrations with justification for top dose:

1. -S9 (Harvest time: 10 hrs): 0, 2500, 3850, 5000 µg/mL
+S9 (Harvest time: 12 hrs): 0, 2500, 3850, 5000 µg/mL

2. 0, 1000, 1600, 3000 or 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The test chemical is soluble in DMSO

2. - Vehicle(s)/solvent(s) used: Serum-free culture medium
- Justification for choice of solvent/vehicle: The test chemical was soluble in Serum-free culture medium

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

cyclophosphamide

mitomycin C

Remarks:

1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

Serum-free culture medium

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

cyclophosphamide

mitomycin C

Remarks:

2

Details on test system and experimental conditions:

1. METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: No data
- Exposure duration:
- S9: 8 hrs
+ S9: 2 hrs
- Expression time (cells in growth medium): 8 hrs
- Selection time (if incubation with a selection agent): No data available
- Fixation time (start of exposure up to fixation or harvest of cells): -S9: 10 hrs, +S9: 12 hrs

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

NUMBER OF REPLICATIONS: No data

NUMBER OF CELLS EVALUATED: One hundred to 200 cells from each of the three highest scorable doses were analyzed

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

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

OTHER: No data available

2. METHOD OF APPLICATION: in medium

Cells at the start of experiment: 1.2 x 106 cells

DURATION
- Preincubation period: Not applicable
- Exposure duration:
Without S9: 2 hrs
With S9: 2 hrs
- Expression time (cells in growth medium):
Without S9: 10 hrs
With S9: 11 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): 6% Giemsa stain

NUMBER OF REPLICATIONS: No data

NUMBER OF CELLS EVALUATED: One hundred cells were scored for each dose. Only metaphase cells in which the chromosome number was between 19 and 23 were scored

Details on slide preparation:

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:

1. All aberrations were individually classified (e.g., chromatid breaks, chromosome breaks, triradials, etc.). These data were combined as the percent of cells with simple (deletions), complex (exchanges), and total (simple, complex and other) aberrations. Only the total percent cells with aberrations was considered in the statistical evaluation. Gaps and endoreduplications were recorded but were not included in the statistical analyses.

2. The cell line was observed for chromosome aberrations. The chromosome or chromatid type aberrations were classified into three categories: simple (breaks, fragments, double minutes), complex (interchanges, rearrangements), and other (pulverized, more than ten aberrations/cell).

Statistics:

1. Trend test.

2. The percentage of cells with aberrations was analyzed. Both the dose-response curve and individual dose points were statistically analyzed. A statistically significant (P < 0.003) trend test or a significantly elevated dose point (P < 0.05) was sufficient to indicate a chemical effect

Species / strain:

Chinese hamster Ovary (CHO)

Remarks:

CHO-WBL / 1

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Species / strain:

Chinese hamster Ovary (CHO)

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. TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: 7.0 – 7.5
- 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: Chemicals were tested up to 5 mg/ml or as limited by solubility and/or toxicity. Solubility tests were conducted to determine dose range and choice of solvent (water, dimethyl sulfoxide, acetone, or ethanol, in that order of preference). In the assays for chromosomal aberrations, the top dose (TD) was based on toxicity, solubility, or the upper testing limit (5 mg/ml). The doses used were generally the TD, 0.75 TD, 0.50 TD, 0.25 TD, 0.1 TD, 0.075 TD, 0.05 TD, and 0.025 TD. The highest three doses with a sufficient number of cells were analyzed for chromosomal aberrations

COMPARISON WITH HISTORICAL CONTROL DATA: No data

ADDITIONAL INFORMATION ON CYTOTOXICITY: No data

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 dose levels for ABS studies were chosen based on the toxicity of the test chemical observed in the SCE studies.

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 aberrations in the CHO cells in the presence and absence of exogeneous metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

Executive summary:

Data from various test chemicals was reviewed to determine the mutagenic nature of the test chemicals. The studies are as mentioned below:

In vitro mammalian chromosome aberration test was performed to determine the mutagenic nature of the test chemical. The study was performed using CHO-WBL cells in the presence and absence of exogeneous metabolic activation system. The test chemical was dissolved in DMSO and used at dose levels upto 5 mg/mL. In the chromosome aberration assay without activation, cells were exposed to the test chemical for 8 hr. The test chemical was washed off, and the cells were treated with 0.1µg/ml Colcemid for 2-2.5 hr. With metabolic activation, the cells were exposed to the test chemical plus the metabolic activation mixture for 2 hr, washed, incubated for 8 hr, and then treated with Colcemid for 2-2.5 hr. A delayed harvest was used in the aberration assay in most instances when cell cycle delay was observed in the SCE assay. In these tests the cell growth period was extended to about 20 hr. Cells were harvested. Air-dried slides were coded and stained with Giemsa. One hundred to 200 cells from each of the three highest scorable doses were analyzed and the chromosomal aberrations were scored. The test chemical did not induce chromosomal aberrations when tested to toxicity. Precipitate was evident at doses of 250µg/ml and above. Based on the observations made, the test chemical did not induce chromosome aberrations in the CHO-WBL cells in the presence and absence of exogeneous metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

In another vitro mammalian chromosome aberration test was performed to determine the mutagenic nature of test chemical. The study was performed using Chinese hamster ovary cells in the presence and absence of S9 metabolic activation system. The test chemical was dissolved in serum free culture medium and used at dose level of0, 1000, 1600, 3000 or 5000 µg/plate. Concurrent solvent and negative control chemicals were also included in the study. Approximately 24 hr prior to cell treatment, 1.2 x 10⁶cells were seeded per 75 cm2 flask. For assays without metabolic activation, the cells were treated for about 10 hr. Colcemid was added 2-3 hr prior to cell harvest by mitotic shake-off. In the test protocol for assays with metabolic activation cells were harvested approximately 11 hr after removal of the S9 fraction. Colcemid was added 2 hr prior to harvest. Slides were stained in 6% Giemsa for 5-10 min. One hundred cells were scored for each dose in early studies and 200 cells per dose in later studies. All slides except high-dose positive controls were coded. Only metaphase cells in which the chromosome number was between 19 and 23 were scored. Acid red 14 did not induce ABS at doses up to 5000µg/ml in either the presence or the absence of S9. Based on the observations made, the test chemical did not induce chromosome aberration in Chinese hamster ovary cells 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.

Based on the data available for the various test chemicals, the test chemical did not induce chromosomal aberrations in the CHO cells in the presence and absence of exogeneous metabolic activation system 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 various test chemicals was reviewed to determine the mutagenic nature of the test chemical. The studies are as mentioned below:

Ames test:

Ames assay was performed to investigate the potential of the test chemical to induce gene mutations in comparison to negative control according to the plate incorporation test (Trial I) and the pre-incubation test (Trial II) using theSalmonella typhimuriumstrains TA 1535, TA 1537, TA 98, TA 100 and TA 102. The assay was performed in two independent experiments both with and without liver microsomal activation. Each concentration, including the negative, positive controls was tested in triplicate. Based on the solubility and precipitation test results eight different concentrations viz., 0.0 (NC), 0.002, 0.005, 0.016, 0.050, 0.158, 0.501, 1.582 and 5.0 mg/plate were selected for pre-experiment. Based on the pre-experiment results, the test item was tested with the following concentrations 0.0 (NC), 0.005, 0.016, 0.050, 0.158, 0.501 mg/plate for main study, both in the presence of metabolic activation (+S9) and in the absence of metabolic activation (-S9). No substantial increase in revertant colony numbers in any of the tester strains were observed following treatment with the test chemical at any dose level in both the confirmatory trials, neither in the presence nor in the absence of metabolic activation (S9 mix). There was also no tendency of higher mutation rates with increasing concentrations in the range below the generally acknowledged border of biological relevance. The spontaneous reversion rates in the negative, positive controls are within the range of our historical data. The positive controls used for various strains showed a distinct increase in induced revertant colonies in both the methods i.e. Plate incorporation method and Pre-incubation method. In conclusion, it is stated that during the described mutagenicity test and under the experimental conditions reported, the test chemical did not induce gene mutations by base pair changes or frame shifts in the genome of the strains used.  

Gene mutation toxicity study was performed to determine the mutagenic nature of the test chemical. The study was performed using S. typhimurium strains TA98 and TA100 with and without S9 metabolic activation system. The test was performed as per the plate incorporation assay at dose level of 0 (negative control), 50 or 200µg/plate. The chemical was dissolved in water. The result was considered positive when a reproducible, dose-related, at least two-fold increase in the number of revertants over background was observed. Concurrent positive and negative control chemicals were also included in the study. The test chemical did not induce a doubling of revertant colonies over the negative control using S. typhimurium strains TA98 and TA100 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.

Based on the observations made, the test chemical did not induce gene mutation in the genome of the Salmonella typhimurium strains in the presence and absence of S9 metabolic activation system and hence it is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.

Chromosome aberration study:

In vitro mammalian chromosome aberration test was performed to determine the mutagenic nature of the test chemical. The study was performed using CHO-WBL cells in the presence and absence of exogeneous metabolic activation system. The test chemical was dissolved in DMSO and used at dose levels upto 5 mg/mL. In the chromosome aberration assay without activation, cells were exposed to the test chemical for 8 hr. The test chemical was washed off, and the cells were treated with 0.1µg/ml Colcemid for 2-2.5 hr. With metabolic activation, the cells were exposed to the test chemical plus the metabolic activation mixture for 2 hr, washed, incubated for 8 hr, and then treated with Colcemid for 2-2.5 hr. A delayed harvest was used in the aberration assay in most instances when cell cycle delay was observed in the SCE assay. In these tests the cell growth period was extended to about 20 hr. Cells were harvested. Air-dried slides were coded and stained with Giemsa. One hundred to 200 cells from each of the three highest scorable doses were analyzed and the chromosomal aberrations were scored. The test chemical did not induce chromosomal aberrations when tested to toxicity. Precipitate was evident at doses of 250µg/ml and above. Based on the observations made, the test chemical did not induce chromosome aberrations in the CHO-WBL cells in the presence and absence of exogeneous metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

In another vitro mammalian chromosome aberration test was performed to determine the mutagenic nature of test chemical. The study was performed using Chinese hamster ovary cells in the presence and absence of S9 metabolic activation system. The test chemical was dissolved in serum free culture medium and used at dose level of0, 1000, 1600, 3000 or 5000 µg/plate. Concurrent solvent and negative control chemicals were also included in the study. Approximately 24 hr prior to cell treatment, 1.2 x 10⁶cells were seeded per 75 cm2 flask. For assays without metabolic activation, the cells were treated for about 10 hr. Colcemid was added 2-3 hr prior to cell harvest by mitotic shake-off. In the test protocol for assays with metabolic activation cells were harvested approximately 11 hr after removal of the S9 fraction. Colcemid was added 2 hr prior to harvest. Slides were stained in 6% Giemsa for 5-10 min. One hundred cells were scored for each dose in early studies and 200 cells per dose in later studies. All slides except high-dose positive controls were coded. Only metaphase cells in which the chromosome number was between 19 and 23 were scored. Acid red 14 did not induce ABS at doses up to 5000µg/ml in either the presence or the absence of S9. Based on the observations made, the test chemical did not induce chromosome aberration in Chinese hamster ovary cells 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.

Based on the data available for the various test chemicals, the test chemical did not induce chromosomal aberrations in the CHO cells in the presence and absence of exogeneous metabolic activation system and hence it is not likely to classify as a gene mutant in vitro.

On the basis of data available for the various test chemicals and applying the weight of evidence apprach, the test chemicals does not exhibit gene mutation in vitro. Hence 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

On the basis of data available for the various test chemicals and applying the weight of evidence apprach, the test chemicals does not exhibit gene mutation in vitro. Hence the test chemical is not likely to classify as a gene mutant as per the criteria mentioned in CLP regulation.