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Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: well performed OECD study with GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
3-nitro-p-toluic acid
EC Number:
202-549-3
EC Name:
3-nitro-p-toluic acid
Cas Number:
96-98-0
Molecular formula:
C8H7NO4
IUPAC Name:
4-methyl-3-nitrobenzoic acid
Details on test material:
purity: 98.0 %

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
rat S9-mix
Test concentrations with justification for top dose:
5.0, 2.5, 1.25, 0.625 and 0.312 mg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
4-nitroquinoline-N-oxide
9-aminoacridine
2-nitrofluorene
sodium azide
other: 2-Aminoanthracene,
Details on test system and experimental conditions:
Plate incorporation method was carried out with concentrations of 5.0, 2.5, 1.25, 0.625 and 0.312 mg/plate; where the test item, solvent, positive control and the tester strains along with S9/Phosphate Buffer Saline were mixed with 2 mL soft agar and poured on to Minimal Glucose Agar plates. Five concentrations of the test item were plated, with each of the following tester strains: TA98, TA100, TA1535, TA1537 and E. coli WP2 uvrA (pKM 101) with and without metabolic activator. Plates were incubated at 37°C for 48 hrs.
Statistics:
The data of number of revertants were subjected to computer statistical processing using Graphpad prism software version 5 wherever possible.
. Differences between the solvent control, treatment with different concentrations of test item and positive control groups were tested by one-way ANOVA with Dunnett’s ‘t’ test at a 5% level (p<0.05) of significance.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

3-Nitro-p-toluic acid is found to be mutagenic at and up to the highest concentration of 5 mg/plate in Bacterial Reverse Mutation Test in the presence and absence of metabolic activator
Executive summary:

The test item 3-Nitro-p-toluic acid wasevaluated for mutagenicity in Bacterial Reverse Mutation Test as per the OECD guideline for the testing of chemicals No. 471, “Bacterial Reverse Mutation Test”, adopted on21stJuly 1997.

The test item 3-Nitro-p-toluic acid was assessed for its mutagenic effects using Salmonella typhimurium strains: TA98, TA100, TA1535, TA1537 and E. coli WP2 uvrA (pKM101) strain. The test item was tested at the concentrations of 5.0, 2.5, 1.25, 0.625 and 0.312 mg/plate using Dimethyl Sulphoxide (DMSO) as solvent based on the initial cytotoxicity test. The study was conducted, with and without the metabolic activator (S9 fraction). The S9 fraction was prepared from Sodium Phenobarbitone and β-Naphthoflavone induced rat liver. Solvent control and appropriate positive controls (2-nitrofluorene, sodium azide and 9-Aminoacridine, 4-nitroquinoline 1-oxide for trials “without metabolic activator” and 2-Aminoanthracene for trials “with metabolic activator”) were tested simultaneously. One trial was carried out for this study in triplicates with Plate Incorporation method (Trial I). Data was statistically analyzed and expressed as mean ±SD.

From the experimental results obtained, the mean numbers of revertant colonies at and below 5 mg/plate showed positive results in plate incorporation method compared to solvent control, in the presence and absence of metabolic activation. There was significant increase in number of revertant colonies tested at different concentrations.

From the results obtained, the test item 3-Nitro-p-toluic acid is found to be mutagenic at and up to the highest concentration of 5 mg/plate in Bacterial Reverse Mutation Test in the tester strainSalmonella typhimurium: TA98, TA100, TA1535, TA1537 andEscherichia coliWP2 uvrA (pKM101)in the presence and absence of metabolic activator in plate incorporation method under laboratory conditions applied.

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