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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well performed GLP compliant study following a company guideline similar to OECD 471, but without confirmation of negative results ba follow up experiments

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1984
Report date:
1984

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: company guideline similar to OECD 471
Deviations:
yes
Principles of method if other than guideline:
as compared to current guideline without confirmation of negative results ba follow up experiments
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Chemical structure
Reference substance name:
3-methyl-1-p-tolyl-5-pyrazolone
EC Number:
201-708-4
EC Name:
3-methyl-1-p-tolyl-5-pyrazolone
Cas Number:
86-92-0
Molecular formula:
C11H12N2O
IUPAC Name:
5-methyl-2-(4-methylphenyl)-1,2-dihydro-3H-pyrazol-3-one

Method

Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Species / strain / cell type:
S. typhimurium TA 1538
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induce rat liver S9-Mix
Test concentrations with justification for top dose:
Toxicity experiment and dose range finding: 0, 4, 20, 100, 500, 2500, 10000 µg/plate
Mutagenicity experiment: 0, 4, 20, 100, 500, 2500, 5000 µg/plate
Vehicle / solvent:
DMSO
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
N-ethyl-N-nitro-N-nitrosoguanidine
benzo(a)pyrene
other: 2-Aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: plate incorporation

DURATION

- Exposure duration: incubation for 48 to 72 hours at 37°C

NUMBER OF REPLICATIONS: triplicate plates per dose

DETERMINATION OF CYTOTOXICITY
- Method: A reduced rate of spontaneously occuring colonies as well as visible thinning of the bacterial lawn were used as indicator for toxicity.
Evaluation criteria:
criteria for a negative result: absence of a significant increase in the number of revertant colonies and of a dose dependent effect

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: slightly toxic to some of the bacterial strains
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: slightly toxic to some of the bacterial strains
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS

- Precipitation: no

RANGE-FINDING/SCREENING STUDIES:

- Toxicity and dose range finding experiments were performed

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):
negative

Summarizing, i t can be stated that the test item is not mutagenic in these bacterial test systems neither with nor without exogenous metabolic
activation at the dose levels investigated.

Findings do not meet criteria for classification according to Regulation (EC) No 1272/2008.
Executive summary:

The test substance was tested for mutagenicity with the strains TA 100, TA 1535, TA 1537, TA 1538, TA 98 of Salmonella typhimurium and Escherichia coli WP2uvrA.

The mutagenicity studies were conducted in the absence and in the presence of a metabolizing system derived from rat liver homogenate. A dose range of 6 different doses from 4 µg/plate to 5 000 µg/plate was used.

Control plates without mutagen showed that the number of spontaneous revertant colonies was similar to that described in the literature. All positive control compounds gave the expected increase in the number of revertant colonies.

Toxicity: The test compound proved to be slightly toxic to some of the bacterial strains, at 500 to 5 000 µg/plate. 5 000 µg/plate was chosen as top dose level for the mutagenicity study.

Mutagenicity: In the absence of the metabolic activation system the test compound did not show a dose dependent increase in the number of revertants in any of the bacterial strains. Also in the presence of a metabolic activation system, treatment of the cells with the test substance did not result in a relevant increases in the number of revertant colonies.