Methyl benzoylformate

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Methyl benzoylformate

EC Number:

239-263-3

EC Name:

Methyl benzoylformate

Cas Number:

15206-55-0

Molecular formula:

C9H8O3

IUPAC Name:

methyl oxo(phenyl)acetate

Method

Target gene:

his, trp

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital i.p. and β-naphthoflavone induced liver S9 mix from rats

Test concentrations with justification for top dose:

33 μg - 5 200 μg/plate (SPT)
33 μg - 5 200 μg/plate (PIT)

Vehicle / solvent:

DMSO

Controls

Controls 1

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with S9 mix

Controls 2

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

other: 4-nitro-o-phenylenediamine, N-methyl-N'-nitro-N-nitrosoguanidine

Remarks:

without S9 mix

Details on test system and experimental conditions:

DETAILS ON TEST SYSTEM
METHOD OF APPLICATION: in agar (plate incorporation); preincubation
DURATION
- Preincubation period: 20 min
- Exposure duration: 37°C for 48 - 72 hours
NUMBER OF REPLICATIONS: in triplicate
NUMBER OF CELLS EVALUATED: all revertants / colonies counted
DETERMINATION OF CYTOTOXICITY
Toxicity detected by a
• decrease in the number of revertants
• clearing or diminution of the background lawn (= reduced his- or trp- background growth)
• reduction in the titer is recorded for all test groups both with and without S9 mix in all experiments

Evaluation criteria:

The test substance was considered positive in this assay if the following criteria were met:
• A dose-related and reproducible increase in the number of revertant colonies, i.e. at least doubling (bacteria strains with high spontaneous mutation rate, like TA 98, TA 100 and E.coli WP2 uvrA) or tripling (bacteria strains with low spontaneous mutation rate, like TA 1535 and TA 1537) of the spontaneous mutation rate in at least one tester strain either without S9 mix or after adding a metabolizing system.

A test substance was generally considered non-mutagenic in this test if:
• The number of revertants for all tester strains were within the historical negative control data range under all experimental conditions in at least two experiments carried out independently of each other.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 5

Species / strain:

E. coli WP2

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

SOLUBILITY: No precipitation of the test substance was found with and without S9 mix.

TOXICITY: A weak bacteriotoxic effect was occasionally observed depending on the strain and test conditions from about 2 600 μg/plate onward.

Applicant's summary and conclusion

Conclusions:

Under the experimental conditions of this study, the test substance is considered not mutagenic in the Salmonella typhimurium/Escherichia coli reverse mutation assay in the absence and the presence of metabolic activation.

Executive summary:

In this guideline (OECD 471) study conducted with GLP certification, the test material (EC 239-263-3) did not meet the criteria to be considered genotoxic in all tested strains. Testing was performed with and without metabolic acitivation and no precipitation was observed at any test concentration. The reverse mutagenicity test was performed upon strains of Salmonella typhimurium and Escherichia coli.