Ethanone, 1-(3-methyl-2-benzofuranyl)-

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:

1997-01-28 to 1997-03-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

429-100-6

EC Name:

-

Cas Number:

23911-56-0

Molecular formula:

C11H10O2

IUPAC Name:

1-(3-methyl-1-benzofuran-2-yl)ethan-1-one

Method

Target gene:

The Salmonella typhimurium histidine (his) reversion system measures his- → his+ reversions. The Salmonella typhimurium strains are constructed to differentiate between base pair (TA1535, TA100) and frameshift (TA1537, TA98, TA 1538) mutations.

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 100

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 98

Species / strain 3

Species / strain / cell type:

S. typhimurium TA 1538

Species / strain 4

Species / strain / cell type:

S. typhimurium TA 1537

Species / strain 5

Species / strain / cell type:

S. typhimurium TA 1535

Metabolic activation:

with and without

Metabolic activation system:

Type and composition of metabolic activation system:
- Source of S9: Organon Teknika Corporation, Durham, USA and from ICN Biomedicals GmbH (both from Sprague-Dawley male rats (8-10 weeks old) induced with Aroclor 1254 (500 mg/kg body weight))
- Method of preparation of S9 mix: For 1 mL of S9 mix preparation, 0.1 mL of S9 was mixed with S9 cofactor solution (0.335 mL distilled water, 0.5 mL 0.2 M phosphate buffer, 0.04 mL 0.1 M NADP, 0.005 mL 1 M glucose-6-phosphate and 0.02 mL 0.4 M/1.65 M MgCl2/KCl.
- Concentration or volume of S9 mix and S9 in the final culture medium: 0.5 mL of S9 mix (containing 0.05 mL of S9) in 2.7 mL final culture medium
- Quality controls of S9: Enzymatic activity (tested by benzo(a)pyrene and 2-aminoanthracene induced mutagenesis with tester strains TA98 and TA100), sterility controls

Test concentrations with justification for top dose:

The test item was tested in concentrations ranging between 5 and 5000 µg/plate in the presence and absence of metabolic activation. The top concentration was chosen according to the applicable guidelines and on the basis of the results of a previous range finding test.

Vehicle / solvent:

- Vehicles used: DMSO (test item, 2-aminoanthracene, 2-nitrofluorene) and distilled water (9-aminoacridine, sodium azide)

- Justification for choice of solvent/vehicle: The test item showed good solubility in 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

other: 2-aminoanthracene

Remarks:

Without S9: NaN3: 0.5 µg/plate (TA 1535, TA100) 2-AA: 50 µg/plate (TA 1537) 2-NF: 2.5 µg/plate (TA 1538, TA98) With S9: 2-AA: 1 µg/plate (TA 1538, TA98, TA100) 2-AA: 3 µg/plate (TA 1535, TA1537)

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration: Triplicate
- Number of independent experiments: 2

METHOD OF TREATMENT/ EXPOSURE:
- Test method: Plate incorporation

TREATMENT AND HARVEST SCHEDULE:
- Exposure duration/duration of treatment: 48 hours

METHODS FOR MEASUREMENT OF CYTOTOXICITY
Inhibition of background lawn

METHODS FOR MEASUREMENTS OF GENOTOXICIY
Number of revertant colonies

Rationale for test conditions:

The number of cultures and the top concentration of 5000 µg/plate were chosen according to the recommendation of the applicable guidelines and on the basis of the results of an initial toxicity test.

Evaluation criteria:

Not specified

Statistics:

The X2-test was used to estimate statistical significance of the difference between the mean number of revertants in the negative controls and the plates at each dosage level.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 2

Key result

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:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 3

Key result

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:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

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:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Key result

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:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

STUDY RESULTS
- Concurrent vehicle negative and positive control data: See "Attached background material"

Ames test:
- Signs of toxicity: In the presence of S9, the test item was bacteriotoxic at 1500 µg/plate towards all tester strains. In the absence of S9, the test item was bacteriotoxic at 500 µg/plate towards strains TA1535 and TA98 and at 1500 µg/plate towards strains TA1537, TA1538, and TA100.
- Individual plate counts: See "Attached background material"
- Mean number of revertant colonies per plate and standard deviation: See "Attached background material"

HISTORICAL CONTROL DATA
- Positive historical control data: Not provided.
- Negative (solvent/vehicle) historical control data: Not provided. The laboratory stated that the number of spontaneous revertants observed using each of the five strains was very close to those previously established historical rate and was within the range obtained by Ames et al. (1975) as well as reported by De Serres and Shelby (1979).

Applicant's summary and conclusion

Conclusions:

In a bacterial reverse mutation assay according to OECD guideline 471, results indicated that the test item under the experimental conditions described, was not mutagenic to Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98, and TA100 in the presence and absence of a metabolizing system.

Executive summary:

The mutagenicity of the test item was tested in a GLP compliant study according to OECD guideline 471. Five mutant strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA98, and TA100) were used. The investigations were carried out using the standard plate incorporation assay with and without liver homogenate (S9) from Aroclor 1254 pretreated male rats as metabolic activation system. The test item was dissolved DMSO and tested in concentrations of 5 to 5000 µg per plate in the presence and absence of S9. In the presence of S9, the test item was bacteriotoxic at 1500 μg/plate towards all tester strains. In the absence of S9, the test item was bacteriotoxic at 500 µg/plate towards strains TA1535 and TA98 and at 1500 pg/plate towards strains TA1537, TA1538, and TA100. Sodium azide, 2-nitrofluorene, 9-aminoacridine, and 2-aminoanthracene served as positive controls to confirm the reversion properties and the specificity of the bacterial strains as well as the efficacy of the metabolizing system. In the concentration range investigated, the test item did not induce a significant increase in the spontaneous mutation frequency in any of the tester strains in the absence and presence of a metabolic activation system.

 

In conclusion, these results indicate that the test item under the experimental conditions described, was not mutagenic to Salmonella typhimuri-um strains TA1535, TA1537, TA1538, TA98, and TA100 in the presence and absence of a metabolizing system.