4-(4-chlorophenyl)-2-phenyl-2-[(1H-1,2,4-triazol-1-yl)methyl]butanenitrile

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

18-November-1992 to 09-March-1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

no fifth strain inlcuded

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

4-(4-chlorophenyl)-2-phenyl-2-[(1H-1,2,4-triazol-1-yl)methyl]butanenitrile

EC Number:

406-140-2

EC Name:

4-(4-chlorophenyl)-2-phenyl-2-[(1H-1,2,4-triazol-1-yl)methyl]butanenitrile

Cas Number:

114369-43-6

Molecular formula:

C19H17ClN4

IUPAC Name:

4-(4-chlorophenyl)-2-phenyl-2-[(1H-1,2,4-triazol-1-yl)methyl]butanenitrile

Method

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

S9-Mix

Test concentrations with justification for top dose:

Test 1: Fenbuconazole: 20, 50, 200, 500, and 2000 µg/plate;
Test 2: Fenbuconazole: 160, 300, 500, 900 and 1600 µg/plate with metabolic activation and 30, 50, 90, 160 and 300 µg/plate without metabolic activation

Vehicle / solvent:

Dimethyl sulfoxide (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:

Remarks:

2-anthramine: 2 µg/plate for all strains
2-nitrofluorene: 3 µg/plate for strain TA98
Sodium azide: 2 µg/plate for strains TA100 and TA1535
9-aminoacridine: 100 µg/plate for strain TA1537

Evaluation criteria:

A mutagenicity assay is considered valid if the following conditions are met:
The spontaneous reversion rate, with and without metabolic activation, must be reasonably
consistent with the expected range for the strain being used
- The positive control materials must elicit a positive response
- Strains must maintain characteristics (nutritional requirements, crystal violet sensitivity and
ampicillin resistance)

Statistics:

Statistical methods beyond the calculation of the mean and standard deviation are not considered necessary for the interpretation of this study.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

True negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

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 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

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 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

not determined

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

not examined

Untreated negative controls validity:

not examined

True negative controls validity:

not examined

Positive controls validity:

not examined

Additional information on results:

The test item was evaluated initially at doses of 20, 50, 200, 500, and 2000 µg/plate in the presence and absence of S-9 (see Table 1 below). A precipitate was observed in all strains with metabolic activation at 2000 µg/plate and in all strains without metabolic activation at 500 µg/plate and greater. A contaminant was observed throughout strain TA1535. The assay was repeated in that strain at the above doses (see Table 2 below). An independent confirmatory assay was performed at lower concentrations ranging from 160, 300, 500, 900 and 1600 µg/plate with metabolic activation and from 30, 50, 90, 160 and 300 µg/plate without metabolic activation (see Table 3 below). Precipitation of the test item was observed only in strains with metabolic activation at doses of 500 to 1600 µg/plate. A mutagenic response was not detected in the above 4 tester strains in any of the experiments conducted.

Applicant's summary and conclusion

Conclusions:

Fenbuconazole was evaluated for mutagenic activity in the Salmonella typhimurium gene mutation assay (Ames test), following the OECD 471 guideline. Under the conditions of this study, fenbuconazole is not mutagenic in the Salmonella gene mutation assay.