Fenamiphos

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:

October to November 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

Principles of method if other than guideline:

The study was conducted in accordance with the Salmonella/microsome test as described by Ames et al. (1973a, 1975). There were no deviations from the regulatory guideline considered to compromise the scientific validity of the study. Although no E. Coli strain has been tested the study has been considered adequate to address the endpoint of point mutations also during the 1st peer review of the test substance. Although the study was conducted in 1985, it is considered to comply in general with the OECD Guideline of 1997; any deviations from that guideline are considered not to have had a siginificant impact on the overall conclusion of the study.

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Fenamiphos

EC Number:

244-848-1

EC Name:

Fenamiphos

Cas Number:

22224-92-6

Molecular formula:

C13H22NO3PS

IUPAC Name:

{ethoxy[3-methyl-4-(methylsulfanyl)phenoxy]phosphoryl}(propan-2-yl)amine

Test material form:

solid: crystalline

Method

Target gene:

His

Species / strain

Species / strain / cell type:

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

Additional strain / cell type characteristics:

other: Partly deficiency in lipopolysaccharide side chains, ampicillin resistance, crystal violet sensitivity, UV sensitivity

Metabolic activation:

with and without

Metabolic activation system:

S-9 mix was used to metabolise. It was made from the livers of at least six adult male Sprague Dawley rats, approx. 200 - 300 g in weight. For enzyme induction the animals received a single intraperitoneal injection of aroclor 1254 at a dose of 500 mg/kg body weight, dissolved in peanut oil, five days before preparation. The animals were prepared as specified by Ames et al. (1975), and the S-9 fraction stored at -80° C in 10 ml portions. These portions were thawed slowly for use. The S-9 mix was prepared fresh (Ames et al., 1973a), the S-9 fractions being taken from the preparation dated 28.8.1984 and forming 30 % of the finished S-9 mix.

Test concentrations with justification for top dose:

The dose ranges were 0, 20, 100, 500, 2500, 2500 μg/plate in the preliminary assay and 0, 125, 250, 500, 1000, 2000 μg/plate in the confirmatory assay. 2000 µg per plate was used in the confirmatory test due to the substance's toxicity.

Vehicle / solvent:

DMSO, water

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

DMSO and demineralized water for endoxan

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

methylmethanesulfonate

other: 2-aminoanthracene (2-AA), trypaflavine, endoxan

Details on test system and experimental conditions:

NUMBER OF REPLICATIONS:
- Number of cultures per concentration: Four plates per strain per dose were used for each substance
- Number of independent experiments: 2

METHOD OF TREATMENT:
- Test substance added in medium (nutrient broth)

TREATMENT AND HARVEST SCHEDULE:
- Exposure duration: 48 h


METHODS FOR MEASUREMENT OF CYTOTOXICITY
- Method: background growth inhibition


METHODS FOR MEASUREMENTS OF GENOTOXICITY: mutant count

Rationale for test conditions:

The test followed the directions of Ames et al. (1973a, 1975).

Evaluation criteria:

A reproducible dose-related increase in the mutant counts of at least one strain is considered positive, and about double the negative control count should be reached.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

E. coli WP2

Metabolic activation:

not applicable

Genotoxicity:

not determined

Cytotoxicity / choice of top concentrations:

not determined

Vehicle controls validity:

not applicable

Untreated negative controls validity:

not applicable

True negative controls validity:

not applicable

Positive controls validity:

not applicable

Test results 2

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at and above 2500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

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:

cytotoxicity

Remarks:

at 12500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 4

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at and above 2500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Test results 5

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at 2000 µg/plate and 12500 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not applicable

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

The test substance did not induce point mutations in S. typhimurium under the examined conditions.

Executive summary:

The test substance was evaluated in the Salmonella/microsome test, in doses up to 12500 µg per plate, on four Salmonella typhimurium LT2 mutants for mutagenic effect with and without S-9. The strains concerned were the histidine auxotrophs TA 1535, TA 100, TA 1537 and TA 98. Endoxan, trypaflavine, MMS, 4-NQO and 2-amino-anthracene were used as positive controls. The dose ranges were 0, 20, 100, 500, 2500, 2500 μg/plate in the preliminary assay and 0, 125, 250, 500, 1000, 2000 μg/plate in the confirmatory assay, both using DMSO as solvent. Test item concentrations up to 12500 µg/plate did not produce an increase in the mutant count with and without S-9 mix. Bacteriotoxic effects after 500 µg/plate was observed, both with and without S-9 mix. The positive controls demonstrated a clear mutagenic effect in comparison to the negative controls. The test substance was non-mutagenic in the reverse mutation assay with and without metabolic activation.