N-phenyl-N'-[(phenylamino)sulfonyl]urea

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

one study for the endpoint gene mutation in bacteria is available, this study is an OECD guideline study.

due to the available data and the intended registration (1 -10 tpa), no further information is needed.

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08. Jun. 2015 - 18 Aug. 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

Target gene:

histidine or tryptophan deficiency

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:

Rat Liver S9 fraction

Test concentrations with justification for top dose:

Examined concentrations in the Initial Mutation Test were 5000, 1581, 500, 158.1, 50, 15.81, 5 and 1.581 μg/plate.
Examined concentrations in the Confirmatory Mutation Test were 5000, 3162, 2372, 1581, 500, 158.1, 50 and 15.81 μg/plate.

Concentrations were selected on the basis of the Preliminary Compatibility Test and Preliminary Concentration Range Finding Test (Informatory Toxicity Test). In the Initial Mutation Test and Confirmatory Mutation Test, different concentrations were used.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Based on the results of a solubility test, DMSO was selected for vehicle (solvent) of the study. The formulation at 100 mg/mL concentration using this vehicle was achievable and considered to be suitable for the test.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

sodium azide

methylmethanesulfonate

other: 2-aminoanthracene, 4-nitro-1,2-phenylene-diamine

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); pre-incubation

DURATION
- Preincubation period:
- Exposure duration: 30 min

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: number of colonies in relation to negative and solvent control

EVALUATION OF EXPERIMENTAL DATA
The colony numbers on the untreated / negative (vehicle/solvent) / positive control and test item treated plates were determined by manual counting. Visual examination of the plates was also performed; precipitation or signs of growth inhibition (if any) were recorded and reported.

Rationale for test conditions:

standard conditions as described in literature and Guideline

Evaluation criteria:

Criteria for Validity:
The study was considered valid if:
- the number of revertant colonies of the negative (solvent) and positive controls were in the historical control range in all strains of the main tests;
- at least five analyzable concentrations were presented in all strains of the main tests.

Criteria for a Positive Response:
A test item was considered mutagenic if:
- a dose–related increase in the number of revertants occurred and/or;
- a reproducible biologically relevant positive response for at least one of the dose groups occurred in at least one strain with or without metabolic activation.

Criteria for a Negative Response:
The test item was considered to have shown no mutagenic activity in this study if it produces neither a dose-related increase in the number of revertants nor a reproducible biologically relevant positive response at any of the dose groups, with or without metabolic activation.

Statistics:

none

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:

valid

Positive controls validity:

valid

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:

valid

Positive controls validity:

valid

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

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

Species / strain:

E. coli WP2 uvr A

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:

Inhibitory, cytotoxic effect of the test item (reduced/slightly reduced background lawn development/pinpoint colonies) was observed in the Initial Mutation Test in all examined bacterial strains at 5000 μg/plate concentration with and without metabolic activation.

Conclusions:

The test item N-phenyl-N'[(phenylamino)sulfonyl]urea had no mutagenic activity in the examined bacterial strains under the test conditions of this study.

Executive summary:

The test item N-phenyl-N'[(phenylamino)sulfonyl]urea was tested for potential mutagenic activity using the Bacterial Reverse Mutation Assay.

The experiments were carried out using histidine-requiring auxotroph strains of Salmonella typhimurium (Salmonella typhimurium TA98, TA100, TA1535 and TA1537) and the tryptophan-requiring auxotroph strain of Escherichia coli (Escherichia coli WP2 uvrA) in the presence and absence of a post mitochondrial supernatant (S9 fraction) prepared from the livers of phenobarbital/β-naphthoflavone-induced rats.

The study included a Preliminary Compatibility Test, a Preliminary Concentration Range Finding Test (Informatory Toxicity Test), an Initial Mutation Test (Pre-Incubation Method) and a Confirmatory Mutation Test (Plate Incorporation Method).

Based on the available information and the results of a solubility test, the test item was formulated in DMSO. Concentrations of 5000, 2500, 1000, 316, 100, 31.6 and 10 μg/plate were examined in the Preliminary Concentration Range Finding Test. Based on the results of the preliminary experiment, the test item concentrations in the Initial Mutation Test were 5000, 1581, 500, 158.1, 50, 15.81, 5 and 1.581 μg/plate. Based on the results in the Initial Mutation Test, the test item concentrations in the Confirmatory Mutation Test were 5000, 3162, 2372, 1581, 500, 158.1, 50 and 15.81 μg/plate.

In the Initial Mutation Test and Confirmatory Mutation Test, none of the observed revertant colony numbers were above the respective biological threshold value. There were no dose-related trends and no indication of any treatment effect. In all test item treated groups, the numbers of revertant colonies did not exceed the biological relevance when compared to the vehicle control and were within the normal biological variability of the test system.

No precipitate was detected on the plates in the main tests in any examined bacterial strains with and without metabolic activation.

Inhibitory, cytotoxic effect of the test item (reduced/slightly reduced background lawn development/pinpoint colonies) was observed in the Initial Mutation Test in all examined bacterial strains at 5000 μg/plate concentration with and without metabolic activation.

The mean values of revertant colonies of the negative (vehicle/solvent) control plates were within the historical control range, the reference mutagens showed the expected increase in the number of revertant colonies, the viability of the bacterial cells was checked by a plating experiment in each test. At least five analyzable concentrations were presented in all strains of the main test, the examined concentration range was considered to be adequate. The study was considered to be valid. The reported data of this mutagenicity assay show (see Appendix 2 to 5) that under the experimental conditions applied the test item did not induce gene mutations by base pair changes or frameshifts in the genome of the strains used.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

no studies available, due to the available data and the intended registration (1 -10 tpa), no further information is needed.

Justification for classification or non-classification

The available information is conclusive but not sufficient for classification.