Bontron E-108

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 November 2000 to 15 January 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: February 28th 2000. Fate of signature: April 26th 2000

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Details on test material:

Sponsor's identification :S178207
Description : white powder
Batch number : SBT-5-0254
Label : SUBSTANCE S178207
Date received : 08 November 2000
Storage conditions :room temperature in the dark

Method

Target gene:

Histidine auxotrophs of Salmonella
Tryptophan auxotrophs of Escherichia

Species / strain

Species / strain 1

Species / strain / cell type:

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

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not applicable

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

phenobarbitone/beta­naphthoflavone induced rat liver (S9 mix)

Test concentrations with justification for top dose:

Preliminary toxicity study: 0, 0.15, 0.5, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate.

Mutation Study - Experiment 1: 50, 150, 500, 1500 and 5000 µg/plate

Mutation study - Experiment 2: 50, 150, 500, 1500 and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: acetone

- Justification for choice of solvent/vehicle: not stated in report

Controls

Controls 1

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

Remarks:

Without S9 mix

Migrated to IUCLID6: (ENNG)

Controls 2

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

Without S9 mix

Migrated to IUCLID6: (9AA)

Controls 3

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

Remarks:

Without S9 mix

Migrated to IUCLID6: (4NQO)

Controls 4

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

benzo(a)pyrene

Remarks:

With S9 mix

Migrated to IUCLID6: (BP)

Controls 5

Untreated negative controls:

yes

Remarks:

Spontaneous mutation rates

Negative solvent / vehicle controls:

yes

Remarks:

Acetone

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-Aminoanthracene (2AA)

Remarks:

With S9 mix

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)


DURATION
- Preincubation period: 10 hours
- Exposure duration: 48 - 72 hours
- Expression time (cells in growth medium): not applicable
- Selection time (if incubation with a selection agent): not applicable
- Fixation time (start of exposure up to fixation or harvest of cells): 48 - 72 hours


SELECTION AGENT (mutation assays): not applicable
SPINDLE INHIBITOR (cytogenetic assays): not applicable
STAIN (for cytogenetic assays): not applicable


NUMBER OF REPLICATIONS: triplicate plating


NUMBER OF CELLS EVALUATED: not applicable


DETERMINATION OF CYTOTOXICITY
- Method: frequency or revertant colonies


OTHER EXAMINATIONS:
- None

Evaluation criteria:

Acceptance Criteria
The reverse mutation assay may be considered valid if the following criteria are met:
All tester strain cultures exhibit a characteristic number of spontaneous revertants per plate in the vehicle and untreated controls. Historical control ranges for 1998 and 1999 are presented in Appendix 1. (See attached background material).
The appropriate characteristics for each tester strain have been confirmed, eg rfa cell-wall mutation and pkM101 plasmid R-factor etc.
All tester strain cultures should be in the approximate range of 1 to 9.9E+09 bacteria per ml.
Each mean positive control value should be at least two times the respective vehicle control value for each strain, thus demonstrating both the intrinsic sensitivity of the tester strains to mutagenic exposure and the integrity of the S9-mix.
There should be a minimum of four non-toxic test material dose levels.
There should be no evidence of excessive contamination.

Evaluation Criteria
The test material may be considered positive in this test system if the following criteria are met:
The test material should have induced a reproducible, dose-related and statistically (Dunnett's method of linear regression(5)) significant increase in the revertant count in at least one strain of bacteria.

Statistics:

Standard deviation

Results and discussion

Test results

Test results 1

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Remarks:

tested up to the maximum recommended dose level of 5000 µg per plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Remarks:

tested up to the maximum recommended dose level of 5000 µg per plate

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: not stated in report
- Effects of osmolality: not stated in report
- Evaporation from medium: not stated in report
- Water solubility: not stated in report
- Precipitation: A white oily precipitate was observed at 5000 µg/plate - this did not prevent the scoring of revertant colonies.
- Other confounding effects:


RANGE-FINDING/SCREENING STUDIES:
Preliminary Toxicity Study
The test material was non-toxic to the strains of bacteria used (TA100 and WP2uvrA-). The test material formulation and S9-mix used in this experiment were both shown to be sterile.


COMPARISON WITH HISTORICAL CONTROL DATA:
Prior to use, the master strains were checked for characteristics, viability and spontaneous reversion rate (all were found to be satisfactory). These data are not given in the report. The S9 mix used in both experiments was shown to be sterile.
Results for the negative controls (spontaneous mutation rates) were considered to be acceptable. These data are for concurrent untreated control plates performed on the same day as the Mutation Study.



ADDITIONAL INFORMATION ON CYTOTOXICITY:

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

The test material caused no visible reduction in the growth of the bacterial background lawn at any dose level. However, a small decrease in the frequency of revertant colonies was observed in most of the tester strains with and without S9-mix at 5000 µg/plate. The test material was, therefore, tested up to the maximum recommended dose level of 5000 µg/plate. A white, oily precipitate was observed at 5000 µg/plate, this did not prevent the scoring of revertant colonies.

No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test material, either with or without metabolic activation.

All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies thus confirming the activity of the S9-mix and the sensitivity of the bacterial strains.

For Tables of results, please refer to the attached Appendix 1.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

The test material was considered to be non-mutagenic under the conditions of this test.

Executive summary:

Introduction. The method was designed to meet the requirements of the OECD Guidelines for Testing of Chemicals No. 471 "Reverse Mutation Study", Method B14 of Commission Directive 92/69/EEC and the USA, EPA (TSCA) OPPTS harmonised guidelines.

Methods. Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 and Escherichia coli strain WP2uvrA^-were treated with suspensions of the test material using the Ames plate incorporation method at five dose levels, in triplicate, both with and without the addition of a rat liver homogenate metabolising system (10% liver S9 in standard co-factors). The dose range was determined in a preliminary toxicity assay and was 50 to 5000 µg/plate in the first experiment. The experiment was repeated on a separate day using the same dose range as Experiment 1, fresh cultures of the bacterial strains and fresh test material formulations.

Results. The vehicle (acetone) control plates gave counts of revertant colonies within the normal range. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with and without metabolic activation. Thus, the sensitivity of the assay and the efficacy of the S9-mix were validated.

The test material caused no visible reduction in the growth of the bacterial background lawn at any dose level. However, a small decrease in the frequency of revertant colonies was observed in most of the tester strains with and without S9-mix at 5000 µg/plate. The test material was, therefore, tested up to the maximum recommended dose level of 5000 µg/plate. A white, oily precipitate was observed at 5000 µg/plate, this did not prevent the scoring of revertant colonies.

No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test material, either with or without metabolic activation.

Conclusion.The test material was considered to be non-mutagenic under the conditions of this test.