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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10 May 2006 to 31 July 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
not specified
Qualifier:
according to guideline
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Qualifier:
according to guideline
Guideline:
other: Japanese Guideline: Kanpoan No. 287 - Environment Protection Agency
Qualifier:
according to guideline
Guideline:
other: Japanese Guideline: Eisei No. 127 - Ministry of Health & Welfare
Qualifier:
according to guideline
Guideline:
other: Japanese Guideline: Heisei 09/10/31 Kikyoku No. 2 - Ministry of International Trade & Industry
GLP compliance:
yes (incl. QA statement)
Remarks:
RCC Cytotest Cell Research GmbH, In den Leppsteinwiesen 19, 64380 Roβdorf
Type of assay:
bacterial reverse mutation assay

Test material

Constituent 1
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): FAT 40826/A
- Purity: Approx. 78%
- Lot/batch No.: TZ 5604 BOP 01/06
- Expiration date: 1 february 2011
- Storage conditions: At room temperature in the desiccator.
- Stability in solvent: 7 days in water, saline, PEG, and CMC
Specific details on test material used for the study:
Identity: FAT 40826/A
Batch: TZ 5604 BOP 01/06
Purity: Content of organic part (Na-salt): approx. 78 %; Oligomers: 13 %; Main component: approx. 48 %
Appearance: Solid, orange powder
Stability in solvent: Stable for 7 days in water, saline, polyethylene glycol, and CMC at room temperature
Expiration date: February 01, 2011
Storage: At room temperature at about 20 °C in a desiccator.

Method

Target gene:
histidine and tryptophan
Species / strainopen allclose all
Species / strain / cell type:
E. coli WP2 uvr A
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
Phenobarbital/ß-Naphthoflavone induced rat liver S9 mix
Test concentrations with justification for top dose:
Pre-Experiment/Experiment I: 3, 10, 33, 100, 333, 1000, 2500, and 5000 µg/plate
Experiment II: 33, 100, 333, 1000, 2500, and 5000 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: The solvent was chosen because of its solubility properties and its relative non-toxicity to the bacteria.
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene, 2-AA
Remarks:
Strain TA 1535, TA 1537, TA 98, TA 100, WP2 uvrA, with metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
Strain WP2 uvrA, without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
Strain TA 1535 and TA 100, without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylene-diamine, 4-NOPD
Remarks:
Strain TA 1537 and TA 98, without metabolic activation
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar

NUMBER OF REPLICATIONS: 3

STORAGE AND PRECULTURE
The strain cultures were stored as stock cultures in ampoules with nutrient broth + 5 % DMSO (MERCK, D-64293 Darmstadt) in liquid nitrogen. From the thawed ampoules of the strains 0.5 mL suspension was transferred into 250 mL Erlenmeyer flasks containing 20 mL nutrient medium. A solution of 20 µL ampicillin (25 µg/mL) was added to the strains TA 98 and TA 100. The bacterial cultures were incubated in a shaking water bath for 4 hours at 37 °C.

DETERMINATION OF CYTOTOXICITY
To evaluate the toxicity of the test item a pre-experiment was performed with strains TA 1535, TA 1537, TA 98, TA 100, and WP2 uvrA. Eight concentrations were tested for toxicity and mutation induction with three plates each. The experimental conditions in this pre-experiment were the same as for the experiment I (plate incorporation test). Toxicity of the test item results in a reduction in the number of spontaneous revertants or a clearing of the bacterial background lawn. The pre-experiment is reported as main experiment I, if the following criteria are met: Evaluable plates (>0 colonies) at five concentrations or more in all strains used.

DOSE SELECTION
In the pre-experiment the concentration range of the test item was 3 - 5000 µg/plate. The pre-experiment is reported as experiment I since no relevant toxic effects were observed and 5000 µg/plate were chosen as maximal concentration.

EXPERIMENTAL PERFORMANCE
In the pre-incubation assay 100 µL test solution, 500 µL S9 mix / S9 mix substitution buffer, 100 µL bacterial suspension were mixed in a test tube and shaken at 37 °C for 60 minutes. After pre-incubation 2.0 mL overlay agar (45 °C) was added to each tube. The mixture was poured on selective agar plates. After solidification the plates were incubated upside down for at least 48 hours at 37 °C in the dark. The colonies were counted using the Petri Viewer Mk2 (Perceptive Instruments Ltd, Suffolk CB 7BN, UK) with the software program Ames Study Manager.
Evaluation criteria:
ACCEPTABILITY OF THE ASSAY:
The Salmonella typhimurium and Escherichia coli reverse mutation assay is considered acceptable if it meets the following criteria: regular background growth in the negative and solvent control, the spontaneous reversion rates in the negative and solvent control are in the range of our historical data, the positive control substances should produce a significant increase in mutant colony frequencies.

EVALUATION OF RESULTS
A test item is considered as a mutagen if a biologically relevant increase in the number of revertants exceeding the threshold of twice (strains TA 98, TA 100, and WP2 uvrA) or thrice (strains TA 1535 and TA 1537) the colony count of the corresponding solvent control is observed. A dose dependent increase is considered biologically relevant if the threshold is exceeded at more than one concentration. An increase exceeding the threshold at only one concentration is judged as biologically relevant if reproduced in an independent second experiment. A dose dependent increase in the number of revertant colonies below the threshold is regarded as an indication of a mutagenic potential if reproduced in an independent second experiment. However, whenever the colony counts remain within the historical range of negative and solvent controls such an increase is not considered biologically relevant.
Statistics:
No statistical evaluation of the data is required.

Results and discussion

Test resultsopen allclose all
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: all strains/cell types tested

Applicant's summary and conclusion

Conclusions:
FAT 40826/A is considered to be mutagenic in the Salmonella typhimurium and Escherichia coli reverse mutation assay.
Executive summary:

In a GLP-compliant reverse mutation assay, performed according to OECD guideline 471, 4 Salmonella typhimurium strains (TA 1535, TA 1537, TA 98, and TA 100) and 1 Escherichia coli strain WP2 uvrA, were used to the test the mutagenic potential of the test substance (33, 100, 333, 1000, 2500, 5000 µg per plate), both with and without metabolic activation. The plates incubated with the test item showed normal background growth up to 5000 µg/plate with and without metabolic activation in both independent experiments. No toxic effects occurred in the test groups with and without metabolic activation. A moderate but dose dependent increase in revertant colony numbers was observed following treatment with the test substance in strains TA 98 (without metabolic activation) and TA 100 with and without metabolic activation in both experiments. In experiment I, the required threshold of two times the number of the corresponding solvent control could not be reached. However, the number of colonies was above the laboratory's historical control range in strains TA 98 and TA 100 from 1000 up to 5000 µg/plate without metabolic activation and in strain TA 100 at 2500 and 5000 µg/plate with metabolic activation. Based on these equivocal results, the more sensitive pre-incubation design was chosen for experiment II. Again, a moderate but dose dependent increase in revertant colony numbers was observed in strain TA 98 without S9 mix and in strain TA 100 with S9 mix. The threshold was exceeded in strain TA 98 at 5000 µg/plate without S9 mix (factor 2.3). In strain TA 100, the required threshold was not quite reached but a dose dependent response was observed in the presence of metabolic activation. Therefore, a possible mutagenic potential of the test item cannot be excluded. In conclusion, FAT 40826/A induced gene mutations by base pair changes or frameshifts in the genome of the strains TA 98 and TA 100.

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