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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:
05-Mar-2012 to 15-Mar-2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: Colourless to mild yellowish liquid
Details on test material:
- Name of test material (as cited in study report OS 2600
- Substance type: Colourless to mild yellowish liquid
- Physical state: Liquid
- Storage condition of test material: In refrigerator (2-8°C) protected from light under nitrogen



Method

Target gene:
- S. typhimurium: Histidine gene
- E. coli: Tryptophan gene
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Rat liver S9-mix induced by a combination of phenobarbital and ß-naphthoflavone
Test concentrations with justification for top dose:
Experiment 1
Preliminary test (without and with S9) TA100 and WP2uvrA: 3, 10, 33, 100, 333, 1000, 3330 and 5000 µg/plate
Main study: TA1535, TA1537 and TA98:
Without and with S9-mix: 100, 333, 1000, 3330 and 5000 µg/plate
Experiment 2:
Without and with S9-mix: 100, 333, 1000, 3330 and 5000 µg/plate

Of
Main study: TA1535, TA1537 and TA98:
Without S9-mix: 1, 3, 10, 33, 66 and 100 µg/plate
With S9-mix: 1, 3, 10, 33, 100 and 200 µg/plate.
Experiment 2:
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle:
Test compound was soluble in DMSO and DMSO has been accepted and approved by authorities and international guidelines
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
methylmethanesulfonate
Remarks:
without S9: 650 µg/plate in DMSO for TA100
Positive control substance:
2-nitrofluorene
Remarks:
without S9, 10 µg/plate in DMSO for TA98 and 15 µg/plate for TA1537
Positive control substance:
4-nitroquinoline-N-oxide
Remarks:
without S9: 10 µg/plate in DMSO for WP2uvrA
Positive control substance:
sodium azide
Remarks:
without S9 : 5 µg/plate in saline for TA1535
Positive control substance:
other: 2-aminoanthracene in DMSO for all tester strains
Remarks:
with S9
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hour

NUMBER OF REPLICATIONS:
- Doses of the test substance were tested in triplicate in each strain. Two independent experiments were conducted.

NUMBER OF CELLS EVALUATED: 10E8 per plate

DETERMINATION OF CYTOTOXICITY
- Method: The reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies.

OTHER EXAMINATIONS:
- The presence of precipitation of the test compound on the plates was determined.
Evaluation criteria:
A test substance is considered negative (not mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 is not greater than two (2) times the concurrent control, and the total number of revertants in tester strains TA1535, TA1537, TA98 or WP2uvrA is not greater than three (3) times the concurrent control.
b) The negative response should be reproducible in at least one independently repeated experiment.

A test substance is considered positive if:
a) A two-fold (TA100) or more or a three-fold (TA1535, TA1537, TA98, WP2uvrA) or more increase above solvent control in the mean number of revertant colonies is observed in the test substance group.
b) In case a repeat experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one independently repeated experiment.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium, other: TA1535, TA1537, TA98 and TA100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation was observed up to and including the top dose of 5000 µg/plate

RANGE-FINDING/SCREENING STUDIES:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

COMPARISON WITH HISTORICAL CONTROL DATA:
- The negative and strain-specific positive control values were within our laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

Applicant's summary and conclusion

Conclusions:
OS 2600 is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay
Executive summary:

OS 2600 was tested up to 5000 μg/plate in the Salmonella typhimurium reverse mutation assay in accordance with OECD Guideline 471 with four histidine-requiring strains of Salmonella typhimurium (TA1535, TA1537, TA98 and TA100) and in the Escherichia coli reverse mutation assay with a tryptophan-requiring strain of Escherichia coli (WP2uvrA). The test was performed in two independent experiments in the presence and absence of metabolic activation. OS 2600 did not induce a significant dose-related increase in the number of revertant (His+) colonies in each of the four tester strains (TA1535, TA1537, TA98 and TA100) and in the number of revertant (Trp+) colonies in tester strain WP2uvrA both in the absence and presence of S9-metabolic activation. These results were confirmed in an independently repeated experiment. In this study, the negative and strain-specific positive control values were within the laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.