Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
1997
Deviations:
no
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
Multi-constituent substance.
degree of purity: >=94%
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch 624730
- Expiration date of the lot/batch: 2017-12
- Purity test date: 05 May, 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: Dosed neat

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Dosed neat

Method

Target gene:
Histidine operon and tryptophan operon.
Species / strain
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:
Aroclor 1254-induced rat liver S9
Test concentrations with justification for top dose:
1.5, 5, 15, 50, 150, 500, 1500 ug/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Test article solubility and test system compatibility.
Controls
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
methylmethanesulfonate
other: 2-aminoanthracene
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation)
- Cell density at seeding (if applicable): 0.3 x 10^9 cells per mL

DURATION
- Preincubation period: 12 hours
- Exposure duration: 48-72 hours
- Expression time (cells in growth medium): 60-84 hours
- Selection time (if incubation with a selection agent): 48-72 hours

SELECTION AGENT (mutation assays): Histidine and tryptophan-minimal agar.

NUMBER OF CELLS EVALUATED: All colonies were counted with a Sorcerer Colony Counter or by hand if automated counting was not possible.

DETERMINATION OF CYTOTOXICITY
- Method: Background lawn condition.
Rationale for test conditions:
According to OECD 471.
Evaluation criteria:
For the test article to be evaluated positive, it must cause a dose-related increase in the mean revertants per plate of at least one tester strain over a minimum of two increasing concentrations of test article as specified below:
Strains TA1535 and TA1537:
Data sets were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 3.0-times the mean vehicle control value and above the corresponding acceptable vehicle control range.
Strains TA98, TA100 and WP2 uvrA:
Data sets were judged positive if the increase in mean revertants at the peak of the dose response was equal to or greater than 2.0-times the mean vehicle control value and above the corresponding acceptable vehicle control range.
An equivocal response is a biologically relevant increase in a revertant count that partially meets the criteria for evaluation as positive. This could be a dose-responsive increase that does not achieve the respective threshold cited above or a non-dose responsive increase that is equal to or greater than the respective threshold cited. A response was evaluated as negative if it was neither positive nor equivocal.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
1500 ug/plate with and without S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
500 ug/plate and greater without S9, 1500 ug/plate with S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
500 and greater without S9, 1500 ug/plate with S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
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
Remarks:
1500 ug/plate with and without S9
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Based on the results of the study, MTDID 47403 was negative in the Ames mutagenicity assay with and without metabolic activation (S9 mix).
Executive summary:

The mutagenic potential of MTDID 47403 was evaluated in the Bacterial Reverse Mutation Assay with Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 and E. coli strain WP2 uvrA in the presence and absence of metabolic activation (S9-mix). The test method was based on OECD 471 and Ames et al. (1973) and was performed in compliance with GLP. The test article was dissolved in DMSO. A dose range-finding test was performed with concentration up to 5000 μg/mL in the absence and presence of metabolic activation. Based on the results of the dose range finding test, the test article was dosed at concentrations of 1.5, 5, 15, 50, 150, 500, 1500 ug/plate. Each culture was run in triplicate. The following procedure was carried out for each strain. One-half (0.5) milliliter of S9 or Sham mix, 100 μL of tester strain (cells seeded) and 50.0 μL of vehicle or test article dilution were added to 2.0 mL of molten selective top agar at 45°C. When plating the positive controls, the test article aliquot was replaced by a 50.0 μL aliquot of appropriate positive control. After vortexing, the mixture was overlaid onto the surface of 25 mL of minimal bottom agar. After the overlay had solidified, the plates were inverted and incubated for 48-72 hours at 37°C. Plates that were not counted immediately following the incubation period were stored at 2-8°C until colony counting could be conducted. The condition of the bacterial background lawn was evaluated for evidence of test article toxicity by using a dissecting microscope. Precipitate was evaluated after the incubation period by visual examination without magnification. Toxicity and degree of precipitation were scored relative to the vehicle control plate using codes ranging from normal (1 or no code) to absent (6; complete lack of any microcolony lawn over greater than or equal to 90% of the plate). As appropriate, colonies were enumerated either by hand or by machine. No substantial increases in the revertant colony numbers of any of the tester strains were observed following treatment with the test article at any dose level with and without metabolic activation. Vehicle and positive controls responded as expected. Based on the results of the study, MTDID 47403 was negative in the Ames mutagenicity assay with and without metabolic activation (S9 mix).