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Toxicological information

Genetic toxicity: in vitro

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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:
From 13 October to 03 November 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study run to a reliable method and to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Batch No.: 20.9.88/1
Purity: Not specified

Method

Target gene:
Histidine
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
S. typhimurium TA 1538
Metabolic activation:
with and without
Metabolic activation system:
S-9 mix
Test concentrations with justification for top dose:
Dose range finding test: 5000, 500, 50, 5 μg/plate
Mutation tests: 5000, 1500, 500, 150, 50, 15, 5, 1.5 μg/plate
Vehicle / solvent:
Dimethylsulphoxide
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: N-ethyl-N'-nitro-N-nitrosoguanidine
Remarks:
In the absence of S9 mix for strains TA 1535 and TA 100.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
In the absence of S9 mix for strain TA 1537.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
In the absence of S9 mix for strains TA 1538 and TA 98.
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
In the presence of S9 mix for all strains.
Details on test system and experimental conditions:
Ames test procedure
(a) Without metabolic activation
0.1 mL aliquots of bacterial suspension and 0.5 mL of sterile 0.1 M sodium orthophosphate buffer are added to each of one set of sterile bijou bottles.
0.1 mL of the test compound is added to cultures at five concentrations separated by half-log 10 intervals. The negative control is the chosen solvent. The appropriate positive control is also included. Three bottles are used at each dose level.
2.0 mL of histidine deficient agar is added to each of the bottles, thoroughly mixed and then overlaid onto previously prepared plates containing 25 mL of minimal agar. Plates are incubated for 72 hours at 37℃.
Colonies are counted using a Biotran Automatic Colony Counter, and the mean number of revertant colonies per treatment group assessed.
(b) With metabolic activation
0.5 mL of liver homogenate S-9 mix is added to bijou bottles in place of sterile buffer. Plates will be prepared without the addition of bacteria in order to assess the sterility of the test compound and S-9 mix.

Second mutation test
The procedure is repeated at a later data, though the concentrations of the test substance used in the second test may be altered, if the results of the first test indicate this may be expedient.
Evaluation criteria:
The mean number of revertant colonies for all treatment groups is compared with those obtained for negative and positive control groups. The effect of metabolic activation is assessed by comparing the results obtained both in the presence and absence of the liver microsomal fraction for each treatment group.
A compound is deemed to provide evidence of mutagenic potential if a statistically significant dose-related increase in the number of revertant colonies of at least twice the concurrent solvent control is obtained in two separate experiments.
Statistics:
None stated

Results and discussion

Test resultsopen allclose all
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:
not specified
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No substantial increases in revertant colony numbers of any of the five tester strains were observed following treatment with the test substance at any dose level, either in the presence or absence of metabolic activation (S-9 mix).
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

It is concluded that no evidence of mutagenic potential of the test substance was obtained in this bacterial test system at the dose levels used.