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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: according to Ames et al. (1975), Mutation Res 31, 347-364 4 bacterial strains used

Data source

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

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Principles of method if other than guideline:
according Ames et al. Mut Res 31, 347-364 (1975), thymol was investigated in the Salmonella/microsome test in doses up to 5000 µg per plate on four Salmonella typhimurium LT2 mutants
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Thymol (purity: 99,73 %)

Method

Species / strain
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain characteristics:
other: partly deficient in lipopolysaccharide side chains in their cell walls
Metabolic activation:
with and without
Metabolic activation system:
S9 mix
Test concentrations with justification for top dose:
first test: 0, 8, 40, 200, 1000, 5000 µg per plate
repeat test 1: 0, 6, 12, 24, 48, 96, 192 µg per plate
Vehicle:
the solvent used for thymol was ethanol, and for the positive controls DMSO
Controls
Negative controls:
yes
Solvent controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
other: sodium azide (only TA 1535), nitrofurantoin (only TA 100), 4-nitro-1,2-phenylene diamine (TA 1537 + TA 98), 2-aminoanthracene
Details on test system and conditions:
Ames test
Evaluation criteria:
A reproducible and dose-related increase in mutant count of at least one strain is considered to be a positive result. For TA 1535, TA 100 and TA 98 this increase should be about twice the amount of the negative controls, whereas for TA 1537 at least a threefold increase should be reached. Otherwise the result is evaluated as negative.
Statistics:
no data

Results and discussion

Test results
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
other: 200 µg per plate
Vehicle controls valid:
yes
Negative controls valid:
yes
Positive controls valid:
yes
Remarks on result:
other:
Remarks:
Migrated from field 'Test system'.
Additional information on results:
no further data

Any other information on results incl. tables

None of the four strains used showed a dose-related and biologically  
relevant increase in mutant counts over those of the negative controls.  
This applied both to the tests with and without S-9 mix and was confirmed  
by the results of the repeat tests.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative
Executive summary:

method: according Ames et al. Mut Res 31, 347-364 (1975), thymol was investigated in the Salmonella/microsome test in doses up to 5000 µg per plate on four Salmonella typhimurium LT2 mutants

result: negative, no evidence of mutagenic activity of thymol was seen (with and without mutagenic activation)

reference: Herbold/Bayer AG, 1989