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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Restriction: No strain included that could detect certain oxidising or cross-linking agents (e.g. TA 102); no information on positive control substances
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1984

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
The method of Ames, McCann & Yamasaki (1975) was followed.
Deviations:
yes
Remarks:
Deviation from OECD TG 471: No strain included that could detect certain oxidising or cross-linking agents (e.g. TA 102)
GLP compliance:
no
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Target gene:
his operon
Species / strainopen allclose all
Species / strain / cell type:
other: TA92
Details on mammalian cell type (if applicable):
The test strain was originally provided by Dr B. N. Ames, University of California, Berkeley, USA.
Species / strain / cell type:
other: TA94
Details on mammalian cell type (if applicable):
The test strain was originally provided by Dr B. N. Ames, University of California, Berkeley, USA.
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Details on mammalian cell type (if applicable):
The test strains were originally provided by Dr B. N. Ames, University of California, Berkeley, USA.
Metabolic activation:
with and without
Metabolic activation system:
liver microsome fraction (S-9) prepared from the liver of Fischer rats (Charles River Japan Co.)
Test concentrations with justification for top dose:
Six concentrations were tested (max. 5.0 mg/plate) to determine the maximum dose.
Vehicle / solvent:
dimethylsulphoxide (DMSO)
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubation with the test sample and with or without the S-9 mix

DURATION Preincubation: 20 min at 37°C

NUMBER OF REPLICATIONS: 2 for each concentration

OTHER: If no reasonable dose response was detected, additional experiments using different doses or induced mutation frequency assays were performed.
Evaluation criteria:
The number of revertant (his+) colonies was scored after incubation at 37°C for 2 days.
The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated).

Results and discussion

Test resultsopen allclose all
Species / strain:
other: TA94
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Species / strain:
other: TA92
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
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:
no cytotoxicity
Vehicle controls validity:
valid
Additional information on results:
The maximum dose was 5.0 mg/plate, which represents the highest non-cytotoxic dose used in the experiment.

Applicant's summary and conclusion

Conclusions:
The test item was found not to be genotoxic in an Ames test using the S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98.
Executive summary:

In the current study no OECD guideline was followed and the study was not according to GLP, however, the method of Ames, McCann & Yamasaki (1975) was followed which is similar to the OECD Guideline 471.

The assay included the S. typhimurium strains TA92, TA1535, TA100, TA1537, TA94 and TA98 and the genotoxicity of the test item was investigated with and without metabolic activation, which was the liver microsome fraction (S-9) from Fischer rats.

The test item was found to be negative for all S. typhimurium strains, which indicates that no significant increase in the number of revertant colonies were detected at a maximum dose of 5.0 mg/plate, at which no cytotoxic effects were observed.