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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:
1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline conform study according to GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid

Method

Target gene:
histidine and tryptophan reversion
Species / strain
Species / strain / cell type:
other: TA 100, TA 1535, TA 1537, TA 1538, TA 98, WP2uvrA
Metabolic activation:
with and without
Metabolic activation system:
S 9 from rat liver
Test concentrations with justification for top dose:
0; 4; 20; 100; 500; 2500; 5000 µg/plate / first experiment with and without metaboloc activation0; 0.16; 0.8; 4; 20; 100; 500 µg/plate / second experiment with and without metabolic activation
Vehicle / solvent:
Deionised water
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
not specified
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
2-nitrofluorene
sodium azide
other: N-Methyl-N'-nitro-N~nitrosoguanidine (MNNG):
Remarks:
without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
not specified
True negative controls:
no
Positive controls:
yes
Positive control substance:
benzo(a)pyrene
other: 2-aminoanthracene
Remarks:
with metabolic activation
Evaluation criteria:
In the Ames test with Salmonella typhimurium strains the effect of the test compound upon the number of back mutations to histidine prototrophy using histidine auxotrophic mutants is investigated. Using Escherichia coli WP2uvrA, a tryptophan dependent auxotroph strain, mutagenicity is based on -reversion to tryptophan independence. The strains TA 100 and TA 1535 were originally derived by a substitution mutation, the strains TA 1537, TA 1538 and TA 98 by frame shift mutations from histidine prototrophic bacteria. All five Salmonella strains are deficient in the complete structure of their lipopolysaccharide layer and in DNA excision repair system. TA 98 and TA 100 possess a modified postreplication DNA repair system which frequently causes an increase in the rate of mutations. Strain WP2uvrA carries a defect in one of the genes for tryptophan biosynthesis and is deficient in the uvrA system of DNA repair. The reversion can beinduced by a base change (substitution) .

Results and discussion

Test results
Species / strain:
other: TA 100, TA 1535, TA 1537, TA 1538, TA 98, WP2uvrA
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
valid
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 with and without metabolic activationThe diluted test item (concentration 78 %; details see confidential details on test material) was tested for mutagenicity with Salmonella typhimurium strains TA 100, TA 1535, TA 1537, TA 1538, TA 98 and E. coli WP2uvrA in the absence and presence of a metabolic activation system.The diluted test item did not cause a significant increase in the number of revertant colonies with any of the tester strains neither in the absence nor presenceof 5-9 Mix. No dose dependent effect was obtained. It is concluded that the test substance is toxic but not mutagenic in these bacteria1 test systems neither in the absence nor in the presence of an exogenous metabolizing system.
Executive summary:

The diluted test item (concentration 78 %; details see confidential details on test material) was tested for mutagenicity with the strains TA 100, TA 1535, TA 1537, TA 1538, TA 98 of Salmonella typhimurium and Escherichia coli WP2uvrA.

The mutagenicity studies were conducted in the absence and in the presence of a metabolizing system derived from rat liver homogenate. A dose range of 6 different doses from 4-10 000 (1. experiment) and 0.16 µg/plate to 500 µg/plate

(2. experiment) was used. Control plates without mutagen showed that the number. of spontaneous revertant colonies was similar to that described in the literature. All the positiv control compounds gave the expected increase in the number of revertant colonies.

Toxicity: The test compound proved to be very toxic to most of the bacterial strains at 20 or 100 µg/plate. For this reason 500 µg/plate was chosen as top dose level for the mutagenicity study in the repeat experiment.

Mutagenicity: In the absence of the metabolic activation system -the test compound did not show a dose dependent increase in the number of revertants in any of the bacterial strains. Also in the presence of a metabolic activation system, treatment of the cells with the diluted did not result in relevant increases in the number of revertant colonies.

Summarizing, it can be stated that the diluted test item is toxic but not mutagenic in these bacterial test systems neither with nor without exogenous metabolic activation at the dose levels investigated.