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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:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: reasonably well described publication with minor shortcomings: only 3 strains were used, only pre-incubation method used
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Version / remarks:
adopted 1997-07-21
Deviations:
yes
Remarks:
only 3 strains used
GLP compliance:
not specified
Remarks:
GLP status not specified in the publication.
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified
Details on test material:
- Name of test material (as cited in study report): Cobalt

Method

Target gene:
not applicable
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 100
Species / strain / cell type:
S. typhimurium TA 98
Species / strain / cell type:
E. coli WP2 uvr A pKM 101
Metabolic activation:
with and without
Metabolic activation system:
S9 mix (10%): from male Sprague Dawley rat liver
Test concentrations with justification for top dose:
Strain TA100: 0, 100, 500, 1000, 2500, 5000 and 7500 µg/plateStrain TA98: 0, 100, 500, 1000, 1500, 2500, 3500, 5000 and 7500 µg/plateStrain E. coli pKM101: 0, 5, 25, 50, 75, 100, 150, 200, 300, and 450 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: water
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
sodium azide
methylmethanesulfonate
other: 4-nitro-o-phenylenediamine
Remarks:
Positive control without metabolic activation: 2-nitrofluorene or 4-nitro-o-phenylenediamine (strain TA98), sodium azide (strain TA100) and methyl methanesulfonate (strain E. coli WP2 uvrA pKM101)
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene (or occasionally, sterigmatocystin)
Remarks:
Positive control with metabolic activation: all strains
Details on test system and experimental conditions:
METHOD OF APPLICATION: preincubationA test tube containing a suspension of one strain of Salmonella typhimurium (or E. coli) plus S9 mix or plain buffer without S9, is incubated for 20 minutes at 37º C with the test chemical. Control cultures, with all the same ingredients except the test chemical, are also incubated. In addition, positive control cultures are prepared; these contain the particular bacterial tester strain under investigation, the various culture ingredients, and a known potent mutagen. After 20 minutes, agar is added to the cultures and the contents of the tubes are thoroughly mixed and poured onto the surface of Petri dishes containing standard bacterial culture medium. The plates are incubated, and bacterial colonies that do not require an excess of supplementalhistidine appear and grow. These colonies are comprised of bacteria that have undergone reverse mutation to restore function of the histidine-manufacturing gene. The number of colonies is usually counted after 2 days.
Evaluation criteria:
Spontaneous mutations (those that occur by chance, not by chemical treatment) will appear as colonies on the control petri dishes. If the test chemical was mutagenic to any particular strain of bacterium, the number of histidine-independent colonies arising on those plates will be significantly greater than the corresponding control plates for that strain of bacteria. The positive control plates are also counted, and the number of mutant colonies appearing on them must be significantly increased over the spontaneous control number for the test to be considered valid. Failure of the positive control chemical to induce mutation is reason to discard the experiment.
Statistics:
no data

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 98
Metabolic activation:
without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
E. coli WP2 uvr A pKM 101
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Remarks on result:
other: strain/cell type:
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):ambiguous without metabolic activationCobalt showed and increased revertant reate in S. typhimurium strain TA98 in the absence of S9 metabolic activation, but not in the presence of S9 metabolic activation. The responses observed were weak and not well correlated with dose level, hence are of questionable biological relevance. No mutagenicity was detected in strain TA100 or E. coli pKM101, with or without S9.