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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in mammalian cells
Remarks:
Type of genotoxicity: gene mutation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted according to OECD Guideline under GLP conditions.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)
GLP compliance:
yes
Type of assay:
mammalian cell gene mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Method

Target gene:
thymidine kinase, TK +/-, locus of the L5178Y mouse lymphoma cell line
Species / strain
Species / strain / cell type:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Metabolic activation system:
S9 mix
Test concentrations with justification for top dose:
Experiment 1: 0, 5, 10, 20, 40, 60 ug/ml (4hr exposure without S9 activation)
Experiment 1: 0, 10, 20, 40, 80, 160 ug/ml (4hr exposure with S9 activation)
Experiment 2: 0, 2.5, 5, 10, 20, 30, 40 ug/ml (24 hr exposure without S9 activation)
Experiment 2: 0, 20, 40, 80, 160, ug/ml (24 hr exposure with S9 activation)
Vehicle / solvent:
DMSO
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Remarks:
Migrated to IUCLID6: at 400 and 150 ug/ml for Experiment 1 and 2, respectively (without activation)
Positive controls:
yes
Positive control substance:
cyclophosphamide
Remarks:
Migrated to IUCLID6: at 2 and 1 ug/ml in Experiments 1 and 2, respectively (with activation)
Evaluation criteria:
The normal range for mutant frequency per survivor is 50 -200 x 10(-)6 for the TK +/- locus in L5178Y cells at this laboratory. Vehicle controls must be within ranges, although minor errors in cell counting and dilution or exposure to the metabolic activation system may cause this to be slightly elevated. Experiments where the vehicle control values are markedly greater than 200 x 10(-)6 mutant frequency per survivor are not normally acceptable and will be repeated. Positive controls should give significant increases in mutant frequency per survivor over the negative controls or at least a three to five fold but preferably 10 fold difference.

For the test material be considered to give a significant result, two or more of the following criteria must be met: A greater than three fold increase in the mutant frequency per survivor over the negative control value; a dose-related increase in the mutant frequency per survivor; an increase in the absolute number of mutants. The test result may be reported as equivocal if only one of the above criteria are met. Small statistical increases designated by the UKEMS statistical package will be reviewed using the above criteria and may be disregarded at the Study Director's discretion.
Statistics:
Calculation of the % Relative Suspension Growth (RSG) was performed along with Calculation of the Plating Efficiency (P.E.). The Calculation of Mutant Frequency was determined. The experimental data were analysed using a dedicated computer program which follows the statistical guidelines recommended by UKEMS.

Results and discussion

Test results
Species / strain:
mouse lymphoma L5178Y cells
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
Experiment 1: There was evidence of toxicity following exposure to the test material in both the presence and absence of metabolic activation, as indicated by the decrease in % RSG and RTG values. Optimum levels of toxicity were not achieved in the absence or presence of metabolic activation due to the steep toxicity of the test material. The toxicity observed at 60 ug/ml in the absence of metabolic activation exceeded the upper acceptable limit of 90%, therefore., this dose was excluded from the statistical analysis. The excessive toxicity observed at 80 ug/ml in the absence of activation and 240 ug/ml in the presence of activation resulted in these dose levels not being plated for viability or TFT resistance. Vehicle and positive controls were within normal limits. The test material did not induce any statistically significant or dose related (linear trend) increases in the mutant frequency x 10(-)6 per viable cell in either the presence or absence of metabolic activation. No precipitate of the test material was observed at any dose level.

Experiment 2: There was evidence of a dose-related reduction in %RSG and RTG values in cultures dosed with the test material in both of the exposure groups. There was no evidence of a reduction in Day 2 (%V) viability, therefore, indicating that no residual toxicity occurred in either the absence or presence of metabolic activation. The excessive toxicity observed at 200 ug/ml and above in the presence of metabolic activation resulted in these dose levels not being plated out for viability or TFT resistance. Both positive controls induced acceptable reductions in both the %RSG value and Day 2 (%V) viabilities and RTG values. Vehicle and positive controls were within normal limits. The test material did not induce any statistically significant or dose related increases in the mutant frequency in either the presence or absence of metabolic activation.
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

In an OECD 476 study Molyvan 855 did not induce any toxicologically significant increases in the mutant frequency at the TK +/- locus in L5178Y cells and is therefore considered to be non-mutagenic under the conditions of the test.