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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2001
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2001
Report Date:
2001

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Qualifier:
according to
Guideline:
EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
Qualifier:
according to
Guideline:
EPA OPPTS 870.5375 - In vitro Mammalian Chromosome Aberration Test
GLP compliance:
yes (incl. certificate)
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
Chinese hamster lung fibroblasts (V79)
Details on mammalian cell type (if applicable):
- Type and identity of media:
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
Metabolic activation:
with and without
Metabolic activation system:
S9 Mix
Test concentrations with justification for top dose:
See below (Table 1)
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controlsopen allclose all
Untreated negative controls:
yes
Remarks:
Culture medium
Negative solvent / vehicle controls:
yes
Remarks:
DMSO
True negative controls:
no
Positive controls:
yes
Positive control substance:
ethylmethanesulphonate
Remarks:
Migrated to IUCLID6: in the group without S9 mix
Positive controls:
yes
Positive control substance:
cyclophosphamide
Remarks:
Migrated to IUCLID6: in the group with S9 mix
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 4, 18 and 28 hours (see Table 1)
- Expression time (cells in growth medium): 4, 18 and 28 hours (see Table 1)

NUMBER OF REPLICATIONS: 2

NUMBER OF CELLS EVALUATED: 10o well spread metaphase plates per culture, only metaphases with chromosome numbers of 22+/-1 were included in the analysis

DETERMINATION OF CYTOTOXICITY
- Method: cell number and/or mitotic indices blow 50 % of the control
Evaluation criteria:
Breaks, fragments, dilations, exchanges and chromosome disintegrations were recorded as structural chromosome aberrations.

A test item is classified as non-clastogenic if:
- the number of induced structural chromosome aberrations in all evaluated dose groups is in the range of our historical control data (0.0-4.0%
aberrant cells, exclusive gaps).
and/or
- no significant increase of the number of structural chromosome aberrations is observed.

A test item is classified as clastogenic if:
- the number of induced structural chromosome aberrations is not in the range of our historical control data (0.0-4.0% aberrant cells, exclusive
gaps).
and
- either a concentration-related or a significant increase of number of structural chromosome aberrations is observed.

Statistical significance was confirmed by means of the Fisher’s exact test (p<0.05). However, both biological and statistical significance should be considered together. If the criteria mentioned above for the test item are not clearly met, the classification with regard to the historical data and the biological relevance is discussed and/or a confirmatory experiment is performed.

Statistics:
Fisher’s exact test (p<0.05)

Results and discussion

Test resultsopen allclose all
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
Chinese hamster lung fibroblasts (V79)
Metabolic activation:
with
Genotoxicity:
ambiguous
Remarks:
Increased frequency of chromosome aberration observed at the level of cytotoxicity. It can not be excluded that indirect non-genotoxic DNA damaging mechanisms were responsible for this result
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no relevant influence
- Effects of osmolality: no relevant influence
- Water solubility: above tested concentrations
- Precipitation: not observed

RANGE-FINDING/SCREENING STUDIES: performed
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Cytotoxicity was observed after treatment with 300 µg/mL and above in the absence of S9 mix and with 600 µg/mL and above in the presence with S9 mix.

In the absence of S9 mix no increased aberration frequencies s were observed.

In the presence of S9 mix at interval 18 h, in experiment IA and IB, statistical significant and biological relevant increase in the cells carrying structural chromosomal aberrations were observed after treatment with the test item. In experiment IA cultures after treatment with 150, 300, 350 and 425 µg/mL revealed a dose related increase (1.0, 2.0, 3.0 and 9.0 % aberrant cells excluding gaps) whereas after treatment with 500 µg/mL the aberration frequency was at the border of the historical control data (0.0 to 4.0 % aberrant cells excluding gaps). Therefore a confirmatory experiment was performed revealing dose related increased aberration frequencies with 275, 350 and 425 µg/mL (2.5, 11.5 and 19.5 % aberrant cells excluding gaps).

It has to be mentioned that increased aberration frequencies were observed only in the presence of strong test item induced toxicity at the early preparation interval (18 hrs). At the late preparation interval (28 hrs), no increased aberration frequencies were observed, indicating that the damaged cells did not survive. Therefore, it can not be excluded that indirect non-genotoxic DNA damaging mechanisms were responsible for this result.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative without metabolic activation
ambiguous with metabolic activation Increased frequency of chromosome aberration observed at the level of cytotoxicity. It can not be excluded that indirect non-genotoxic DNA damaging mechanisms were responsible for this result.
Executive summary:

The in vitro chromosome aberration with CTFEP (purity 91.4%) in Chinese Hamster V79 cells was determined in a GLP compliant test according to OECD 473, EU Method B.10 and OPPTS 870.5375. Since the study from Czich (2001) was performed under GLP and according the guideline and based on the good documentation the study was awarded with Klimisch 1. Cytotoxicity was observed after treatment with 300 µg/mL and above in the absence of S9 mix and with 600 µg/mL and above in the presence with S9 mix. In the absence of S9 mix no increased aberration frequencies s were observed. In the presence of S9 mix at interval 18 h, in experiment IA and IB, statistical significant and biological relevant increase in the cells carrying structural chromosomal aberrations were observed after treatment with the test item. In experiment IA cultures after treatment with 150, 300, 350 and 425 µg/mL revealed a dose related increase (1.0, 2.0, 3.0 and 9.0 % aberrant cells excluding gaps) whereas after treatment with 500 µg/mL the aberration frequency was at the border of the historical control data (0.0 to 4.0 % aberrant cells excluding gaps). Therefore a confirmatory experiment was performed revealing dose related increased aberration frequencies with 275, 350 and 425 µg/mL (2.5, 11.5 and 19.5 % aberrant cells excluding gaps). It has to be mentioned that increased aberration frequencies were observed only in the presence of strong test item induced toxicity at the early preparation interval (18 hrs). At the late preparation interval (28 hrs), no increased aberration frequencies were observed, indicating that the damaged cells did not survive. Therefore, it can not be excluded that indirect non-genotoxic DNA damaging mechanisms were responsible for this result.