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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2002-11-27 to 2002-12-12
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: according GLP and OECD guideline, well documented, read across substance

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Version / remarks:
adopted 21st July 1997
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
Version / remarks:
adopted on 08-Jun-2000
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Species / strain
Species / strain / cell type:
lymphocytes: cultured human
Metabolic activation:
with and without
Metabolic activation system:
post-mitochondrial fraction from Aroclor 1254 induced rat liver (S9 mix)
Test concentrations with justification for top dose:
- 4.89, 9.77, 19.53, 39.06, 78.13, 156.3, 312.5 and 625 µg/mL, for the first experiment with and without S9 mix,
- 9.77, 19.53, 39.06, 78.13, 156.3 and 312.5 µg/mL, for the second experiment with and without S9 mix.

Vehicle / solvent:
- Vehicle used: DMSO
Controls
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Remarks:
without S9 mix: mitomycin C (MMC) with S9 mix: cyclophosphamide (CPA)
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: 48 hours
1. Experiment
- Exposure duration: 3 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 20 hours from the beginning of treatment, corresponding to approximately 1.5 normal cell cycles.

2. Experiment
- Exposure duration: continuously (without S9 mix), 3 hours (with S9 mix)
- Fixation time (start of exposure up to fixation or harvest of cells): 20 hours and 44 hours from the beginning oftreatment, corresponding to approximately 1.5 normal cell cycles and 24 hours later.

NUMBER OF REPLICATIONS: duplicate

NUMBER OF CELLS EVALUATED: 1000 cells examined

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index (number of cells in mitosis/1000 cells examined)

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes
- Other: multiple aberrations and pulverizations

Evaluation criteria:
A reproducible and statistically significant increase in the frequency of cells with structural chromosome aberrations for at least one of the dose-level and one of the two harvest times was considered as a positive result. Reference to historical data or other considerations of biological relevance, was also taken into account in the evaluation of the findings.
Statistics:
For each test and for each harvest time, the frequency of cells with structural chromosome aberrations (excluding gaps) in treated cultures was compared to that of the vehicle control cultures. If necessary, the comparison was performed using the y² test, in which p = 0.05 was used as the lowest level of significance.

Results and discussion

Test results
Species / strain:
lymphocytes: cultured human
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
Without S9 mix at dose-levels >= 19.53 µg/mL and with S9 mix at 625 µg/mL at the 20-hour harvest time and at 44-hour harvest time at all dose -levels tested (by all slight to moderate effect).
Vehicle controls validity:
valid
Untreated negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no influence
- Effects of osmolality: no influence

COMPARISON WITH HISTORICAL CONTROL DATA: Results consistent with historical data.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
Experiments without S9 mix:
A slight to moderate decrease in the mitotic index was noted mainly at dose-levels > 19.53 µg/mL: up to 61% following the 3 and 20-hour treatments and up to 40% following the 44-hour treatment.
Experiments with S9 mix:
A slight to marked decrease in mitotic index was noted (up to 68% decrease noted at 625 µg/mL), at the 20-hour harvest time. At the 44-hour harvest time, a moderate decrease in mitotic index was noted at all dose-levels tested.
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